^[TilC - WUR

I . j ' ! ,;1, • ] ! I .-': 1 ' ƒ . * i ,

^[TilC

>. 'I i i\ j

, ' . ) • . ' /

of

National

Ferti l izer Use Recommendat:ion

Project (Phase X)

na 1

Annex XXX

Description of the First Priority

Sites in the Various Districts

Volume 2 8

La. mu. D i s tr i c t

Dis tr ic t No.: 28

Nairobi, June 1987

KG

ilizer ion

Project I)

Pro j

Team of Consultants1) ProfessionalStaff fromNAL2)

H. Strobel (ed.)Project Coordinator

Project CoordinationG.HingaDirector NAL

S.W.NandwaCounterpartCoordinator

R. JätzoldR. Rötter

Aaro-ClimatoloaistsJ.W. Onyango

R.F. van de WegE.M.A. Smaling

Soil Scientists / SurveyorsF.N. MuchenaC.K.K. GacheneJ.M. Kibe

P. PietrowiczSoil Chemists

J.N. QureshiP.O.S. Oduor

A.Y. AllanAgronomists

J.O. Owuor

H. MayrR. DölgerA. Muliro

R. Rötter

Data Processing

Land Surveyors

R.L MilikauD.K. Wamae

B. MwangiS. Wataka

W. BayerAnimal Production

1) German Agency for Technical Cooperation (GTZ) (German AgriculturalTeam (GAT))

2) National Agricultural Laboratories

o f "fc-ne Final Reoort

z. : Methodology and Inventory of Existing Information

: Compilation-of results from Former Fertilizer TrialsIn Kenya (2 Volumes)

- X : Inventory of Farming Systems Research in Kenya

2 : Influence of Fertilizer Application on RuminantProduction

3 : Maintaining Soil Fertility with Little or No Use ofFertilizers

Detailed Description of the First Priority Sites in theVarious Districts :

1. Kisii 17. Narok2. South Nyanza 18. Samburu3. Kisumu 19. Nyandarua4. Siaya 20. Kiambu5. Busia 21. Muranga6. Bungoma 22. Nyeri7. Kakamega 23. Kirinyaga8. Nandi 24. Embu9. Kericho 25. Meru

10. Trans Nzoia 26. Machakos11. Uasin Gishu 27. Kitui12. West Pokot 28. Lamu13. Keyo Marakwet 29. Kilifi14. Baringo 30. Taita Taveta15. Laikipia 31. Kwale16. Nakuru 32. Nairobi

Annex XV : Description of Computer Programmes Establishedin Phase I

Scanned from original by ISRIC - World Soil Information, as ICSUWorld Data Centre for Soils. The purpose is to make a safedepository for endangered documents and to make the accruedinformation available for consultation, following Fair UseGuidelines. Every effort is taken to respect Copyright of thematerials within the archives where the identification of theCopyright holder is clear and, where feasible, to contact theoriginators. For questions please contact [email protected] the item reference number concerned.

District: Lamu General Aspects 28.0

Volume 2 8

Page

Clia.p-fc.ear 2 8 . O :

General Aspects 0.1

Legend of the Soil Map of Lamu District 0.27

Chapter 28.Ir

Description of the Mpeketoni Trial Site 1.1

Please note the following numbering mode of Tables and Maps:First NumberSecond NumberThird Number

District NumberTrial Site NumberNumber of Table or Map within Chapter

- 0.1 -

District: Lama General Aspects 28.0

Contents of flfrgpfcer 28.0:

General Aspects

Page

1. Climate and Soils of the District 0.3

2. Location of the Trial Site and Criteria for its Final Position 0.13

3. Names and Addresses of Government Officers Involved in FURPActivities 0.15

4. Trial Design and Execution Plan 0.16

5. Areas in Lamu District Represented by FURP Trial Sites 0.16

List of Tables

Table 28.0.1 Climate in the Agro-Ecological Zones of Lamu District 0.6

Table 28.0.2 Agro-Ecological Zone and Soil Classification of the Trial

Sites 0.9

Table 28.0.3 Ratings of Criteria Used for Trial Site Selection 0.14

Table 28.0.4 Names and Addresses of Government Officers in the

District 0.15Table 28.0.5 Major Soil Properties and Climatic Conditions of the

Agro-Ecological Units in Lamu District 0.23

List" fff

Map 28.0.1 66% Reliability of Rainfall in First Rains 0.4

Map 28.0.2 66% Reliability of Rainfall in Second Rains 0.5

Map 28.0.3 Agro-Ecological Zones and Trial Sites of the District 0.7

Map 28.0.4 Soils and Trial Sites in Lamu District 0.11

Map 28.0.5 Groupings of Soil Mapping Units Represented by Trial

Sites in Lamu District 0.21

Map 28.0.6 Agro-Ecological Units in Lamu District 0.25

Legend of the Soil Map of Lamu District 0.27

- 0.2 -

District: Lama General Aspects 28.0

1. Climate and Soils of the District

It is difficult to define the climatic potential accurately because thereare very few long-term rainfall recording stations in this District. Theamount of rainfall in the first rains decreases from a coastal strip ofabout 10 km width to the hinterland at a rate of about 100 mm per 5 km. Thesecond rains increase from the coast for the first 10 km, and then dropagain. The Intermediate rains between both seasons (very important forrelay-planted such as simsim and cowpeas) are most frequent a fewkilometres inland from the coast. For these reasons the highest averageannual rainfall >1000 mm occurs about 5-20 km inland, interrupted by theMkunumbi Bay. From the climatic point of view, this high rainfall zoneincludes the Coconut-Cassava Zone L 3 (=CL 3).The Cashewnut-Cassava Zone L 4 (-CL 4) extends around AEZ L 3. Towards thehinterland, the rainfall in dry years is often not concentrated enough toencourage cassava to form big tubers. The rainfall distribution alsobecomes less suitable for cashewnuts. The short rains occur during theflowering period and in wet years cause poor fruit setting black spots onthe nuts. Northwards, this danger lessens but there is also a generaldecrease in rainfall in this direction. The actual boundary of L 4 is verydifficult to define, since apart from Kiunga on the coast there is no otherrainfall station in the area. Moreover, the influence of groundwater andsub-surface flow is difficult to estimate. The Map on Agro-Ecological Zones(Map 28.0.3) gives an optimistic view, the Agro-Climatic Zonation of H.M.H.BRAUN1) is more pessimistic. The real extension of the various zones is mostimportant for settlement prospects2) in this sparsely populated area.

The L 5 Agro-Ecological Zone should be used for ranching (like L 6) untiltechnology allows an economically viable cultivation of this area.

The 66% reliability of rainfall i.e. amount surpassed in 20 out of 30years, is shown in Map 28.0.1 for the first rains and in Map 28.0.2 for the"second rains".

The high temperatures at night (mean minimum >20°C at the coast) hampercrop growth and quality. Humidity of the air is relatively high.Evaporation is high and ranges between 2000 and 2300 mm per year.

A summary of climatic data is compiled in Table 28.0.1, which can be usedas a key to the Agro-Ecological Zones Map 28.0.3.

1) Zonation by H.M.H. BRAUN in: W.G. SOMBROEK et al. (1982):Exploratory Soil Map and Agro-Climatic Zone Map of Kenya, scale1:1,000,000 - Rep. El, Nairobi

2) For an example, see the pre-feasibility study of the "Seminar fürLandwirtschaftliche Entwicklung": The Hindi-Magogoni SettlementScheme in Lamu District, Berlin 1978.

- 0.3 -

40ft 30- 411E

I

O

LAMU

^7/AAs /\*/w / */>\ /*<><-/ / /

V / / /\ / / /

Nal Agr Labs. German Agr Team. R Jaetzold

Broken boundaries are uncertain

because ol lack of rainfall records

f Map 28.0.1

66% RELIABILITY OF RAINFALLIN AGROHUMID PERIOD

OF FIRST RAINS(March-Sept, or less)

Amounts in mm, surpassednorm, in 20 out of 30 years

I

Map 28.0.2

66% RELIABILITY OF RAINFALLIN AGROHUMID PERIOD

OF SECOND RAINS(end of Oct.-end of Jan. or less)

Amounts in mm, surpassednorm, in 20 out of 30 years

Broken boundaries are uncertain

because of lack of rainfall records

Nd! ACT t_aDs Germai Agr Team R Jaeuold

Table 28.0.1 : Climate in the Agro-Ecological Zones in Lamu District

Agro-EcologicalZone

L34>Coconut-Cassava Zone

L44>Cashewnut-CassavaZone

L54>LowlandLivestock-Millet Zone

L64>LowlandRanching Zone

Subzone

m i vsm i(vs)m i

m/s i (vs)m/s im/s i + is/m is/mi (vs)s/ms i (vs)s iss/vs i(vs)

(s/vs) 1 + (vs)

s/vsivs/s i(vs)(vs/s) i + (vs)vs/s(vs) + i

b r

Altitude

in m

1-80

1-100

1 7fl1 — /U

60-70

Annual meantemperature

in°C

27.0-26.5

27.0-26.4

27.0- .6

27.0-26.9

Annual av.rainfallin mm

1000-1 100980-1 100950-1 050

Very small750- 980900-1 000650- 950Very small880- 920680- 900700- 800800- 850680- 850

580- 680

500- 600620- 750550- 650

480- 520550- 580

<55O

66% reliabilityof rainfall ' )

1st rainsin mm

600-700600-700600-700

2nd rainsin mm

150-200130-18080-130

and transitional550-630550-650500-600

120-15070-12040-130

transitional strip580-620 < 5 0450-550400-530500-550350-450

200-350

280-400350-400170-250

180-280130-180

< 130

130-18050-130<50

100-180

150-180

<50150-200130-160

<50100-130

<100

66 % reliabilityof growing period

1st rainsin days

135-155135-155135-155

115-135115-135105-115

105-11585-10585-10585-1057 5 - 85

7 5 - 80

7 5 - 855 5 - 755 5 - 705 5 - 754 0 - 55

< 4 0

2nd rainsin days

40-5540-50<40

< 3 0< 4 0

-

_

40-50_

-40-50

40-50

_

40-5040-50

-< 4 0

<30

Total2>in days^

175-210175-205

-

---

. _

125-155-

-105-135

-

95-125\ -

--

-

*) Amounts surpassed normally in 6 out of 10 years, falling during the agro-humid period which allows growing of most cultivated plants.*) Only added if rainfall continues at least for survival (> 0.2 EQ) of most long term crops3' Interrupted by a period with water supply between 0.2 and 0.4 Eo for more than 50 days (intermediate rains)4 ) Here CL •• Coastal Lowlands, if this further differentiation is wanted.

Source: Jaetzold R., and H. Schmidt, eds. (1982): FarmManagement Handbook of Kenya, Volume II/C EastKenya, page 39o.

- 0.6 -

MAP 28.0.3 AEZS AND TRIAL SITES IN LAMU DISTRICT

4 t . _ . 41°13O'E

• Site of first priority

28.1 Mpeketoni

ivestock - .<

y

IßiGRO - ECOLOGICALZONES

soil boundary, see Map 4

Beit of A.E ZonesA E ZonesSubzones ••Climatic data for AEZ formulas see tables 11 2,H 1 4 and 31.0. 1

a . _ Broken zonal boundariesare uncertain ormean transitional slfips

Nat. Res.

L = here CL, CoastalLowlands

Steep slopes, unsuitablefor cultivation

_~—~ Water-logging or flooding~ during rainy season/ Mangrove

miS '

FERTILIZER USE RECOMMENDATION PROJECT (1987)

10 15 20 25 km

Ministry of AgricultureNational Agricultural LaboratoriesGerman Agricultural Team


The Mpeketoni Trial Site (No. 28.1) represents the Coconut-Cassava Zone(L 3 = CL 3).

The better areas of the Cashewnut-Cassava Zone (CL 4) with at least amedium or medium to short agro-humid period (i.e. 115-154 days) in thefirst rains are represented by the Mtondia-Tezo Trial Site (No. 29.1). andthe drier parts of Cl 3 (Coconut-Cassava Zone) are covered by the MtwapaCoast Agricultural Research Station (C.A.R.S.) Trial Site in KilifiDistrict. In the drier parts of the Cashewnut-Cassava Zone (CL 4), the riskof crop failure is high.

Approximately 30-35% of the district area consist of Lowland Livestock-Millet and Ranching Zones (see Map 28.0.3), which are not represented byFURP trial sites.

The soils of Lamu District are shown in Map 28.0.4. The entire District isbuilt up of the so-called Kilindini sands, lagoonal deposits of "lowfertility", which occur as an elongated strip along the Kenyan coast.

Unit PcJ6 is predominant. Soils are classified as (ferralo-) chromicLuvisols and cambic Arenosols, with smaller inclusions of gleyic and albicLuvisols, sodic phase, and dystric and solodic Pianosols. They all have aloamy sand to sandy clay loam texture and in many places they are sodic.Salinity and sodicity are also high in the soils of units PcJ2 and PcJ5.

Bottomlands are widespread. Units BJ1 and BJ2 have gleyic Phaeozems andhumic Pianosols respectively, with inclusions of saline and sodic soils.

Beach ridges (unit Zl) have very deep rhodic Ferralsols.The basic climatic and soil designations referring to the trial site inLamu District are summarized in Table 28.0.2.

Table 28.0.2: Agro-Ecological Zone and Soil Classification of the TrialSite in Lamu District

SiteNo.

28.1

SiteName

Mpeketoni

Agro-EcologicalZone

Coconut-CassavaZone (CL 3 = L 3)

Soil Classification

chromic LUVISOL

- 0.9 -

MAP 28.0.4 SOILS AND TRIAL SITES IN LAMU DISTRICT

• Site of first priority28.1 Mpeketoni

For LEGEND See APPENDIX

SOURCEEl Exploratory Soil Map of Kenya,

1980(scale 1:1,000,000)

KEYLB1 soil mapping code— soil boundary£ • towns and major villages=^= tarmac road===== other all-weather roads

district boundarynational park boundary

— — - river


5 10 15 20 25 km



2. Location of the Trial Site and Criteria for its Final Position

In Lamu District, one first priority site was selected as shown in Map28.0.4.

The site is on the Extension Training Centre in Mpeketoni, a sub-station ofMtwapa C.A.R.S.

The soils on this rectangular plot, which has some micro-topographicaldifferences, key out as Luvisols. Upon digging two pits, it appeared thatprofile development was similar for both the "higher" area and the "lower"area.Farmers' fields are within close range.

The nearest rainfall-recording station: 09240014, Mpeketoni DivisionalOffice is 1.3 km SSE of the trial plot.Accessibility is moderate, due to temporary impassibility of the Malindi-Garsen-Lamu main road. Demonstration effect is very high, as the area is asettlement area, where the application of fertilizer is not yet commonpractice.

The criteria for the final position of the trial site are listed in Table28.0.3, which is self-explanatory. Criteria have been rated very good (1),good (2), moderate (3), poor (4) or non-relevant (nr).

- 0.13 -


Table 28.0.3 Ratings of Criteria Used for Trial Site Selection in LamuDistrict

Criterion Sitenumber

1. Representativeness Agro-Ecological Zone2. Representativeness Soils3. Representativeness Topography

4. Adequacy of size and shape of the trial plot5. Absence of trees and hedges6. Absence of rocks and boulders7. Absence of termite mounds8. Uniformity of previous land use

9. Accessibility10. Demonstration effect11. Proximity to a long-term rainfall station

12. Availability of storage facilities13. Availability of sturdy fences14. Availability of housing facilities for T.A.

15. Farmer's willingness to cooperate16. Security - theft17. Security - intruding animals

18. Proximity of on-farm trials19. Representativeness of soils at on-farm trials

s

28.1

222

21113

322

142

123

22

- 0.14 -


3. Names and Addresses of Government Officers Involved in FURP Activities

The names and addresses of the agricultural staff members of the districtare listed in Table 28.0.4.

Table 28.0.4: Names and Addresses of Government Officers in the District

OFFICER

DISTRICTD.C.D.A.O.D.C.O.

DIVISIONDiv. Ext.OfficerLoc. Ext.OfficerTechnicalAssistant

SITE

28.1

28.1

28.1

NAME

Mr. Mate*David JilaniM. Muthembwa

Jackson Mulinge

not met

not met

SETTLEMENT SCHEMEEXTENSION

Officer-in- chargeFarmmanager

CENTRE

28.1

28.1

Joseph Mkutano

Simon A. Jilo

P.O. BOX

41 - Lamu40 - Lamu40 - Lamu

15 -Mpeketoni

15 -Mpeketoni15 -Mpeketoni

TEL. NO.

10 - Lamu10 - Lamu

31 -Mpeketoni

31 -Mpeketoni31 -Mpeketoni

* not met during site selection.

Period of site selection in the District: November 1986.

- 0.15 -


4. Trial Design and Execution Plan, Lamu.

(Full details of the methodology for carrying out the trials are shown inChapter IV of the main report).

Selection of Crops: The proposed crop sequences in each of the threemodules for the Lamu trial are:

Site 28.1 Mpeketoni,Lamu.

RAINY SEASONS1st, Long, March - May

51 Maize.& Sorghum52 Maize & Cowpeas53 Cotton

Coast CompositeC.C.+Cowpeas (Local) Relay PI. May/June

Cotton UKA 59-240 continues for one year

The 1st sequence or module is pure maize once a year.The 2nd module is maize, relay-planted with cowpeas in May/June.The 3rd is cotton which is continued over one year and is likely to berotated with another suitable crop.

Each module contains 2 Experiments, namely Experiment 1 and Experiment 2.

Experiment 1 is a 4N x 4P factorial, with 2 replications in each module.Experiment 2 at this site is a 2NP x 2K x 2CFM x 2FYM factorial, also with2 replications in each module. (CFM = Coconut Frond Mulch, also known asMakuti, used here to reduce soil temperatures during the first four weeksafter planting and to conserve moisture.)

Each module thus consists of 64 plots, and the total for the 3 modules is192 plots.

Mineral fertilizers, FYM and CFM will in all three modules be applied onceper year during planting time in the March/April rains. The relay-croppedcowpeas .will not receive any fertilizer at planting directly but will"scavenge" from the maize and from residual fertilizer left after the firstseason.

5. Areas in Lamu District Represented by FURP Trial Sites

The aim of FURP Phase I is to select trial sites which, as far as possible,are representative of the agriculturally high and medium potential areas ofKenya. This consideration constituted the backbone for making decisions asto where to establish these FURP trial sites.

Two representativeness maps are drawn per district. One refers to the soilsonly (Map 28.0.5: Groupings of Soil Mapping Units), and in the second (Map28.0.6) Agro-Ecological Units (AEUs) are shown in which, according to theinformation available, the soils and the climate can be consideredhomogeneous.

- 0.16 -


Map 28.0.5 shows the representativeness of FURP trial sites for LamuDistrict only as far as soils are concerned. Since FURP can only covermajor physiographic units (mainly uplands, plateaus and plains), minorunits such as mountains, hills, floodplains and bottomlands indicated inthe Soil Map (Map 28.0.4) and described in the accompanying Legend (cf.Appendix: M, H, A and B-units), are beyond consideration when it comes torepresentativeness.

The explanation for Map 28.0.5 shows two generalized "Groupings of SoilMapping Units". These groupings have the same or similar soil propertiesand, as such, they represent a specific soil environment, typified by oneof the FURP trial sites.

The codes in the explanation to Map 28.0.5 refer to a specific trial site(28.1, etc.) and to a specific degree of representativeness of soils (A,B+, B-). The combination of both forms a "Soil Representativeness Code".Grouping 28.1.A/B-/C, for instance, covers an area some of which is highlyrepresented, some of which is moderately represented and some of which isnot represented at all by the Mpeketoni Trial Site (28.1).

The explanation to Map 28.0.5 also lists those units of the Soil Map (Map28.0.4) which are considered in the various groupings. A breakdown of soilproperties referring to the Groupings of Soil Mapping Units is given aspart of Table 28.0.5.

The soils of Lamu District are partly represented by the FURP trial sites,as shown in Map 28.0.5. Soil map units PcJ6, Dl, Zl and Z2 constituteGrouping 28.1.A/B-/C."A" stands for the Luvisols, the Acrisols and the Ferralsols."B-" stands for the Arenosols."C" stands for the soils with a sodic phase, for Planosols and forRegosols. These classifications can be found in the Legend to the soil map(Appendix).

Areas which are not represented by any one trial site with respect to soilsare coded C. This involves the remaining soil map units of Lamu District,which have mainly saline and/or sodic soils.

The second representativeness map, Map 28.0.6, shows the integratedrepresentativeness of FURP trial sites involving both soils and climate.The map units are named "Agro-Ecological Units", and represent a specificsoil-climate environment, typified by FURP trial sites.

All combinations of the different soil-climate environments occurring inLamu District are shown in the Agro-Ecological Unit Map (Map 28.0.6) andare explained in Table 28.0.5. The codes for the Agro-Ecological Unitsconsist of three parts: site, soil representativeness and climaticrepresentativeness. Site and soil representativeness are taken from Map28.0.5.

In addition, Map 28.0.6 and Table 28.0.5 indicate the codes which refer tothe representativeness of the climatic environment (small letters).

- 0.17 -


Several degrees of representativeness are given according to the prevailingtemperature regime and the rainfall in the agro-humid period of the longrains.

All areas in Map 28.0.6 which are marked with code "a" (highlyrepresentative) are within the same temperature belt and receive the sameamount of rainfall (+/- 10%) in the agro-humid period of the long rains asthe trial site to which the code refers.

The map units marked with code "b" (e.g.: b-H-, b+- ,b+*) are only modera-tely represented by trial sites. In the AEU 28.I.A.b-H-, for instance, thesoils are highly represented by the Mpeketoni Trial Site (28.1.A), but theclimate (b++) indicates that this Agro-Ecological Unit belongs to the nextwarmer temperature belt and receives 10-20% more rainfall than theMpeketoni Trial Site.

Areas which are not represented by any one trial site, i.e. soils and/orclimate not represented by any site, are coded 0.

The criteria set for the sub-division of the various degrees of represen-tativeness with respect to soils and climate are further elaborated upon inChapter IV.2 of the main report.

- 0.18 -

E X P L A N A T I O N T O N A P 28.0.5

I

o

oI

Degree of representativeness

A

B+

B-

C

Trial

28.1

highly representative

moderately representative(soils of map unit are slightly morefavourable than soils at the trial site)

moderately representative(soils of map unit are slightly lessfavourable than soils at the trial site)

non-representative

site

Mpeketoni - Lamu District

Groupings of soil map units

•Soil RepresentativenessCode (Map 28.0.5) "•>

28.1.A/B-/C

C

Soil NapIncluded

PcJ6, D1,

others

Units(Map 28.0.4)

21, 22

1) Digits show trial site number; letters indicate degree of representativeness.For cartographic reasons, Soil Representativeness Code C is not indicated for the many scattered hills, bottomlands, and floodplains. These areas should be considered inclusions of units with Representativeness Codes A, B+, and B-.

MAP 28.0.5 GROUPINGS OF SOIL MAPPING UNITS REPRESENTED BY TRIAL SITES IN LAMU DISTRICT4QPJ30

• Site of first priority

28.1 Mpeketoni

i.A/r/csoil groupings mapping code

soil groupings boundary

i^.1 .-..'.; l*iV./i~-i.ü.Y ~L;ù i'i'Ul' -1 i OUS PAGE


SOURCEEl E x p l o r a t o r y S o i l Map of Kenya,

1980( sca l e 1:1 ,000,000)

KEYLB1 soil mapping code

— _ soi1 boundary

£ • towns and major villages

- tarmac road

^=^=z other all-weather roads

district boundary

national park boundary

—- river

F E R T I L I Z E R USE RECOMMENDATION P R O J E C T ( 1 9 8 7 )

10 15 20 25 km


Table 28.0.5: Major Soil Properties and Cliiatic Conditions of the Agro-Ecological Units in the Latu District

Agro-Ecological Unit

Site Soil ClimateDo. Code Code

28.1. A28.1. B-28.1. C a

b<-b«x

C

0

Soil properties

drai- eff. nutr. top- loist. classi-nage depth avail, soil st.cap. fication

v vd vl 0 • a fe-ch t ch Luse-ï vd vl 0 l-i cb Araw-p sh-d vl 0 1 gl Lu, sodic;

dy PI t so Pi

soil not representative

Climatic Conditions

tenp.l) temp. 1) rainfall Agro-Ec. Agro-Ec.lean ann. mean lin. 661 prob.2) Subione 3) Zone

25-28 21-24 560-680 m i vs to s CL 3-425-28 21-24 500-560 m/s i to s i CL 4

(vs)25-28 21-24 435-500 s i (vs) CL 4

to s i

soil and/or cliiate are not representative

Key:

Effective soil depth lutrient availability

ed extremely deep > 180 ci. h highvd very deep 120-180 cm. n moderate

deep 80-120 ci. 1 lownoderately deep 50- 80 ci.

vl very lowsh shallow 25- 50 ci. Specification givenvsh very shallow < 25 ci. in Chapter IV.2 (tain report)

lopsoil properties Soil classification

i hunic (base lu luvisols cb chroiic fe-ch ferralo-chroiicsaturation )50 t) Ar Arenosols dy dystric gl gleyic

ah acid humic (base PI Pianosols cb caibic so solodicsaturation <50t)

2 thick (30-60 ci.)1 thin (<30 cm.)0 non-hunc

Dtaimqe Moisture storage casacitr

se sosewhat excessive vh very high > 1(0 in.v «ell h higt 120-1(0 u .mv moderately veil m moderate 80-120 a»,i iiperfect 1 low < 80 it.p poor

1) Temperature (*C)(differentiated according to AEZ belts

2) laiofall 65» probability (in ii.)-referring to agro-humiâ period oflong rains only:

-for definition of rainfall ranges seeexplanation to Hap ...0.6:-66» probability leans that aiount ofrainfall will be exceeded in at least20 out of 30 years.

3) Agro-Ecological Subxone-approximative indication only, sincesubzones are not directly related toaiount of rainfall;

-"--" in formula means "followed by";-for further explanation of subionessee Chapter IV on methodology;-Agro-ecological zones and subionesare shown in Map ...0.3.

- 0.23 -

E X P L A N A T I O N T O M A P 28.0.6

Soil Codes Climatic Codes

= A = highly representative

= B+ = moderately representative(soils of map unit are slightly morefavourable than soils at the trial site)

= B- = moderately representative(soils of map unit are slightly lessfavourable than soils at the trial site)

i

o

highly representative,i.e. same Agro-Ecol.ZonesBelt and long rains (+/-1O%) as at trial site

moderately representative

long rains 10-20% higherlong rains similar <+/-10%)long rains 10-20% lowerlong rains 10-20% higherlong rains similar (+/-10%)long rains 10-20% lowerlong rains 10-20% higherlong rains 10-20% lowerlong rains 20-30% higherlong rains 20-30% lower

++ = 1+• = 1+- = 1-+ = 1-• = 1— = 1

AEZAEZAEZAEZAEZAEZ

BeltBeltBeltBeltBeltBelt

warmer,warmer,warmer,cooler,cooler,cooler,

•+ = AEZ Belt the same,•- = AEZ Belt the same,xx = 2xx = 2

AEZAEZ

BeltsBelts

warmer,cooler,

Trial sites

28.1 Mpeketoni (Lamu District)

Areas not represented

= not represented by soils and/or climate

For further explanation see Table 28.0.5

MAP 28.0.6 AGRO-ECOLOGICAL UNITS REPRESENTED BY TRIAL SITESIN LAMU DISTRICT

40*130'E

• Site of first priority28.1 Mpeketoni

agro-ecological unit boundary

For EXPLANATION see PREVIOUS PAGEand TABLE 28.0.5


SOURCEEl E x p l o r a t o r y S o i l Map of Kenya,

1 9 8 0 ( s c a l e 1 : 1 , 0 0 0 , 0 0 0 )

KEYLB1 soil mapping code

— soil boundary

W • towns and major villages

— - tarmac road

===: other all-weather roads

district boundary

national park boundary

river


10 15 20 25 km



LEGEND TO THE SOIL MAP OF LAMU DISTRICT

1—Explanation of first character ( physiography )

Pc Coastal PlainsÀ FloodplainsB BottomlandsD DunesT Tidal Flats and SvanpsZ Coastal Beach Ridges

2—Explanation of second character (litholoqyh

A Alluvial Sedinents fron Various SourcesJ Laqoonal DepositsL Limestones and Calcitic Hudstones

3 — S o i l descriptions

PcJ2 Inperfectly drained, deep to very deep, very dark greyish brown to olive brown, nottled,f i n to very fini, sandy clay to clay; moderately calcareous and noderately saline and sodicthroughout or in deeper subsoilluvo-orthic SOLOHETZ, saline phase and vertic LOVISOLS, saline-sodic phase

PcJ5 Imperfectly drained, very deep, brown, very firm, sandy loam to sandy clay loam, abruptlyunderlying a thick topsoil of friable loamy sand and with a slightly to moderately sodicdeeper subsoil; with inclusions of many small bottomlands of unit BJ1solodic PLANOSOLS

PcJ6 Somewhat excessively drained to moderately well drained, very deep, yellowish brown to grey-ish brown, mottled, friable to firm, sandy loam to sandy clay loam, in many places with athick (60-100 cm) topsoil of light brownish grey to yellow, very friable loamy sand; withinclusions of many small bottomlands of unit BJ2(ferralo-)chromic LDVISOLS and cambic ARENOSOLS; with gleyic and albic LOVISOLS, sodicphase, and dystric and solodic PLANOSOLS

PcLl Hell drained, shallow to moderately deep, red to dark reddish brown, friable, rocky, loam tosandy clay loamLITHOSOLS; with ferralic CAHBISOLS, lithic phase

AA4 Hell drained to imperfectly drained, very deep, dark brown to yellowish brown, stratified,micaceous, strongly calcareous, predominantly loamy soilscalcaric FLDVISOLS

AA5 Imperfectly drained to poorly drained, very deep, dark reddish brown to dark greyish brown,firm to very fin, cracking clay; in many places mottled and with a calcareous, saline andsodic deeper subsoilchromic VEETISOLS, saline-sodic phase

BJ1 Inperfectly drained to poorly drained, very deep, light brownish grey to brown, mottled,firm to very firn clay; in places sodic and cracking; higher-level depressionsgleyic PHAEOZEHS; with verto-luvic PHAEOZEHS and pellic VEKHSOLS, sodic phase

- 0.27 -


BJ2 Poorly drained, very deep, greyish brown, mottled, very fini clay, abruptly underlying atopsoil of friable, humic sandy clay loan; lover-level depressionshumic PLANOSOLS

Dl Excessively drained to veil drained, very deep, brovn to pale brovn, loose, slightly tostrongly calcareous, medium sand to loamy medium sandcanbic AKENOSOLS and calcaric BEGOSOLS

T Very poorly drained, very deep, olive to greenish grey, soft, unripe, excessively saline,moderately to strongly sodic, loam to clay; in many places vitb sulfidic materialtbionic FLUVISOLS, saline phase and gleyic SOLOHCHAKS

Zl Well drained, very deep, red, very friable, sandy clay loamrhodic FEBRALSOLS

Z2 Moderately veil drained, very deep, dark brovn to reddish brovn, firm to very firm, oftenmoderately sodic, sandy clay loam, underlying a thick topsoil of friable loamy sand; inplaces shallow over coral rockferralo-chromic/orthic ACRISOLS, sodic phase; with solodic PLAHOSOLS

KOTES:

1. mollic Nitisols ajd. chrono-luvic Phaeozems: soils are equally important2. mollic Nitisols, vith chromo-luvic Phaeozems: Nitisols are prevalent3. in places: in <30% of the area4. in many places: in 30-50% of the area5. predominantly : in >50% of the area6. deeper subsoil: belov 80 cm.

- 0.28 -

District: Lama. Trial Site 28.1 Mpeketoni

Contents of Chapter 28.1:

Detailed Description of the Mpeketoni Trial Site

Page

1. Geographical and Additional Technical Information 1.41.1 Final Position of the Trial Site 1.41.2 Sketch of the Trial Sites 1.51.3 Physiography 1.71.4 Vegetation, Past and Present Land Use 1.81.5 Names and Addresses of Government Officers from the Division

and Farmers Involved in FURP Activities 1.9

2. Climate 1.102.1 Prevailing Climatic Conditions 1.10

2.1.1 Agro-Climatic Classification of the Area Represented 1.102.1.2 Relevant Meteorological Data 1.112.1.3 Crop Suitability from the Climatic Point of View 1.15

.2.2 Proposal for the Monitoring of Agro-Climatic Conditions inPhase II 1.19

3. Soils 1.203.1 Survey Data 1.20

3.1.1 Brief Soil Description and General Information on theSoil 1.20

3.1.2 Detailed Profile Description and Soil Classification 1.213.1.3 Soil Sampling 1.23

3.2 Laboratory Data 1.233.3 Evaluation of Soil Data 1.28

3.3.1 Literature References and Soil Correlation 1.283.3.2 Representativeness 1.283.3.3 Variability of Soil Properties within the Trial Site 1.293.3.4 Fertility Status of the Soil 1.30

3.3.4.1 Soil Profile and Global Fertility Rating 1.303.3.4.2 Soil Fertility Assessment of Composite Samples 1.31

3.4 Sampling Programme for Laboratory Analysis 1.333.4.1 Soil Samples . 1.333.4.2 Plant Samples s 1.343.4.3 Other Samples 1.34

4. Conclusions from the Analyses of Climate and Soils 1.344.1 Moisture Availability 1.344.2 Nutrient Availability in Relation to Possible Fertilizer

Requirement 1.354.3 Other Relevant Land Qualities 1.36

5. Trial Design and Execution Plan 1.37

- 1.1 -

District: Lami Trial Site 28.1 Mpeketoni

List of Tables1)

Page

Table 28.1.1 Physiography of the Mpeketoni Trial Site 1.7

Table 28.1.2 Vegetation, Past and Present Land Use 1.8

Table 28.1.3 Names and Addresses of the Divisional Staff Members and

Farmers of the Mpeketoni Trial Site 1.9

Table 28.1.4 Data of the Nearest Long-Term Rainfall Station 1.12

Table 28.1.5 Temperature 1.13

Table 28.1.6 Potential Evaporation (Eo) 1.13

Table 28.1.7 Agro-Climatological Crop List for Mpeketoni 1.15

Table 28.1.8 Crop Development Stages and Crop Coefficients 1.17

Table 28.1.9 Detailed Profile Description of the Mpeketoni Trial Plot 1.22

Table 28.1.10 Analytical Results (physical and chemical analyses) 1.24

Table 28.1.11 Analytical Results (chemical analysis, trial plot) 1.25

Table 28.1.12 Analytical Results (chemical analysis, farmers' fields) 1.27

Table 28.1.13 Soil Correlation with Respect to the Mpeketoni Trial

Site 1.28Table 28.1.14 Evaluation of Mehlich Analysis Data According to NAL

Standards 1.33

1) See Footnote next page.

- 1.2 -

District: Lamu Trial Site 28.1 Hpeketoni

List of Figures1)

Page

Figure 28.1.1 Demarcation of the Mpeketoni Trial Site 1.4

Figure 28.1.2 Access Map of the Mpeketoni Trial Site 1.5

Figure 28.1.3 Map of the Trial Plot, Mpeketoni 1.6

Figure 28.1.4 Location of Farmers' Fields for On-Farm Trials, Mpeketoni 1.7

Figure 28.1.5 Rainfall and Potential Evaporation 1.14

Figure 28.1.6 Water Requirement and Availability for Maize Pwani,

First Rains 1.18

Figure 28.1.7 Location of Composite Sampling Blocks and Profile Pitat the Mpeketoni Trial Plot 1.23

1) Numbering mode of Tables and Figures:First Number: District NumberSecond Number: Trial Site NumberThird Number: Number of Table or Figure within Chapter.

- 1.3 -

District: Lamx Trial Site 28.1 Mpeketoni

1. Geographical and Additional Technical Information

1.1 Final Position of the Trial Site

The position of the site at Mpeketoni is shown in Figure 28.1.1, extractedfrom Map No. 180/3 - Mkunumbi. Its UTM grid coordinates are E 87.5 and N37.5. The elevation is 10 m. Further details on the final position areshown in Figure 28.1.2 and a sketch map of the trial plot is to be found inFigure 28.1.3.

Figure 28.1.1: Demarcation of the Mpeketoni Trial Site on the 1:50,000Topographic Map

- 1.4 -

District: Lamu Trial Site 28.1 Mpeketoni

1.2 Sketch of the Trial Site.

The location of and the access route to the Mpeketoni site are shown inFigure 28.1.2 and the map of the trial plot are in Figure 28.1.3.

0.5 1.5 2Km.

Figure 28.1.2: Access Map of the Trial Site, Mpeketoni

- 1.5 -

District: Lama Trial Site 28.1 Mpeketoni

I • 1 « ' 10 10 20 30 40 50m

Figure 28.1.3: Map of the Trial Plot, Mpeketoni

- 1.6 -


The approximate location of the on-farm trials is indicated in Figure28.1.4.

Figure 28.1.4: Location of Farmers' Fields for On-Farm Trials, Mpeketoni

1.3 Physiography

Information on the physiography of the trial site and its surroundings issummarized in Table 28.1.1 below.

Table 28.1.1: Physiography of the Mpeketoni Trial Site

Elevation

Landform

Physiographic position of

Topography of surrounding

Slope on which trial plot

Aspect

Microtopography

the site

country

is sited

10 m.

coastal

plain

level or(slopes

0-2%

Nil

formingwestern

plain

nearly level0-2%)

broad gully alongplot boundary

- 1.7 -

District: Laan Trial Site 28.1 Mpeketoni

1.4 Vegetation, Past and Present Land Use

Information on vegetation and on past and present land use is summarized inTable 28.1.2 below:

Table 28.1.2: Vegetation, Past and Present Land Use of the Mpeketoni TrialSite

Vegetation

Cropping system.

(a) cleared since:(b) crops grown:

(c) fallow periods:(d) present land use:

Inputs

(a) mineral fertilizers:(b) organic manure:(ç) means of land preparation:(d) means of weeding:(e) frequency of weeding:(f) other capital inputs:(g) level of know-how:

Produce

(a) maize

Livestock

Undifferentiated clearingsand cultivations

1970-1971maize, cotton, cowpeas,green grams, sweet potatoescassava, sorghum, simsimrarelymaize (1986 long rains)Coast Composite

TSP and CANnot appliedtractormanual2-4 times per crop standpesticides (a.o. dipterex)high

15-20 bags/acre(90 kg bags)

dairy cattle, poultry willbe kept in near future

RemarksFertilizer application is not common in the area. The farmers'fields have never received any fertilizer.

- 1.8 -

1.5


Names and Addresses of Government Officers Involved in FURPActivities

Names and addresses of the divisional staff members and of all farmersinvolved are given in Table 28.1.3.

The codes used for the additional "on-farm" farmers refer to the locationof their farms as indicated in Figure 28.1.4.

Table 28.1.3: Names and Addresses of Divisional Staff Members and ofFarmers at the Mpeketoni Trial Site

DivisionalStaff

D.E.O.L.E.O.T.A.

Farmers

Officer-in-charge

On-Farm trials

28.1.A28.1.B28.1.C28.1.D28.1.E28.1.F28.1.G28.1.H

Name

Jackson Mulingenot metnot met

Name

Joseph Mkutano

Address

Box 15-Mpeketoni

Address

Box 15-Mpeketoni

LOCATION: MpeketoniSUB-LOCATION: Mpeketoni(Lake Kenyatta Settlement Scheme)

Name

Samwel WaweruMuchiri NgathogaMary NjokiNaftaly GitongaAli NgomboreWainaina MicharaPeter NjugunaTitus Mwanike

Remarks

plot 40, Centralplot 51, Centralplot 72, Mapenyaplot 75, Mapenyaplot ? , Mapenyaplot 321 Lakeplot 5, Kenyattaplot 13,

Period of site selection: November 1986.

- 1.9 -

District: Lama Trial Site 28.1 tipeketoni

2. Climate

2.1 Prevailing Climatic Conditions

2.1.1 Agro-Climatic Classification of the Area Represented by theMpeketoni Trial Site

The following brief climatic description refers to the existinginformation:

ACZ : III1 (H.M.H. BRAUN, 1982)1)

AEZ : CL 3, m i (vs) (R. JÄTZOLD, 1983)2)

Next long-term rainfall station: 09240014, Mpeketoni Divisional Office

Agro-Climatic Zone (ACZ):

Moisture availability Zone III (r/Eo): annual average precipitation is 50-65% of the potential evaporation (Eo).

Temperature Zone 1: mean annual temperature is 24-30°C

Agro-Ecological Zone fAEZ):

CL 3 = Coconut-Cassava Zone

CL = Coastal Lowland Zone: mean annual temperature is >24°C, meanmaximum <31°C

3 = semi-humid; annual average precipitation is 50-65% of thepotential evaporation (Eo)

Sub-zone according to growing periods for annual crops (calculated for a"normal" crop in 60% probability)

m i (vs) = with a medium cropping season, intermediate rains, anda (weak) very short cropping season.

1) According to H.M.H. BRAUN in: W.G. SOMBROEK, et al. (1982):Exploratory Soil Map and Agro-Climatic Zone Map of Kenya, scale1:1,000,000 - Rep. El, Nairobi

2) According to R. JÄTZOLD and H. SCHMIDT, eds. (1983): FarmManagement Handbook of Kenya, Vol.II/C EAST KENYA - Nairobi andTrier.

- 1.10 -


Formula Cropping season Lengths of growing perio4(exceeded in 6 out of 10 years)

m medium 135 - 154 daysvs very short 40 - 54 days

i => intermediate rains (at least 5 decades more than 0.2 Eo); thatmeans moisture conditions are above wilting point for most crops.

() = weak performance of growing period (most decades less than 0.8 Eo)

2.1.2 Relevant; Meteorological Data-for the Mpeketoni Trial Site

In this Section a breakdown is given of the following climatic parameters:rainfall, potential evaporation and temperature.

Rainfall :

Rainfall data were obtained from the Witu long-term rainfall station:09240003 (in rainfall-index called: Lamu District Office: elevation: 5 m),28 km W of the trial site (elevation: 10 m ) , since the data from thenearest rainfall-recording station: 09240014, Mpeketoni Divisional Office(elevation: 10 m ) , 1.3 km SSE of the trial plot were not available in theformat required by the FURP computer system. The data are listed in Table28.1.4. In 20 out of 30 years Mpeketoni gets about 620 mm in the agro-humidperiod of the first rains, and approximately 90 mm during the second rains(no real agro-humid period). The methods of rainfall-data analysis are des-cribed in Chapter IV.2.2 of the main report.Temperature and potential evaporation(Eo):

Potential evaporation (Eo) is calculated using the PENMAN formula, modifiedby MC CULLOCH (1965). The input parameters employed - temperature, windrun,sunshine hours and relative humidity - are obtained from 09240001, LamuMeteorological Station (elevation: 10 m ) , 25 km NE of the trial site.

Temperature and evaporation data for the Mpeketoni Site are given in Table28.1.5 and 28.1.6, and the rainfall pattern and potential evaporation areshown in Figure 28.1.5.

For more detailed information on the methodology of climatic descriptionsee Chapter IV.2.2 of the main report.

- 1.11 -

Table 28.1.4 : Data of the Nearest Long-Term Rainfall Station

Station No.: 09240003WituElevation: 30 m

Total years for calculation: 26First year included: 1931Last year included: 1956

Average annual rainfall: 1048 mm

Rainfall surpassed in 20 out of 30 years (=66% Probability):

1st rains: 600 mm(end of Mar. - mid Jul.)

2nd rains: 120 mm(mid. Nov. - end of Dec.)

Decadesand

Month*

1 JAN234 FEB567 MAR8910 APR1 11213 MAY141516 JUN171819 JUL202122 AUG232425 SEP262728 OCT293031 NOV323334 DEC3536

ArithmeticMean(mm)

16.05.82.31 .10.54.78.79.4

18.334.829. 938. 1

118.9101 .073.746.541 .059.234.125. 126.518.221 .619.213.218.816.19. 1

35.916.418.124.835.745.936.623.4

Average Number of RainyDays with Rainfall>= 1 mm

1 .70.50.30.30.10.30.70.71.52.62.83.55.65.85.04.54.75.24.63.73.73.13.23.02.42.92.01 .61 .81 .61 .42. 12.73.43.02.4

>= 5 mm

1 .70.50.30.30. 10.30.70.71 .52.62.83.55.6 -5.84.94.44.55.24.63.63.73.03.12.92.42.92.01 .61 .81 .61 .42. 12.73. 43.02.4

=66% Probabi-lity of ex-

ceeding . . .mm

6. 90.00.00.00.00.01 .72.39.0

22. 116.721 .081 .970.642.929.626.640.024.213.218.111.49.6

10.25.58.84.63.33.58.85.8

13.821 .633.420.913.9

Yearsanal-ized

262626262626262626262626262626262626262626262626262626262626262626262626

- 1.12 -


Table 28.1.5:

MeanMeanMean

MeanMeanMean

temp,max.temp.min.temp.

temp,max.temp.min.temp.

Temperature (°

JAN.

27.430.624.3

JUL.

25.127.322.9

FEB.

27.931.224.7

AUG.

25.227.5

. 23.0

annual mean: 26.8 mean max.

O

MAR.

28.832.125.6

SEPT.

25.628.023.3

: 29.5

APR.

27.930.725.2

OCT.

26.629.124.1

mean

MAY

26.528.824.3

NOV.

27.430.424.4

min. :

JUN.

25.628.023.4

DEC.

27.630.824.5

24.1

Table 28.1.6: Potential Evaporation

1st decade2nd decade3rd decadeTotal :

1st decade2nd decade3rd decadeTotal :

average annual

JAN.

595965183

JUL.

4848

_53149

FEB.

616149171

AUG.

5252

161

MAR.

636369195

SEPT.

5454

_54162

(Eo) in

APR.

555555165

OCT.

5858

_64180

potential evaporation: 2006

mm per

MAY

484852148

NOV.

.5757_5Z171

nun.

Decade :

JUN.

494949147

DEC.

5656

_62174

For all the climatic data published in this Section, a data bank has beenestablished by FURP on Personal Computers at the National AgriculturalLaboratories in Nairobi.

- 1.13 -

Figure 28.1.5: Rainfall and Potential Evaporation

Rainfall Station: 09240003 Lamu D. 0.

Meteorological Station:

09240001 Lamu Met. Station

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC


2.1.3 Crop Suitability from the Climatic Point of View

A summary of the agro-climatic suitability of the most important seasonalcrops is given in Table 28.1.7 below. Additional information on other cropsconsidered suitable from the agro-climatic viewpoint is given in the FarmManagement Handbook, Vol. II/C, East Kenya1).

Table 28.1.7: Agro-Climatological Crop List for Mpeketoni

Crop/variety(or place ofbreeding)e = earlym •= medium1 - late

Maize/m.mat.like Pwani 1

Cowpeas/1ikee.mat.Katuli

Simsim/m. mat.local

Sorghum/m.mat. likeLamu White

Green Grams

Av.No.ofdays tophysiol.maturity

100-120

70-90

100-140

90-130

75-90

Altitudes2)accordingto growingperiod

On.)

0 - 1200

0 - 1500

0 - 1300

0 - 1500

0 - 1200

Requirem.ofwell distri-buted rain-fall 3) ingrow.period

(mm. )

550-700

200-400

300-600

320-590

190-400

Yieldpotential ace.to water avai-lability 4)a - 1st rainsb - 2nd rains

a) good

a) goodb) fair - poor

fair(Jun./Jul.-Sep./Oct.)



1) R. JÄTZOLD and H. SCHMIDT, eds.(1983): Farm Management Handbook ofKenya, Vol. II/C, East Kenya - Nairobi and Trier.

2) Most suitable altitudes; the length of the growing periodincreases with altitude; growth is also possible beyond theindicated altitude range, as long as the ecological limits havenot been reached.

3) Lower figure for fair results, higher for very good results withsome corrections due to rainfall distribution, evaporation andrun-off losses.

4) Estimated yield potential: very good >80%, good - 60-80%, fair -40-60%. and poor <40% of the expected yield under optimum wateravailability adapted from R. JÄTZOLD and H. SCHMIDT, eds. (1982):Farm Management Handbook of Kenya, Vol. II/A, West Kenya.

- 1.15 -


For the most important seasonal crops in the area around the MpeketoniTrial Site, the crop coefficients (kc) are shown in Table 28.1.8,differentiated according to decades (10 day periods) of the growing seasonwhich is the time between planting or sowing and physiological maturity.Furthermore, four crop development stages are distinguished in Table28.1.8.The crop coefficients for the climatic conditions at the Mpeketoni TrialSite were estimated on the basis of data obtained from DOORENBOS and PRUITT(1977)1) and DOORENBOS and KASSAM (1979)*).

The data on the duration of each of the growing seasons and on the variousdevelopment stages of each crop were assessed on the basis of localobservations made under average climatic conditions.

The crop coefficients estimated for the various decades of the growingseasons were used to estimate the maximum (potential) evapotranspiration(ETm) under the prevailing climate, assuming that water was not a limitingfactor for plant growth. For this calculation the following approximativeformula was employed:

BTm kc Eo

whereby: ETm= maximum (potential) evapotranspirationkc = crop coefficientEo = potential evaporation (climatic evaporative demand)

In Figure 28.1.6, the ETm-values are used to indicate the estimated maximumwater requirements of an important seasonal crop for optimum growth.Furthermore, the rainfall data at 66% reliability are shown in Figure28.1.6 to give an indication of the water availability. However, whenreading these figures, it must be borne in mind that the actual availabi-lity of water for the plants also depends, to a large degree, on factorssuch as the run-off, the moisture storage capacity of the soil, the deeppercolation of water etc.

The placement of the growing seasons of the various crops on the time axisas presented in Figure 28.1.6 was mainly based on the pattern of rainfall,whereby the peak water requirements of the plants should be met by high andreliable rainfall.

Detailed information on the calculation procedures and references are givenin Chapter IV.2.2 of the main report. The interpretation of the above-mentioned diagrams follows in Section 4 of this Volume (Conclusions fromthe Analyses of Climate and Soils).

1) FAO (1977): Crop Water Requirements - (= Irrigation and DrainagePaper, 24), Rome

2) FAO (1979): Yield Response to Water - (= Irrigation and DrainagePaper, 33), Rome

- 1.16 -

Table 28.1.8 : Crop development stages 1) and crop coefficients (Kc) 2) for approx. uxiiui (potential) crop evapotranspiration of the tost iiportantseasonal crops grown at Hpeketoni (site no. 28.1)

Crop/Variety

MAIZEPVANI

COVPEASKATULI

SOflGHÜHSERENA

SIK5IMLOCAL

Huiber of decades froi seeding resp. planting to (physiological) uturity1 2 3 4 5 6 7 8 9 10 11 12 13 14 IS 16 17 18 19 20 21 22 23 24

0.55 0.6 0.68 0.83 0.97 1.05 1.05 1.05 0.93 0.66I I II II II III III III IV IV

0.55 0.66 0.93 1.05 1.05 1.05 0.89 0.38I II II III III III IV IV

0.55 0.6 0.68 0.89 1.0 1.0 1.0 0.89 0.64I I II II III III III IV IV

0.55 0.6 0.69 0.81 0.93 1.0 1.0 1.0 0.89 0.59 0.28I I II II II III III III IV IV IV

1) Crop development stages as defined in chapter IV 2.2 (lain report)I = initial stage II = development stage III : lid season IV = late season

2) Kc = crop coefficient as defined in chapter IV 2.2 («in report)

Figure 28.1.6: Water requirementsand availability for cropMaize/Pwani, first rains

Rainfall Station: 09240003Lamu D.O.

00

I

mm

90-,

8CH

Trial Site 28.1 Mpeketoni

ETm

APR


2.2 Proposal for the Monitoring of Agro-Climatic Conditions inPhase II

For Phase II the agro-climatic recording programme should include:

1) Rflfrffffi'l records:

A rain gauge has to be installed at the Mpeketoni Trial Site tö measure theactual precipitation on the spot. Subsequently, the data can be comparedwith both rainfall for a particular year and the long-term average of thenearest rainfall recording station of the Meteorological Department:09240014, Mpeketoni Divisional Office (formerly called: Lake KenyattaCotton Project), 1.3 km SSË of the trial plot. Note, that the short-distance variability of rainfall in the Mpeketoni area is very high and forthis reason the installation of a rain gauge at the plot is recommended,although there is rainfall-recording station nearby.

2) Records on other relevant meteorological parameters:

Data on temperature, windrun, sunshine hours and relative humidity can beobtained from: 09240001, Lamu Meteorological Station (elevation: 10 m ) , 25km NE of the trial site, in order to calculate Eo (climatic evaporativedemand). For this purpose a computerized PENMAN formula, modified byMC CULLOCH (1965) is available on PC.

3) Phenological records :

Dates of planting or seeding of each crop, emergence, start of tasselling(for maize crop), budding (for the cowpea crop), flowering, ripeness orphysiological maturity and harvest have to be recorded. Additionally theleaf area index (LAI) has to be determined every week (at least for thecereal crops) in order to provide a sound basis for water balancecalculations. Other important features should also be recorded, above allrolling and wilting leaves, which indicate water stress and wilting pointrespectively before physiological maturity has been reached.

Moreover, soil moisture checks and observations on rooting depth at theabove—mentioned growing stages would be needed to estimate the actualevapotranspiration of the various crops correctly. Soil moisture checks arenecessary to reveal the influence of ground water and sub-surface flow,which cannot be estimated.

For most of the data to be recorded, official forms from the MeteorologicalDepartment are available.

Detailed information on calculation procedures, as proposed for themonitoring of agro-climatic conditions, is given in Chapter IV.2.2 of themain report.

- 1.19 -


3. Soils

In this Section, survey and laboratory data concerning the trial site and,more specifically, the soil profiles are given.The evaluation of these data is shown in Sub-Section 3.3.

3.1 Survey Data

3.1.1 Brief Soil Description and General Information on the Soil

The brief description of the soils of the trial plot is followed by arating of relevant soil-related land factors. The classes for these factorshave been adapted from Andriesse and van der Pouw (1985), and a key forthem is to be found in Chapter IV.2.3 of the main report.

Brief soil description

The soils are very deep, strong brown to yellowish red in colour, andconsist of very friable sandy clay loam to sandy clay. They have a weaksub-angular blocky structure, which evolves into porous massive in thesubsoil. Bioporosity is very high in the topsoil, but only moderately highin the subsoil.

Rating of soil-related land factors

- Parent rock 123

richmoderately richpoor: unconsolidated sandy andloamv flazoonal) deposits

- Drainage

- Effective soil depth

- Inherent fertility

- Topsoil properties

1 (somewhat) excessively drained2 well drained3 moderately well drained4 imperfectly drained5 (very) poorly drained

1 extremely deep2 very deep3 deep4 moderately deep5 shallow6 very shallow

1 high2 moderate3 poor4 very poor

01 humic2 thick humicla acid humic2a thick acid humic

- 1.20 -

District: Lama Trial Site 28.1 Hpeketoni

- Salinity 0 non-saline1 slightly saline2 saline

- Sodicity 0 non-sodic1 slightly sodic2 sodic

- Stoniness

- Rockiness

- Consistency (moist)

- Moisture storage capacity

0 non-stony1 slightly stony2 stony3 very stony

0 non-rockv1 slightly rocky2 rocky3 very rocky

1 half-ripe2 loose3 very friable4 friable5 firm6 very firm

1 very high2 high3 moderate4 low

- Excess surface water 0 none1 occasional2 seasonal3 permanent

3.1.2 Detailed Profile Description and Soil Classification

Detailed information on the various soil properties as they occur in thedifferent horizons is given in Table 28.1.9.

The location of the profiles near the trial plot is shown in Figure 28.1.7.

The soil profiles are classified according to two systems, which areexplained in Chapter II.2.2 of the main report.

1. Legend to the Soil Map of the World (FAO-Unesco, 1974), with adjustmentsaccording to the Kenya Concept (Siderius and van der Pouw, 1980):chromic Luvisol.

2. USDA Soil Taxonomy (Soil Survey Staff, 1975): arenic Haplustalf. fine-loamv familv

- 1.21 -

Table 28.1.9: Detailed Profile Description of Trial Plot Mpeketoni

IMIM

Profile nuaber:Date of exaaination: .Authors:

SaapleNo.

28.1.1111

28.1.2|111

28.1.3111

28.1.4|1 ... .1

28.1.51|i

i

28 122:11-1987Saaling

H o r i z o n

Genetic | Depth | Boundary

Ap

Ah

AB

Btl

Bt2

0-15

15-30

30-45

45-65

65-115

clearsiooth

gradualsaooth

gradualsaooth

gradualsaooth

Colour(Moist)

10 YR 3/2

10 YE 4/3

10 YB 4/4

5 YR 3/4

5 YH 4/6

Mottling

—

—

Texture

loaaysand

loaiysand

sandyloaa

sandyclayloai

sandyclay

Cutans

—

brokenthinclay

bridging

brokenthinclay

bridging

brokenthinclay

bridging

Structure

weakfine

subangularblocky

weak•ediua

subangularblocky

•oderate•ediuaangularblocky

•oderate•ediuaangularblocky

porousaassive

Biopores jConsistencejField1 l p H

•any v.f.! soft: !•any f. v.friable; n.d.•any a. si. sticky-!•any c. si.plastic

•any v.f.' soft: ]•any f. v.friable; n.d.•any •• si. sticky-!couon c. [non-plastic!

aany v.f. si.hard;•any f. v.friable; n.d.few a. si.sticky-no c. si.plastic

aany v.f. si.hard;aany f. v.friable; n.d.few a. si.sticky-no c. ! si.plastic

aany v.f.' si.hard;aany f. v.friable; n.d.few a. si.sticky-no c. si.plastic

1 111 ,1 1

Concretions

...

...

Other !Features

1

—

!

—

—

Beurks: Biopores: v.f. = ver? fine; f.: fine; a.: aediua; c.= coarseConsistence: si. = slightly; v.= veryField pB: n.d. = not determined


3.1.3 Soil Sampling

Soil samples (profile, composite, farmers' fields, pF rings) are listed inSub-Section 3.2.Figure 28.1.7 shows the location of the composite sampling Blocks (I toIII) as well as the location of the profile pits.

9&t

64m.

profile pit20 » tO 50m

Figure 28.1.7: Location of Composite Sampling Blocks and Profile Pit at theMpeketoni Trial Plot

3.2 Laboratory Data

The soil samples from the profile and the composite samples from thevarious blocks of the main trial site and from the farmers' fields wereanalyzed in the laboratory. The results are compiled in Tables 28.1.10 to28.1.12. The methodology applied for obtaining these results is describedin detail in Chapter IV.2 of the main report.

- 1.23 -

District: Laou Trial Site: 28.1 Hpeketoni

Table 28.1.10 : Analytical Results (physical and cheoical analysis, results on air dry soil basis)Profile Saaples from Trial Site

Horizon DepthCO.

FieldNo.

Lab.No.

) 2 SandX

SiltX

Clay TextureI Class

PHKCl

PHH20

Diff. Cond.pH H20

1 Ah2 AB3 Btl4 Bt2t06 Ah/8 Ah9 'AB10 Btl11 Bt21213 Ah

1

1234CJ

6

8910111213

0.160.150.100.12

0.10

0.150.110.090.13

0.10

0-2222-3838-7373-120

control

0-2020-4444-6868-118

control

K

1.250.970.680.56

1.20

0.690.750.510.41

0.73

28.1.128.1.228.1.328.1.4

28.1.5

28.1.628.1.728.1.828.1.9

28.1.10

Hgme./lOOga

1.551.241.551.30

1.45

1.301.541.861.70

• 1.18

Moisture Retention CapacityHorizon

1 Ah2 Btl34

Depthen.

10-1550-55

10628/85106291063010631

10632

10633106341063510636

10637

Ca. Acetate

5.805.904.403.60

6.80

4.705.104.403.50

4.60

Vol.1bar 0pF 0

17.322.6

————

«

«——

—

CEC pH8.2

16.9013.5013.7010.20

15.10

13.7014.5013.6013.50

12.70

Moisture1/10

2

13.717.4

70605662

68

76605860

76

BasesZ

51.8361.1949.1254.71

63.25

49.9351.7250.4442.52

52.05

1/32.5

10.814.6

2222

2

2222

2

Bases+Alne./lOOgo

8.768.266.735.58

9.55

6.847.506.865.74

6.61

53.7

7.010.4

28384236

30

22384038

22

AlZ

NANANANA

NA

NANANANA

NA

154.2

6.710.0

SCLSCSC

SC/SCL

SCL

SCLSCSCSC

SCL

Org. CZ

0.960.510.280.16

0.77

0.890.390.230.20

0.64

5.85.65.75.6

5.8

5.85.75.75.6

5.8

NZ

6.66.46.56.3

6.6

6.66.56.56.6

6.7

C/N

Avail. MoistureCapacityßiQ./lOcm.

7.07.4

0.80.80.80.7

0.8

0.80.80.81.0

0.9

P OlsenPP».

18887

11

7444

7

0.050.080.040.04

0.10

0.070.050.040.07

0.06

105 deg.Cin rel.toair dry

Bulk Denskg./l.105 deg.C

1.481.36

NA : not applicableœe./lOOgiB. : ailliequivalents per 100 go. of soilAgTU : Silver Thio Urea ExtractionAcetate : Bases by Ammonium Acetate pH 7, CEC by Sodium Acetate pH 8.2pH and conductivity in suspension 1:2.5 v/v

- 1 .24 -

District: Lanu Trial Site: 28.1 Hpeketoni

Table 28.1.11 : Analytical Results (chemical analysis, results on air dry soil basis)Trial Site Composite Samples

1 !! 2t 7

1 0

! 4! 5! 6! 7! 8! 91 t n1 10! 11! 12! 13! 14: is

1 1 -J

1 1/: is! 19! 20

CSJ

! 22! 23| ft A

i 24! 25! 26I AI

i 2/! 28î 291 ini 30! 31! 32! 33! 34! 35! 36! 37! 38

i 40! 41! 42! 43! 44! 45! 46! 47! 48! 49! 50! 51! 52! 53! 54! 55! 56! 57! 58

Depth

Lab. No. /86

Fine earth Z

Vol.weight kg./l.

105 deg.C / air dry

pH H20 1/1

pH H20 1/2.5

pH N KC1 1/2.5

C org. Z

N tot. Z

C/N

Hod.Olsen Abs. 260nra(1/1000)

S04 soluble ppm.

P Heh.1/5 ppm.

P Olsen ppm.

P mod.Olsen ppm.

P Citric ac. ppm.

ECEC AgTU me./100gin.! Bases Zi All

Hp BaCl2 me./100gm.

!H & Al KC1 me./100gm

!A1 3- KCl me./100gm.

!A1 3- AgTU me./lOOgm

iSat.Ext. Z H20

Sat.Ext. El.Cond.

Sat.Ext. pH

cm.

2050

205020502050

20'5020502050

205020502050

2050

2050

2050205020502050

202020

20502050205020

205020502050

Block numberI II

10614 1061610615 10617

100 100100 100

6.1 6.56.3 6.56.5 7.27.1 7.15.9 6.15.7 5.8

0.89 0.920.59 0.680.08 0.070.06 0.04

11 1310 17

38 3817 17104

27 274 4

not applicablenot applicablenot applicablenot applicablenot applicablenot applicablenot applicable

not applicablenot applicablenot applicablenot applicablenot applicablenot applicable

III IV

1061810619

100100

6.87.27.37.66.26.3

0.850.550.070.041214

468

3013

V VI VII !

----

X

100100

6.476.677.007.276.075.93

0.890.610.070.0512.1413.53

40.6714.00

23.00! 7.00

s

00

000000

000013

45

15

0000

.35

.47

.44

.29

.15

.32

.04

.07

.01

.01

.01

.59

.62

.20

.73

.20

Hax. !diff. !

0.00 !

o.oo ;

0.70 !0.90 !0.80 !0.50 :0.30 !0.60 !

0.07 !0.13 !0.01 i0.02 !2.02 !7.17 !

8.00 !9.00 !

3.00 !9.00 !

- 1 .25 -

con t.

District: Lamu Trial Site: 23.1 Hpeketoni

Table 28.1.11 : Analytical Results (chemical analysis, results on air dry soil basis)Trial Site Composite Samples

! 1! 2I yi 0

! 59: 60: 6i: 62: 63! 64! 65: 66! 67! 68! 69! 70! 71! 72! 73! 74! 75! 76! 77! 78! 79! 80! 81! 82! 83! 84! 85! 86! 87! 88! 89! 90! 91! 92! 93! 94! 95! 96! 97! 98! 991100ilOl11021103!1O41105

!Lab. No.1I

!Na Heh.1/511

!Na Ag-TU me1l

/86

me./100gm

./lOOgm.

iK Heh.1/5 me./100gm.11

'K mod.01. me./lOOgm.11

lit Ag-TU me.I1

!Hg Heh.1/5

!Hg mod.01.11

!Hg Ag-TU OIEI

iCa Heh.1/5!ICa mod.01.

!Ca Ag-TU meI1

!Hn Heh.1/51t

inn mod.01.11

!Hn Ag-TU me11

!Zn HCl ppmii

!Zn mod. 01!

!Cu HCl ppm!!Cu mod. 011

1

i!Fe HCl ppmri

!Fe mod. 01!

IFe Oxalatej!Al ûxalate1

/lOOgra.

me./100gm

me./100gm

./lOOgm.

me./100gm

me./100gm

./lOOgm.

me./100gm

me./100gm

./lOOgm.

ppm.

ppm.

ppm.

Z

z

Depthcm.

2050

205020

2050205020

2050205020

2050205020

2050.205020

20502050

20502050

20502050

20502050

Block numberI

1061410615

0.120.12

0.620.540.920.69

1.502.002.242.07

4.405.6010.708.90

0.580.780.190.11

2.802.151.901.20

0.400.452.701.60

3.502.503625

II

1061610617

0.120.08

0.620.580.800.71

1.601.802.191.99

6.405.6010.208.70

0.740.560.130.12

1.601.10

1.901.50

3019

III IV

1061810619

0.120.12

0.540.500.710.61

2.001.702.482.41

6.404.4010.9010.70

0.700.54

olio0.07

1.001.00

2.301.60

2121

V VI VIIX

0.120.11

0.590.540.810.67

1.701.832.302.16

5.735.2010.609.43

0.670.630.140.10

1.501.10

2.301 1.57

29.0021.67

S

0.000.02

0.050.040.110.05

0.260.150.160.22

1.150.690.361.10

0.080.130.050.03

0.460.10

0.400.06

7.553.06

Hax. !diff. !

0.00 !0.04 !

0.08 !0.08 !0.21 !0.10 !

0.50 !0.30 !0.29 !0.42 !

2.00 i1.20 !0.70 !2.00 !

0.16 !0.24 !0.09 !0.05 !

0.90 !0.20 !

0.80 !0.10 !

15.00 !6.00 f

•

!

l

NA : not applicableme./100gm. : milliequivalents per 100 gm. of soilHeh. : Hehlich Analysisnod. 01. : Hodified Olsen ExtractionAgTU : Silver Thio Urea Extraction

- 1.26 -

District: Lam Trial Site: 28.1 Hpeketoni

Table 28.1.12 : Analytical Results (cheiical analysis, results on air dry soil basis)Farnrs' Fields Conposite Sanples

1 11 21 31 41 Ci 3

1 678A3

101112Id

14<[13

1617iflID

192021222324252627282930313233

351600

3738394041

|Lab. NO.IFine earth I; Vol.»eight kg./l.1105 deg. C / air dry

|pH H20 1/1IpH H20 1/2.5|pH N KC1 1/2.5i

|C org. 1IN tot. XIC/N

iMod.Olsen Abs.260nn.

IP Meh. 1/5 ppi.IP nd.Olsen ppn.

|Na Meh.1/5 n./IOOgn.11.

IK Heh. 1/5 n./IOOgn.|K nd.01. n./IOOgn.1I

|Hg Meh.1/5 n./IOOgn.|Hg nd.01. n./100gn.1I

ICa Heh. 1/5 n./IOOgn.ICa nd.01. n./IOOgn.1I

|Mn Meh.1/5 n./IOOgn.|Hn nd.01. n./IOOgn.11

|Zn nd.01. ppn.

|Cu nd.01. ppn.

|Fe nd.01. ppn.Ii

|Hp BaC12 n./100gn.|H 1 Al KC1 n./100gn.|A1 KC1 n./100gi.

Depthen.

20202020

202020

202020

20

2020

20

2020

2020

2020

2020

20

20

20

202020

FarnrsA

10620100

6.406.905.80

0.840.06

14

5140

0.10

0.440.44

1.201.86

4.408.50

0.740.12

1.50

1.80

28.00

1 fieldsB

10621100

7.107.806.80

1.080.08

14

210120

0.18

0.800.74

1.603.75

10.4017.10

0.660.13

1.50

2.00

30.00

not applicablenot applicablenot applicable

(code)C

10622100

6.306.705.40

0.840.07

12

2011

0.12

0.400.34

1.801.50

2.806.90

0.560.16

0.80

1.90

33.00

D

10623100

6.807.306.10

1.540.13

12

13653

0.18

0.880.81

2.603.69

9.2016.20

0.540.09

0.60

2.80

41.00

E

10624100

6.506.805.90

1.160.10

12

5134

0.14

0.500.57

2.002.00

5.208.90

0.680.14

1.10

1.50

29.00

F

10625100

6.406.705.60

0.960.08

12

4618

0.12

0.470.49

1.701.96

4.809.10

0.520.11

0.60

2.20

40.00

G

10626100

6.707.105.90

1.480.12

12

11480

0.18

0.860.89

2.203.40

8.4015.70

0.520.12

0.50

2.20

68.00

H

10627too

6.406.805.90

0.850.10

9

7847

0.08

0.580.56

1.202.05

4.009.50

0.360.13

2.90

2.40

37.00

Trial siteaverage

100

6.477.006.07

0.890.07

12

4128

0.12

0.590.81

1.702.30

5.7310.60

0.670.14

1.50

2.30

29.00

X

100

6.567.015.94

1.070.0911.99

82.9647.79

0.14

0.610.63

1.782.50

6.1011.39

0.580.13

1.22

2.12

37.22

s

0.00

0.260.360.39

0.270.021.53

60.3133.90

0.04

0.180.19

0.450.86

2.603.85

0.120.02

0.75

0.38

12.55

Max. 1diff. 1

0.00 I

0.80 I1.10 I1.40 |

0.70 |0.07 |5.50 |

190.00 |109.40 |

0.10 |

0.46 |0.55 I

1.40 |2.25 1

7.60 110.20 |

0.38 |0.07 |

2.40 |

1.30 1

40.00 I

MA : not applicablen./100gi. : •illiequivalents per 100 gn. of soilppi. : parts per lillionHeh. : Hehl ich AnalysisNod. 01. : Modified Olsen Extraction

- 1 .27 -


3.3 Evaluation of Soil Data

3.3.1 Literature References and Soil Correlation

Since 1972, the Kenya Soil Survey has carried out many soil surveys andsite evaluations and, in addition, some surveys were conducted by otheragencies. A complete list of soil survey reports is given in Chapter II.2of the main report. The report referring to the area in which the trialsite is situated is listed below.

Literature references:

ElW.G. Sombroek, H.M.H. Braun and B.J.A. van der Pouw(1982). Exploratory Soil Map and Agro-Climatic ZoneMap of Kenya, 1980, scale 1:1,000,000.

In order to correlate existing information with findings at the trial site,the map units and classification units in the above-mentioned reports havebeen grouped in Table 28.1.13. Moreover, the FURP soil map unit (Map28.0.4) and the classification of the soil of the profile at the trial plotare given.

Table 28.1.13: Soil Correlation with Respect to the Mpeketoni TrialSite

Reference

El

FURP

Map unit

Pc4

PcJ6

Trial plot profile

Soil Classification

(ferralo-)chromic Luvisols andcambic Arenosols, with gleyic +albic Luvisols, sodic phase, anddystric and solodic Pianosols

(ferralo-)chromic Luvisols andcambic Arenosols, with gleyic +albic Luvisols, sodic phase, anddystric and solodic Planosols

chromic LUVISOL

Out of the many soil classification units mentioned by El, the soils at thetrial site appeared to key out as chromic Luvisols.

3.3.2 Representativeness

For two reasons, statements about the representativeness of the soils ofthe trial site should be made with care.Firstly, soil classification units are mainly based on properties of arelatively permanent nature, i.e. those of the sub-surface horizons and notthose of the topsoil.

- 1.28 -


Secondly, the generally high variability of topsoil properties within shortdistances is not reflected in relatively small-scale reconnaissance soilmaps (1:100,000 to 1:1,000,000).

In this report, soils of a map unit considered to be within the "area ofrepresentativeness" must meet the following requirements:

(a) the soil-related land factors must have the same or similarratings ;

(b) soil classification must be the same or similar.

The extent to which all the FURP trial sites are representative of thesoils of Lamu District is shown in Map 28.0.5: "Groupings of Soil MappingUnits Represented by Trial Sites in Lamu District". This map is discussedin Sub-Section 28.0.5.Distinction is made between high representativeness - code A - and moderaterepresentativeness - code B if soil conditions are slightly morefavourable than at the trial site and code B- if soil conditions areslightly less favourable than at the trial site. Code C is applied for theremaining parts of the District, where none of the FURP trial sites arerepresentative.

Within Lamu District, the Mpeketoni Trial Site is highly, moderately andnon-representative (28.1.A/B-/C) for soil map units PcJ6, Dl, Zl and Z2respectively.

"A" refers to Luvisols, Acrisols, and Ferralsols."B-" refers to Arenosols."C" refers to Regosols, Pianosols, and soils with a sodic phase.

These classifications can be found in the Legend to the Soil Map.

The Mpeketoni Trial Site is not representative of areas outside LamuDistrict, but it shows a certain degree of similarity with the trial sitesin Kilifi District (29.1, 29.2).

3.3.3 Variability of Soil Properties within the Trial Site

The plot has micro-topographical discrepancies. In order to investigateeventual differences in profile development, two pits were dug andexamined. Samples were taken from both pits. A comprehensive listing of theaccompanying soil test data is given in Tables 28.1.10 to 28.1.12.

For the sake of comparison, data on pH and organic carbon content of thetopsoil are repeated in this Sub-Section.

pH-KCl: profile pits: 5.8composite samples: 5.9-6.2farmers' fields: 5.4-6.8

- 1.29 -


organic carbon.content :profile pits: 0.7-0.9%composite samples: 0.9%farmers' fields: 0.8% (fields A,C) - 1.5% (fields D,G)

3.3.4 Fertility Status of the Soil

The criteria applied for the interpretation of the analytical data areoutlined in Chapter IV.2 of the main report.

As the site was not selected and sampled until the end of Phase I (pre-paratory phase) of FURP, it was not possible to carry out the entire set ofdeterminations planned. The following analyses were omitted: total N in theprofile samples, exchangeable bases by Silver-Thiourea, P by citric acid,S04 solubility, Fe and Al by acid oxalate, volume weight and humidity ofsieved sample.

3.3.4.1 Soil Profile

For this trial site two profiles were described, located at opposite edgesof the plot (see Figure 28.1.7). The analytical data are presented in Table28.1.10 and are interpreted in the following paragraphs. Sample numbers28.1.1 to 28.1.5 (lines 1-6 in the Table) are from pit "a", while theremaining samples (lines 8-13) are from pit "b".

The rooting depth of the very deep soil is limited neither by physicalobstacles nor by extreme acidity in the subsoil. The capacity for plantavailable moisture in the upper 100 cm. of the profile may be roughly esti-mated from the pF determinations carried out on the Ap and the Btlhorizons; it attains approximately 75 mm. As plant roots may exploit aconsiderably deeper soil volume, the available moisture capacity may berated moderate (80-120 mm.).

The entire profile down to a depth of 120 cm. (maximum sampling depth)shows a low to moderate CEC (pH 8.2) of 10-17 me./100 gm. The base satura-tion is medium to high (42-62%). Both CEC and base saturation decreaseslightly with depth and are higher in profile "a" than in profile "b".

With reference to the CEC; exchangeable K is very high (0.56-1.25 me./100gm. in profile "a" and 0.41-0.75 me./100 gin. in profile "b"). Mg is alsovery high (1.2-1.9 me./100 gm.). In profile "a" Mg appears almost constantover the entire profile, while in profile "b" it decreases slightly withdepth. Ca is low in comparison to the other bases and in the medium range(3.5-6.8 me./100 gm.). The topsoil of profile "a" shows a much higher Castatus than in profile "b". Exchangeable bases appear well balanced withrespect to plant nutrition. The K/Mg ratio, however, tends to be narrow.

The soil reaction is slightly acid (pH KC1 5.6-5.8) and almost constant forboth profiles. This soil pH is very favourable for plant growth.

The organic matter content of the Ah horizons is medium (0.9 % C). Thehumus content decreases rapidly with depth to very low values below the Ah.

- 1.30 -


In both profiles the control samples show a much lower humus content thanthe original Ah samples.

Available P (Olsen method) varies considerably in the two profiles. Whileprofile "b" appears poor in P, profile "a" shows a high P level in thetopsoil.

3.3.4.2 Soil Fertility Assessment of Composite Samples

The analytical results for the composite samples from the trial site(depths 0-20 cm. and 20-50 cm.) are presented in Table 28.1.11. The datafor the farmers' fields (depth 0-20 cm. only) are given in Table 28.1.12.

The composite samples were analyzed to assess the chemical fertility statusof the soil, with special emphasis on the availability of the importantnutrient elements to the plants. The "available nutrients" were estimatedby means of two complementary methods, the "Mehlich" diluted double-acidmethod (NAL routine) and a "modified Olsen" bicarbonate + EDTA extraction.

The interpretation of the analytical data presented is in so far tentativefor both methods as the validity of the applied ratings (ranges for Low,Medium, High) has not yet been verified by field trials in the variousregions of Kenya.

The total N contents of the moderately humic soils are low to medium (0.06-0.12% N). The C/N ratios are generally wide. This and the other prevailingsoil factors indicate that the N supplying capacity of the soil is probablylow, changing only a little with the humus content of the soil and the C/Nratio.

Available P appears very erratic. The topsoil samples generally show highto very high values, ranging from 20-210 ppm. by Mehlich analysis and from11-120 ppm. by the modified Olsen method. For the trial site a high Pstatus is indicated (40 ppm. by Mehlich analysis; 30 ppm. by modified Olsenmethod). Subsoil samples, available only for the trial plot, show a low tomedium P status (Blocks I and II: 17 ppm. by the Mehlich analysis, 4 ppm.by the modified Olsen method; Block III: 8 ppm. by the Mehlich analysis, 13ppm. by the modified Olsen method). Obviously these data reflect the more/

or less extensive use of P fertilizer in the various fields. P values over80 ppm. by Mehlich analysis or 60 ppm. by the modified Olsen methodcertainly indicate over-fertilization, provided that a representativesample was obtained from the field. Excessive P levels are encountered infarmers' fields B, D, G and H, but only field C shows a moderate P status.

The P availability of the natural, unfertilized soils of the region may notbe deducted from these analytical results. However, the coastal sands arenormally poor in P.

All trial site composite samples are high to very high in K (0.5-0.6me./100 gm. by the Mehlich analysis, and 0.6-0.9 me./100 gm. by the modi-fied Olsen method). The K supply of the farmers' fields varies in a widerrange from medium to very high (0.4-0.86 me./100 gm. according to the Meh-

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District: Lamu Trial Site 28.1 Hpeketoni

lieh analysis, 0.34-0.89 me./lOO gm. according to the modified Olsenmethod). Only in field C is a medium K level reported. All other fieldsappear high in K.

According to both methods (Mehlich analysis and modified Olsen method), theavailable quantities of Mg are high to very high throughout (1.5-3.75me./100 gm. by the modified Olsen method). The Ca levels are medium to high(6.9-17.1 me./100 gm. by the modified Olsen method) and appear as erraticas the Mg values. Within the trial site Ca and Mg show almost the samevalues in all three blocks.

According to the Mehlich analysis, available Mn is well within the adequaterange (0.36-0.78 me./100 gm.). The modified Olsen method shows much lowervalues than the Mehlich analysis, but Mn deficiency may not be expected.

According to the modified Olsen method, Zn is only available in very lowamounts, with most samples showing Zn values below the deficiency level of1.5 ppm. The modified Olsen-Cu values appear low to moderate in all samples(1.5-2.8 ppm.), and acute deficiencies are not be expected. However, theexcessively high P status of some soils may interfere with Cu uptake by theplants and Cu deficiency may occur even though soil Cu appears adequate. Itis not known whether or not the modified Olsen method is sensitive to theseinterferences. HC1 extractable Zn, Cu, and Fe, as determined in Block I ofthe trial site, are below the critical level (<5 ppm. Zn; <1 ppm. Cu; <10ppm. Fe). The amount of Fe extracted by the modified Olsen method ismedium.

The soil reaction (pH) of the composite samples is in the slightly acid toneutral range (pH KC1 5.4-6.8). These conditions are favourable for plantgrowth. In the soils with a pH (KC1) close or above 7 the availability ofP, B and Mo is limited and NH4 turns to volatile NH3.

The evaluation of the Mehlich Analysis data according to NAL standards isgiven in Table 28.1.14.

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District: Lamu Trial Site 28.1 Mpeketooi

Table 28.1.14: Evaluation of the Mehlich Analysis Data According to NALStandards

Parameter

Soil reaction (pH)Acidity (Hp )

Available nutrientsSodiumPotassiumCalciumMagnesiumManganesePhosphorus

Total NitrogenOrganic Carbon

C / N RatioCa / Mg RatioCa / K RatioK / Mg Ratio

Trial Site

Slightly acidLow

LowAdequateAdequateAdequateAdequateAdequate

LowLow

FavourableFavourableFavourableFavourable

Farmers' Fields

Slightly acidLow

LowAdequateAdequateAdequateAdequateAdequate

LowLow

FavourableFavourableFavourableFavourable

Remarks on Trial Site:Soil reaction is quite favourable. Positive yield responses to manure and Napplications are expected. Yield responses to K, lime and P applicationsare unlikely.

Remarks on Farmers' Fields :Same as for Trial Site.

3.4 Sampling Programme for Laboratory Analyses

3.4.1 Soil Samples

Soil samples will be collected once a year at the beginning of the longrains in April/May just after ploughing and before the fields are plantedThe samples will be taken individually from two depths (0-20 cm. and 20-50cm.) for each replication of the selected fertilizer treatments, and onlyfrom the plots in Module 2 with maize/cowpeas relay cropping.

The treatments to be sampled are :

Trial I: N0:P0 N75:P0 N0:P75

Trial II: 0mulch

FYMmulch+NP

FYM+NPmulch+NP+FYM

N75:P75

NP+Kmulch+NP+K

Farmers' fields: Fields B, C, and H are proposed

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3.4.2 Plant Samples

Harvest samples from the maize/cowpeas relay crop include individualsamples of grain and straw from maize and cowpeas respectively. Sampleswill be collected separately from each replication of the treatments wheresoil samples were taken, i.e.:

Trial

Trial

I:

II:

N0:P0

0mulch

N75:P0

FYMmulch+NP

N0:P75

FYM+NPmulch+NP+FYM

N75:P75

NP+Kmulch+NP+K

Farmers' fields: Harvest samples will only be collected from those farmers'fields where soil samples were taken. Individual samples of grain and straware only required from the maize crop.

3.4.3 Other Samples

From every batch of applied FYM and mulch (e.g. shrub prunings, coconutfrond, or grass) three representative samples will be taken.

4. Conclusions from the Analyses of Climate and Soils

4.1 Moisture Availability

The amount of rainfall which is surpassed in 20 out of 30 years (i.e. 66%probability) constitutes the basis for estimating moisture availabilityduring the growing periods. Other parameters of the water balance such asmoisture storage capacity, run-off and deep percolation also have to beconsidered in order to obtain a comprehensive picture of the moistureavailability.

For example, the water requirements and the water availability forMaize/Pwani, first rains, at the Mpeketoni Trial Site, can be interpretedas follows:

Figure 28.1.6 shows that the maximum water requirements (ETm) of themaize crop are quite in line with the rainfall pattern at the 66%probability level. In June, however, there are deficits of rainfallaccording the 66% probability level.

Since the moisture storage capacity of the soil is rated moderate (i.e.80-120 mm), the water surplus of May can partly offset the probabledeficits of June and early July. Early planting is risky, because offeeble and unreliable rainfall (see Figure 28.1.5).

Run-off is considered to be low: the trial plot is located on almostflat land (slope 0-2%) and, moreover, the crop provides sufficientground cover at the time of maximum rainfall intensity in May.

Deep percolation could be estimated, but can be omitted, since it isgenerally very low. Run-on occurs to some extent, favouring the lowerparts of the plot.

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Lateral sub-surface flow and ground water possibly bring some additionalwater, but they have to be checked carefully by monitoring the soilmoisture to find out to what extent they influertce the water balance.

Summarizing the evaluation of the climatic factors, the yield potentialfrom the climatic point of view can, for the maize crop in the first rains,be rated good on a "20 out of 30 year" basis.

It must be borne in mind, however, that the figures on rainfall amountspresented (rainfall station: 09240003, see Figures 28.1.5 and 28.1.6), areslightly higher than at the Mpeketoni Trial Site.Growing crops in the "second rains" is unlikely to be successful. In fact,the very short cropping season with low rainfall is no real agro-humidperiod (see Figure 28.1.5).

4.2 Nutrient Availability in Relation to Possible Fertilizer Requirement

The N supplying capacity of the moderately humic soils appears low to mode-rate. Available P is generally very high. Some farmers' fields show evenexcessive levels of P; most probably these values reflect the more or lessextensive use of P fertilizer. In all samples, K tested high. While Mg ap-pears very high in all samples, Ca was extracted in medium to high amounts.All samples show very low Zn values; Cu should normally be available insufficient amounts.

The plant uptake of S04 (not tested), Zn, Cu, and B (not tested) should beclosely monitored during the trials.

Fertilizer applications should first of all consider N as the mostimportant plant nutrient.

For sustained high yields regular N fertilization will be necessary, eitherfrom FYM or green manure or in mineral form. When mineral N is applied, itshould be supplemented with mulch and other organic amendments. This is toprotect the topsoil, particularly during the heavy rains in April andOctober/November, and to maintain or, preferably, raise its humus content.The humus plays an essential role in stabilising the structure of the top-soil, enhancing infiltration rate and moisture storage capacity, and inpreventing applied nutrients from leaching too quickly.

P fertilizers are not needed at all at the present stage, since responsesto P are very unlikely. In some farmers' fields even negative reactions toadditionally applied P may occur. The trials will-have to show for how longthe high P levels are maintained under intensive cropping.

In fields with a low or medium P status, P may be applied as TSP, SSP, DAPor any other fertilizer with high water solubility. Under the prevailingslightly acid to neutral soil conditions, rock phosphate will not be read-ily available to plants and far less efficient than TSP. The efficiency ofP application may be enhanced-by the addition of fresh FYM to stimulatesoil biological activity.

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District: Lami Trial Site 28.1 Npeketoni

Liberal applications of N and P may induce or intensify deficiencies ofmicro-elements, notably Zn and Cu in this trial site.

K applications are at the present stage not required and response to K maybe only erratic or not be obtained at all for the duration of the trialsover five years. However, the analytical data provide no information on thereserves of K beyond the exchangeable pool. Permanent high applications ofmineral N and P might, in the long run, need to be supplemented with K tocompensate the quantities of K removed with the harvests. FYM is normally agood source of K.

If K fertilizer is to be applied, K2S04 should generally be preferred to KC1(both contain 50% K20). The S04-ion is an important plant nutrient, and itenhances P availability. The form in which K is applied should also takeinto account crop requirements (e.g. KC1 to cabbages, but not to Irishpotatoes).

Under the prevailing soil conditions lime must not be applied. The acidify-ing effects of the applied mineral or organic fertilizers will besufficiently buffered by the soil.

4.3 Other Relevant Land Qualities

In addition to an assessment of moisture and nutrient availability, thefollowing land qualities are relevant in the context of fertilizer use:

a) Oxygen availability.In sandy to loamy soils like those at the trial site, exchange of oxygenand carbon dioxide is generally not hampered. When persistent, heavydownpours occur, the soils face temporarily anaerobic conditions,accompanied by retarded crop growth. The porous massive subsoil whichprevails in the soils of the trial site may enhance the danger of impededexchange of gases.

b) Rootability.The soils provide an environment which is suitable for root development andtuber expansion, although the porous, massive subsoil does not allow bigroots to penetrate.

c) Resistance to erosion.Low to moderate erodibility of the sandy to loamy soils and almost leveltopography turn resistance to erosion into a land quality of minorimportance.

d) Ease of cultivation and scope for agricultural implements.There are no serious limitations as to manual land preparation, oxen ortractor ploughing.

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5. Trial Design and Execution Plan, Mpeketoni

(Full details of the methodology for carrying out the trials are shown inChapter IV of the main report.)

Selection of Crops: The proposed crop sequences in each of the threemodules for the Lamu Trial Site are:

Site 28.1 Mpeketoni,Lamu.

RAINY SEASONS1st, Long, March - May

51 Maize.& Sorghum52 Maize & Cowpeas53 Cotton

Coast CompositeC.C.+Cowpeas (Local) Relay Pi. May/June

Cotton UKA 59-240 continues for one year

The 1st sequence or module is pure maize once a year.The 2nd module is maize, relay-planted with cowpeas in May/June.The 3rd is cotton which is continued over one year and is likely to berotated with another suitable crop.

Each module contains 2 Experiments, namely Experiment 1 and Experiment 2.

Experiment 1 is a 4N x 4P factorial, with 2 replications in each module.Experiment 2 at this site is a 2NP x 2K x 2CFM x 2FYM factorial, also with2 replications in each module. (CFM = Coconut Frond Mulch, also known asMakuti, used here to reduce soil temperatures during the first four weeksafter planting and to conserve moisture.)

Each module thus consists of 64 plots, and the total for the 3 modules is192 plots.

Mineral fertilizers, FYM and CFM will in all three modules be applied onceper year during planting time in the March/April rains. The relay-croppedcowpeas will not receive any fertilizer at planting directly but will"scavenge" from the maize and from residual fertilizer left after the firstseason.

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