The suitability of domestic roof harvested rainwater as source of irrigation water for homestead

gardening.

Akintola, O.A*. and Sangodoyin, A.Y**.

*National Horticultural Research Institute of Nigeria, Idi-Ishin, Ibadan. Nigeria. E-mail: akinbolanle97@yahoo.co.uk ** Department of Agricultural and Environmental Engineering, Faculty of Technology, University of Ibadan, Ibadan. Nigeria.

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OUTLINE OF PRESENTATION

Introduction

Methodology

Results and Discussions

Conclusions

INTRODUCTION Good quality food is essential in the right quantity and

quality to enhance quality of life.

Due to some problems associated with horticultural crop handling in developing countries such as indiscriminate application of chemicals and other dangerous farming practices, homestead gardening seem to be a way of ensuring that each householder has access to good quality food.

To achieve this, a source of irrigation is imperative.

Contamination of surface and shallow wells due to improper handling of industrial and domestic wastes is the main reason why the use of domestic roof harvested rainwater (DRHRW) is generally being recommended.

INTRODUCTION (CONTD.)

Rainwater is expected to be clean since it has been purified in the hydrological cycle.

Previous work had focused on quantity rather than the quality of harvested rainwater.

Hence this study investigated the quality of DRHRW harvested under varying environmental conditions in relation to its use for irrigation of homestead garden.

METHODOLOGY The areas used for this study were Ibadan (7o2314711N, 3o551011E), Lagos

(6o271111N, 3o2314511E) and Port-Harcourt (4o451011N, 7o01011E) in Nigeria (Fig. 1)

The samples were collected at twelve locations per city in three replicates.

Four different roof materials, namely corrugated iron sheet, long span aluminium, asbestos and step-tiles in service condition in some pre-selected locations in Ibadan (residential), Lagos (industrial) and Port-Harcourt (gas flaring) regions were investigated (Fig. 2)

The rainwater samples were collected from roofs with varying length of service viz: < 5years; 5 to 10years and >10years of service.

Water samples were harvested using clean and sterile polyethylene bowls and transferred into clean polyethylene containers at about 1.5m above the ground surface.

The procedure eliminated possible contamination through splashes from the ground surface or the introduction of other sources of contamination outside the scope of this study.

METHODOLOGY (CONTD.)

Microbiological Analysis Samples were collected into McCartney bottles using

sterile plastic buckets and bowl.

All the samples were analyzed within 24 hrs.

The procedure employed include: determination of the total viable count by pour plate method; presumptive coliform test for the detection of coliform as well as detection of pathogens using differential media.

The chemicals used in the study were of analytical grade. All the microbiological media used were produced by Difco and the preparation was done according to test guidelines (APHA, 1995; Coker and Ehimika, 2005).

 

METHODOLOGY (CONTD.)

Chemical Analysis Samples were collected using clean

buckets and bowls into clean and pre-treated polyethylene container.

Metals in the samples were preserved in 5mls conc. HNO3 in 1L of water (John-De-Zuane, 1990).

Sample preparations and handling were done according to standard procedures viz John-De-Zuane (1990), APHA (1995) and WHO (2004).

RESULTS AND DISCUSSIONS

Microbiological Quality The samples showed evidence of contamination which is

likely to be either from dust or bird droppings (Table 1).

Escherichia coli (E. coli) was isolated from almost all the samples considered. The value was observed to be below the infection dose of 106cfuml-1 (Hazen and Toranazos, 1990).

It will only be of major concern if the water is used to irrigate

fruit crops and the fruits are eaten without washing.

Pseudomonas fluorescens, on the other hand was detected in about 25, 50 and 70% in the samples from residential, industrial and gas flaring regions respectively.

RESULTS AND DISCUSSIONS (CONTD.) P. fluorescens strains (CHAO or Pf-5) present

bio-control properties, protecting the roots of some plant species against parasitic fungi such as Fusarium and Pythium, as well as phytophagous nematodes (Anon.,2007).

DRHRW that is “contaminated” with P. fluorescens can be a good source of irrigation water and may assist the farmer in curtailing the problem of nematode invasion thereby increasing crop yield.

Age of roof and roof type does not have major impact on the distribution of E.coli and P.fluorescens (Table 1).

RESULTS AND DISCUSSIONS (CONTD.)

Chemical Quality Lead was detected in about 62% of samples from Ibadan

(residential) and all the samples from Lagos (industrial) and Port-Harcourt (gas flaring) areas.

Cadmium was detected in all the samples from Industrial area as well as in about 69 and 84% of samples from residential and gas flaring areas.

Lead and Cadmium were detected from DRHRW in all the three locations in the range 0.01 – 0.13mg/L and 0.01 – 0.15mg/L respectively (Figs. 3 - 5). These were traced to anthropogenic factors.

Mean Cd value of 0.02, 0.06 and 0.05 (Fig. 6) for Ibadan, Lagos and Port-Harcourt respectively indicate almost 3 times Cd levels between residential and industrial or gas flaring in rainwater samples

RESULTS AND DISCUSSIONS (CONTD.) Rainwater harvested in industrial and gas flaring regions must

not be considered for irrigation purpose so as to avoid situations in which cultivated crops will accumulate heavy metals and pass it to man via food chain.

Iron and nitrate were detected in almost all the samples investigated in the range of 0.21 – 1.13mg/L and 51.05 – 305.93mg/L respectively (Table 2).

Nitrate content in DRHRW samples collected were higher than the WHO recommended standard of 45mgl-1 for all locations.

This however does not pose any risk to its being use to irrigate homestead gardening. On the other hand, it is an indication of its suitability for irrigation purposes.

The concentrations of iron detected is also within the safe limit recommended for use by health authorities even for potable uses (WHO, 2004: USEPA, 1994).

CONCLUSSIONS Findings from this research work indicated that the quality of

DRHRW in industrial and gas flaring environments are not suitable for irrigation of homested gardening because of its chemical constituents.

It is contaminated with lead and cadmium which are suspected to be from anthropogenic source.

Those harvested from residential environment however

proved to be suitable for irrigation purposes.

The presence of Pseudomonas flourescens in all location indicated that DRHRW may also serve as a nemanticide to some extent, if used to irrigate homestead garden

Thanks for your patience

Fig.1. Site maps indicating sampling sites

Corrugated iron sheet in service condition.

Long span aluminium in service condition

Asbestos roof in service condition.

Step tiles in service condition.

Fig 2. The four roof materials investigated

Ibadan Lagos Port-Harcourt

Rtp Age E.coli Pse fl. E.coli Pse fl. E.coli Pse fl.

1 1 1.33 ± 0.01 0.83 ± 0.01 2.00 ± 0.01 1.67 ± 0.01 1.75 ± 0.01 3.01 ± 0.01

1 2 1.27 ± 0.21 nd 6.00 ± 0.01 0.50 ± 0.00 1.27 ± 0.02 nd

1 3 nd nd 3.67 ± 0.01 1.17 ± 0.01 1.04 ± 0.01 0.83 ± 0.01

2 1 2.50± 0.00 nd 3.17 ± 0.01 nd 1.07 ± 0.01 0.50 ± 0.00

2 2 1.17 ± 0.01 nd 2.00 ± 0.01 0.33 ± 0.00 1.24 ± 0.01 0.84 ± 0.01

2 3 1.83 ± 0.01 nd 1.78 ± 0.01 nd 1.24 ± 0.00 0.83 ± 0.01

3 1 1.60 ± 0.01 nd 3.83 ± 0.01 0.83 ± 0.01 1.57 ± 0.01 nd

3 2 2.50± 0.00 1.00 ± 0.00 5.16 ± 0.02 0.50 ± 0.00 3.11 ± 0.01 1.17 ± 0.01

3 3 2.17 ± 0.02 nd nd nd 0.49 ± 0.01 0.83 ± 0.01

4 1 1.27± 0.21 nd 2.93 ± 0.01 nd 1.24 ± 0.00 0.50 ± 0.00

4 2 2.00 ± 0.01 1.06 ± 0.01 0.98 ± 0.01 nd 1.25 ± 0.01 nd

4 3 1.00 ± 0.00 nd 1.62 ± 0.01 nd 1.24 ± 0.01 1.16 ± 0.01

Contr 1.62 ± 0.04 nd 6.00 ± 0.01 1.83 ± 0.01 2.11 ± 0.01 nd

Table 1. Microbiological qualities of domestic roof harvested rainwater under investigation.

All parameters in cfu/ml All parameters in cfu/ml (x 105Cfu/ml).Rtp- Roof type. Rtp- Roof type. Rtp 1 to 4 represent corrugated iron sheet, long span aluminium, asbestos and step-tilesRtp 1 to 4 represent corrugated iron sheet, long span aluminium, asbestos and step-tilesAges 1 to 3 represent 5, 5 – 10 and ˃ 10 years in service conditionsAges 1 to 3 represent 5, 5 – 10 and ˃ 10 years in service conditionsContrContr - Control - Control i.ei.e rainwater samples collected without input from roof materials. rainwater samples collected without input from roof materials.

Fig. 3. Box and Whisker presentation of concentrations of Cd and Pb (Mg/l) for Ibadan, Lagos and Port-Harcourt, Nigeria referred to as locations 1, 2 and 3 repectively. Thus Pb1 refer to concentration of Pb in samples from Ibadan area

Fig. 4. Box and Whisker presentation of concentrations of Cd and Pb for age of roof: ˂5, 5 – 10 and ˃ 10 years in service condition denoted by 1, 2 and 3 repectively. Thus Cd1 refer to concentration of Cd for from roof that is ˂ 5years in service condition

Fig. 5. Box and Whisker presentation of concentrations of Cd and Pb for corrugated iron sheet, long-span aluminium, asbestos and step tiles denoted by 1, 2 and 3 respectively. Thus Cd 4 refer to concentration of Pb in samples from step tiles’ roof

Fig. 6 Mean Cadmium concentrations (Mg/L) for the three locations under consideration.

Ibadan Lagos Port-HarcourtRtp Ag

e Fe NO3 Fe NO3 Fe NO3

1 1 0.47 ± 0.02

152.79 ± 0.61 0.69 ± 0.01 204.14 ± 0.08 0.66 ± 0.02 153.49 ± 0.61

1 2 0.39 ± 0.01

255.93 ± 1.21 0.57 ± 0.01 102.44 ± 1.60 0.73 0.02 203.84 ± 0.61

1 3 0.45 ± 0.02

255.23 ± 1.05 0.60 ± 0.02 51.05 ± 1.05 0.50 ± 0.02 153.49 ± 0.61

2 1 0.65 ± 0.01

203.49 ± 1.21 0.58 ± 0.02 51.40 ± 1.60 0.21 ± 0.01 204.54 0.60

2 2 0.71 ± 0.01

203.52 ± 1.15 0.59 ± 0.02 103.14 ± 1.05 1.13 ± 0.03 101.74 ± 0.60

2 3 0.77 ± 0.02

153.14 ± 1.05 0.56 ± 0.01 153.49 ± 0.61 0.46 ± 0.03 102.44 ± 0.61

3 1 0.73 ± 0.01

255.23 ± 0.00 0.67 ± 0.02 51.40 ± 0.60 0.39 ± 0.01 102.48 ± 0.57

3 2 1.13 ± 0.01

152.78 ± 0.63 0.65 ± 0.02 102.44 ± 0.61 0.35 ± 0.01 102.44 ± 1.60

3 3 0.55 ± 0.01

305.93 ± 0.61 0.59 ± 0.02 255.53 ± 0.65 0.73 ± 0.01 204.14 ± 0.08

4 1 0.57 ± 0.01

255.23 ± 1.05 0.58 ± 0.01 203.84 ± 1.60 0.95 ± 0.04 102.09 ± 0.00

4 2 0.75 ± 0.01

152.79 ± 0.61 0.60 ± 0.02 101.74 ± 0.60 1.05 ± 0.02 nd

4 3 0.57 ± 0.03

255.23± 1.05 0.56 ± 0.02 102.14 ± 0.08 0.37 ± 0.02 152.09 ± 1.05

Contr 0.63 ± 0.01

204.19 ± 1.05 0.52 ± 0.02 152.09 ± 1.05 0.56 ± 0.02 152.79 ± 1.60

Rtp- Roof type. Rtp 1 to 4 represent corrugated iron sheet, long span aluminium, asbestos and step-tilesAges 1 to 3 represent 5, 5 – 10 and ˃ 10 years in service conditionsContr - Control i.e rainwater samples collected without input from roof materials

Table 2. Concentrations of Fe and NO3 in domestic roof harvested rainwater under investigation