COVER CROPS AND SOIL HEALTHlandresources.montana.edu/soilfertility/documents/PDF... ·...
Transcript of COVER CROPS AND SOIL HEALTHlandresources.montana.edu/soilfertility/documents/PDF... ·...
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Susan Tallman, CCA USDA-NRCS, Bozeman Area Agronomist
Clain Jones, Perry Miller, Justin O’Dea, Macdonald Burgess,
Anton Bekkerman, Cathy Zabinski, Meg Housman
Dept. of Land Resources and Environmental Sciences
COVER CROPS AND SOIL HEALTH
Photo: Scott Smith
Photo: Steve Spence
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Overview
Soil Health overview
Montana and Big Horn County
Study 1: The Power of Peas
Study 2: Cocktails Plot Study
Study 3: Cocktails Farm Study
Study 4: Long Term Study
Conclusions and Resources
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The Summerfallow Challenge
PROS:
Soil moisture recharge
N benefit
CONS:
Loss of organic matter
Increased soil erosion
Decreased soil structure
Decreased water holding capacity
Increased saline seeps
Increased N leaching
Decreased soil biological activity
Photo: Susan Tallman
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Soil Quality vs Soil Health
Soil Quality
Texture
pH
CEC
Soil Health
Aggregation
Microbial activity
Tilth
Nutrient availability
Water holding
capacity
Compaction
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Increased Organic Matter
= Healthier Soils
Increased nutrient and water availability
Support greater root and plant growth
Increased microbial activity
Provide resilience to uncontrollable factors
such as weather and markets
Problem: Hard to change much because
amount is so large (~40,000 lb/ac in upper 6”)
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No-Till and Crop Intensification
Photo: Steve Spence
Soil aggregation
Water holding capacity
Erosion
Photo: Susan Tallman Legume Green Manure (LGM)
Organic matter
N benefit
Management Issues
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40”
45”
50”
55”
60” 65” 70” 75”
80” 85”
90” 95”
55” 55”
50” 45” 40”
Annual Class A Pan Evaporation 50”
Provided by David Nielsen
cover crop study
locations (where less success w/ cover crops than in MT and east and north of MT)
Montana Study Locations
40”
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Precipitation;1981-2010
0
1
2
3
4
J F M A M J J A S O N D
Pre
cip
itat
ion
(in
che
s)
Month
Bismarck
Great Falls
Hardin
Western Regional Climate Center
High Plains Regional Climate Center
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Terminating legume cover crop at early bloom produced higher organic wheat yields the following year than terminating at flat pod in 2006-2007 (Miller et al. 2011)
Our MT studies confirmed early Saskatchewan
studies that termination timing is key
Similar results for advantage of bloom over pod in conventional
systems
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Study 1: Three 2-year cycles,
no-till and till, plot scale
Objective: Determine effects of legume
species and tillage on subsequent spring
wheat.
~14 inch annual precip. (Gallatin Valley, MT)
Field had been no-till for several years
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4 Tillage Treatments 3 Crop Treatments
Study 1: Design
X
• Green manures
terminated at first flower
• Spring wheat planted at 4
N rates following year
Spring Pea Manure
Spring Lentil Manure
Fallow
No-Till (NT)
No-Till, Till (NTT)
Till (T)
Till, No-Till (TNT)
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Study 1: (3-year plot scale)
Results
Burgess et al., 2012
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Study 1: Take home messages
Early-terminated spring cover crops did not
hurt subsequent grain yield or protein
compared to fallow.
Higher N fixation by pea often produced higher
subsequent spring wheat yield and/or protein
than lentil especially in no-till at low N rates.
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QUESTIONS?
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Study 2: Cover Crop Cocktails Plot
Study Objectives 1. Compare agronomic response variables of
fallow, pea LGM, and multi-species cocktails
Biomass
Biomass quality
Soil water and nitrate
Wheat yield
2. Compare select soil biology parameters of fallow,
pea LGM, and multi-species cocktails
Potentially mineralizable nitrogen Microbial respiration rate
Soil enzyme activity Mycorrhizal colonization
Soil temperature
3. Determine the specific effects of 4 plant
functional groups
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Plant Functional Groups & Species
Brassica
Nitrogen Fixers
Tap Root
Fibrous Root
Spring Pea
Pisum sativum
Lentil
Lens culinaris
Oats
Avena sativa Proso millet
Panicum miliaceum
Safflower
Carthamus tinctorius
Purple Top Turnip
Brassica rapa
Winter Canola
Brassica napus
Daikon radish
Raphanus sativus
2013
2012
2013
2012
2013
2012
Common Vetch
Vicia sativa Italian Ryegrass
Lolium multiflorum
Camelina
Camelina sativa
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Fallow Full Pea
Brassicas Tap Roots Fibrous Roots Nitrogen Fixers
Minus Nitrogen
Fixers
Minus Fibrous
Roots
Minus Tap Roots Minus Brassicas (no turnip)
All photos: Steve Spence; Amsterdam, 14 June 2012
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2012 2013 2014
Amsterdam Cover crop Spring wheat Cover crop
Conrad Cover crop Spring wheat Cover crop
Bozeman -- Cover crop Spring wheat
Dutton -- Cover crop Spring wheat
Four Site-years
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2012 Cover Crop Biomass
Photo: Steve Spence
Amsterdam 2012
0.9 Mg ha-1
= 0.4 ton acre-1
Photo: Steve Spence
Conrad 2012
0.4 Mg ha-1
= 0.2 ton acre-1
Photo: Evette Allison
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2012 Cover Crop Biomass
0.0
1.0
2.0
3.0
4.0
Pea NF TR BC MFR
< <
Conrad p<0.001
Mg
ha-
1
0.0
1.0
2.0
3.0
4.0
PEA FULL NF FR TR BC MNF MFR MTR MBC
< < <
p<0.001 Amsterdam
Mg
ha-
1
>
Tallman et al.,
2014
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Bozeman
2013 Cover Crop Biomass
Dutton
2.7 Mg ha-1
= 1.2 ton acre-1
Bozeman
3.7 Mg ha-1
= 1.7 ton acre -1
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2013 Cover Crop Biomass
Bozeman
0
1
2
3
4
PEA FULL NF FR TR BC MNF MFR MTR MBC
< <
p<0.001
Mg
ha-
1
0
1
2
3
4
PEA FULL NF FR TR BC MNF MFR MTR MBC
Dutton p=0.81
Mg
ha-
1
Tallman et al., 2014
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Lessons Learned • Early weed control is
essential
• Common vetch difficult
to terminate
• Camelina, Italian
ryegrass, and lentil not
competitive
• Radish bolts in late
spring
• Millet not competitive in
spring mix
• Possible biological
control benefits of
wheat-stem sawfly with
oat and radish
Photo: Susan Tallman
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Lessons from the Literature
Many studies in native, perennial systems indicate a positive effect of plant diversity on
total biomass.
However, over 30 studies have shown that plant species identity matters more than
plant species number in driving belowground processes.
Which plant species affect which soil processes in which ecosystems?
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Cover Crop C:N
Statistically different
only at one site year.
Practical significance?
0
10
20
30
Amsterdam Conrad
*
p=0.03 p=0.8
2012
0
10
20
30
Bozeman Dutton
p=0.15 p=0.1
2013
Tallman et al., 2014
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2013 Soil Water
0
100
200
300
< < < < < < <
mm
Dutton p=<0.001
p=<0.001
0
100
200
300
< < < < < < < < <
mm
Bozeman
Tallman et al., 2014
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2013 Soil Nitrate
0
100
200
300
Fallow Pea Full
a
b
c
kg
NO
3-N
ha-
1
Bozeman – July 2013
0
100
200
300
Fallow Pea Full
a b
b
kg
NO
3-N
ha-
1
Dutton – July 2013
Tallman et al., 2014
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Effect of cover crop treatment on spring
wheat grain yield at Dutton (2014)
Averaged over 0, 60, 120 lb N/acre
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Spring wheat yield at Dutton vs
previous year cover crop biomass
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10
15
20
25
30
35
40
6/7 6/14 6/21 6/28 7/5 7/12 7/19 7/26 8/2 8/9 8/16 8/23
2013 Soil Temperature study
Cover crops terminated on 5 July
Bozeman Te
mpera
ture
°C
Jones, Miller, et al.
unpublished
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Microbial Biomass Preliminary Results
*
*
MFR
b
a
ab
ab
a
b
Tallman, Housman,
et al., 2014
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a
ab
b
*
MFR
*
a
a
b
b
a
b
*
Potentially Mineralizable Nitrogen
Tallman, Housman,
et al., 2014
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Mycorrhizal Colonization
0
20
40
60
80
100
Amsterdam Conrad
Pe
rce
nt
Co
lon
izat
ion
*
100x
Photo: Susan Tallman
Photo: Susan Tallman
Photo: Susan Tallman
Tallman et
al., 2014
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Study 2 : Take home messages on yield
and soil quality
After one cycle, spring wheat grain yields
higher after pea and N fixers than most
other mixes.
Higher cover crop biomass correlated with
lower spring wheat yield, likely b/c of water
and N use.
Relatively few soil health differences; not
unexpected given only one cycle.
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QUESTIONS?
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Study 3: Cover Crop Cocktail
Farm Study, (2012 – 2013)
3 sites (Gallatin Valley and two in Triangle)
Cover crops selected by growers and/or NRCS
Growing season length somewhat on long side:
Site 1 (Gallatin Valley): May 29 – Aug 29
Site 2 (Triangle): Apr 12 – July 1
Site 3 (Triangle): May 5 – July 20
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Study 3: Wheat Results (after mixed CC,
farm-scale, Gallatin Valley)
Why was protein so much lower after mixed
cover crops, when generally not lower after
pure legume in Study 1?
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Percent legume and termination timing
affects plant available N (PAN)
Willamette Valley, Oregon
Sullivan and Andrews, 2012
This study:
~40% Legume.
Take home: Legume % less than 50 can result in
low available N esp if terminated late
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Study 3: Wheat Results (after mixed CC,
farm-scale, Golden Triangle)
Crop Grain Yield (bu/ac) Grain Protein (%)
After
fallow
After mixed
cc
After fallow After mixed
cc
Barley 83 a 65 b
Spring Wheat 46 a 38 b
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Study 3: Wheat Results (after mixed CC,
farm-scale, Golden Triangle)
Crop Grain Yield (bu/ac) Grain Protein (%)
After
fallow
After mixed
cc
After fallow After mixed
cc
Barley 83 a 65 b 12.1 a 9.5 b
Spring Wheat 46 a 38 b 14.5 a 14.0 b
Yield and protein less after mixed cover crops on farmers’
fields, likely due to late termination and high water & N use
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Study 3: Take home messages on yield
and protein
Spring wheat grain yield was lower after CC
than fallow in two of three field-scale studies
Spring wheat grain protein was lower after CC
than after fallow in all 3 studies.
High water use from late termination was likely
cause of yield differences.
Low N availability from late termination & low
legume % was likely cause of protein differences.
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QUESTIONS?
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Study 4: Eight-year, plot study
Objective: Determine long-term effects of legume-containing rotations vs. fallow on subsequent wheat mainly in no-till.
~16 inch annual precip. (4 miles west of Bozeman)
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Study 4: Experimental Design
Unique feature is deep, uniform silt loam soil and
relatively abundant winter precip. to recharge soils
Focus here on no-till pea forage/legume cover
crop-wheat vs. fallow-wheat
Pea forage grown in 2003, 05, 07 and pea CC
grown in 2009, terminated at full pod
Spring or winter wheat planted in even years. 2010
was wettest of wheat years, 2012 record drought.
2 N rates: Full (3 lb available N/bu) and ½ N
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Pea and Fallow Year
Wheat Year
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Study 4: Grain yield in 8th year
@ 12% moist
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Study 4: Grain protein in 8th year
Pea cover crop after 4 CC-wheat rotations
saved 124 lb N/ac compared to fallow.
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Study 4: Soil Biology Results after
8 years
Potentially Mineralizable Nitrogen
Pea-W = LGM-W > W-W = F-W
Microbial biomass
Pea-W> W-W > F-W
Aggregate Stability
No treatment differences
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Study 4: Economics (2009 – 2012) 4 y
r A
vera
ge D
isco
unte
d P
rese
nt Val
ue o
f
Net
Retu
rns
($/a
c)
500
400
300
200
Pea CC-Wht
(full N)
Fallow-Wht
(full N) Pea CC-Wht
(1/2 N)
Fallow-Wht
(1/2 N)
*
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Image: Roy Lichtenstein
In short term (1 CC-cycle studies), grain
yield and protein are generally equal or less
than after fallow.
Early termination (by ~ first pea bloom) is
key to preventing yield and protein losses.
In cover crop mixtures, the presence of a
dominant legume affects available N to
following cash crop
In long term (4+ cycles), yield, protein, and
net revenue can be higher after cover crops
than fallow, likely from more available N.
Cover crop value to soil health and
subsequent crops is expected to increase
over time.
Conclusions
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Additional Resources
MSU
landresources.montana.edu/soilfertility/covercrops.html
NRCS
http://www.nrcs.usda.gov/wps/portal/nrcs/main/national/ soils/health/
Susan Tallman, CCA USDA-NRCS Bozeman Area Agronomist 406-587-6856 [email protected]
Dr. Clain Jones
Soil Fertility Extension Specialist
406-994-6076
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http://www.sare.org/Learning-Center/
Books/Building-Soils-for-Better-Crops-3rd-
Edition
Photo: David Wolfe
Active Organic Matter Test
Hardin NRCS Office
Cornell Soil Health Test http://soilhealth.cals.cornell.edu/
• Active organic matter
• Soil respiration
• Standard fertility
• More
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Thank You • USDA – AFRI
• USDA – WSARE
• NRCS – CIG
• USDA-ARS, Mandan, ND
• Montana Fertilizer Advisory Committee
• Montana Wheat and Barley Committee
• Numerous landowners
• Ann McCauley
• Jeff Holmes
• Ann Fischer – USDA, NRCS
• Stacey Eneboe – USDA, NRCS
• Jane Holzer - Montana Salinity Control
Assoc.