Cover Crops to Improve Soil Health and Reduce Soil Erosion...Studies have measured reductions in...
39
Cover Crops to Improve Soil Health and Reduce Soil Erosion Dr. Eileen Kladivko Agronomy Department Purdue University
Transcript of Cover Crops to Improve Soil Health and Reduce Soil Erosion...Studies have measured reductions in...
Slide 1Cover Crops to Improve Soil Health and Reduce Soil
Erosion
Dr. Eileen Kladivko Agronomy Department Purdue University
Thanks to many colleagues over past 10 yrs!
Midwest Cover Crops Council www.mccc.msu.edu
Indiana Conservation Cropping Systems Initiative (CCSI) www.ccsin.org
Corn Systems and Climate CAP www.sustainablecorn.org
Rationale for cover crops
A living, growing plant at times of year when we normally have nothing growing.
Capture sunlight, feed soil organisms, sequester carbon, trap and recycle nutrients
Make better use of the resources and time available!
7 Month “Brown Gap” for soybean and corn, fallow period
Cover crop grows and takes up N during some of that normally fallow season. This would shrink the “brown gap” and keep the land green for longer time.
Cover crops are part of a system!
Different potential benefits and challenges for each type of cover crop
Must adapt cropping system, including nutrient mgmt, NT (tillage) system, manure, pest mgmt, crop rotation
Learning curve—need to do homework!
Cereal rye, SE Indiana
Outline today • Potential benefits to soil health • Examples of data on soil changes • Reminder of details being highly site-specific!
What are the potential benefits? (What are your main goals?) Nitrogen scavenger Nitrogen producer (legume) Reduce erosion Improve soil quality– aggregation,
infiltration, soil biological activity, rooting Increase soil organic matter (sequester C) Conserve soil moisture Recycle nutrients Weed control, pest suppression, extra forage Increase crop yields over long-term, and
decrease year-to-year variability in yields
Soil Health Indicators
Chemical Physical
Reviews used heavily for this talk
Kaspar, T.C., and J.W. Singer. 2011. The use of cover crops to manage soil. In J.L. Hatfield and T.J. Sauer (eds.), Soil management: Building a stable base for agriculture. ASA/SSSA, Madison, WI.
Blanco-Canqui et al. 2015. Cover crops and ecosystem services: Insights from studies in temperate soils. Agron. J. 107:2449-2474.
Classic purpose of cover crops—to cover the soil to reduce erosion Studies have measured reductions in soil
erosion and water runoff Protection of soil surface by living plants and
dead residues, even in NT Anchor surface residues, reducing their mvmt. Less detachment by raindrops, flowing water Increased infiltration Greater surface storage Slowed water velocity of runoff
Also reductions in wind erosion
NO COVER CROP OAT COVER RYE COVER
After Simulated Rainfall
Tom Kaspar, Iowa
100
67
45
100
47
11
0
20
40
60
80
100
Interrill Erosion Rill Erosion
Relative Rill and Interrill Erosion Rate in No-till Soybean as Affected by Cover Crops
No Cover Crop Oat Rye
Kaspar et al., 2001, J. Soil Water Conserv.
Chart3
Relative Erosion Rate (%)
Relative Rill and Interrill Erosion Rate in No-till Soybean as Affected by Cover Crops
100
67.2161172161
45.4212454212
100
46.5987942214
10.8946649983
Chart2
1997
1997
1997
1998
1998
1998
Control
Oat
Rye
Erosion Rate (tons/acre/hr)
Rill Erosion Rate after 5 inch Rain in 1 hr as Affected by Cover Crops
47.8588
17.0236
3.5332
37.9016
21.8416
5.4604
Chart1
1997
1997
1997
1998
1998
1998
Control
Oat
Rye
2.98 a
2.36 a
1.06 b
1.36 b
0.22 c
0.34 c
0.024 a
0.039 a
0.042 a
0.023 a
0.019 b
0.036 a
0.012 a
0.015 b
0.022 b
0.029 a
0.034 a
0.036 a
0.011 b
0.014 b
0.030 a
Control
Oat
Rye
18.96
18.5
20.34
15.63
16.88
14.76
10.87
11.78
13
Control
Oat
Rye
Erosion Rate (tons/acre/hr)
Interrill Erosion Rate after 5 inch Rain in 1 hr as Affected by Cover Crops
Rill Erosion
19.97 a
20.37 a
22.89 a
5.54 b
12.16 b
17.37 b
Total Cover
13.06 a
16.39 a
21.14 a
13.52 a
15.14 a
20.24 ab
11.67 a
17.25 a
19.02 b
18.96 a
15.63 a
10.87 b
18.50 a
16.88 a
11.78 ab
20.34 a
14.76 a
13.00 a
12.05 b
11.65 b
9.13 b
26.48 a
19.86 a
14.64 a
Control
Oat
Rye
Rill Erosion g/m2/sec
Interrill Erosion g/m2/sec
Relative Erosion Rate (%)
Relative Rill and Interrill Erosion Rate in No-till Soybean as Affected by Cover Crops
1997
1998
1997
1998
1997
1998
Control
2.98
2.36
a
a
Control
47.86
37.90
tons/ac/hr
1997
1998
0.005
Oat
1.06
1.36
b
b
Oat
17.02
21.84
0.239294
0.189508
Rye
0.22
0.34
c
c
Rye
3.53
5.46
0.085118
0.109208
0.017666
0.027302
1997
1998
1997
1998
Tracked
1.38
1.45
a
a
Untracked
1.46
1.01
a
a
Control
Oat
Rye
2.98 a
2.36 a
1.06 b
1.36 b
0.22 c
0.34 c
1.38 a
1.45 a
1.46 a
1.01 a
Control
Oat
Rye
Erosion Rate (tons/acre/hr)
Rill Erosion Rate after 5 inch Rain in 1 hr as Affected by Cover Crops Assuming Rills Occupy 0.5% of Surface Area
1996
1997
1998
1996
1997
1998
Control
78
76
81
a
a
a
Oat
79
79
80
a
a
a
Rye
84
81
85
a
a
a
1996
1997
1998
1996
1997
1998
Tracked
74
77
82
b
a
a
Untracked
87
81
82
a
a
a
Control
Oat
Rye
78 a
76 a
81 a
79 a
79 a
80 a
84 a
81 a
85 a
74 b
77 a
82 a
87 a
81 a
82 a
March 16, 2010, central Indiana. Surface shows some daikon radishes out of ground, some partially out of ground. Shows webbed appearance of dead leaves of radish.
Within a few more weeks, soil surface is bare—should not plant radishes alone, but combine with something else!
But cover crop species matters!
Tom Kaspar, Iowa
Corn silage land with and without a cereal rye cover crop
Keep your expensive soil on YOUR field!
Soil physical properties improved
exudates feed microbes which then produce polysaccharides that “glue” particles together
Porosity, permeability (esp. tap-rooted) Deep roots, macropores, can aid water infiltration,
aeration, rooting
Soil surface protected, plus better aggregation, can mean less crusting or erosion
Roots give strength to soil for trafficability
Rorick, Frank, Kladivko
T. Kaspar, Iowa
Roots or shoots?
When building soil quality, esp. with NT, the cover crop ROOTS are probably more significant than the shoot growth
Still need good shoot growth for erosion control, mulch effects for moisture conservation, weed suppression, etc.
Tap root extended another 18+ inches beyond the end of tuber. These roots are probably of more benefit for soil structure and permeability than the tuber itself.
Cover crops and soil organic matter
Potential to increase soil organic matter (SOM) or soil organic carbon (SOC) Greater inputs of biomass Less erosion losses Perhaps slower decomp., if wetter/cooler
Studies show slow increases (compared to no cover crop), or sometimes no change
Many factors affect the rate of change, and the ability to detect the changes—site specific
Factors affecting magnitude of SOC changes with cover crops (or any changes)
Cover crop biomass production (more) Cover crop species, mixes, roots/shoots Years of cover crop use (more) Soil texture, initial SOC (clay) Tillage mgmt. (no-till) Climate (production, decomp., weather) Ability to detect– number of samples, strict
control of depth, variations w/ row position and short-term crop history, lab methods
~2500 lb/A~710 lb/A
Amount of growth affects the magnitude of cover crop impacts on soil or cash crop!
Cereal Rye Cover Crop Effect on Soil Quality in a Corn Silage-Soybean System after 10 years
• A rye cover crop “increased” total soil organic matter (SOM) in the top 4 inches (10 cm) from 4.8% to 5.3%, or ½% change in SOM
• (spring biomass production ~2.8 Mg/ha after silage, 0.5 Mg/ha after soybean)
• 44% greater particulate organic matter (POM) in top 2 inches (5 cm)
• 38% greater potentially mineralizable N (PMN) in top 2 inches (5 cm)
These are really hard measurements to make – 400 cores in 3.7 acres Moore
Moore et al. 2014Iowa data
More examples of SOC changes
Using data from 37 studies worldwide, meta- analysis (Poeplau and Don, 2015) estimated gain of ~0.3 Mg/ha/yr to 22cm depth (approx. 0.01% yearly gain in SOC)
Blanco-Canqui (semi-arid), 0.1-1.0 Mg/ha/yr gain of SOC, cover+NT vs NT alone
Olson (IL), hairy vetch+cereal rye, sequestered: 0.9, 0.5, 0.1 Mg/ha/yr under NT, chisel, moldboard, respectively (12 yr)
Review by Blanco-Canqui et al., 2015, Agron. J. 107:2449-2474
Soil moisture
Effects on soil moisture are complex While living, cover crops transpire water, so
may dry soil more than fallow field—good or neutral or bad, depending……
After termination, cover crop residues often increase infiltration, decrease evaporation, leaving more moisture in soil for crop use. Can be benefit in summer.
Example soil moisture effects that sometimes occur. CCSI project; cereal rye terminated April 17; then corn grown.
~1000 kg/ha cereal rye at termination
Rye Cover Crop Effect on Plant Available Water after 12 years (Iowa) • A rye cover crop increased soil water storage
capacity (plant available water) in the top 30 cm by 18%, which is equivalent to an extra 0.75 cm of water every time the upper 30cm of soil was rewetted by rainfall.
• The rye cover crop does use water in the spring, but in 5 out of 7 years this was replenished by the time of main crop planting.
• In most years after cover crop termination water contents in the upper 30 cm were higher following a rye cover crop in the summer.
Basche et al. 2015Basche et al., 2015
Effects on cash crop rooting?
Chen and Weil (2010, 2011) studied forage radish, rapeseed, cereal rye, vs no cover, under different levels of compaction
More corn roots grew deeper after radish and rapeseed > rye > no cover, in compacted plots
They suggested mix of radish or rapeseed for deep root growth, and cereal rye for surface mulch, as way to access deep water plus conserve surface moisture
Soil biology
Plant growth during normally “fallow” period (Sept-Nov, March-April) provides more food for soil organisms
Diversity of plant materials may also increase diversity of soil biological community
Soil organic matter maintained or increased
Purdue Univ.
Crusting inhibits seedling emergence, especially on low organic matter soils
Southeastern IN (SEPAC)
Evaluated practices to improve soil structure and crop productivity on poorly-drained, low organic matter, poorly structured silt loam
Earthworm populations were generally higher in: No-till vs. chisel Tiled vs. untiled Covers, rotation, manure vs. control
Soil physical properties tended to be improved by cover crops and rotation
Earthworm populations, spring 1994
Shallow-dwelling earthworm counts, after 10 years of treatments. Clermont silt loam, SEPAC
CC=Cont.corn, no cover WR=Wheat or cereal rye cover MN=Manure (mostly poultry) RO=Rotation with hay crop
Infiltration rate, tiled subfield, 1991
0
0.5
1
1.5
2
2.5
Manure (mostly poultry)
Other soil biology?
Evidence for greater biomass and/or activity of bacteria, fungi, micro- and meso-fauna
Arbuscular mycorrhizal fungi Soil enzyme activity Diversity of populations Methods for measurements, plus
interpretations for practical use, are still evolving. Potential is great but the impacts aren’t clear yet!
Potential impacts for Midwest/Ontario
Soil health and crop productivity Conservation of soils resource base Water quality Resilience to stresses from climate
variations Magnitude of effects is site-specific! But much more work needed to take full advantage of the possibilities!
Resources
Cover Crop Selector Tools (link on left sidebar)
Cover Crops to Improve Soil Health and Reduce Soil Erosion
Thanks to many colleagues over past 10 yrs!
Rationale for cover crops
Slide Number 6
Soil Health Indicators
Reviews used heavily for this talk
Classic purpose of cover crops—to cover the soil to reduce erosion
After Simulated Rainfall
Roots or shoots?
Slide Number 19
Cover crops and soil organic matter
Factors affecting magnitude of SOC changes with cover crops (or any changes)
Slide Number 22
Cereal Rye Cover Crop Effect on Soil Quality in a Corn Silage-Soybean System after 10 years
More examples of SOC changes
Soil moisture
Slide Number 26
Slide Number 27
Slide Number 28
Rye Cover Crop Effect on Plant Available Water after 12 years (Iowa)
Effects on cash crop rooting?
Soil biology
Dr. Eileen Kladivko Agronomy Department Purdue University
Thanks to many colleagues over past 10 yrs!
Midwest Cover Crops Council www.mccc.msu.edu
Indiana Conservation Cropping Systems Initiative (CCSI) www.ccsin.org
Corn Systems and Climate CAP www.sustainablecorn.org
Rationale for cover crops
A living, growing plant at times of year when we normally have nothing growing.
Capture sunlight, feed soil organisms, sequester carbon, trap and recycle nutrients
Make better use of the resources and time available!
7 Month “Brown Gap” for soybean and corn, fallow period
Cover crop grows and takes up N during some of that normally fallow season. This would shrink the “brown gap” and keep the land green for longer time.
Cover crops are part of a system!
Different potential benefits and challenges for each type of cover crop
Must adapt cropping system, including nutrient mgmt, NT (tillage) system, manure, pest mgmt, crop rotation
Learning curve—need to do homework!
Cereal rye, SE Indiana
Outline today • Potential benefits to soil health • Examples of data on soil changes • Reminder of details being highly site-specific!
What are the potential benefits? (What are your main goals?) Nitrogen scavenger Nitrogen producer (legume) Reduce erosion Improve soil quality– aggregation,
infiltration, soil biological activity, rooting Increase soil organic matter (sequester C) Conserve soil moisture Recycle nutrients Weed control, pest suppression, extra forage Increase crop yields over long-term, and
decrease year-to-year variability in yields
Soil Health Indicators
Chemical Physical
Reviews used heavily for this talk
Kaspar, T.C., and J.W. Singer. 2011. The use of cover crops to manage soil. In J.L. Hatfield and T.J. Sauer (eds.), Soil management: Building a stable base for agriculture. ASA/SSSA, Madison, WI.
Blanco-Canqui et al. 2015. Cover crops and ecosystem services: Insights from studies in temperate soils. Agron. J. 107:2449-2474.
Classic purpose of cover crops—to cover the soil to reduce erosion Studies have measured reductions in soil
erosion and water runoff Protection of soil surface by living plants and
dead residues, even in NT Anchor surface residues, reducing their mvmt. Less detachment by raindrops, flowing water Increased infiltration Greater surface storage Slowed water velocity of runoff
Also reductions in wind erosion
NO COVER CROP OAT COVER RYE COVER
After Simulated Rainfall
Tom Kaspar, Iowa
100
67
45
100
47
11
0
20
40
60
80
100
Interrill Erosion Rill Erosion
Relative Rill and Interrill Erosion Rate in No-till Soybean as Affected by Cover Crops
No Cover Crop Oat Rye
Kaspar et al., 2001, J. Soil Water Conserv.
Chart3
Relative Erosion Rate (%)
Relative Rill and Interrill Erosion Rate in No-till Soybean as Affected by Cover Crops
100
67.2161172161
45.4212454212
100
46.5987942214
10.8946649983
Chart2
1997
1997
1997
1998
1998
1998
Control
Oat
Rye
Erosion Rate (tons/acre/hr)
Rill Erosion Rate after 5 inch Rain in 1 hr as Affected by Cover Crops
47.8588
17.0236
3.5332
37.9016
21.8416
5.4604
Chart1
1997
1997
1997
1998
1998
1998
Control
Oat
Rye
2.98 a
2.36 a
1.06 b
1.36 b
0.22 c
0.34 c
0.024 a
0.039 a
0.042 a
0.023 a
0.019 b
0.036 a
0.012 a
0.015 b
0.022 b
0.029 a
0.034 a
0.036 a
0.011 b
0.014 b
0.030 a
Control
Oat
Rye
18.96
18.5
20.34
15.63
16.88
14.76
10.87
11.78
13
Control
Oat
Rye
Erosion Rate (tons/acre/hr)
Interrill Erosion Rate after 5 inch Rain in 1 hr as Affected by Cover Crops
Rill Erosion
19.97 a
20.37 a
22.89 a
5.54 b
12.16 b
17.37 b
Total Cover
13.06 a
16.39 a
21.14 a
13.52 a
15.14 a
20.24 ab
11.67 a
17.25 a
19.02 b
18.96 a
15.63 a
10.87 b
18.50 a
16.88 a
11.78 ab
20.34 a
14.76 a
13.00 a
12.05 b
11.65 b
9.13 b
26.48 a
19.86 a
14.64 a
Control
Oat
Rye
Rill Erosion g/m2/sec
Interrill Erosion g/m2/sec
Relative Erosion Rate (%)
Relative Rill and Interrill Erosion Rate in No-till Soybean as Affected by Cover Crops
1997
1998
1997
1998
1997
1998
Control
2.98
2.36
a
a
Control
47.86
37.90
tons/ac/hr
1997
1998
0.005
Oat
1.06
1.36
b
b
Oat
17.02
21.84
0.239294
0.189508
Rye
0.22
0.34
c
c
Rye
3.53
5.46
0.085118
0.109208
0.017666
0.027302
1997
1998
1997
1998
Tracked
1.38
1.45
a
a
Untracked
1.46
1.01
a
a
Control
Oat
Rye
2.98 a
2.36 a
1.06 b
1.36 b
0.22 c
0.34 c
1.38 a
1.45 a
1.46 a
1.01 a
Control
Oat
Rye
Erosion Rate (tons/acre/hr)
Rill Erosion Rate after 5 inch Rain in 1 hr as Affected by Cover Crops Assuming Rills Occupy 0.5% of Surface Area
1996
1997
1998
1996
1997
1998
Control
78
76
81
a
a
a
Oat
79
79
80
a
a
a
Rye
84
81
85
a
a
a
1996
1997
1998
1996
1997
1998
Tracked
74
77
82
b
a
a
Untracked
87
81
82
a
a
a
Control
Oat
Rye
78 a
76 a
81 a
79 a
79 a
80 a
84 a
81 a
85 a
74 b
77 a
82 a
87 a
81 a
82 a
March 16, 2010, central Indiana. Surface shows some daikon radishes out of ground, some partially out of ground. Shows webbed appearance of dead leaves of radish.
Within a few more weeks, soil surface is bare—should not plant radishes alone, but combine with something else!
But cover crop species matters!
Tom Kaspar, Iowa
Corn silage land with and without a cereal rye cover crop
Keep your expensive soil on YOUR field!
Soil physical properties improved
exudates feed microbes which then produce polysaccharides that “glue” particles together
Porosity, permeability (esp. tap-rooted) Deep roots, macropores, can aid water infiltration,
aeration, rooting
Soil surface protected, plus better aggregation, can mean less crusting or erosion
Roots give strength to soil for trafficability
Rorick, Frank, Kladivko
T. Kaspar, Iowa
Roots or shoots?
When building soil quality, esp. with NT, the cover crop ROOTS are probably more significant than the shoot growth
Still need good shoot growth for erosion control, mulch effects for moisture conservation, weed suppression, etc.
Tap root extended another 18+ inches beyond the end of tuber. These roots are probably of more benefit for soil structure and permeability than the tuber itself.
Cover crops and soil organic matter
Potential to increase soil organic matter (SOM) or soil organic carbon (SOC) Greater inputs of biomass Less erosion losses Perhaps slower decomp., if wetter/cooler
Studies show slow increases (compared to no cover crop), or sometimes no change
Many factors affect the rate of change, and the ability to detect the changes—site specific
Factors affecting magnitude of SOC changes with cover crops (or any changes)
Cover crop biomass production (more) Cover crop species, mixes, roots/shoots Years of cover crop use (more) Soil texture, initial SOC (clay) Tillage mgmt. (no-till) Climate (production, decomp., weather) Ability to detect– number of samples, strict
control of depth, variations w/ row position and short-term crop history, lab methods
~2500 lb/A~710 lb/A
Amount of growth affects the magnitude of cover crop impacts on soil or cash crop!
Cereal Rye Cover Crop Effect on Soil Quality in a Corn Silage-Soybean System after 10 years
• A rye cover crop “increased” total soil organic matter (SOM) in the top 4 inches (10 cm) from 4.8% to 5.3%, or ½% change in SOM
• (spring biomass production ~2.8 Mg/ha after silage, 0.5 Mg/ha after soybean)
• 44% greater particulate organic matter (POM) in top 2 inches (5 cm)
• 38% greater potentially mineralizable N (PMN) in top 2 inches (5 cm)
These are really hard measurements to make – 400 cores in 3.7 acres Moore
Moore et al. 2014Iowa data
More examples of SOC changes
Using data from 37 studies worldwide, meta- analysis (Poeplau and Don, 2015) estimated gain of ~0.3 Mg/ha/yr to 22cm depth (approx. 0.01% yearly gain in SOC)
Blanco-Canqui (semi-arid), 0.1-1.0 Mg/ha/yr gain of SOC, cover+NT vs NT alone
Olson (IL), hairy vetch+cereal rye, sequestered: 0.9, 0.5, 0.1 Mg/ha/yr under NT, chisel, moldboard, respectively (12 yr)
Review by Blanco-Canqui et al., 2015, Agron. J. 107:2449-2474
Soil moisture
Effects on soil moisture are complex While living, cover crops transpire water, so
may dry soil more than fallow field—good or neutral or bad, depending……
After termination, cover crop residues often increase infiltration, decrease evaporation, leaving more moisture in soil for crop use. Can be benefit in summer.
Example soil moisture effects that sometimes occur. CCSI project; cereal rye terminated April 17; then corn grown.
~1000 kg/ha cereal rye at termination
Rye Cover Crop Effect on Plant Available Water after 12 years (Iowa) • A rye cover crop increased soil water storage
capacity (plant available water) in the top 30 cm by 18%, which is equivalent to an extra 0.75 cm of water every time the upper 30cm of soil was rewetted by rainfall.
• The rye cover crop does use water in the spring, but in 5 out of 7 years this was replenished by the time of main crop planting.
• In most years after cover crop termination water contents in the upper 30 cm were higher following a rye cover crop in the summer.
Basche et al. 2015Basche et al., 2015
Effects on cash crop rooting?
Chen and Weil (2010, 2011) studied forage radish, rapeseed, cereal rye, vs no cover, under different levels of compaction
More corn roots grew deeper after radish and rapeseed > rye > no cover, in compacted plots
They suggested mix of radish or rapeseed for deep root growth, and cereal rye for surface mulch, as way to access deep water plus conserve surface moisture
Soil biology
Plant growth during normally “fallow” period (Sept-Nov, March-April) provides more food for soil organisms
Diversity of plant materials may also increase diversity of soil biological community
Soil organic matter maintained or increased
Purdue Univ.
Crusting inhibits seedling emergence, especially on low organic matter soils
Southeastern IN (SEPAC)
Evaluated practices to improve soil structure and crop productivity on poorly-drained, low organic matter, poorly structured silt loam
Earthworm populations were generally higher in: No-till vs. chisel Tiled vs. untiled Covers, rotation, manure vs. control
Soil physical properties tended to be improved by cover crops and rotation
Earthworm populations, spring 1994
Shallow-dwelling earthworm counts, after 10 years of treatments. Clermont silt loam, SEPAC
CC=Cont.corn, no cover WR=Wheat or cereal rye cover MN=Manure (mostly poultry) RO=Rotation with hay crop
Infiltration rate, tiled subfield, 1991
0
0.5
1
1.5
2
2.5
Manure (mostly poultry)
Other soil biology?
Evidence for greater biomass and/or activity of bacteria, fungi, micro- and meso-fauna
Arbuscular mycorrhizal fungi Soil enzyme activity Diversity of populations Methods for measurements, plus
interpretations for practical use, are still evolving. Potential is great but the impacts aren’t clear yet!
Potential impacts for Midwest/Ontario
Soil health and crop productivity Conservation of soils resource base Water quality Resilience to stresses from climate
variations Magnitude of effects is site-specific! But much more work needed to take full advantage of the possibilities!
Resources
Cover Crop Selector Tools (link on left sidebar)
Cover Crops to Improve Soil Health and Reduce Soil Erosion
Thanks to many colleagues over past 10 yrs!
Rationale for cover crops
Slide Number 6
Soil Health Indicators
Reviews used heavily for this talk
Classic purpose of cover crops—to cover the soil to reduce erosion
After Simulated Rainfall
Roots or shoots?
Slide Number 19
Cover crops and soil organic matter
Factors affecting magnitude of SOC changes with cover crops (or any changes)
Slide Number 22
Cereal Rye Cover Crop Effect on Soil Quality in a Corn Silage-Soybean System after 10 years
More examples of SOC changes
Soil moisture
Slide Number 26
Slide Number 27
Slide Number 28
Rye Cover Crop Effect on Plant Available Water after 12 years (Iowa)
Effects on cash crop rooting?
Soil biology
