1.
Soil and Yield Changes by Cover Crops
on a Corn-Soy Bean Rotation
Clark J. Gantzer, Ranjith P. Udawatta, and Shibu Jose
School of Natural Resources, University of Missouri

2.
Cover Crops
Close-growing crops that provide soil
protection, and soil improvement.
They are often
used between
periods of normal
field-crop
production.

3.
• Cover crops can improve soil physical, chemical,
and biological properties (Doran and Zeiss,
2000)
• Soil physical properties of bulk density,
aggregation, and soil temperature are modified
“improved” when using cover crops (Sainju and
Bharat, 1997)
• Cover crops can increase soil organic matter
(SOM), soil microbial biomass and enzymatic
activity thus improve soil quality (Ding et al.,
2006, Hoorman, 2009)
Cover Crops

4.
•Cover crops can improve nutrient cycling,
nutrient storage, and nitrogen fixation
•Cash-crop yields can improve when using
winter cover crops through improved
nitrogen dynamics and soil water
•Cover crops can increased water use from
increased evapotranspiration, but cover
crop may also conserve soil water from
improved infiltration, and decreased
evaporation
Cover Crops

5.
Cover crop use is receiving increased
attention for helping solving problems as
they may have both environmental and
production benefits to farming lands.
Recently an increase both in acreage and
the percentage of farmers using cover crop
in the U.S.
This increase is because of their potential
benefit for reducing soil erosion and
improving soil health and crop productivity.
Cover Crops

6.
Adoption of CC is still very low.
0
20
40
60
80
100
120
140
160
2011 2012 2013 2014 2015 2016 2017
Hectares
Year
Average increase in acreage of cover crop per
respondent (SARE, 2016, n = 1,379)
Cover Crops

7.
The lack of reliable information from well-
designed scientific studies is identified
as a most important factor for lack of
adoption among landowners in 48 states
(SARE, 2016).
Cover Crops

8.
A field study on the economic effects of
cover crops on cash-crop production was
conducted at the soil health farm in
Chariton County, Missouri.
The study compared the annual economic
profitability of production of corn, wheat,
and soybeans with and without a cover
crop in the rotation by examining the cost of
the cover crop, the costs and revenues
generated by the cash crop, and the cash
crop yields.
Introduction

9.
Materials and Methods
• This project was initiated in 2012 at the Chariton
County Cover Crop Soil Health Research and
Demonstration Farm in north central Missouri
(39o30’N, and 92o43’W).
Experimental site and management

10.
Plots A and B are managed with cover crops and C and D without cover crops.
Plots B and D have Grundy silt loam, and A and C have Armstrong loam.
Cover
Crop
No Cover Crop
Chariton County Cover Crop Soil Health
Research and Demonstration Farm

11.
Jan 2017 Feb 2017 Apr 2017
May 2017 Jun 2017 Jun 2017
Cover crop development at the Chariton County Cover Crop Soil
Health Research and Demonstration Farm in 2017

12.
•Cover crop establishment was
initiated in 2012
•The fields are managed under
using no-till management corn-
soybean or corn-soybean-wheat
rotations during summers with
cover crop during winter
Materials and Methods

13.
Major soils &
1-ft Topo Contour
- Armstrong loam
(Aquertic
Argiudolls),
5-9% slopes –
50001 45%
- Grundy silt loam
(Aquertic
Hapludalfs),
2-5% slopes –
30085, 45%
x
788’
Chariton County Cover Crop Soil Health
Research and Demonstration Farm

14.
• Mean annual precipitation is 1069 mm
• Mean annual temperature is 12.1oC
• Average monthly minimum -7.7oC in
January
• Average monthly maximum of 30.9oC in
July
• Average annual snowfall is 450 mm
(https://www.ncdc.noaa.gov/data-access/land-based-station-
data/land-based-datasets/climate-normals/1981-2010-normals-
data)
Chariton County Cover Crop Soil Health
Research and Demonstration Farm

15.
Soil
Sampling
2013
and
2017
• CEC
• Potassium
• Phosphorus
• Organic Matter
• pH

16.
Organic Matter
• Accumulation of
Organic Matter
• Slower breakdown,
long history of deep
rooted native
perennial plants

17.
Soil Organic Matter (%)
2013 2017
The accumulation from no-till

18.
• Waterscout SM100 (Spectrum Technologies) capacitance soil
moisture sensors were installed at,
• Six locations per plot, and
• Three depths (20, 30 and 40cm) at each location
• Three monitoring locations in each plot were at the summit
landscape position and three at foot slope position
• Volumetric soil water content was estimated at 15 minute
intervals throughout the growing year except during
harvesting and planting
Soil Moisture study, Chariton County Cover Crop Soil Health
Research and Demonstration Farm
Instrumentation and Data collection for Soil Water

19.
Plots A and B are managed with cover crops and C and D without cover crops.
Plots B and D have Grundy silt loam, and A and C have Armstrong loam.
Cover
Crop
No Cover Crop
Chariton County Cover Crop Soil Health
Research and Demonstration Farm

20.
Average Volumetric soil water content (@10 AM) from May 2016
to April 2017
21
23
25
27
VWC(%)
20 cm depthCover crop No cover crop
26
28
30
32
34
VWC(%)
30 cm depth
26
28
30
32
34
VWC(%)
40 cm depth
16-May 16-Jun 16-Jul 16-Aug 16-Sep 16-Oct 16-Nov 16-Dec 17-Jan 17-Feb 17-Mar 17-Apr
Highlighted; Lighter: Cash crop growth period, Darker: Cover crop growth period

21.
Average Volumetric soil water from February to April 2017
(Active cover crop growth period)
21
23
25
27
VWC(%)
20 cm depthCover crop No cover crop
26
28
30
32
34
VWC(%)
30 cm depth
26
28
30
32
34
VWC(%)
40 cm depth
February 2017 March 2017 April 2017

22.
•During active Cover Crop growth of a
grass Cover Crop mixture, the volumetric
soil water tended to be higher with cover
crops at the 20cm and 30cm depths.
•Whereas, the volumetric soil water with
Cover Crops at 40cm depth is not
different.
Soil Water

23.
Soil Sampling sites for soil enzymes

24.
5
10
15
20
25
30
35
50 100 150 200
Depth(cm)
5
10
15
20
25
30
35
50 100 150 200
Depth(cm)
β-glucosidase (µg p-nitrophenol released /g dry soil /h)
β-glucosidase
Summit
Back slope
Foot slope
5
10
15
20
25
30
35
50 100 150 200
Depth(cm)
5
10
15
20
25
30
35
50 100 150 200
Depth(cm)
CC – Watershed 01
NCC – Watershed 03 NCC – Watershed 04
CC – Watershed 02
2016
β-glucosidase level: Cellulose degradation
(µg p-nitrophenol released g-1 dry soil h-1)

25.
Simulated Benefit-cost ratios under different
cover-crop costs and cash-crop revenues for
2013 and 2014 for the Soil Health Farm
In 2013, cover-crop BCRs
were greater than 1.0. To
match the profitability of
using no cover crop, 76% of
cover-crop cost would have
to be shared by the
government. However, in
2014, the cover crop, BCR is
1.0 if 55% of cover-crop cost
was cost shared to farmers, or
the cost of the cover crop
needs to be reduced by ~55%.

26.
Simulations results of different
sales revenue values suggest that
an increase in revenue leads to
an increase in the BCRs.
2013, revenue from the cover
crop field would have to increase
33% to match the profitability of
the no cover-crop due to the
cost of aerial seeding.
However, In 2014, cover crops
BCR reaches 1.0 when the cash-
crop revenue increases by just
5%.
Simulated Benefit-cost ratios under different
cover-crop costs and cash-crop revenues for
2013 and 2014 for the Soil Health Farm

27.
Benefit-cost ratios under different cover-crop
costs and cash-crop revenues for 2013 and
2014 for the Soil Health Farm
These findings suggest that changes may be
needed in the designing of future conservation
incentive programs.
Some current programs use a flat rate to
calculate cost-shares for farmers for planting
cover crops. The Environmental Quality
Incentive Program, for example, provides a flat
rate of ~$28.00 per acre per year

28.
Two possible ways of compensating farmers’ short-
term economic losses associated with establishing
a cover-crop rotation:
(1)share 55.0% to 77.5% of the cost of the cover
crop;
(2)provide a cash incentive based on farmers’
cash-crop revenues. About 5% to 33% of total
revenue from sales of the cash crop could be
provided to farmers to compensate them for
the added cost of the cover crop.
Benefit-cost ratios under different cover-crop
costs and cash-crop revenues for 2013 and
2014 for the Soil Health Farm

29.
A field study of the economic effects of
cover crops on cash-crop production was
conducted at the soil health farm in Chariton
County, Missouri.
The study compared the annual economic
profitability of production of corn, wheat, and
soybeans with and without a cover crop in
the rotation by examining the cost of the
cover crop, the costs and revenues
generated by the cash crop, and the cash
crop yields.
Summary

30.
Results showed use of a cover crop increased
the yield and revenue of a subsequent cash
crop.
However, net revenue was reduced in the first
two years because of the additional cost
associated with the cover crop.
In the fourth year, use of cover crops led to an
increase in revenue from the cash crop relative
to production without the cover crop as the
cover crop improves the soil.
Conclusions

31.
• Results indicate that including a cover
crops in a rotation system produce
benefits of improved soil and water
quality and enhanced nutrient cycling
in as little as two years.
• These benefits are likely to have a
positive impact on the cash crop yield
in the long-term.
Conclusions

32.
• During a four-year corn-soybean rotation,
use of cover crops was less profitable than
a system without the cover crop.
• To match the economic return from the no-
cover-crop treatment, the cost of the cover
crop would have to be reduced by at least
77% to 55% in the two years studied.
• If financial assistance were based on
revenue from cash crop sales, compensation
would have to be increased from 5% to 33%
of the revenue.
Conclusions

33.
Study results should help policymakers
implementing financial assistance programs
that provide incentives and compensate for
losses associated with establishing cover crops
The short-term cover crop costs had a negative
economic impact on cash-crop production that
may be replaced with a positive impact in
subsequent years because of improved yields.
Conclusions