The Feasibility of Cover Crops
in Dryland Cropping Systems in SW Colorado and SE Utah
Abdel Berrada, Courtney Roseberry & Project Team
Southwest Ag Seminar, October 22, 2016
No reproduction of the content of this presentation is allowed without the authors’ permission.
Presentation Outline
Project Rationale
Objectives
Methodology
Preliminary Results & Conclusions
Project Website
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CHALLENGE
How to make
dryland farming
more sustainable?
Soil productivityEconomic viabilityEnvironmental health
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Monthly Precipitation at the SWCRC
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Water
Erosion
Wind Erosion
Capturing & Storing Precipitation is Key to Dryland Farming
Soil Water
Maximize
Water
Storage
Minimize
Evaporation
Losses
Gary Peterson
Optimize
Crop Water
Use
Efficiency
Cover Crops!
2014 Cover Crop Trial
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Dryland Irrigated
Western SARE Project Goal
Determine if & how cover crops can
enhance the sustainability of
dryland farming in SW Colorado &
SE Utah.
HOW?
Increase soil O.M. (LT), fertility, and
biological activity
Reduce soil erosion
Suppress weeds
Project Objectives
1. Quantify the effects of cover crops on:Soil moisture
Soil fertility, quality & health
Weed control
Cash crop
1. Share findings with farmers and others via field tours, workshops,
publications, Internet, etc.
3. Determine which cover cropping strategies are profitable!
Cover crops are grown on fallow ground or with winter
wheat.
Cover crops are tailored to each farm & cropping system
and may include up to 10 species. Role of USDA-NRCS.
Initial project is for three years (2015-2018)
On-Farm Tests
Cooperator Barry (2) Garchar Lewis CrowleyWaschke
(add McCart)
Crop Rotation Wheat-FallowWheat-
Sunflower-FallowWheat-Fallow
Wheat-Safflower-
FallowWheat-Fallow
Management No-Till Conv. Till No-Till Organic Organic
Spring 2015 CC Planting No Planting No Planting Aug-14 No Planting 10/29/14
Spring CC Termination N/A N/A Apr-15 N/A 06/20/15
Fall 2015 CC Planting 07/30/15 No Planting No Planting 09/10/15 No Planting
Fall CC Termination 03/11/16 N/A N/A 04/22/15 N/A
Spring 2016 CC Planting 04/03/16 04/20/16 No Planting No Planting No Planting
Spring CC Termination 06/11/16 07/06/16 N/A N/A N/A
Fall 2016 CC Planting No Planting 08/23/16Anticipated Nov.
2016No Planting No Planting
Research Center Tests (replicated)
Cooperator CSU_SWCRC #1 CSU_SWCRC #2
Rotation Wheat-Fallow Wheat-Fallow
Management No-Till Conv. & No Till
Spring 2015 CC Planting No Planting No Planting
Spring CC Termination N/A N/A
Fall 2015 CC Planting 09/28/15 No Planting
Fall CC Termination 06/10/16 N/A
Spring 2016 CC Planting No Planting No Planting
Spring CC Termination N/A N/A
Fall 2016 CC Planting No Planting 08/11/16
Soil water content & infiltration rate
Traditional soil test analysis
Haney & Cornell soil health tests
Worm count
Soil microbial community (PLFA)
Soil Measurements
Ground cover (transect method)
Plant biomass
Cash crop yield and quality
OTHER:
• Field operation records
• Costs & returns
Plant Measurements
Cover Crop Mixtures on Farmers’ Fields
Farmers CCMs Cover Crop Species (%) Lbs/acre $/acre
Waschke (Fall’14)-1 Austrian Peas (100%) 20.0 $18.40
Barry (Fall’15)-9
Winter Peas (25%), Buckwheat (20%), Berseem Clover (10%), Sorghum-Sudan
(10%), Proso Millet (10%), Nitro Radish (5%), Purple Top Turnip (5%), Sunflower
(5%), Teff (5%)
15.5 $19.95
Crowley (Fall’15)-7 Winter Peas (44%), Winter Lentils (22%), Flax (18%), Tillage Radish (7%),
Rapeseed (5%), Impact Forage Collards (4%) 25.0 $32.22
Barry (Spring’16)-6 Spring Pea (26%), Forage Barley (32%), Spring Oats (32%), Rapeseed (3%),
Safflower (3%), Flax (5%)38.0 $12.05
Garchar (Spring’16)-5 Fixation Balansa (43%), Ryegrass (20%), Frosty Berseem Clover (16.6%),
Crimson Clover (13.3%), Radish (6.6%)15.0 $43.37
Garchar (Fall’16)-8 Sorghum-Sudan (21.7%), Barley (14.5%), Dry Beans (29%), Oats (7.2%), Corn
(2.9%), Maple Peas (7.2%), Sunflower (2.9%), Yellow Peas (14.5%) 34.5 $14.68
Lewis (Fall’16)-7Cowpeas (14.7%), Sainfoin (34.4%), Yellow Sweet Clover (14.7%), Pearl Millet
(9.8%), Tillage Radish (4.9%), Flax (19.7%), Purple Top Turnip (1.4%)20.3 $15.25
Cover Crop Mixtures at CSU-SWCRC
SWCRC CCMs Cover Crop Species (%) Lbs/acre $/acre
Trial #1 Mix 1 (Fall’15)-3 Winter Pea (83%), Hairy Vetch (14%), Yellow Sweet Clover (3%) 28.9 $34.16
Trail #1 Mix 2 (Fall’15)-4Winter Pea (48%), Winter Rye (43%), Hairy Vetch (8%), Yellow Sweet Clover
(2%) 35.2 $31.92
Trial #1 Mix 3 (Fall’15)-6Winter Rye (53%), Winter Pea (34%), Hairy Vetch (6%), Winfred Turnip (3%),
Winter Canola (3%), Yellow Sweet Clover (1%) 28.3 $29.63
Trail #2 Mix 1 (Fall’16)-9
Winter Pea (67%), Sorghum-Sudangrass (11%), Proso (8%), Teff (4%),
Berseem Clover (4%), Nitro Radish (2%), Sunflower (2%), Purple Top Turnip
(1%), Yellow Sweet Clover (1%)
24.7 $24.47
Trial #2 Mix 2 (Fall’16)-4Winter Pea (85%), Flax (10%), Nitro Radish (3%), Rapeseed (1%), Impact
Forage Collards (1%) 33.1 $24.38
Trial #2 Mix 3 (Fall’16)-4Winter Pea (66%), Winter Triticale (31%), Rapeseed (2%), Purple Top Turnip
(1%)43.0 $24.49
Trial #2 Mix 4 (Fall’16)-5Winter Pea (54%), Winter Triticale (38%), Yellow Sweet Clover (4%),
Rapeseed (2%), Nitro Radish (2%) 35.1 $22.12
Trial #2 Mix 5 (Fall’16)-5Winter Pea (50%), Winter Triticale (35%), Hairy Vetch (8%), Sorghum-Sudan
(5%), Nirto Radish (2%) 38.0 $27.95
Trial #2 Spring Mixes (Srping’17)--3
Preliminary Results
2016 Soil Moisture
Post CC Soil Moisture (g/g) Inches (0-24" depth)
Fallow Cover Crop Fallow Cover Crop
Crowley 18.2% 16.9% 3.0 2.5
Barry SW 12.8% 9.3% 1.2 0.0
Barry N 14.0% 9.2% 1.6 0.0
SWCRC Cover Crops Trial #1--Post CC (6/14) Soil Moisture
7.5%
10.1%
16.4%
18.9%
17.1%18.2%
0"-12" 12"-24"
Avg. CCM
Fallow
SWCRC Cover Crops Trial--Post CC (9/16) Soil Moisture
15.5%
10.8% 10.5%
16.4%
19.0%17.8%
17.2%
0"-12" 12"-24" 24"-36"
Avg. CCM Fallow
Winter Wheat Yields asInfluenced by Cover Crop
Conditions
Wh
ea
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ield
(b
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Dry DryWet Wet
after fallow
after cover crop
after single species
after mixture
Data averaged over locations
John Holman, KSU
Infiltration Rates
Location/Treatment
Average Infiltration
Rate (in/hr)
Average Infiltration
Rate at Steady
State (in/hr)
Barry North Fallow 0.359 0.522
Barry North Cover Crop 0.263 0.422
Barry SW Fallow 0.610 0.777
Barry SW Cover Crop 0.400 0.412
SWCRC #1, Fallow Average 0.467 0.411
SWCRC #1, Mix 1 Average 1.099 1.129
SWCRC #1, Mix 2 Average 0.847 0.980
Waschke Fallow 0.583 0.274
Waschke Cover Crop 0.431 0.125
Non-Cropland Average 0.459 0.319
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ate
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Time (min)
SWCRC #1 - Fallow #2 Infiltration Rate
Soil Test Results-Haney
McCartSpring 2016 (Haney)
Soil #144 Soil #116 Soil #62
pH 7.8 7.8 7.8
P2O5 (lbs/acre) 25.9 12.6 80.0
K2O (lbs/acre) 50.4 45.5 144.1
Nitrate N (lbs/acre) 1.3 (3.5) 2.1 (6.1) 7.3 (45.6)
O.M. (%) 1.3 1.6 3.0
Solvita CO2, ppm C 14.8 12.5 98.1
Organic C:N 29.3 16.5 11.3
Soil Health 1.5 2.2 11.7
Soil Test Results-PLFA
McCart
Spring 2016 (PLFA)
Soil #144 Soil #116 Soil #62
Total biomass (ng/g) 939.9 1246.1 2980.8
Bacteria (%) 29.2 35.4 46.1
Fungi (%) 9.8 7.3 13.8
Protozoa (%) 0.0 0.0 1.3
Undifferentiated (%) 61.1 57.4 38.8
Diversity Index (%) 1.46 1.42 1.63
Rating Good Good Excellent
Soil Test Results
Barry North (NT)Spring 2016 Fall 2016
Fallow Cover Crops Fallow Cover Crops
pH 7.5 7.5 7.5 7.7
P2O5 (lbs/acre)
Traditional 56.4 69.7 66.9 65.5
Haney 40 57.9 33.7 34.1
K2O (lbs/A)
Traditional 571.0 631.2 609.5 597.5
Haney 92.7 89.6 105.6 100.2
Nitrate N (lbs/acre)
Traditional 5.6 6.0 36.6 19.8
Haney 3.7 (10.2) 3.9 (8.6) 27.2 (34.2) 15.4 (19.3)
HANEY
Organic Matter (%) 1.3 1.5 1.9 1.9
Solvita CO2, ppm C 9.7 26.4 5.2 5.2
Organic C:N (Haney) 18.3 18.1 25.5 20.3
Soil Health (Haney) 2.3 3.4 1.5 1.7
Soil Test Results-PLFA
Barry North
Spring 2016 Fall 2016
Fallow Cover Crops Fallow Cover Crops
Total biomass (ng/g) 1078.3 1559.8 2978.0 1315.5
Bacteria (%) 41.7 45.0 28.9 43.7
Fungi (%) 8.1 12.0 8.3 9.8
Protozoa (%) 0.0 0.6 0.2 0.0
Undifferentiated (%) 50.2 42.4 62.7 46.5
Diversity Index 1.5 1.6 1.4 1.4
Rating Good V. Good Good Good
Soil Test Results
SWCRC #1Fall 2016
Fallow CCM #1 CCM#2
pH 6.8 6.7 7
P2O5 (lbs/acre)
Traditional 84.9 73.6 82.0
Haney 72.2 76.2 94.0
K2O (lbs/acre)
Traditional 362.2 408.0 389.5
Haney 85.5 83.2 85.0
Nitrate N (lbs/acre)
Traditional 62.3 35.3 37.3
Haney 53.3 (66.8) 28.4 (43.5) 29.9 (45.6)
HANEY
Organic Matter (%) 1.7 1.8 1.8
Solvita CO2, ppm C 17.7 21.7 21.5
Organic C:N (Haney) 9.5 10.1 9.0
Soil Health (Haney) 3.5 4.0 4.4
Cornell CASH Assessment--Fall 2016 Sampling
SWCRC #1 Fallow Mix 1 Mix 2
Available Water Capacity (g/g) 0.24 0.23 0.25
Surface hardness (psi) 189 148 223
Subsurface hardness (psi) 176 203 237
Wet Aggregate Stability (%) 4.1 6 5.4
Organic Matter (%) 1.8 1.9 1.8
ACE Soil Protein Index (mg/g) 2.6 2.5 2.4
Soil Respiration (mg CO2/g) 0.2 0.2 0.2
Active Carbon 194 270 317
pH 6.9 6.6 7.1
P2O5 (lbs/acre) 38.0 29.8 70.1
K2O (lbs/acre) 368.1 413.2 422.1
Magnesium (lbs/acre) 719.2 744.8 666
Iron (lbs/acre) 1.2 1.4 1.2
Manganese (lbs/acre) 14.8 18.4 14.8
Zinc (lbs/acre) 1.4 1.4 1.4
Overall Quality Score 54/Medium 56/Medium 53/Medium
Soil Test Results-PLFA
SWCRC #1Fall 2016
Fallow CCM #1 CCM#2
Total biomass (ng/g) 584.1 1030.1 925.1
Bacteria (%) 42.7 53.2 40.3
Fungi (%) 3.9 7.3 3.4
Protozoa (%) 0.0 0 0.0
Undifferentiated (%) 53.4 39.5 56.4
Diversity Index 1.2 1.3 1.2
Rating Avg. > Avg. Avg.
June 9, 2016
Cover Crops: Balansa
Clover, Crimson Clover,
Ryegrass, Tillage Radish Fallow (VW)
October 14, 2016
Cover Crops: SSG,
Barley, D. Bean, Oat,
Corn, Peas (2),
Sunflower
Winter Peas, Berseem Clover, Sorghum-Sudan, Proso Millet,
Teff, Nitro Radish, Purple Top Turnip, Sunflower, Buckwheat
BSW Field – Spring 2016
Spring Pea, Oat, Barley,
Rapeseed, Safflower, FlaxFallow
Plant Data Barry North: 10/28/2015 & 6/10/2016
Barry North 2015 2016
Total Biomass (lbs/ac) 968 1527
Canopy Cover 44% 75%
Cover crop 44% 67%
Other n/a 7%
Ground Cover 82% 45%
Bare Ground 18% 55%
Cover crop 25% 5%
Residue 21% 39%
Other 36% 1%
Plant Data SWCRC #1--06/08/2016
SWCRC #1 (NT) CCM #1 CCM #2 CCM #3
Plant Biomass (lbs/ac) 4067 4337 5033
Plant Residue (lbs/ac) 4163 2237 4503
Canopy Cover (%) 89% 89% 89%
Cover crop 54% 61% 67%
Volunteer wheat 35% 26% 20%
Weeds 0% 2% 2%
Ground Cover (%) 83% 91% 93%
Bare Ground 17% 9% 7%
Cover crop 0% 2% 0%
Residue 83% 89% 93%
The residue on top of the soil is not soil OM.
0-3 inch soil depth ≡ 1,000,000 lbs of soil/acre
1% = 10,000 lbs of OM
10% of residue becomes OM, rest is mineralized
1% OM will require 100,000 lbs of residue.
#Plant Residue to Increase Soil OM by 1%?
John Holman, KSU
Lessons learned so far!
• It’s too early to draw conclusions about the feasibility of cover
crops in dryland cropping in SW Colorado and SE Utah.
• Fall cover crop planting may be the way to go in dryland farming.
Planting too soon after wheat harvest can be challenging.
• Spring planting may work if one gets in early and plants early
(e.g., 2014 at the SWCRC).
• Choice of cover crop species is important and goes hand in hand
with management.
Lessons learned so far!
• There appears to be an increase in biological activity due to
cover crops (PLFA/SWCRC, Solvita CO2 and Active C) and
possibly soil infiltration rate and aggregate stability.
• There was less water and less N available at wheat planting after
cover crops than after fallow. This could have negative
consequences on the succeeding crop.
• Change (e.g., soil O.M.) takes time especially in our environment
and especially in dryland farming! We’ll be looking for trends over
time.
Lessons learned so far!
• In future years, we’ll also report on the:
– Economic viability of the cropping systems where cover crops are being
tested and the,
– Impact of cover crops on the succeeding crop.
• We have a unique environment. What works in other environments
may not work here. Also, what works with supplemental irrigation
may not work under dryland conditions. That’s why we’re doing this
project!
http://drylandcovercrops.agsci.colostate.edu/
