Page 1
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.
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Presentation Outline
Project Rationale
Objectives
Methodology
Preliminary Results & Conclusions
Project Website
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0
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Cropland Harvested_2012 Irrigated CRP
Ac
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Dolores LaPlata Montezuma
2012 Ag Census
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Wheat Dry Bean Corn Safflower Sunflower All hay
Ac
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Dolores La Plata Montezuma
2012 Ag Census
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Montezuma
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2012 2014D
ry b
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yie
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c)
Dolores Montezuma
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CHALLENGE
How to make
dryland farming
more sustainable?
Soil productivityEconomic viabilityEnvironmental health
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0.0
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v
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in)
Akron (16.6") Yellow Jacket (15.6")
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Monthly Precipitation at the SWCRC
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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Pre
cip
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on
(in
.)2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 1981-2010
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Water
Erosion
Wind Erosion
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Capturing & Storing Precipitation is Key to Dryland Farming
Soil Water
Maximize
Water
Storage
Minimize
Evaporation
Losses
Gary Peterson
Optimize
Crop Water
Use
Efficiency
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2014 Cover Crop Trial
0
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Dry
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tter
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/ac
)
Dryland Irrigated
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Western SARE Project Goal
Determine if & how cover crops can
enhance the sustainability of
dryland farming in SW Colorado &
SE Utah.
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HOW?
Increase soil O.M. (LT), fertility, and
biological activity
Reduce soil erosion
Suppress weeds
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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!
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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)
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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
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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
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Soil water content & infiltration rate
Traditional soil test analysis
Haney & Cornell soil health tests
Worm count
Soil microbial community (PLFA)
Soil Measurements
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Ground cover (transect method)
Plant biomass
Cash crop yield and quality
OTHER:
• Field operation records
• Costs & returns
Plant Measurements
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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
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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
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Preliminary Results
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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
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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
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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
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Winter Wheat Yields asInfluenced by Cover Crop
Conditions
Wh
ea
t Y
ield
(b
u/a
)
0
20
40
60
80
Dry DryWet Wet
after fallow
after cover crop
after single species
after mixture
Data averaged over locations
John Holman, KSU
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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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0
0.1
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0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60
Infiltra
tio
n R
ate
(m
L/m
in)
Time (min)
SWCRC #1 - Fallow #2 Infiltration Rate
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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
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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
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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
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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
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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
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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
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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.
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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
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Winter Peas, Berseem Clover, Sorghum-Sudan, Proso Millet,
Teff, Nitro Radish, Purple Top Turnip, Sunflower, Buckwheat
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BSW Field – Spring 2016
Spring Pea, Oat, Barley,
Rapeseed, Safflower, FlaxFallow
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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%
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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%
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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
Page 47
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.
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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.
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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!
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http://drylandcovercrops.agsci.colostate.edu/