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Cover Crops and Nutrient
CyclingTIM REINBOTT
#1 Reason For Cover
Crops: Erosion ControlApril 1 2014 -5 inch Rain
Soil Erosion-Even With No-
Tillage
Wind Erosion: When The
Soil Is Covered Little Loss
of Soil, When Not………….
Cover Crops Reduce Water
Runoff or Increase Water
Infiltration
Conventionally Tilled-Water
Runoff 30 minutes
Water From Tilled (left), No-Till
(middle) and No-Till With
Cover Crop (right)Tilled No-Tilled No-Till Cover Crop
Run-Off Table
Reduce Erosion and Water
Movement, Reduce Nutrient Loss
Winter 1985 Winter 1988
Treatment No Cover Cover Crop No Cover Cover Crop
Runoff (inches) 0.39 0.44 4.81 2.31
Soil Loss (lb/acre) 4,118 891 15,945 1,970
Soil P Concentration (ppm) 0.14 0.19 0.12 0.15
Total P (lb/acre) 1.2 0.42 5.25 0.82
Nutrient Cycling
Nitrogen-Legumes Cover Crops-
Nitrogen From N2 Fixation
How Much Nitrogen?-Depends
On Species and Time of
Termination
50 lbs N-1,250 lbs 150 lbs N-4,500 lbs
The N Effect From Legumes:
Generally Can Replace Some
Nitrogen
Corn Yield From Kentucky-
0
20
40
60
80
100
120
140
160
0 50 100
Hairy Vetch
Crimson Clover
Rye
Control
187 lb N/acre
50 lb N/acre
36 lb N/acre
From Ebelhar et al, 1986
Corn After Killing Cover Crop-
MU Found Similar Response of
About 40-70 lb N/acre Benefit
Cotton Yield-29 Years in Tennessee.
Tillage Nitrogen Applied (lb N/acre)
Cover Crop Method 0 90
lb lint/acre
None Tillage 672 988
No-Till 610 819
Wheat Tillage 665 832
No-Till 621 838
Hairy Vetch Tillage 865 923
No-Till 870 906
Crimson Clover Tillage 829 870
No-Till 858 904
Zou et al, 2017 Agronomy Journal
What Determines How
Fast the N is Released
and How Much?
Cover Crop Nitrogen Production
and Release-C/N Ratio Key
Plant Dry Nitrogen Percent C/N
Cover Crop Part Matter Accumulation Nitrogen ratio
lb/acre lb/acre %
Cereal Rye shoot 2165 35 1.61 22
Winter Pea shoot 2,768 106 3.85 15
Radish shoot 3,089 86 2.79 12
Root 2125 16 1.82 16
124 18 8.9 5.8
Cereal Crops Last Throughout the
Season-Early August
Cover Crops Breakdown And
Release Nitrogen Dependent
Upon Tilled or No-tilledBuried 8 inches Surface
Your text here
Jananzad, et al., 2016
Soil N Changes After 3 years of Cover Crops In a Corn/Soybean Rotation
Cover Crop 0-6 in 6-12 in 12-18 in
lb/acre
None -220 d -23 c -244 c
Cereal Rye 20 c 22 bc 42 b
Hairy Vetch 129 b 142 a 271 a
HV+Rye 218 a 58 b 276 a
Sainju and Sing, 2008
Do We Mix Cover Crops?
If So, How Much?
Mixture of Hairy Vetch and Cereal Rye
of Above Ground N Content
160 lb Nour text here
90 lb N
If Cover Crop Terminated Early April In
Illinois Not Much Biomass.
Applegate, et al, 2016
Less Than 20 lb N/acre Nitrogen When
Cover Crop Terminated at Normal Corn
Planting Time in Illinois
Applegate et al, 2016
My Suggestion Is That Ahead
of Corn-Plant Cereal Crops
For Erosion Control
Before Soybeans-Full Cover
Crop Mix
Termination Timing When
Planting Corn and
Soybean Are DifferentCorn
Soybean
The N Effect From Legumes: But
There Is More To Cover Crops Than
Just Nitrogen
Cover Crops Can Bring
Nutrients Up From Deeper
Depths
Percent Total Available P and K at
Different Depths in the Soil Profile-30-
55% in top 2 ft
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
P K
36 to 48
29 to 36
24 to 29
18 to 24
12 to 18
9 to 12
3 to 9
0 to 3
Clark and Reinbott, 2012
Soil Potassium Levels After
Three Years of Cover Crops
0
20
40
60
80
100
120
140
0 to 3 3 to 6 6 to 12
none
Rye
Crimson Clover
Hairy VetchlbK
/ac
re
Hargrove et al, 1986
Forage or Diakon Radish
FallSpring
Increase in Soil Test P Around
Tillage Radish Roots by 2X
1.25 inch
2 inches
White and Weil, 2011
Corn Emerging Near
Radish
Phosphorus Release Over
Time From Cover Crop
Your text hereYour text here
Varela et al, 2017
Your text here
Days
Scavenging Nutrients
From the Grain Crop
Nitrogen Capture By
Radish
-10
10
30
50
70
90
110
130
150
Shoot
RootCornCorn
Soybean
Soybean
Lbs/
ac
re
Dean and Weil, J Eniv. Quality 2009
Radish and Rye Capture
Nitrate-N in the Soil Profile
Since Radish Do Not Survive
Winter They Need A Companion
Crop
Back To Soybean and
Cover Crops
Planting Soybeans Into A Heavy
Cover Crop Mix
Fall 2017 Soybeans
Corn Can Struggle
Through The Residue And
Can Reduce Stands
Soybeans Can Also
Struggle But Patience Is
Critical
In Drier Summers Better Results
From Using Cover Crops Before
Soybeans 7 more Bushels/acre-
Seed Cost-$45/acre
7 bushel/acre @
$10/bushel=$70/acre
Or about $25/acre profit
Some years little yield
difference-2014, 2015
Cover Yield and Soybean Yield Following
Cover Crops, 2016 A Wet Year-2nd year with
cover crops Treatment Yield Dry Matter
Bu/acre lb/acre
Control 36 c -
Hairy Vetch 45 ab 3094 c
Crimson Clover 38 bc 523 d
Austrian Winter Pea 39 bc 3436 bc
Cereal Rye 42 b 3276 c
HV+Rye 50 a 4258 b
CC+Rye 47 ab 3649 bc
AWP+Rye 47 ab 3404 bc
Triticale 38 bc 3457 bc
Rye+HV+CC+AWP 39 bc 5348 a
*letters indicate significant differences at the 0.10 level
Corn Yield After Cover Crops
In A Dry Year Corn Yield
Cover Crops Overseeded into Soybean Previous September
Corn
Treatment Yield
Bu/acre
Control 175 b
Hairy Vetch 199 a
Crimson Clover 165 b
Radish 174 b
Cereal Rye 175 b
Hairy Vetch+Rye 187 b
Crimson Clv. +Rye 181 b
Radish + Rye 173 b
Rye+Radish+HV+CC 174 b
Reinbott, 2013
Cover Crop and Corn Grain Yield
Following 2nd year of Cover Crops, 2016
Treatment Yield Dry Matter
Bu/acre lb/acre
Control 196 ab
Hairy Vetch 210 a 2966 a
Crimson Clover 197 ab 683 d
Radish 202 ab 992 d
Triticale 182 bc 1302 c
Triticale+HV 207 a 3927 a
Triticale+CC 176 bc 1654 b
Triticale+Radish 194 ab 1702 b
Cereal Rye 168 c 1088 cd
Triticale+HV+CC+Ra 197 ab 1248 c
*indicates significant difference at the 0.10 probability level
Soil HealthAND NUTRIENTS
Chemical
PhysicalBiological
50pH
Phosphorus
Potassium
ElectricalConductivity
Bulk Density
Water-Filled Pore
Space
Aggregation
Organic Matter
Mineralizable Nitrogen
Microbial Biomass
CGlucosidase
Micronutrients
Active C
Soil Structure-Physical • arrangement of soil solids and voids
• aggregation is controlled by SOC, microorganisms,
ionic bridging, clay
http://vro.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_soil_st
ructure
http://ecomerge.blogspot.com/2010/05/what-soil-
aggregates-are-and-how-its.html
Ultimately Improve Soil
Physical Properties
Soil Physical Property: Calcium
Influence on Soil Structure
Formation of Soil
Structure Flocculation: Bringing
the particles close
together, enhanced by
polyvalent cations
(Al+++, Ca++, etc.). Mg
is not as good as Ca in
flocculation, by an order
of over 2 times!
Aggregates
The Importance of Calcium on
Aggregates (Flocculation)
Single Charge Cations Such as K and Na
have little Flocculating Power Whereas
Divalent Cations Much Greater
Flocculating Power
Your text hereYour text here
Al+3> Sr+2> Ca+2>Mg+2, Cs+2, K+=NH4+>Na+>Li+
Flocculated Particles-Opposite Charges
Line Up: Negative On Clay Particle With
Positive On The Divalent Cation
56
How Does Soil Calcium
Affect Water Infiltration?
Infiltraton Total Runoff Total
Rate Infiltration Rate Runoff
in/h in in/h in
High Ca Soil
2.2 7.4 22.7 17.0
High Mg Soil
0.9 1.6 23.8 23.2
Example With Magnets
Aggregate Stability: Interaction of Soil
Microbes, Clay, Ca, and Humus
From Muneer and Oades, 1989
Aggregate Stability-How Quick Can it
Change?
Water Aggregate Stability After Two Years:
Rotation Water Aggregate Stability (mg/kg)
Corn/Soybean 38 b
Corn/rye/Soybean/rye 41 a
Corn/rye/Soybean/hairy vetch 43 a
Corn/rye/Soybean/hairy vetch+rye 44 a
Letters indicate significant difference at the0.10 probability level
From Villamil, et al, 2006
Change In Aggregate Stability After 3
Years of Fertilizer Treatments
Treatment percent
N only 31.0 b
NPKS+Ca 33.3 a
NPKS only 30.4 b
NPKS+Mg 25.1 c
P and K only 28.7 bc
Different Letters Indicate Significance at the 0.05 probability Level
Sanborn Field Study-Higher Fertility and
Wheat Has Greater Aggregate Stability:
Why?
No Fertility Full Fertility 6 tons Manure
Corn 3 6 14
Continuous Wheat 15 18 18
0
2
4
6
8
10
12
14
16
18
20
% W
ate
r Sta
ble
Ag
gre
ga
tes
Comparison of % Water Stable Aggregates Under Continuous Corn
Versus Continuous Wheat at Sanborn Field
We Tilled Our Study and
Tillage Destroys Aggregate
StabilityMy son doing his favorite thing After a two inch rain
Influence of Structure on Water
MovementGranular Prismatic Blocky Platey
Flocculated by Ca Restricted
Enhanced by OM Movement
The Slake Test Video
