Building better soils with cover cropsDeAnn Presley @soilsdiva @GPGrazing @KStateAgron deann@ksu.edu

Credit

• Cite: Dr. DeAnn Presley, Kansas State University, Department of Agronomy.

• All photographs were taken by DeAnn Presley. • Two exceptions are noted, one photo on slide 7 and one on slide 12

• Information and photographs in this file may be used for educational purposes.

• Journalists may contact DeAnn Presley for further explanation. deann@ksu.edu Phone: 785-532-1218

Bad news first

• We’ve been hard on soils, and it shows

Stevens County, KS: Wind erosion after corn stalk baling

Pawnee County, KS: Water erosion on endrows going right in a road ditch

Principles of building soil properties

•Reducing soil disturbance

•Covering the soil surface

•Increasing the diversity of the cropping system

•Adding carbon to the system: more plants, manure, compost, etc

Cover crops do all of these things!

Overview

• Importance of soil physical properties• Precipitation capture and storage

•Biological soil properties

• Improving soils

•Cover crop mixtures: species composition and forage quality

Soil Health Definition

•“The capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health” (Doran and Zeiss, 2000).

Definition of cover crops• “Close growing crop, that

provides soil protection and soil improvement between periods of normal crop production, or between trees in orchards or vines in vineyards.

• When plowed under and incorporated into the soil, cover crops may be referred to as green manure crops.”

• Source: Soil Science Society of America glossary

Photo credit: http://covercropimages.sare.org/

Cover Crop History

• The past:

• In 1938, the USDA Yearbook of Agriculture recommended cover crops to maintain soil organic matter (Pieters and McKee, 1938).

• Present-day Kansas estimates:

• Cover Crops were planted on 2,498 farms, 322,454 acres (US Census of Ag 2012)• Out of 21 million acres of cropland harvested/year

• 1.5% of acres cover cropped each year

Farmer Survey: Why they say they use covers

SARE 2015-2016 Survey

Purposes of cover crops, continued

• Soil improvement and protection from erosion

•Reduce compaction

•Weed control

•Break disease and pest cycles

•Cycle plant nutrients

• Legumes fix N

Sunn hemp, a warm-season legume

Purposes of cover crops, continued

Q: If you graze a cover crop is it still a cover crop or is it a forage?

A: The soil benefits either way, as long as you leave some cover.

Photo credit: http://www.greatplainsgrazing.org/

Evapotranspiration

Sunn hemp

Crotalaria juncea

Covers improve soilsBlanco-Canqui, H., Claassen, M. M., & Presley, D. R. (2012). Summer cover crops fix nitrogen, increase crop yield and improve soil-crop relationships. Agronomy Journal, 104(1), 137-147.

b

a

a

aa a

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No Cover

Crop

Late

Maturing

Soybean

Sunn Hemp

Soil O

rgan

ic C

arb

on

(g k

g-1

)

0- to 7.5-cm

7.5- to 15-cmA

c

ab

bc

a

a

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aa

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0 25 50 75 100 125

Nitrogen Application Rate (kg ha-1)

0- to 7.5 cm

7.5- to 15-cm

B

2.8%

3.4%

3.6%

Infiltration

• Infiltration: Movement of water through the surface: Precipitation capture

• In this no-till experiment, cover crops increased infiltration

• Cover crops planted every other year

Build it and they will come

• Measured worms by digging up soil in December 2009 in grain sorghum stalks.

• How long had it been since the covers were green and living?

• About 13-14 months. Worms still preferred the cover crop plots.

“Worms prepare the ground in an excellent manner for the

growth of fibrous-rooted plants and for seedlings of all kinds.”

Charles Darwin, 1881

Earthworm specifics• Stimulate microbial activity. • Earthworms consume microbes,

many more microorganisms are present in their feces or casts than what they consume (gut)

• They fragment and inoculate with microorganisms

• Available plant nutrients (N, P, & K) tend to be higher in fresh earthworm casts than soil

(Edwards et al., 1995)

Sunn hemp, a warm-season legume

Earthworms, continued

• Earthworms increase mineral N in soil,

• and also readily exchangeable phosphorus (P) (Suarez et al., 2004),

• potassium, calcium and magnesium (Adejuyigbe et al., 2006).

• Productivity and earthworms: very positive relationship, and they must be fed.

Blouin et al., 2013, European J. Soil Sci. https://iees-paris.ufr918.upmc.fr/images/publi/5a9176088a0d2568fa128a053bca0f1d.pdf

0 2 4 6 8 10 12

No cover

Radish

Rye

Rye and radish

Rye, radish, alfalfa

7 way mix

Earthworms per cubic foot

Ottawa Corn-Soybean Cover Crop ExperimentCollected April 2015 Prior to Soybean Planting

Presley et al.’s unpublished data

Soil structure and aggregation

Wet aggregate measurement illustrated

Wet aggregate measurement illustrated

Wet aggregate measurement illustrated

050

100150200250300350400

Wichita Spring 2014

050

100150200250300350400

Olathe Spring 2014

Microbial Biomass Carbon (μg C g-1soil)

p = 0.48 p = 0.19

Both sites: Cover vs. no cover was significant

Infiltration: Movement of water into soil, not as many differences as aggregates

0

5

10

15

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Min

ute

s to

Infi

ltra

te1

" p

on

ded

wat

erWichita July 2015

p = 0.14

LFS soil, CT hard as a rock,Others friable. Pumpkin runners?Where happier?

Evapotranspiration

EvapotranspirationRoller-crimped rye: Reduces soil temperature, which aids in reducing E

“A temperature of 80 to 100° F is found most favorable to the production of a maximum fermentative activity.”Soil: Ferments important in agriculture, Yearbook of the USDA, 1895, p. 73.

Takeaway points

•Methods to improve soil include reducing disturbance, leaving soil covered, diversifying a crop rotation. Cover crops can be used in systems that are no-tilled or tilled, and lead to improvements in the soil.•Will improvements in the soil lead to increased

profit for a farmer? Will the effort pay for itself, or increase profits? Will it save time, save energy? Will grazing a cover crop allow for pastures to rest?

Midwest Cover Crops Council Decision Tool

• Location

• Cash Crop

• Objectives

http://www.mccc.msu.edu/

Questions

This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2012-02355 and 2013-69002-23146.

Learn more about the project at

greatplainsgrazing.org

Building better soils with cover cropsDeAnn Presley @soilsdiva @GPGrazing @KStateAgron deann@ksu.edu

No problem can be solved from the same level of consciousness that created it. Albert Einstein

In our every deliberation, we must consider the impact of our decisions on the next seven generations. From the Great Law of the Iroquois Confederacy