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Extension > Agriculture > Crops > Soil management and health > Cover crops > Evaluation of cover crops for grazing systems

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Evaluation of cover crops for grazing systems

Brad Heins and Jim Paulson

Introduction

brown midrib

Figure 1. Brown midrib sorghum–sudangrass.

University of Minnesota researchers identified cover crop species that needed investigation to establish cultural practices and nutritional value if utilized for forage. To become more profitable, dairy producers may need forages that can fill slumps in grazing systems, extend the grazing season and provide emergency cover and forage. Dairy producers are looking for ways to integrate cover crops in their cropping and pasture systems. A demonstration was designed to determine the forage potential and nutritional value of selected cover crop species and mixtures on Minnesota farms.

Cover crop evaluation

The following cover crops were evaluated: Annual ryegrass, berseem clover, buckwheat, BMR sorghum–sudangrass, crimson clover, fodder beets, forage oats, forage peas, grazing corn, kale, lentils, pearl millet, Phacelia, Rox Orange cane, sorghum–sudangrass, soybeans, sugarbeet, Sunn hemp, teff, and turnip.

Study methods

Replicated plots of cover crops were planted at the West Central Research Center in Lamberton and on a dairy farm in Lanesboro, MN. The plots were planted June 24 and harvested August 20. A plot flail harvester was used to harvest the cover crops and dry matter yields were determined. A sample of harvested forage was retained from selected plots for dry matter determination and forge quality analysis. Forage analysis was conducted by Dairyland Laboratories in St. Cloud, MN.

Results

Forage analysis differed among species with crude protein ranging from a high of 24.0 percent for fodder beet tops to a low of 10.9 percent for BMR sorghum–sudangrass (Table 1). Total digestible nutrients (TDN) was highest for sugarbeets and turnip tops with 68.6 and 67.8 percent, respectively; however, TDN was the lowest for forage peas and grazing corn (45.5 and 48.4 percent, respectively). Taller plants, such as BMR sorghum–sudangrass and Rox Orange yielded greater amounts of dry matter per acre. The lush turnip and kale tops excelled in forage quality, but were lower in dry matter yield per acre. From these data, we can better recommend combinations of species to fit certain cover crop and grazing scenarios.

Table 1. Cover crop yield and forage quality, 2015.

Cover crop Dry matter yield Crude protein NDFd Lignin TDN
kg/acre tons/acre percent (%)
Annual ryegrass 2183 2.4 21.7 37.9 5.4 60.6
Berseem clover 1013 1.1 22.4 38.5 6.6 60.9
Buckwheat 1507 1.7 13.6 42.4 7.3 58.0
BMR sorghum–sudan 4045 4.5 14.3 53.7 2.8 62.2
Crimson clover 1371 1.5 20.4 38.1 3.9 63.6
Fodder beets 1266 1.4 24.0 33.4 3.7 66.7
Forage oats 1436 1.6 16.6 51.0 3.7 62.2
Forage peas 2909 3.2 13.5 41.1 7.2 45.5
Grazing corn 5797 6.4 13.4 32.7 3.3 48.4
Kale 1239 1.4 23.2 39.0 4.5 65.2
Lentils 566 0.6 14.8 49.8 4.8 52.2
Pearl millet 3066 3.4 15.9 54.8 2.6 60.6
Phacelia 404 0.4 21.4 34.2 4.2 63.7
Rox Orange cane 9130 10 12.7 51.3 3.0 63.2
Sorghum–sudangrass 6580 7.2 10.9 56.1 3.3 58.4
Soybean 612 0.7 22.1 37.9 4.4 62.6
Sugarbeet 2845 3.1 21.7 29.3 3.3 68.6
Sunn hemp 1790 2.0 19.8 37.6 4.9 62.6
Teff 3059 3.4 17.7 59.0 4.0 60.2
Turnip 1600 1.8 17.2 28.6 2.4 67.8

This project was funded by a grant from the Midwest Forage Association.

2015

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