Cover Crop Nutrient Removal

2001-2002
COVER CROP NUTRIENT REMOVAL
COMPARING CEREAL RYE, ANNUAL RYEGRASS
AND ITALIAN RYEGRASS

University of Maryland
Western Maryland
Research & Education Center

INTRODUCTION

Cereal rye has been the cover crop of choice in the mid-Atlantic region for decades due to its cold tolerance, rapid growth, ease of seeding, and seeding window. It is used in row crop and vegetable systems as a burn-down or plow-down cover crop and in corn silage systems as a cover crop that is also harvested for forage.

In 1997, research was initiated in Maryland introducing annual ryegrass as an alternative cover crop/forage crop. A late summer seeding of annual ryegrass acts as a winter annual growing vigorously in the fall, going dormant over winter then growing vigorously again in April and May until going to seed in late June to early July. Annual ryegrass is an important short duration grass. Highly palatable and very digestible, this grass is valued in beef, dairy, and other livestock forage systems to be utilized as pasture, haylage, green chop or dry hay. It is adaptable to many environments when fast cover or quick feed is required. It is this rapid growth of highly nutritious forage that increased the use of annual ryegrass in the mid-Atlantic region from several hundred pounds of seed in 1996 to over 750,000 pounds of seed in 2002. The implementation of nutrient management regulations in Maryland and other states is requiring farmers to follow nutrient management plans justifying fertilizer and manure applications based on crop removal rates of nitrogen (N) and phosphorous (P). Forage crop systems by their very definition of harvesting the entire plant remove more pounds of N and P from the field than grain crops, thereby justifying increased manure application rates. The following chart demonstrates this point.

CROP REMOVAL OF PHOSPHOROUS

Crop	Yield	% P ₍₁₎	Lbs. P Removed	Gal. Dairy Manure _{(2) (3)}
Corn Silage	7 T DM	.21	29.4	3700
Annual Ryegrass	3 T DM	.43	25.8	3220
Corn Grain	100 bu.	.32	18.0	2250
Alfalfa	5 T DM	.35	35.0	4400

(1) Forage and grain analysis from Ensminger and Washington County data
(2) Manure analysis averaged from several Washington County dairy farms @ 8 lb. actual P per 1000 gal.
(3) Amount of dairy manure allowed to be applied based on P removal rates

Annual ryegrass (Marshall), cereal rye (Wheeler), and Italian ryegrass (Feast II) were seeded September 5, 2001 at Western Maryland Research and Education Center in small plots (four replications) with 18 other ryegrasses and small grains. At seeding, the plots received 50 lbs. of N per acre. In the spring of 2002, 50 lbs. of N was applied on March 15, April 29, and May 25. The first cutting was made on April 15. Four cuttings were completed on both of the ryegrasses and cereal rye by May 23, simulating an intensive grazing system with harvests about every 14 days. An additional two cuttings were made on the annual and Italian ryegrasses by June 23. The following data summarizes the DM yields and nutrient removal rates of these cuttings.

Cover Crop Nutrient Removal

Cereal Rye

Cutting	DM lbs/A	% CP	N lbs/A	% P	P lbs/A
1	2893	23.8	110.2	.37	10.7
2	301	26.7	12.9	.57	1.7
3	744	29.2	34.8	.49	3.6
4	220	25.7	9.0	.47	1.0
Total	4158		166.9		17.0

Annual Ryegrass

Cutting	DM lbs/A	% CP	N lbs/A	% P	P lbs/A
1	3339	23.7	126.6	.34	11.4
2	989	22.3	35.3	.55	5.4
3	981	30.6	48.0	.49	4.8
4	728	21.7	27.2	.45	3.5
5	986	16.4	25.9	.45	4.4
6	412	19.5	12.9	.38	1.6
Total	7489		275.9		31.1

Feast II "Italian" Ryegrass

Cutting	DM lbs/A	% CP	N lbs/A	% P	P lbs/A
1	836	30.9	41.3	.43	3.6
2	756	28.3	34.2	.49	3.7
3	1127	32.3	58.2	.47	5.3
4	801	26.5	34.0	.46	3.7
5	1149	21.2	39.0	.42	4.8
6	1062	27.0	45.9	.37	3.9
Total	5731		252.6		25.0

Nutrient removal by a forage crop is a function of yield and forage quality. The cereal rye growth was completed by the May 23 cutting, but the ryegrasses were still being harvested by June 19. Even compared at the May 23 cutting (#4) the annual ryegrass (Marshall) removed more total nutrients (42% more N and 48% more P) due largely to producing 46% more dry matter yield than the cereal rye. Although the Italian ryegrass (Feast II) produced only 85% of the cereal rye dry matter yield by May 23 (cutting #4), it removed essentially the same amount of N and P. In a corn silage and winter annual cover crop system in the Piedmont of Maryland, the corn crop is usually planted in mid to late May after a single mechanical harvest of cereal rye or another winter annual cereal. The multiple harvest potential of an annual ryegrass cover crop with a mechanical harvest system requires further research to determine its comparative potential to remove N and P from the soil. If you would like further information on cover crop/double crop nutrient removal, please contact the authors.

Stanley W. Fultz
Extension Agent, Dairy Science
Maryland Cooperative Extension
Frederick County Office
330 Montevue Lane
Frederick, MD 21702
301-631-3578
sfultz@umd.edu

Jeff Semler
Extension Agent, Agriculture and Natural Resources
Maryland Cooperative Extension
Washington County Office
7303 Sharpsburg Pike
Boonsboro, MD 21713
301-791-1304
jsemler@umd.edu

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For more information, contact Jeff Semler

Last updated: 03/13/2009