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Title: Enhancing Nutrient Cycling by Coupling Cover Crops with Manure Injection

Author
item Singer, Jeremy
item Cambardella, Cynthia
item Moorman, Thomas

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2008
Publication Date: 11/7/2008
Citation: Singer, J.W., Cambardella, C.A., Moorman, T.B. 2008. Enhancing Nutrient Cycling by Coupling Cover Crops with Manure Injection. Agronomy Journal. 100(6):1735-1739.

Interpretive Summary: Combining winter small grain cover crops and fall liquid manure injection may increase manure nutrient capture. The objectives of this research were to quantify manure injection effects using different target manure nitrogen rates on cover crop plant density and dry matter, nutrient uptake, and corn yield. A winter rye-oat cover crop was established prior to fall manure injection. Manure injection lowered cover crop plant density 25% because of plant mortality in the injection zone. Fall cover crop dry matter was 26% lower in the manure treatments than the no manure cover crop control, although no difference was detected for nitrogen or phosphorus uptake. No difference was detected for spring dry matter between the cover crop no manure and cover crop with manure treatments, although using a cover crop with increasing manure nitrogen rates increased dry matter, nitrogen, and phosphorus uptake until approximately 200 lb of manure nitrogen was added per acre. Corn grain yield was unaffected by the use of a cover crop and responded positively to manure application. Farmers who combine winter small grain cover crops with manure injection can increase nutrient capture without lowering corn yield.

Technical Abstract: Coupling winter small grain cover crops (CC) with liquid manure injection may increase manure nutrient capture. The objectives of this research were to quantify manure injection effects using target manure N rates of 112, 224, and 336 kg N ha-1 on CC plant density, fall and spring shoot biomass, N, P, and K uptake and subsequent corn (Zea mays L.) yield. A winter rye (Secale cereale L.)-oat (Avena sativa L.) CC was established prior to fall manure injection. Manure injection lowered mean CC plant density 25% because of CC mortality in the injection zone. Fall CC dry matter (DM) was 26% lower in the manure treatments than the no manure CC control, although no difference was detected for N (9.4 kg ha-1) or P (1.4 kg ha-1) uptake. No difference was detected for spring DM between CC no manure and manure treatments. Shoot DM, N, P, and K uptake increased 29, 41, 31, and 25% from the CC manure 112 to CC manure 224 with no increase above CC manure 224. Cover crop N uptake was higher in CC manure vs. no manure (60.1 vs. 35.6 kg ha-1). Cover crop P and K uptake were also higher in CC manure vs. no manure (9.2 vs. 6.6 kg P ha-1 and 41.3 vs. 30.0 kg K ha-1). Corn grain yield was unaffected by CC and responded positively to manure application (11022 vs. 9845 kg ha-1). Coupling manure injection and cover crops can increase nutrient capture without lowering corn yield.