Effect of Dairy Cattle Manure on Millet and Rye Forage and Soil Properties
1976
Mugiwra, L. M.
Dairy cattle manure was incorporated in plots of Decatur silty clay loam (Thermic Rhodic Paleudults) at rates of 0, 22, 44, 89, 178, and 267 metric tons/ha (dry weight) for 3 successive years. Pearl millet (Pennisetum americanum L. K. Schum) was grown in summer and was clipped twice and ‘Wrens Abruzzi’ rye (Secale cereale L.) was grown as a winter cover crop. Annual applications of 22 and 44 metric tons/ha manure were more effective than higher rates in stimulating millet growth, but rye forage yields were generally not influenced by manure application. The uptake of P, Ca, and Mg tended to level out at 44 tons/ha, but the removal of N, K, NO₃-N, and Na by millet and rye from the soil continued to increase with the rate of manure applied. The high rates of manure caused excessive accumulation of nitrate in plants and soils. The range of nitrate-N in millet was 5,037 to 8,675 ppm at 178 and 267 metric tons/ha compared with 602 to 4.010 ppm on the NPK check plots. Nitrate-N in the top 90 cm of the soil over the 3 years averaged 840 kg/ha at 178 and 267 tons/ha compared with 239 kg/ha of NO₃-N on the check. Dry matter and soil and plant analyses indicated that 44 metric tons/ha was the highest annual application rate of manure that could be used on this soil with consistent increases in plant growth and nutrient uptake and without excessive nitrate accumulation in soils and plants.
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