RESIDUAL EFFECTS OF DAIRY-CATTLE MANURE ON MILLET AND RYE FORAGE AND SOIL PROPERTIES

Dairy cattle manure was applied to plots on Decatur silty clay loam. The manure rates were 0, 22. 5, 45, 90, 180, and 270 metric tons/ha (dry wt. ) Pearl millet was grown in summer and clipped twice and 'Wrens Abruzzi' rye was grown in winter. The residuals of three annual applications of 180 and 270 metric tons/ha of manure were more effective than the lower rates in increasing millet and rye forage yields in 1974 to 1976 and total N and NO//3-N in 1974 and 1975. Phosphorus and, to some extent, Zn levels in millet were increased by the 22. 5- and 45-metric ton rates, leveling or decreasing at higher manure rates. The manure residuals also increased the levels of K in 1974 and, generally, Mg in millet and K and Ca in rye and decreased Mn in millet and rye. Plant and soil data suggested that N limited plant growth in manured plots except at the 180- and 270-metric ton rates.; Dairy cattle manure was applied to plots on Decatur silty clay loam (Thermic Rhodic Paleudults) in 1971, 1972, and 1973. The manure rates were 0, 22.5, 45, 90, 180, and 270 metric tons/ha (dry wt). Pearl millet (Pennisetum americanum, L.K. Schum) was grown in summer and clipped twice and 'Wrens Abruzzi' rye (Secale cereale L.) was grown in winter. The residual effects of the manure treatments on forage yields and mineral composition evaluated in 1974, 1975, and 1976 are reported in this study. The residuals of three annual applications of 180 and 270 metric tons/ha of manure were more effective than the lower rates in increasing millet and rye forage yields in 1974 to 1976 and total N and NO3-N in 1974 and 1975. Phosphorus and, to some extent, Zn levels in millet were increased by the 22.5- and 45-metric ton rates, leveling or decreasing at higher manure rates. The manure residuals also increased the levels of K in 1974 and, generally, Mg in millet and K and Ca in rye and decreased Mn in millet and rye. Plant and soil data suggested that N limited plant growth in manured plots except at the 180- and 270-metric ton rates. At the higher rates there was significantly higher nitrate movement down the profile than the NPK check. The NO3-N and total N levels in forage also suggested that N mineralization from three consecutive annual manure applications of 22.5 metric tons/ha was largely completed within the following 3 years.