CORN RESPONSE AND SOIL NITROGEN TRANSFORMATIONS FOLLOWING VARIED APPLICATION OF POULTRY MANURE TREATED TO MINIMIZE ODOR
The response of corn (Zea mays L.) to manure that had been treated to minimize odor was investigated in a greenhouse trial with two silt loam soils of pH 4.2 and 7.1. Pretreatment of manure resulted in sources initially high in organic N and NH4+, but low in NO3−. One pretreatment gave high initial NO2− concentrations. In soil at pH 4.2, NH4+ was the major N source utilized by corn grown to 36 days, and dry matter yields were superior to those from soil at pH 7.1 where soluble NO3− was the major source of N. At pH 7.1, NO2− remained in significant quantities and decreased dry matter yields at 6 wk. Soil inorganic N concentrations varied between soils and was attributed to soil pH differences. Rate of NO2− disappearance decreased with increase in soil pH, and NH4+ accumulation increased with decrease in soil pH, whereas NO3+ production was favored by neutral pH conditions. Some NO3− production was observed in pH 4.2 soil after 36 days' incubation