Yield and Nutrient Export of Grain Corn Fertilized with Raw and Treated Liquid Swine Manure

Treatment of liquid swine manure (LSM) is an option to improve nutrient management. Mineral fertilizer, raw LSM, and LSM treated by anaerobic digestion, flocculation, filtration, or natural decantation were sidedressed (100 kg N ha-1) to grain corn (Zea mays L.) on a clay and a loam soil. Over 3 yr, corn grain yield (6 to 11 Mg ha-1), N export (83 to 176 kg ha-1), and P export (19 to 40 kg ha-1) were similar among LSM types and between LSMs and mineral fertilizer. This was attributed to the immediate incorporation of LSM to minimize N volatilization. Treated LSMs reduced P input to soil by 3 to 24 kg ha-1, compared with raw LSM. This reduced corn P export by 2 to 4 kg ha-1 on the clay soil, but had no effect on the loam soil. Soil NO3 content after harvest was higher with the mineral fertilizer (19-31 kg NO3-N ha-1) than with LSMs (13-20 kg NO3-N ha-1) in the clay soil, but was similar for all treatments in the loam soil. We conclude that when sidedressed to corn and immediately incorporated, raw and treated LSMs have a fertilizer value similar to the mineral fertilizer. Moreover, the risk of postharvest NO3 accumulation with the raw and treated LSMs was similar to mineral fertilizer on the loam and lower on the clay.