Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/10/1996
Publication Date: N/A
Interpretive Summary: Long-term application of animal manures can promote phosphorus (P) accumulation in soils, even when the manure is applied on the basis of crop needs. The objective of this study was to evalutate the effects of replacing animal manure with ammonium nitrate as a fertilizer for pastures. Four fields in NW Arkansas were chosen for this study; two were fertilized with ammonium nitrate, the other two with poultry litter. The results of this study showed that when inorganic fertilizer was used there was less P runoff and less P accumulation in soils.
Technical Abstract: Long-term land application of animal manures, even at agronomic rates, can promote accumulation of soil phosphorus (P) which can, in turn, contribute to increased P loadings to downstream waters. The objective of this study was to assess the soil and runoff effects of replacing animal manure as a soil amendment with inorganic fertilizer (ammonium nitrate, NH4NO3) on fields that had been treated previously with animal manures. Runoff from two pairs of small fields (0.57 to 1.46 ha) was sampled from September 1991 to April 1994. All fields had been treated previously with animal manures; runoff monitoring began, one field of each pair received only NH4NO3, while the other of each pair continued to receive animal manure. Both soil and runoff P concentrations exhibited statistically significant decreasing trends over the monitoring period. The results demonstrate the potential for positive influencing runoff quality in a relatively short duration by replacing animal manures with ammonium nitrate for fields already having sufficient soil P.