Influence of Poultry Litter On N-Star Soil Test Values.

Rice (Oryza sativa L.) is one of the most important global cereal crops and is grown on approximately five hundred thousand hectares in Arkansas each year. Arkansas is the leading rice producing state in the United States. The development and release of N-STaR (Nitrogen-Soil Test for Rice) by Roberts et al. (2011) allows producers to predict site-specific N fertilizer needs for rice production. Poultry litter (PL) is applied to a large fraction of rice acreage in Arkansas and N-STaR has not been adequately researched on soils that have recently received an application of PL. The objective of this study is to evaluate the ability of N-STaR to quantify N release from a pelletized PL application and identify how a PL application influences N-STaR recommendations over time. Four field experiments, two each in 2011 and 2012, were established to evaluate soil responsiveness to PL as a fertilizer and for an estimated N credit in rice using N-STaR. The influence of PL on N-STaR values was analyzed as a randomized complete block with year included as a random effect. There was not a three-way interaction, but a significant application time by location interaction, which indicated that the addition of PL had varying effects on N-STaR soil test values prior to the establishment of a permanent flood. The Pinetree location had higher N-STaR values for both of the application times with the at planting application time having the highest value. However, N-STaR values slightly increased as PL application rate increased at both locations, but it was not significant. Results of this study indicate that soil samples collected at least one month following a PL application for N-STaR analysis are not influenced by either PL rate or time of application.