Comparison of Nutrient Concentration in Four Fertility Treatments After Poultry Litter Application to Orchardgrass and Sorghum-Sundangrass Hayfield Soils

Field experiments were established in 2001 at the Agricultural Research and Education Complex in Bowling Green, Kentucky to evaluate soil fertility values before and after poultry litter application to orchardgrass and sorghum-sudangrass hayfields. A randomized complete block design was utilized with each treatment being replicated four times. Orchardgrass plots consisted of sixteen 7.6 m rows, 91 m in length and separated by alleys 4.6 m in width. Sorghum-sudangrass plots consisted of sixteen 7.6 m rows, 60.96 m in length and separated by alleys 4.6 m in width. Four separate fertility treatments were utilized: inorganic fertilizer (I), poultry litter applied to meet nitrogen requirements (N), poultry litter applied to meet phosphorous requirements (P), and poultry litter applied to meet phosphorous requirements with a supplemental inorganic fertilizer (NP). In the poultry litter applications, plant available P was estimated to be 80% while N availability was estimated at 50% the first year. Fifteen soil samples were taken in a random, representative manner from each plot of orchardgrass and sorghum-sudangrass prior to litter application and after each harvest. Soil samples were analyzed for pH, N, P, K, Mg, Ca, Fe, Cu, and Zn levels, which were evaluated based upon fertilizer treatment differences Water pH has statistically remained the same thus far, indicating that it is currently not determining nutrient availability among treatments in orchardgrass and sorghum-sudangrass soils. Nitrate concentrations exhibited increases in treatments N and P for orchardgrass soils, while sorghum-sudangrass soils indicated all three treatments N, I, and P were different from each other. There were no differences among treatments for ammonium in orchardgrass soils; however, sorghum-sudangrass soils exhibited a higher concentration in treatments P and I. In both orchardgrass and sorghum-sudangrass soils, treatment N exhibited an increase in phosphate, copper, and zinc concentrations over all other treatments; magnesium and potassium concentrations were highest in treatment N in sorghum-sudangrass hayfield soils. Potassium concentrations were higher in treatments P and N in sorghum-sudangrass soils and the NP and I in orchardgrass soils. Sorghum-sudangrass soils indicated a higher K concentration in treatment N from all other treatments. While orchardgrass soils exhibited no differences in Mg, sorghumsudangrass soils indicated a higher amount in treatment N from all other treatments. Copper and zinc both exhibit a higher concentration in treatment N in comparison to all other treatments in both orchard and sorghum-sudangrass soils