Daniel Sweeney, Kansas State University - Southeast Agricultual Research Center, Parsons, KS, Gary Pierzynski, Agronomy, Kansas State University, Mahattan, KS and Philip Barnes, Kansas State University, Wamego, KS
Use of poultry litter as an alternative to commercial fertilizer has increased in southeastern Kansas because of the availability from production facilities in surrounding states. Little information is available comparing nutrient management of turkey litter to commercial fertilizers on the claypan soils typical of the area. The objectives of this study were: i) to compare grain sorghum yield, yield components, and nutrient uptake influenced by applications of turkey litter and fertilizer and ii) to determine the influence of tillage on yield and nutrient uptake with the use of turkey litter. The experiment was conducted from 2005 through 2007 near Girard, KS. The soil was a Parsons silt loam overlying a claypan B horizon. The treatments were: 1) control – no fertilizer or turkey litter applied, 2) fertilizer – only commercial fertilizer to supply N and P with no turkey litter, 3) turkey litter (N-based) – turkey litter applications to supply all N [that also provides excess P], 4) turkey litter (P-based) – turkey litter applications to supply all P with supplemental fertilizer N, and 5) turkey litter (P-based) – same as treatment #4 but with incorporation of litter and fertilizer. Treatments 1 through 4 were planted with no tillage, but treatment #5 was planted after chisel and disk incorporation of the litter and fertilizer. Three-year average grain sorghum yields were 39 to 69% greater with application of fertilizer and/or turkey litter than obtained in the control. Yield was 21% greater with N-based turkey litter application compared with P-based litter applications, but yield was intermediate with fertilizer only or when P-based turkey litter was incorporated. Yield response was correlated to the number of kernels per head with both responding similarly to treatments. Although early through midseason N uptake was affected by treatments, the differences were not significant by physiological maturity. In contrast, marginal P uptake differences due to treatments early in the season became more pronounced with time. Budgets suggest that the high turkey litter rates applied in the N-based treatment result in greater amounts of unaccounted-for nutrients, especially P, than in the fertilizer, P-based turkey litter, or control treatments.