Continued Studies of Past Broiler Litter Applications On Soybeans.

In 1997, research at the Pullen Farm located in Murray Kentucky was initiated to determine the residual effects of different levels of long-term broiler litter applications on corn and soybeans. In years of corn (1997-2002 and 2008), there were eight long-term treatments that included: 0, 2.2, 4.5, 6.7, 9.0, 11.2, 13.4, and 15.7 Mg/ha of broiler litter applied each year.  In 2003 and 2004, corn was grown with reduced rates. From 2005 to 2007, soybeans were grown with no broiler litter applications. However, plots receiving the low historical treatments of 2.2 and 4.5 Mg/ha each year were fertilized with 0.258 Mg/ha of P₂O₅ and 0.280 Mg/ha of K₂0 commercial fertilizer. Research in 2005 and 2006 found that soybeans that were grown on the high levels of residual broiler litter yielded significantly better than those that were treated with the commercial fertilizer. In 2007, plant tissue analysis at the R6 stage showed a significant correlation between the soybean uptake of Cu and yield(r=0.4437). This result has led into the current soybean experiments for 2009. For the broiler litter experiment, the same fertilization program was used as in the previous soybean years.  Measurements on the broiler litter experiment were continued, similar to past soybean crops.  A new experiment was initiated to study Cu fertilization on soybean yield. The three treatments were: 0, 11.2, and 22.4 kg/ha of Cu, applied as CuSO₄ to the soil. The results of plant tissue analysis and yield will be reported at completion of the 2009 growing season.