Comparison of a Poultry Litter Fertilizer Program to a Commercial Fertilizer Program - Five Consecutive Crop Years.

A comparison of organic manure and commercial fertilizer on soil potassium, soil phosphorus, and crop productivity were studied under a corn-soybean-wheat cropping system in a five crop year experiment, which was established in 2002 on Hoytville soils in Northwest Ohio.  The study was set up with two treatments replicated four times in a randomized complete block design. One treatment consisted of a soil fertility program based on a combination of poultry litter and commercial fertilizers; the other treatment was based solely on the use of commercial fertilizers.  A single application of poultry litter was intended to supply multiple years of phosphorus and potassium in the poultry litter plots.  A poultry litter application at a rate of 3.75 ton/acre was made for each poultry litter plot on April 16, 2003.  The poultry litter used in this trial contained 77 lb P₂O₅, 57 lb K₂O, and 31 lb total nitrogen per ton based on laboratory analysis.  Each plot is 105 feet wide by 1030 feet long, for an area of 2.48 acres per plot.  The study field was planted to corn in 2003, soybeans in 2004, wheat in 2005, corn in 2006, and soybeans in 2007. Results indicate that a 3.75 ton/acre application of poultry litter provided sufficient phosphorus and potassium to corn, soybeans, and wheat during the five year study.  Results from five crop years indicate there was no statistical difference between the two treatments with regards to crop harvest population, moisture or yield.  Six year soil test data indicates the values for soil pH, potassium and phosphorus levels remain similar between the two treatments.  These values are also above the critical soil test level per the Tri-State Fertility Recommendations.