Cucumber Yield and Soil Nutrient Changes with Poultry Litter and Synthetic Fertilizers

Soils in eastern Oklahoma have low N and P levels. The poultry industry in the area produces large amounts of poultry litter. Horticultural producers could benefit from using the poultry litter as a fertilizer for various crops, but many horticultural crops require a fertilizer with a ratio of about 2:1:3 (N: P 2 O 5 : K 2 O). Poultry litter has an approximate ratio of 1:1:1. Poultry litter applied at a rate to supply all needed N or K will supply more P than is needed by the current crop, although low P soils can accumulate significant amounts of P before the P levels are excessive. Poultry litter at different rates and synthetic fertilizers have been applied for 3 years to a field in which cucumbers were produced. Poultry litter rates supplied N at as much as 500 kg·ha –1 and P 2 O 5 at as much as 300 kg·ha –1 . Cucumber yields were recorded, and soil tests were conducted three times a year for N, P, K, Ca, Mg, Mn, Cu, Pb, Zn, and Fe. Cucumber yields from plots fertilized with poultry litter were equal to or greater than yield from plots that received commercial fertilizer. There appears to be a trend toward increasing levels of soil P with all treatments. and decreasing levels of soil Zn with all treatments. After 3 years, there is no evidence of detrimental levels of any of the monitored elements.