Abstract
A 2-year field experiment was conducted to evaluate the single- and combined-application effects of cattle manure and urea on corn (Zea mays L.) production. A randomized complete block design was conducted with five nitrogen (N) rates (36, 72, 108, 144, and 180 kg N ha−1) as urea, cattle manure, or both. The stover yield and aboveground biomass increased with urea application up to 144 kg N ha−1 but remained unchanged at greater N rates. At all N rates, combined application of manure and urea resulted in greater grain yields than single applications. Crop response to applied N was greater in the combined N application system than in the single-application treatments. The greatest grain yield was found in plots that had received a combination of 18 ton manure ha−1 plus 160 kg urea ha−1. Manure application along with urea enhanced crop yield response to urea and reduced its application rate.
Acknowledgments
We are grateful to Ghobad Shabani, Soroosh Ghaedi, Aieej Azmi, Majid Soltani Asl, and Saied Hassan Tabatabaei for help with field work and data organization.