The Effect of Preceding Crop, Nitrogen Fertilizer and Return of Crop Residue on Growth and Yield of Wheat

Abstract This study was conducted under cold temperate climate condition in Khorasan during 2006-2008 growing season to determine the suitable preceding crop, nitrogen and crop residue management for wheat. A randomized complete block design in split-split plot arrangement with three replicates was used. Main plots were rotation with five different crops including wheat-wheat, potato-wheat, silage corn-wheat, clover- wheat and sugar beet-wheat. Sub plots were N fertilizer rates in preceding crop including no N (Control), 50% lower than optimum N rate, optimum N rate and 50% more than optimum rate. The sub-sub plots were preceding crop residue return with two levels including no residue return (Control) and 50% return of crop residue. Results showed that crop rotation and N rate in preceding crop influenced grain yield, biological yield, spike per m2, stem length and spike length in wheat. Interaction of crop rotation and N rate on grain yield and yield components was significant. The highest yield obtained from potato-wheat rotation and the lowest grain yield observed in continuous wheat rotation for all N rates. There was no significant difference for 1000 kernel weight and kernel per spike of wheat in all treatments. Return of crop residue had no significant effect on grain yield but was effective on biological yield, spike per m2 and harvest index. Keywords: Crop rotation, Crop residue management, Nitrogen, Whea