evaluation of tillage, nitrogen fertilizer and crop residue management on some agronomic traits of soybean

this study setout to investigate the effect of wheat residue, tillage, and nitrogen fertilizer management on some agronomic traits of soybean as a split split plot based on randomized complete block design with three replications. the main plots included wheat residue management: collecting and leaving residue and sub plot included tillage (without tillage and conventional tillage), and the sub -sub plots included nitrogen fertilizer consumption: base fertilizer, base fertilizer + nf (nitrogen factor amount of nitrogen needed for wheat residue degradation to prevent nitrogen deficiency for next crop). the anova results showed that the effect of residue management on harvest index was significant at 5% level. nitrogen fertilizer significantly affected on grain oil percentage at 5% level and on grain yield and harvest index at 1% level. the highest grain oil percentage, grain yield, and harvest index were obtained in base fertilizer treatment. moreover, the interactive effect of tillage and residue management on grain yield was significant at 5% probability level. the highest grain yield belonged to residue management and tillage, residue management without tillage, and tillage without residue. interactive effect of residue and nitrogen fertilizer on number of pod per plant was significant at 1% probability level. highest number of pod per plant belonged to residue and base fertilizer. interactive effect of tillage and nitrogen fertilizer on grain oil was significant at 5% level and on the number of pod per plant and grain yield was significant at 1% probability level. highest oil percentage belonged to the treatment without tillage and base fertilizer, tillage and base fertilizer nf+, with tillage and base fertilizer, and the highest number of pod belonged to tillage and base fertilizer, and highest grain yield belonged to the treatments with tillage and base fertilizer nf+, tillage and base fertilizer, and without tillage and base fertilizer.