Effect of Tillage, Nitrogen Fertilization and Crop Residue Management on Wheat and Lentil yield Under Three Course Rotation in Semi -Arid Region of Jordan

Long term experiments (10 years) were conducted to study the effect of different tillage systems, crop residue management and nitrogen fertilization on wheat and lentil yields in three course rotation under rainfed conditions (380 mm mean annual rainfall) in Maru region , north of Jordan. Three tillage systems: moldboard followed by sweep before rain; chisel followed by sweep before rain; and only sweep after rain were commenced. Each with three residue management practices. Incorporation with soil immediately after harvesting, shortly after harvesting; and incorporating the remainder residue left after baling and grazing (traditional) .Nitrogen fertilizer at three levels (0, 20 and 30 kg ha-1) were used. Using moldboard followed by sweep plowing before the rain season starts gave highest average grain wheat yield (2072 kg ha-1), and straw yield (4465 kg ha-1) over nine seasons. The different ways of residue management did not significantly affect the wheat grain yield (1991 -1998 kg ha-1), neither the straw (3965 - 4214 kg ha-1). Combined statistical analysis for tillage – residue treatments (moldboard + sweep before rain + residue bailing then grazing followed by early or late incorporation of the remained residue) gave the highest significant average grain yield. Nitrogen fertilization rate of 30 kg N ha-1 gave highest average grain yield (2064 Kg ha-1) and straw yield (4239 kg ha-1). Highest yields (with no significant differences) of lentil grain and straw were obtained by plowing with moldboard or chisel followed by sweep before rain . Crop residue and nitrogen fertilization treatments had no significant effect on grain and straw yields. Yield of lentil grain and straw without N fertilization was as high as those with fertilization. Residual nitrogen after wheat may be adequate as starter for N fixation by lentil where there was no need for nitrogen addition