different residue type and management and nitrogen on yield and quality of durum wheat(Triticum durum L.)

Abstract
Review and goals: Drought climate conition, no proper crop rotation, collection, and burning of crop residue, over dose application of che mical fertilizer and not application of organic fertilizer caused to decreasing in soil organic matter that the yield and the soil fertilization decreased. Crop residue is one of the most important conservation tillage factors for improving soil’s physical and chemical properties. Residue helps reduce surface runoff and soil loss, conserving soil moisture and improving soil microorganism populations, soil organic matter content, and soil hydraulic/ physical properties. Some researcher reported that the residue remowing affected soil organic carbon. The goal of this research was the evaluation the effects of residue type and management and nitrogen on yield, soil macronutrients and quality of durum wheat (Triticum durum L.) in Ahvaz condition.
Material and Methods:
In order to investigation the effect of different residue type and management and nitrogen on growth characteristics and yield of durum wheat (Triticum durum), an experiment was conducted at Agricultural Faculty of Shahid Chamran University of Ahvaz in 2012-2013.The experimental design was completely randomized block design, with three replications. The treatments including residue types(wheat and canola), residue management( residue burning, residue moving and 30%residue incorporated to the soil) and the third factor was different nitrogen resources(100%urea, 50% urea +Alkazotplus and sulfur seed coated urea). The measured traits were grain yield and protein and nitrogen, phosphorus and potassium of soil and plants. The Behrang cultivar was used with 350 plant/m2 density in 2*3 m plots. The harvest operation was at April 2015.
Results:
The results showed that the highest grain yield (6.92 tones/ha) was achieved at 150 kg/ha urea and canola burning residuse. Also the highest grain protein (15.25%) and nitrogen (2.61%) were observed at canola residue incorporated to the soil and sulfur seed coated urea. The highest grain phosphorus and potash were obtained at biological and chemical combination fertilizers + wheat residue remownig and wheat residue incorporated to the soil + sulfur seed coated urea respectively. Also the results revealed that the residue incorporated to the soil had positive effects and caused to more available the soil nutrients. The highest soil nitrogen and phosphprus were obtained at canola residue incorporated to the soil+ 150 kg/ha urea fertilizer. Also the combination of biological and chemical fertilizer+ canola residue incorporated to the soil had the highest soil potash contents.
Conclusion:
Totally the crop residue incorporated to the soil had positive effects on measured traits and conclouded to increased soil nutrient availability. The highest soil nitrogen and phosphorus were obtained at canola residue incorporated to the soil+ 150 kg/ha urea fertilizer. The canola residue incorporated to the soil+ combination of chemical and biological fertilizer treatments had the highest soil potassium contents. Although residue burning caused to uptake the soil nutrients in short term, but in long time, the disadvantages of this is more than advantages that it conlouded to destruction the soil structure and decreasing in grain yields.
Keywords: Residue type, Alkazotplus, Slow release urea and Durum wheat.