Effect of aggregate stability indices on wheat yield in a soil with high specific surface under different tillage methods

Effects of different tillage systems on dispersion ratio, status of aggregation, degree of aggregation, mean weight diameter, geometric diameter, the rain-fed wheat yield and the yield components were investigated by a field trial using a completely randomized block design with five treatments in four replicates during 2009-2010 growing season at Gorgan University of Agricultural Science and Natural Resources Research Farm located at seyedMiran, Gorgan. Tillage treatments used moldboard plough (20-25 cm) with disc, roto-tiller (12-17 cm), double disc (8-10 cm), Chisel plough (25-30 cm) and No-tillage. Results showed that the maximum and minimum dispersion ratios occured with chisel and moldboard plough respectively which indicate various tillage methods hardly influence aggregate stability in soils with high specific surface. With no concerns for loss in aggregate stability, tillage intensities may be intensified for greater yield goals. Maximum status and degree of aggregation occurred with moldboard ploughing with the consequent increases of potassium root uptake and the yield of wheat at before heading and harvest stages both.