Effect of Tillage Method on Soil Physical Indices, Agronomic Characteristics and Yield of Soybean in Moghan Plain, Iran

This study was conducted to determine suitable soil tillage method. It was carried out for two years in summer planting soybean in the form of stripe-plot with randomized complete block design with four replications on the farm of Agricultural Research Center Moghan. In this experiment, the first factor was three tillage moaldboard plow and disk harrow; Chisel plow and disk harrow and only disk harrow and the second factor included three soybean varieties ( Zane , Williams and L17). Moisture content, bulk density, penetration resistance and crop residue levels before and after implantation and agronomic traits such as grain yield, emergency precentage, plant height, the height of first pod, the number of pods per plant, pod length and the number of grain per pod were measured. Two-year results of the experiment showed that different methods of soil tillage did not cause any significant difference in the grain yield. But the agronomic traits such as plant height, pod length and number of grain per pod showed significant differences at 1% probability. The two-year results of this study also showed soil tillage treatment differences in terms of cone index at the depths of 0-10 and 10-20 cm, but at the depth of 20-30 and 30-40 no significant difference was detected. The lowest and highest cone index in 0-10cm depth were 0.54 and 0.60 MPa with the moaldboard plow and disk harrow and only disk harrow , respectively. Also The two tillage treatments at 10-20 depth with 0.72 and 0.59 Mpa had the highest and lowest cone index, respectively. The difference between treatments was significant in terms of MWD, as Moaldboard plow and disk harrow, Chisel plow and disk harrow and only disk harrow with respectively 16.3, 13.0 and 10.1 mm were divided into three different groups. The index of return of plant residues with averge of 82.41 and 69.83 in the first and second years was statistically significant at the 1% level. On the other hand, the three tillage methods did not lead to significant effect in bulk density and the soil moisture content percentage.