Effect of Tillage Methods on Wheat-Sunflower Yield and Some Soil Physico-Chemical Characteristics

In order to study the effect of tillage methods on crop yield and soil physico-chemicalcharacteristics in wheat-sunflower rotation, this research was conducted in Kalpoush region of Shahrood for four years. The experimental design was RCBD with five replications and four treatments. The treatments were no-tillage (T1), minimum tillage (T2) and conventional tillage with and without gathering residue (T3 and T4). Wheat (Alvand) was planted at autumn 2002 and 2005 and sunflower (Progress) at spring of 2005. Combination analysis of soil moisture content at various soil depths showed that soil moisture content at the 10-20cm in reduced tillage was higher than conventional tillage (at 5% level). At the 50-70 cm, soil moisture content in T1 was significantly (p<.01) lower than other treatments. Wheat yield difference in 2003 was significant (at 5% level) among the treatments. Maximum and minimum crop yield belonged to T3 (3880 kg/ha) and T1 (3170 kg/ha), respectively. Sunflower yield and seed oil percent differences were significant at 1% and 5% levels, respectively. Maximum and minimum yield was obtained at T2 (1683 kg/ha) and T3 (1279 kg/ha), respectively. Sunflower yield difference in T1 and T2 was not significant. Maximum and minimum sunflower yield belonged to T2 and T4, respectively. The results indicated that cone penetration resistance was affected by tillage methods. At the depth of 0-20 cm, minimum and maximum penetration resistance rate was revealed for T3 and T2, respectively. Regarding high soil fertility in the area under study and wheat yield during 2003 and 2005 in reduced tillage treatment, it can be recommended that moldboard plough can be replaced by disk harrow.