Effect of different tillage systems on the quality and crop productivity of a clay–loam soil in semi-arid north-western Turkey

A 2-year study was conducted to investigate the effect of three tillage systems on the properties of clay–loam soil (EutricVertisol) planted with winter wheat (Triticum aestivum L.) in the Canakkale province of north-western Turkey. Crop productivity was also evaluated. The three tillage treatments were: (1) conventional tillage involving mouldboard ploughing followed by two discings (MT); (2) shallow tillage consisting of rototilling followed by one discing (RT); (3) double discing (DD). In the first year of the study, bulk density (BD) was found significantly lower under RT at both 0–10 and 10–20 cm depths with 1.24 and 1.32 Mg cm−3, respectively, when compared to MT treatment. However, MT at 20–30 cm provided the highest BD, at 1.49 Mg cm−3. In the second year of the study, DD had the lowest BD at all depths followed by RT and MT. Based on the 2-year mean, aggregate size distribution (ASD) and mean weight diameter (MWD) were significantly influenced by tillage treatments. The greatest MWD was obtained with DD, followed by MT and RT. Increasing MWD and coarse aggregates decreased seedling emergence. Organic carbon increased after RT, DD, and MT by 58%, 30%, and 18%, respectively, when compared to the amount at the beginning of the study. Similarly, the total N in the soil and straw was higher after RT than the other treatments. At 1.76 MPa, penetration resistance at 18–30 cm was significantly higher during the growing period using DD, followed by RT with 1.35 MPa and MT with 1.33 MPa. There was no significant difference between treatments at 0–18 cm. Increasing OC and total N and decreasing BD and PR under RT increased grain yield to 4611 kg ha−1, followed by MT and DD at 4375 and 4163 kg ha−1, respectively, according to the 2-year mean.