Effect of tillage and irrigation on yield and soil properties under rice (Oryza sativa)-wheat (Triticum aestivum) system on a sandy clay loam soil of Uttaranchal

A field experiment was conducted for 2 years (2001-02 to 2002-03) to study the tillage (conventional and zero) and irrigations effects oil direct seeded rice (Oryza sativa L.)-wheat (Triticum aestivum L. emend. Fiori & Paol.) productivity and soil physical conditions after rice and wheat harvest. There was a reduction up to 6% in soil organic carbon with conventional tillage both after rice and wheat harvest. Soil organic carbon increased (data) significantly with increase in levels of irrigation for both the crops and the highest average value of organic carbon obtained in the most frequently irrigated plots. Soil bulk density decreased significantly with conventional tillage (1.34 and 1.36 Mg/m(3) at 0-15 and 15-30 cm soil depth respectively) at both the soil depths and after both rice and wheat crop. But plant available water capacity was significantly higher in zero tilled plots (5.07 and 4.86 cm/30 cm soil layer after rice and wheat crop respectively) than the conventionally tilled plots (4.23 and 4.21 cm/30 cm soil layer after rice and wheat crop respectively). There was a significant increase in laboratory estimated saturated hydraulic conductivity measured under zero-tilled plots (1.13 and 1.07 cm/hr at 0-15 and 15-30 cm soil layer respectively) after rice harvest. Pooled yield data showed that the performance of conventionally and zero-tilled direct seeded rice was at par but both rice and wheat yields were I and 4% higher respectively in conventionally tilled plots.