Effects of Different Plastic Mulching Methods on Soil Water, Temperature and Nitrate Accumulation in a Dryland Winter Wheat Field

This study has investigated the effects of two different plastic mulching methods on soil water, temperature, and nitrate (NO3-N) accumulation in a dryland winter wheat field after one-year experiment. The drought-resistant wheat (Triticum aestivum) variety Chang-8744 was grown by (i) furrow planting with ridge mulching, (ii) bunch planting with flat mulching, and (iii) conventional flat planting without mulching (or control). Results showed that dryland winter wheat effectively utilized soil water down to 2 m depth, mainly in the first 140 cm. Plastic mulching increased the evapotranspiration during wheat growing season and mostly r flat plastic mulching, by ~18% over the value recorded in the control plots. Soil temperature of the 20-40 cm-layer was higher than the one recorded at 5-10 cm depth during seedling-overwintering stages. Ridge plastic mulching and flat plastic mulching increased soil temperatures at 5 cm, 10 cm, and 40 cm depths during seedling–overwintering stages with reference to the control (no mulching), then lowered them at the same depths during reviving–ripening stages. Residual NO3-N was always detected in the soil after harvesting irrespective of the mulching method. It was mainly concentrated in the first -60 cm accounting for ~50% of soil NO3-N accumulation within the 2-m profile. The highest soil NO3-N accumulation occurred under flat plastic mulching, which represented ~107% of the mean value of the remaining treatments. Finally, flat plastic mulching showed the greatest effects on soil water, temperature, and NO3-N accumulation in dryland wheat field.