Effects of different pre-winter management practices on soiltemperature and winter wheat seedling growth

For winter wheat/summer maize double cropping system in the North China Plain (NCP), the practices of straw incorporation into the top soil and minimum tillage have some negative effects on winter wheat growth. This study examined the effects of straw mulching, winter irrigation and soil compaction on soil temperature and winter wheat seedling growth. Results showed that straw mulching reduced both maximum and minimum soil temperature. Compared with CK, straw mulching increased the average daily minimum soil temperature (Tmin) by 2.37 ℃, 3.18 ℃ and 1.68 ℃ at the soil surface and by 0.57 ℃, 1.28 ℃ and 0.34 ℃ at the 5 cm soil layer at pre-wintering, during over-wintering and after winter dormancy, respectively. Straw mulching reduced daily maximum temperature on the average by 2.68 ℃, 4.40 ℃ and 4.82 ℃ at the soil surface and by 0.54 ℃, 0.75 ℃ and 1.85 ℃ at the 5 cm soil depth for the three periods, respectively. Straw mulching reduced soil temperature, which slowed down winter wheat development. Wheat tiller and biomass reduced by 29.8% and 5.2% during recovery. Although straw mulching positively influenced soil water conservation, winter wheat growth was negatively affected. Winter irrigation increased soil moisture, which in turn reduced both the maximum and minimum soil temperature during over-winter and recovery stage of winter wheat. Average daily minimum temperatures were respectively 0.88 ℃ and 0.93 ℃ higher for treatments with winter irrigation than that for treatments without winter irrigation at the soil surface and 5 cm soil layer during over-wintering. For the same treatments, the differences were 5.35 ℃ and 5.57 ℃ during recovery. Wheat tiller number and biomass also reduced by 27.7% and 21.2% during recovery. Good soil moisture after winter irrigation at the recovery stage reduced soil temperature, which negatively affected winter wheat. Soil compaction after winter wheat sowing did not significantly affect soil temperature and winter wheat seedling growth.