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1土壤墒情土壤含水量占田间最大持水量的70%～80%,才能充分满足种子发芽出土需要。0～20cm土壤最适含水量:黏土22%～30%,壤土18%～33%,沙壤土16%～20%。要使土壤在播种出苗阶段达到这一湿度标准,只靠降水是很难满足出苗要求的。因此,必须在播种之前造足底墒。
1 Soil moisture Soil moisture accounts for 70% to 80% of the maximum water holding capacity in the field to fully meet the needs of seed germination. The optimum moisture content of 0 ~ 20cm soil is 22% ~ 30% clay, 18% ~ 33% loam and 16% ~ 20% sandy loam. It is very difficult to meet the requirement of sprouting only by precipitation to make the soil reach this humidity standard at sowing and seedling stage. Therefore, it is necessary to make enough moisture before sowing.