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玉米产量的变化能引起土地内部氮肥的变化。冬季谷类覆盖作物能吸收土壤中的残留氮，但吸收的能力却要部分地取决于作物在土壤中的生长条件。试验的目的是通过早作玉米后茬种植覆盖作物来获取适度的土壤生物量和氮累积量。在多个测量区中，小麦生物量的变化要大于氮的变化。在同一个土壤单元间的变化相似，大多数的变化是由于同一土壤单元内各区与低洼地区的位置关系不同而产生的。在这些低洼地区附近，适量的氮肥施入显得比利用覆盖作物减少氮的流失更加有效。而在高低洼地区较远的地区，利用覆盖作物吸收氮和增加土壤有机质可能更加切实有效。
Changes in corn production can cause changes in nitrogen within the land. Winter cereal crops can absorb residual nitrogen from soils, but the ability to absorb them depends, in part, on the conditions under which the plants grow in the soil. The purpose of the experiment was to obtain moderate soil biomass and nitrogen accumulation by planting crops as early as corn. In multiple measurement areas, the change of wheat biomass was greater than the change of nitrogen. Similar changes in the same soil unit, most of the changes are due to the same soil unit within the region and the low-lying areas of different positions arising from. Near these low-lying areas, it is more effective to use a suitable amount of nitrogen fertilizer than to reduce the loss of nitrogen by covering crops. In remote areas of high and low lying areas, the use of cover crops to absorb nitrogen and increase soil organic matter may be more effective.