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美国东南部，双季作物大豆占大豆种植总面积约三分之一。旨在研究收获冬小麦之后种植大豆的土壤水分关系，尤其是土壤贮存水的作用。试验处理是：分别在小麦抽穗期、灌浆中期和成熟期用化学药剂杀死小麦，使后续作物大豆播种时土壤贮存水形成三种不同的含水量。1986年，0．9米深度范围内土壤含水量分别为26．0、23．1和21．4厘米，较干旱的初夏使生长初期的大豆长势缓慢。密度降低，但生长中后期降雨充足，这一年大豆产量分别为2760、1600和440公斤/公顷。1987年，0．9米深度范围内初始土壤含水量分别为31．1、27．5和25．1厘米，湿润的初夏使生长初期的大豆长势良好，密度适中，但夏末干旱使大豆在生殖生长阶段受到严重的水分胁迫，这一年大豆产量分别为970、540和300公斤／公顷。1989年，大豆生长期间降雨充足，播种时土壤含水量分别为33．1、34.3和31．6厘米，大豆产量分别为1510、1810和1110公斤／公顷。试验期间的每一年内，大豆播种时的土壤含水量与其产量呈正相关性，但各年之间，降雨量及雨量的分布比土壤含水量对产量的影响更为明显。
In the southeastern United States, bi-crop soybeans make up about one-third of the total area planted with soybeans. The purpose of this study was to investigate the relationship between the soil moisture of soybean grown after winter wheat harvest and especially the effect of soil water storage. The experimental treatments were to kill the wheat with chemical agents during wheat heading stage, middle filling stage and maturity stage, respectively, so as to form three different water contents in the soil storage water in subsequent crop soybean sowing. In 1986, the soil water content in the depth of 0.9 m was 26.0, 23.1 and 21.4 cm, respectively. Compared with the early drought in 1986, the soil moisture in early growth stage was slow. Lower density, but adequate rainfall in the mid-to-late growth period, with soybean production of 2760, 1600 and 440 kg / ha, respectively. In 1987, the initial soil water content in the depth of 0.9 m was 31.1, 27.5 and 25.1 cm, respectively. In early humid summer, the early growing soybean grew well and its density was moderate. However, in the late summer drought, Severe water stress was encountered during the reproductive growth stage, with soybean production of 970, 540 and 300 kg / ha, respectively. In 1989, there was sufficient rainfall during the growth of soybean, soil moisture at planting was 33.1, 34.3 and 31.6 cm respectively, and soybean yields were 1510, 1810 and 1110 kg / ha, respectively. During each year of the experiment, the soil moisture content of soybean planting was positively correlated with its yield, but the distribution of rainfall and rainfall was more obvious than that of soil moisture content.