旱地全膜覆土穴播和全沙覆盖平作对小麦田土壤水分和产量的调节机理

Regulation of whole field soil-plastic mulching with bunch planting and whole field sand mulching with flat planting on soil moisture and yield of spring wheat in semiarid dryland areas

以春小麦品种‘陇春27’为试材,采用田间试验法,以裸地平作为对照,研究半干旱区旱地全膜覆土穴播和全沙覆盖平作对小麦田土壤水分和产量的调节作用。结果表明：与裸地平作（CK）相比,全膜覆土穴播（PM）和全沙覆盖平作（SM）小麦田0-40 cm土壤水分条件明显改善,尤其在干旱年份,能满足小麦前期生长,同时促进小麦出苗后对0-200 cm土壤水分的利用;种植第1年PM在60-80 cm土层耗水量最大,SM和CK在40-60 cm土层耗水量最大;种植第2年PM以120-180 cm土层耗水量最多,SM和CK则以60-80 cm土层耗水量最多。连续种植两年后,PM耗水深度从120 cm延伸到200 cm,SM耗水深度从120 cm延伸到140 cm,CK耗水深度无变化;小麦田休闲效率PM最大,SM次之,CK最小,但是各处理休闲效率随种植年限增加而降低。可见,PM和SM能改善小麦前期生长水分环境,促进出苗后耗水,并加快小麦对土壤深层水分的利用,因而与CK相比,PM产量增加48.77%-815.79%,SM产量增加49.41%-702.24%。但随种植年限增加,耗水深度加大,休闲效率降低,多年种植可能对土壤水分生态产生不利影响。

Whole field soil-plastic mulching with bunch planting is a firstly spreading wheat cultivation technique in Gansu Province. Domestic studies have shown significant increases in yields of wheat, flax and other crops under this cultivation mode.Previous researches mainly focused on the cultivation techniques and yield effects, with little documentation of the mechanism of yield increase. To address this knowledge gap, field experiments were conducted to explore the regulation of whole field soil-plastic mulching with bunch planting（PM） and whole field sand mulching with flat planting（SM） on soil moisture content and yield of spring wheat in semiarid dryland areas. The results showed that compared to uncovered and flat planting（CK）, PM and SM significantly improved soil moisture conditions in the 0-40 cm soil layer. This was especially noticeable in dry years, which supported early growth of wheat by enhancing water use in the 0-200 cm soil layer after wheat emergence. The maximum soil water used by wheat under PM was from 60-80 cm and that under both SM and CK was from 40-60 cm in the first year（median water year） of wheat cultivation. In the second year（less water year） of cultivation, the maximum soil water used under PM was from120-180 cm and that under both SM and CK was from 60-80 cm. After two years of continuous cultivation, the depth of used water under PM increased from 120 cm to 200 cm, that under SM increased from 120 cm to 140 cm and that under CK remainedunchanged. Leisure efficiency of PM was the highest, followed by SM and then CK. Leisure efficiency of each treatment decreased with increasing years of wheat cultivation. In summary, PM and SM improved the moisture environment of the soil in early wheat growth period, promoted water use after wheat emergence and accelerated the use of deep soil moisture. Compared with CK, PM and SM increased wheat yield by 48.77%-815.79% and 49.41%-702.24%, respectively. But with increasing years of cultivation, the depth of used water deepened and leisure efficiency decreased, with negative impacts on soil water balance.