Effect of straw strip covering on ridges on soil water content and potato yield under rain-fed semiarid conditions

Water deficiency is the main factor limiting crop growth in semiarid regions under rain-fed agriculture. Mulching can improve soil micro-environment and thus significantly increase crop yield and water use efficiency. In order to evaluate the effects of different strategies of soil-moisture conservation on soil water content and potato yield in semiarid regions under rain-fed agriculture in Northwest China, four mulching modes — maize-straw strip covering on no-planted ridge (T1), plastic film mulching on planted ridge only (T2), plastic film mulching on both planted ridge and no-planted furrow (T3) and flat field planting without mulching (CK) — were set in potato cultivation in 2014–2015. Potato yield and water use efficiency (WUE), and soil water content were investigated. The results showed that mulching greatly improved soil water storage at the 0200 cm soil layer during potato growth stage. Plastic film mulching had positive effects on soil water storage at the early stage of potato growth, while straw mulching significantly improved soil water storage at the later growth stage. The optimal water storage increasing effect was under T1, which increased soil water content by 2.8%–7.8%. Especially during the tuber formation in summer drought period, soil water content in the 0200 cm soil layer under T1 was significantly higher than under both T2 and T3. In contrast to CK, T1 increased potato yield by 10.5%–34.2% and WUE by 8.9%–29.8% (with WUE of 108.9– 134.0 kg·hm^-2·mm^-1), and increased commodity potato rate by 14.7%–38.8% which reached to 82.3%–92.2%. There was significant positive correlation (r = 0.836) between potato productivity and soil water consumption during the potato growth period. There were significant differences (P < 0.05) in the yield and commodity rate of potato under T1 condition, which were significantly different from those under T2 and T3. This indicated that maize-straw strip covering maintained higher soil moisture and improved plant growth and yield formation. Its application improved the efficiently of rainfall utilization to realize stable and high yields of potato. Maize-straw strip covering was a new cultivation pattern which increased crop productivity and economic benefit of potato in semiarid rain-fed regions of Northwest China.