Abstract: Aiming at the problems of large interannual precipitation variability, low yield and precipitation utilization rate of potato in the arid area of Southern Ningxia, a field fixed position experiment was conducted to study the effect of subsoiling with mulching pattern on soil water during the fallow period and growth stage, potato dry matter accumulation, yield and water use efficiency of potato in rainfed region of southern Ningxia between 2014 and 2016. Three subsoiling tillage with mulching modes were adopted after autumn crops were harvested for three consecutive years, namely, subsoiling with straw mulching, subsoiling with plastic film mulching, subsoiling with no mulching. The conventional tillage with no mulching was used as the control. The results showed that subsoiling combined with different mulching patterns could improve the soil water status in fallow period, and the effect of subsoiling with straw mulching was the best. The average soil water content in 0−200cm layer was significantly increased by 6.41% compared with the control. Compared with the control, the average soil water storage and rainfall recharge rate of 0−200cm layer in fallow period were significantly increased by 49.85%, 121.85% and 46.82%, 83.73%, respectively. Subsoiling combined with different mulching patterns could improve the soil water content of 0−200cm layer during the potato growth period, and regulate the water consumption at different growth periods. Subsoiling with straw mulching treatment had significant effect on soil water conservation in 60−100cm layer at early growth stage (0−60 days), while the control treatment had the highest water consumption, followed by the subsoiling with plastic film mulching treatment, and subsoiling with straw mulching treatment had the lowest water consumption. Subsoiling with straw mulching treatment had better water retention effect on 0−60cm (2016) and 140−200cm (2015) soil layers in the middle growth period (60−120 days), while subsoiling with plastic film mulching had the highest water consumption, followed by the subsoiling with straw mulching treatment, and the control treatment had the lowest water consumption. Subsoiling with straw mulching treatment had the best soil water storage effect on 0−40cm layer at the later growth stage (120−150 days), and the water consumption was the highest at this stage, followed by the subsoiling with straw mulching treatment, and the control treatment was the lowest. The aboveground and underground dry matter accumulation of potato under subsoiling combined with different mulching patterns was significantly higher than that of the control. The effect of subsoiling with plastic film mulching treatment was better in the early growth stage, while the effect of subsoiling with straw mulching treatment in the middle and late growth stage was significant. Subsoiling with mulching patterns could significantly improve potato yield and water use efficiency, and the treatment of subsoiling with straw mulching was the highest, which was 49.33% and 43.80% higher than that of the control, respectively. Therefore, subsoiling with mulching pattern could improve the soil water status during the fallow period, it was beneficial to increase the soil water content and regulate the water consumption during the potato growth periods, and so as to increase the dry matter accumulation of potato and realize the high yield and water use efficiency of potato, particularly the effect of subsoiling with straw mulching treatment was the best.

Key words: Subsoiling with mulching, Soil water, Dy matter accumulation, Potato yield, Water use efficiency