[Effects of subsoiling and straw returning on soil physical properties and maize production in Yellow River irrigation area of Gansu, China].

A field experiment was conducted to examine the effects of subsoiling 35 cm with maize straw returning, subsoiling 35 cm without maize straw returning, and rotary tillage without maize straw returning on soil compaction, soil bulk density, soil infiltration, soil water content in 0-100 cm depth, nutrients uptake and production of maize on sierozem in the Gansu Yellow River irrigated area in 2015-2017. Compared with subsoiling 35 cm without maize straw returning and rotary tillage without maize straw returning, subsoiling 35 cm with maize straw returning significantly decreased the soil compaction and soil density in 0-40 cm depth. Compared with that in 2015 (before experiment), soil compaction and soil bulk density in subsoiling 35 cm with straw returning was decreased by 42.6% and 7.0%, respectively, after harvest in 2017. Compared with other treatments, subsoiling 35 cm with straw returning had the lowest variation of soil compaction (6.1%) and soil bulk density (3.2%) in 0-40 cm depth before sowing and after harvest in 2016 and 2017. The soil infiltration rate in subsoiling 35 cm with straw returning was significantly improved by 33.6% compared with rotary tillage without maize straw returning. Subsoiling 35 cm with straw retention could significantly increase soil water content and decrease water variation in 0-100 cm soil depth in spring (before maize sowing) and autumn (after maize harvest). Compared with rotary tillage without maize straw returning, water storage in subsoiling 35 cm with straw retention was increased by 15.5% and 5.6% in spring and autumn, respectively. The water use efficiency was enhanced by 32.4%. Furthermore, subsoiling 35 cm with straw retention could increase maize economic yield and biomass yield by 25.6% and 33.3%, compared with rotary tillage without straw retention. Subsoilng and straw retention could promote nutrient absorption, with N, PO and KO uptake increased by 49.6%, 51.5% and 37.6%, compared with rotary tillage. Overall, our results suggested that subsoiling 35 cm straw retention could improve soil characteristics, stabilize the phy-sical properties of the plough layer, increase soil water content in the 0-100 cm soil layer, and reduce water variation in spring and autumn. Consequently, it was the best management to promote the water and nutrient utilization of maize and achieve high yield. Our findings could provide theoretical basis for further research on the construction technology of the plough layer in Gansu irrigation area.