旋耕深度对西北黄土高原旱作区土壤水分特性和马铃薯产量的影响

Effects of tillage depth on soil hydrological characteristics and potato yield on northwest Loess Plateau

The subsoiling can break the plough pan and optimize soil hydrological characteristics. However, the study on the effects of tillage depths on soil water characteristics, potato water consumption and yield, is insufficient. The field experiment was conducted with three tillage depths of 15 cm (TT), 40 cm (VRT), and 60 cm (VRT6), to investigate the effect of tillage depths on the yield and water utilization of potato in semiarid rain-fed area in 2016 and 2017 on northwest Loess Plateau. The parameters of soil bulk density, soil hydrological properties, potato SPAD (soil and plant analyzer development) value, leaf area index (LAI), and tuber yield were measured. The soil bulk density, and increased saturation moisture, capillary moisture and field water capacity of VRT6 treatment compared with VRT and TT were decreased in 40-60 cm and 0-60 cm profile, respectively. Water consumption of VRT6 treatment was significantly increased in pre-squaring stage, resulting in the decrement of soil water storage in 0-100 cm profile by 22.3 mm and 49.0 mm in 2016, and 43.9 mm and 56.6 mm in 2017. Water consumption in pre-squaring stage of VRT6 was significantly increased by 42.2 mm and 38.3 mm compared with VRT and TT treatment in 2017, respectively. Based on the excessive water consumption in pre-flowering period, the LAI of VRT6 was significantly higher than TT in whole growth period, than VRT in post-squaring period, and the SPAD value was higher than VRT in expanding stage in 2017, which indicated that the vigorous growth was subsistent in VRT6 treatment. The tuber yield of VRT6 were significantly higher than TT, but it significantly decreased in 2017 compared to VRT, and the water use efficiency (WUE) of VRT6 were significantly decreased by 61.2%-67.5% and 41.0%-53.5%, as compared with VRT and TT. Consequently, the suitable tillage depth for potato cultivation was 40 cm in semiarid area, which could optimize the soil hydrological properties and potato water consuming process, and relieved the drought stress efficiently, resulting in significantly higher tuber yield and WUE.