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

深耕对打破犁底层、优化土壤水分特性有积极作用,但对旱作农田旋耕深度的土壤水分效应及其对马铃薯水分耗散过程和产量的影响缺乏研究分析。本研究设15(TT)、40(VRT)、60 cm(VRT6)3个旋耕深度,测定土壤容重和水分特性、马铃薯叶片SPAD值、叶面积指数(LAI)和产量等,研究旋耕深度对马铃薯水分利用和产量的影响。结果表明,与VRT和TT相比,VRT6分别在40~60 cm和0~60 cm土层降低土壤容重,提高饱和含水量、毛管含水量和田间持水量;VRT6显著提高了马铃薯现蕾前的耗水量,导致盛花期的土壤贮水量在2016年较VRT和TT下降了22.3 mm、49.0 mm,2017年下降了43.9 mm、56.6 mm;VRT6显著提高2017年花后耗水,分别较VRT和TT增加了42.2 mm和38.3 mm。旺盛的花前耗水促进了地上部发育,VRT6的LAI在全生育期高于TT,在现蕾期至收获期高于VRT,并使SPAD值在2017年的块茎膨大期显著高于VRT和TT,呈现明显的地上部旺长特征。基于以上原因,VRT6的块茎产量虽然高于TT,但在2017年显著低于VRT,而且水分利用效率(WUE)较VRT和TT下降了61.2%~67.5%和41.0%~53.5%。因此,在半干旱旱作区马铃薯种植的立式深旋耕作的适宜深度是40 cm,可在优化土壤水分特性和耗水过程的基础上,有效抵御季节性干旱胁迫,显著提高产量和水分利用效率。

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.