定期冬灌对北疆不同土质棉田水盐分布及产量的影响

Effects of regular winter irrigation on water and salt distribution and yield in cotton fields of different soil quality in northern Xinjiang

冬灌是淋洗盐分的有效手段,但对水盐分布的长期影响尚不清楚。为探究冬灌对长期膜下滴灌棉田水盐的时空影响,于2010、2014、2018年对2008—2019年长期膜下滴灌12a的不同土质农田进行灌水定额为2 800 m^(3)/km^(2)的冬灌,对研究区连续监测,分析了非生育期盐分、春播前水分、冬灌时土壤脱盐率、棉花成活率以及产量的变化规律。未冬灌前盐分逐年降低,2010年第1次冬灌后盐分大幅下降且脱盐率>59.07%,成活率和产量分别≥60.3%和4 501.3 kg/hm^(2),之后盐分随耕作年限逐年上升;2014年第2次冬灌后脱盐率>56.66%,成活率和产量分别≥70.2%和4 876.3 kg/hm^(2),随后盐分又逐年累积;2018年第3次冬灌后脱盐率>63.11%,棉花成活率和产量分别≥80%和5 460.7 kg/hm^(2)。观测结果表明:长期使用膜下滴灌技术不会导致积盐;冬灌灌水显著影响了次年土壤水盐分布;不同土壤盐分30~60 cm>60~100 cm>0~30 cm;冬灌时壤质黏土、壤土、砂质壤土盐分最多分别下降4.82 g/kg、5.47 g/kg、9.37 g/kg;2018年第3次冬灌后成活率和产量最高分别可达94%和7 100.2 kg/hm^(2)。本研究结果表明:不同土壤应有适宜的控盐年限和水量策略,砂质壤土应减少灌溉水量和缩短淋洗间隔,壤质黏土应加大水量和增加淋洗间隔。

Winter irrigation is an effective means of leaching salt, but the long-term effect on water and salt is unclear.In order to explore the temporal and spatial effects of winter irrigation on the long-term under-film drip irrigation in the cotton field, in 2010,2014,and 2018,irrigation was conducted on different soil farmlands with a fixed-rate of 2 800 m^(3)/km^(2) from 2008 to 2019 under long-term under-film drip irrigation for 12 years.In the study area, continuous monitoring was carried out to analyze the changes of the salt content in the non-growing period, the water before sowing in spring, the soil desalination rate during winter irrigation, the survival rate of cotton, and the yield.Before the winter irrigation, the salt content decreased year by year.After the first winter irrigation in 2010,the salt content dropped sharply and the desalination rate >59.07%.The survival rate and yield were not less than 60.3% and 4 501.3 kg/hm^(2);after the second winter irrigation in 2014 desalination rate >56.66%,survival rate and yield were not less than 70.2% and 4 876.3 kg/hm^(2) respectively, then the salt accumulates year after year;after the third winter irrigation in 2018 desalination rate >63.11%,cotton survival rate and the output is not less than 80% and 5 460.7 kg/hm^(2),respectively.Observation results show that long-term use of drip irrigation under film will not cause salt accumulation;winter irrigation significantly affects the distribution of soil water and salt in the following year;the salinity at different depths 30~60 cm>60~100 cm>0~30 cm;soil quality during winter irrigation the salinity of clay, loam, and sandy loam decreased by a maximum of 4.82 g/kg, 5.47 g/kg, and 9.37 g/kg respectively;the survival rate and yield after the third winter irrigation in 2018 were up to 94% and 7 100.2 kg/hm^(2),respectively.Studies have shown that different soils should have suitable salt control years and water volume strategies.Sandy loam should reduce irrigation water volume and shorten leaching interval;loamy clay soil should increase water volume and increase leaching interval.