咸水灌溉对土壤水盐分布和小麦产量的影响

Effect of saline water irrigation on water-salt distribution and yield of wheat

在石羊河流域中游开展田间灌溉试验,试验设置3种灌水量,灌溉定额分别为355,280,205 mm(W1,W2和W3);4种灌水矿化度0.7,3.0,5.0和7.0 g/L(S1,S2,S3和S4),共12个处理,每个处理3组重复.研究结果表明:淡水灌溉条件下,土壤积盐率不超过15%,当灌水矿化度在3.0 g/L以上时,土壤剖面盐分积累峰值在20~40 cm层,灌溉水带入的盐分有40%~80%积累在60 cm深度.当灌水矿化度为3.0 g/L时,盐分胁迫造成春小麦减产在10%以下;灌水矿化度为5.0 g/L和7.0 g/L时,春小麦减产严重,最高可达28%.相同灌水矿化度条件下,与充分灌溉(W1)相比,W2和W3分别减产10%和15%左右.拔节期—灌浆期是春小麦需水关键期,灌水要及时,3种灌水量均可以保证春小麦根区含水量维持在田间持水量的60%~80%.因此,3.0g/L的微咸水灌溉不会造成春小麦大幅减产,合理调控灌水时间,灌水量为205~355mm可以保证春小麦土壤含水量维持在适宜的水平.

Field experiments were carried out in the middle reaches of the Shiyang River Basin from2014 to 2015. Three irrigation amount levels of 355,280,and 205 mm（ W1,W2,and W3） and four water salinity levels of 0. 7,3. 0,5. 0,and 7. 0 g/L（ S1,S2,S3,and S4） were settled in the experiments. There were 12 treatments in total and three replicates per treatment. The results show that： Under freshwater irrigation,salt accumulation rate is less than 15%. However,peak value of salt accumulation is in the 20-40 cm layer. About 40%-80% of salt which brings by irrigation accumulated around 60 cm depth while water salinity is higher than 3. 0 g/L. Yield reduction of spring wheat under salt stress is less than 10% while water salinity is 3. 0 g/L. However,yield reduction is up to 28%under water salinity 5. 0 g/L and 7. 0 g/L. Compared with sufficient irrigation W1 at the same water salinity,yield reduction in W2 and W3 is about 10% and 15%. Jointing to filling stage is the critical water requirement period,therefore,irrigation should be timely applied. Under three irrigation amount levels,root zone water content can be maintained in the range of 60%-80% field capacity. It can be concluded that water salinity of 3. 0 g/L will not cause a significant yield reduction of spring wheat.Soil moisture can be guaranteed in suitable level with irrigation amount 205-355 mm,and irrigation time should be regulated reasonably.