冬季咸水结冰灌溉下滨海重盐碱地土壤水盐动态及对棉花出苗和产量的影响

在河北省滨海区,连续3年对当地的盐碱地进行了冬季咸水结冰灌溉,并对土壤的耕层水盐动态、棉花出苗和产量以及植株的盐离子状况进行了观测。结果表明:利用矿化度为8.15~14.27 g.L 1、灌水量为180mm的地下咸水,对滨海盐碱地进行冬季结冰灌溉,后期结合地膜覆盖可显著降低土壤盐分含量和提高土壤含水量。咸水结冰灌溉处理2009—2011年棉花播种期土壤盐分含量分别为0.32%、0.29%和0.17%,土壤含水量分别为26.2%、25.0%和24.2%,保证了棉花正常出苗,3年的棉花出苗率均达到85%以上。结冰灌溉年限越长越有利于土壤盐分的淋洗。苗期棉花根、茎和叶片Na+含量比对照降低57.6%~64.5%,而相应的K+和Ca2+含量显著高于对照(不灌溉不覆膜处理)棉苗,避免了对苗期棉花的单盐伤害。随着当地雨季的来临,棉田耕层土壤可实现周年脱盐,保证了棉花的正常生长,籽棉产量达到2 643.8~3 607.7 kg.hm 2,并且3年的产量呈逐年上升趋势,实现了滨海重盐碱区水土资源的高效利用和棉花丰产。

Effect of frozen saline water irrigation in winter on soil salt and water dynamics,germination and yield of cotton in coastal soils

A three-year field experiment was conducted to investigate soil water and salt dynamics, cotton emergence, seedling salt content and cotton seed yield in coastal soils (Xiaoshan, Haixing County of Hebei Province) under frozen saline water irrigation in winter. The irrigation water salinity and volume were 8.15~14.27 g·L^-1, and 180 mm, respectively. After saline ice melt-water infiltration in spring, the soil was mulched with plastic film to prevent further soil salinization via evaporation. The results showed that soil salt and water contents at sowing in 2009, 2010 and 2011 were respectively 0.32%, 0.29% and 0.17% and 26.2%, 25.0% and 24.2% under saline ice water irrigation. This implied that longer saline ice water irrigation had better soil desalination effect, providing suitable soil water and salt conditions for cotton growth. While cotton germination rate was above 85% under saline ice water irrigation treatment, few cotton seeds emerged under the control treatment (no irrigation and no mulching) due to high soil salinity. Seedling sodium content decreased by 57.6%~64.5% under saline ice water irrigation but potassium and calcium contents remained higher than the control. This prevented mono-ion problems in cotton plants, which further enhanced normal metabolism in cotton plant tissues. Salt content of the topsoil decreased further with the arrival of rainfall, which further ensured normal cotton growth. Overall, cotton seed yield reached 2 643.8~3 607.7 kg·hm^-2 with that of the succeeding year higher than preceding year. The above findings showed that frozen saline water irrigation in winter improved cotton growth in coastal soils in north China.