微咸水膜下滴灌不同灌水下限对盐碱地土壤水盐运移及玉米产量的影响

为了研究盐碱地上微咸水膜下滴灌不同灌水下限对土壤水盐运移和玉米产量的影响,在长胜试验站开展了微咸水膜下滴灌玉米的大田试验。试验采用负压计指导灌溉,控制滴头下20cm深处的土壤基质势下限分别为-10,-20,-30,-40kPa,每个处理重复3次,按随机区组布置。结果表明:膜下滴灌湿润体形状在垂直于滴灌带的滴头所在竖直剖面上近似为半椭圆形,随着灌水下限的增大,湿润层土体含水率增大;玉米根部附近均出现盐分低值区,膜外表层均出现盐分高值区;-20kPa和-30kPa灌水下限适中,既能较充分淋洗膜内表层土壤盐分,又不会造成微咸水中的盐分滞留累积;在玉米生育期内,膜内、膜外地下100cm土体均积盐;-10kPa和-20kPa下限处理对应的湿润体垂直深度约为60cm;玉米收获后,地下100cm土体均积盐,需要进行秋浇或春汇,大量淋洗土壤盐分,保证耕地盐分不逐年累积;试验条件下,玉米产量随着灌水下限的降低而减少。

Effects of Control Lower Limit of Saline Water Mulched Drip Irrigation on Water Salt Movement and Corn Yield in Saline Soil

To study the effects of lower limit of saline water mulched drip irrigation on water salt transport and corn yield, a field experiment about mulched drip irrigation of corn with saline water was conducted in Changsheng experimental station. Tensiometer was used to guide irrigation, in each treatment the matric potential of soil 20?cm depth under the emitter was controlled higher than -10 kPa, -20 kPa, -30 kPa, -40?kPa, respectively. All treatments were repeated three times with the experimental plots following a complete randomized block design. Results showed that the shape of wetted body of mulched drip irrigation on sectional elevation of emitter which was perpendicular to the drip irrigation belt was approximated to semi-ellipsoidal. The water content of wetness soil layer would increase with increasing irrigation lower limit. The zone near maize root of all treatments appeared low salinity zone, surface layer out of the plastic film appeared high salinity area; -20?kPa and -30?kPa irrigation lower limit were moderate, they not only could leach surface soil salinity in the mulch more fully, but also did not lead to the salt in brackish water accumulation. All treatments 100?cm under the surface in and out of the mulch during growth of corn occurred salt?deposit. The depth of wetting layer of -10?kPa and -20?kPa irrigation limit were both about 60?cm. After maize harvest, all treatments occurred salt accumulation under the surface 100?cm, to ensure land salinity not accumulated year by year, massive irrigation to leaching large number of soil salinity in autumn or next spring was required. When irrigation frequency was too low, the maize yield decreased with decreasing irrigation frequency. Under the experimental conditions, the maize yield decreased with decreasing irrigation limits.