坏囿矿化度地下水灌溉对民勤土壤环境的影响

通过野外试验和室内分析相结合的方法,研究了民勤绿洲农田不同矿化度(0.8g·L-1、2.0g·L-1和5.0g· L-1)地下水灌溉对土壤环境的影响.结果表明:随着灌溉水矿化度的增加,生长季水分消耗量逐渐降低,土壤总孔隙度和土壤有机质含量逐渐下降,而土壤有效水含量和土壤电导率则逐渐增加.当灌溉水矿化度为0.8g·L-1时,收获后土壤中上层(0～60 cm)电导率比播种前明显降低,而底层(60～90 cm)电导率略有增加,即淡水灌溉的淋溶作用明显；当灌溉水矿化度为2.0g,L-1时,生长季中的灌水依然对土壤盐分有淋溶作用,但明显弱于淡水的淋溶效果,收获后土壤盐分有明显的表聚现象；当灌溉水矿化度为5.0g·L-1时,收获后在0～60 cm深度电导率明显增加,在60～90 cm深度没有明显变化.

Effects of Irrigation with Water with Three Different Salinities on the Soil Environment in Minqin of Gansu, China

The objective of this paper was to evaluate the effects of the irrigating water salinity on soil environment in the Minqin Oasis. Field work was carried out systematically in the Minqin Desert Control Station. The results showed that with the increase of the irrigating water salinity, the water consumption in the whole growing season, soil total porosity and organic matter decreased. The available water in the root zone and electric conductivity tends to increase due to the increase of the irrigating water salinity. When the irrigating water salinity was 0.8 g·L-1, the electric conductivity in the top layer of soil obviously decrease after harvest. On the contrary, the electric conductivity of soil in the low layer increased, suffesting that eluviation of freshwater irrigation was distinct. When the irrigating water salinity was 2.0 g·L-1, the irrigation lead to eluviation in the soil profile during the growing season, but the effect was not as obvious as the eluviation of freshwater, and after harvest the salt accumulation in the top layer was obvious. When the irrigating water salinity was 5.0 g·L-1, the electric conductivity increased in the 0-60 cm layer after harvest, and there was no obvious change in the 60-90 cm layer.