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利用微咸水灌溉是解决干旱区水资源短缺的重要途径.通过田间小区滴灌试验,研究了不同矿化度微咸水(0.31、3.0、5.0 g·L-1,Na Cl浓度)对土壤过氧化氢酶、蔗糖酶、多酚氧化酶、β-葡萄糖苷酶和纤维素酶活性的影响,采用土壤碳通量和物料袋法研究了土壤CO2通量和有机碳降解对微咸水滴灌的响应.结果表明:微咸水(3.0 g·L-1)处理下蔗糖酶、β-葡萄糖苷酶、纤维素酶的活性分别比淡水处理降低31.7%~32.4%、29.7%~31.6%、20.8%~24.3%,而土壤多酚氧化酶活性则随灌溉水矿化度提高而显著升高,在膜下微咸水、咸水处理多酚氧化酶较淡水处理提高2.4%、20.5%.土壤微生物生物量碳和微生物熵均随灌溉水矿化度提高呈降低趋势,而代谢熵则呈升高趋势.不同处理对土壤CO2通量影响表现为淡水>微咸水≥咸水,且膜下CO2通量显著高于膜间(P<0.05),棉花吐絮期(9月20日)膜下淡水处理较咸水和微咸水处理的CO2通量分别升高29.8%、28.2%,微咸水滴灌显著降低了土壤CO2通量.不同矿化度微咸水滴灌对有机物(棉花和苜蓿秸秆)的降解率表现为淡水>微咸水>咸水,膜下有机物降解显著高于膜间.在培养第125天时,咸水、微咸水、淡水处理的膜间棉花秸秆回收率分别为39.7%、36.3%、30.5%,膜间苜蓿秸秆回收率分别为46.5%、36.5%、35.4%.微咸水灌溉明显抑制了北疆滴灌棉田土壤酶活性,造成土壤微生物量和CO2通量下降,土壤有机物降解率降低,使绿洲农田土壤生物性状变差.
The use of brackish water irrigation is an important way to solve the shortage of water resources in arid areas.Through field drip irrigation experiments, we studied the effect of different salinities brackish water (0.31, 3.0, 5.0 g · L-1, Na Cl concentration) Catalase, cellulase and cellulase activities. The soil carbon flux and material bag method were used to study the effects of soil CO2 flux and organic carbon degradation on the brackish water drip irrigation The results showed that the activity of invertase, β-glucosidase and cellulase decreased by 31.7% -32.4%, 29.7% -31.6% and 20.8 respectively compared with fresh water treatment under the condition of 3.0 g · L-1 % ~ 24.3%, while the activity of soil polyphenol oxidase increased significantly with the salinity of irrigation water increased by 2.4% and 20.5% compared with fresh water treated with brackish water and salt water, respectively. Microbial biomass carbon and microbial entropy both decreased with the salinity of irrigation water, while the metabolic entropy showed a rising trend.The effects of different treatments on soil CO2 flux showed that freshwater> brackish water> saline water, CO2 fluxes were significantly higher than those between the two membranes (P <0.05). Cotton boll-opening (September 20) The CO2 flux of water treatment increased by 29.8% and 28.2% respectively, and the brackish water drip irrigation significantly reduced the soil CO2 flux.The degradation rate of organic matter (cotton and alfalfa straw) Saline water and brackish water, the degradation of organic matter under the membrane was significantly higher than that between the membrane.The recoveries of cotton straw between brackish water, brackish water and freshwater were 39.7%, 36.3%, 30.5% The recoveries of alfalfa straw were 46.5%, 36.5% and 35.4% respectively.The irrigation of brackish water obviously inhibited the enzyme activity of soil in drip irrigation of northern Xinjiang, resulting in the decrease of soil microbial biomass and CO2 flux and the degradation of soil organic matter, Farmland soil biological properties worsened.