增施有机肥对长期微咸水补灌下土壤理化性质与作物产量的影响

The effects of applying manure on soil physical properties and crop yield under long-term brackish water irrigation

  • 摘要: 探究增施有机肥以消减长期微咸水灌溉对土壤物理性状及作物产量的不利影响为目标,基于华北低平原南皮试验站2015年开始的冬小麦夏玉米一年两熟微咸水补灌试验,设置增施有机肥试验,常规施肥作为对照。共4个灌水处理,分别为:在冬小麦底墒充足条件下,在拔节期分别用3g L-1、4g L-1和5 g L-1微咸水补灌,矿化度1 g L-1 淡水作为对照。所有处理夏玉米播种用淡水灌溉出苗水。结果表明,微咸水长期灌溉条件下施用有机肥后,0-20cm土壤有机质、有效钾、有效磷和全氮含量比不施有机肥处理分别提高46.8%、117.0%、75.7%和45.5%,显著提高了土壤肥力;施用有机肥降低了长期微咸水灌溉下0-10cm土壤容重,提高了0-20cm土壤水稳定性团聚体比例,耕层土壤肥力和结构得到改善。施用有机肥可显著提高耕层土壤微生物中细菌、真菌和放线菌3大菌群的数量,比不施有机肥处理平均提高73.8%。由于有机肥本身的含盐量,在冬小麦收获期,施用有机肥处理0-40cm、40-100cm、100-200土壤含盐量高于不施用有机肥处理,至夏玉米收获期施用有机肥处理的土壤各层盐分含量仍高于不施有机肥处理,但差异不显著。施用有机肥改善了土壤结构提高了雨季土壤的脱盐率,在夏玉米收获期,有机肥处理0-40cm、40-100cm和100-200cm的脱盐率分别比不施用有机肥提高了34.3%,14.7%和20.4%,尤其是0-40cm土层脱盐率的提升为作物生长提供了低盐环境。长期微咸水灌溉下施用有机肥带来的小麦季土壤盐分增加对冬小麦产量产生了不利影响,但土壤肥力的提升增加了夏玉米产量,两季作物的产量变化均未达到显著水平。上述结果显示,长期微咸水灌溉条件下增施有机肥可以有效提升土壤有机质含量,维持土壤结构,利于土壤脱盐,生产上可选择含盐量低的有机肥或者减少有机肥的施用量,在缓解长期微咸水灌溉对土壤物理性状不利影响下,降低有机肥施用带来的盐分增加,推动微咸水安全可持续利用。

     

    Abstract:  To maintain the soil quality under long-term saline water irrigation, application of manure was carried out to examine the influences of manure on soil physical properties. The long-term saline irrigation was conducted from 2015 to present at the Nanpi Experimental Station in the Low Plain of North China Plain, which including 4 irrigation treatments, which were: irrigation once at jointing stage for winter wheat with irrigation water containing salt at 1 g L-1 (as fresh water), 3 g L-1, 4 g L-1 and 5 g L-1; maize was irrigated at sowing using fresh water. Under all those irrigation treatments, manure application were conducted, with treatments without manure application as control. Results showed that under long-term irrigation with saline water, the application of manure increased the soil organic matter contents, exchangeable potassium, available phosphorus, and total nitrogen contents in the 0-20 cm soil by 46.8%, 117.02%, 75.7%, and 45.5%, respectively, as compared with the treatments without manure application.The application of manure reduced the bulk density of 0-10 cm soil layer, increased the proportion of water stable aggregates in 0-20 cm soil layer, and improved soil fertility and maintained soil structure of tillage layer. The application of manure significantly increased the amounts of bacteria, fungi, and actinomycetes in the soil microbiota of 0-20cm soil by 73.8% as compared without manure applictaion. Due to the salt contained in manure, application of manure had dual effects on soil salt contents. In winter wheat season, the application manure increased soil salt contents. During summer maize season, due to the high salt leaching effects under manure application, salt contents were significantly reduced which resulted in the smaller difference in salt contents between the manure and the non-manure treatments. The improvement in soil structure under manure application increased soil desalination rate by 38.3%, 14.7%, and 21.3% as compared to treatments without manure application for soil layers of 0-40 cm, 40-100 cm, and 100-200 cm, respectively, during the summer rainfall season. Due to the higher salt contents during winter wheat season under manure application, yield of winter wheat was slightly decreased as compared without manure application. In contrast, the yield of summer maize was slightly improved under manure application, due to the increased soil nutrient contents and the effective salt leaching. The results from this study indicated that manure application helped to maintain soil physical structure which was important for long-term utilization of saline water.

     

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