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通过分析三江平原不同土地利用方式下土壤氮含量及储量的变化,揭示土壤氮库的演变特征。结果表明,湿地土壤的全氮含量及储量明显高于农田、火烧地和弃耕地土壤。开垦导致土壤全氮含量及储量下降,且随耕种年限增加符合一阶指数衰减模型(p<0.01);连续火烧5a导致土壤全氮含量及储量显著降低,而弃耕7a导致其值有所增加,但增加量较小,说明土壤氮库耗竭易、恢复难;土壤全氮与有机质之间呈显著正相关(p<0.01),说明湿地开垦后土壤有机质含量降低是引起土壤氮肥力下降的主要因素,提高土壤有机质含量将有利于维持和提高农田土壤氮肥力;通过向连年火烧湿地输入适量人为氮(如农业排水)可减缓土壤氮的持续损失,进而可防止湿地植被退化及农业排水大量直接排入河流而引起的许多不利影响。
By analyzing the changes of soil nitrogen content and reserves under different land use patterns in the Sanjiang Plain, the evolution characteristics of soil nitrogen pool were revealed. The results showed that the total nitrogen content and storage of wetland soil were significantly higher than that of farmland, burned ground and abandoned farmland. Reclamation led to the decrease of total nitrogen and total reserves of soil, which was consistent with the first-order exponential decay model (p <0.01) with increasing years of cultivation. Continuous burning of 5a led to a significant decrease of total nitrogen and total reserves of soil, (P <0.01), indicating that the reduction of soil organic matter content after wetland reclamation is the main cause of soil nitrogen fertility decline Factors and improve the soil organic matter content will help to maintain and improve soil nitrogen fertility in farmland; through the input of appropriate amount of man-made nitrogen (such as agricultural drainage) to successive years of burning wetland, the sustained loss of soil nitrogen can be slowed, thus preventing wetland vegetation degradation and agricultural drainage Many adverse effects caused by discharge into the river.