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通过对一系列含有不同磷水平的原状土室内模拟磷素流失的方法,在同一降雨强度下,分别研究了不施用磷肥时不同磷含量的土壤径流磷流失和施用磷肥24 h后的径流磷流失量,以及区分土壤本身不同水平的残余磷和新施入的肥料磷对径流流失磷的贡献。结果表明:在所有处理中,施肥量、土壤残余磷与总磷流失均呈正相关关系;溶解反应磷(DRP)是总溶解磷(TDP)的主要成分,而TDP占总磷(TP)的60%以上,是流失磷的主要形态,溶解性难反应态磷(DUP)只占流失总磷的1.2%~4.6%,但实际浓度在OP2有机处理中达到0.28 mg/L,这部分磷不易下沉,特别是施肥后短期内的降雨径流,可能导致DUP流失量大大增加。与不施肥试验相比,施入无机肥后,DRP、TDP量均显著增加,所占流失总磷的相对比例也明显增加,相对应的TPP、DUP占总流失磷的相对比例则依次减少;而与无机肥处理相比,有机肥处理的OP1、OP2变化则不同,DUP占TP的相对比例显著增加,达到4.4%和4.6%,但其它形态磷所占相对比例则略有减少。此外,线性回归分析表明了土壤新施入的磷肥是流失负荷中磷的主要来源。
Through a series of simulating phosphorus loss in undisturbed soils with different phosphorus levels, under the same rainfall intensity, the runoff phosphorus loss with different P content and the runoff phosphorus loss after phosphorus application for 24 h were studied respectively As well as the contribution of residual phosphorus and freshly applied fertilizer P to different levels of soil itself on runoff phosphorus loss. The results showed that there was a positive correlation between fertilization amount, soil residual phosphorus and total phosphorus loss in all the treatments. Dissolved reactive phosphorus (DRP) was the main component of total dissolved phosphorus (TDP), while TDP accounted for 60% of total phosphorus %, Which is the main form of phosphorus loss. Dissolved difficult-to-react phosphorus (DUP) accounts for only 1.2% ~ 4.6% of total phosphorus loss, but the actual concentration is 0.28 mg / L in OP2 organic treatment, Sediment, especially rainfall runoff shortly after fertilization, may result in a significant increase in DUP runoff. Compared with the non-fertilization experiment, the amount of DRP and TDP significantly increased after application of inorganic fertilizers, and the relative proportion of TP lost significantly increased. The relative proportion of TPP and DUP in total phosphorus loss decreased in turn; However, compared with inorganic fertilizer, the changes of OP1 and OP2 under organic fertilizer were different, and the relative proportion of DUP to TP increased significantly, reaching 4.4% and 4.6%, but the relative proportion of other forms of phosphorus decreased slightly. In addition, linear regression analysis showed that the newly applied phosphate fertilizer was the main source of phosphorus in the runoff.