Abstract

Phosphorus plays an important role in double rice cropping systems grown on acidic paddy soil. To improve our knowledge and increase crop utilization of applied phosphorus fertilizers in paddy soils, we investigated changes in the content of soil inorganic phosphorus fractions in response to long-term application of chemical and organic phosphorus fertilizers. In this 35-year-long experiment, paddy soil in a double rice cropping system received one of three different fertilizer treatments: (1) cattle manure, M; (2) a chemical fertilizer of nitrogen (N), phosphorus (P), and potassium (K), NPK; and (3) a combination of NPK and M (NPKM) twice per year. Results showed that the maximum contents of Olsen-P in M, NPK and NPKM stabilized at 12.9, 31.7 and 52.7 mg/kg, respectively over 35 years. In contrast, the proportions of soil inorganic phosphorus content in total phosphorus of M, NPK and NPKM changed from 62.2% at the beginning of the experiment to 53.3, 61.9 and 66.2%, respectively. At equal amounts of accumulated phosphorus surplus, the increasing rates of total inorganic phosphorus content and inorganic phosphorus fractions in NPK were much higher than those in M and NPKM. At an average amount of accumulated phosphorus surplus of 100 kg/ha, the total inorganic phosphorus content of the NPK and NPKM treatments increased by 39.6 and 21.6 mg/kg, respectively. Fertilization mainly decreased the ratio of organic phosphorus to inorganic phosphorus and increased the ratio of aluminum-bound-phosphorus (Al-P) to inorganic phosphorus, especially under the NPK and NPKM treatments. Redundancy analysis showed that total phosphorus and Olsen-P were more closely correlated to iron-bound-phosphorus (Fe-P), calcium-bound-phosphorus (Ca-P) and Al-P fractions. This study suggests that the NPK and NPKM treatments increased phosphorus supply and inorganic phosphorus fractions compared to the manure application. Therefore, to avoid accumulation of a surplus of unabsorbed phosphorus and minimize phosphorus-leaching risk from acidic paddy soil, rates of inorganic phosphorus application, such as the combined application of manure and inorganic phosphorus fertilizer, should be reduced.

中文翻译：

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35年以上长期施用化肥和有机肥对酸性稻田土壤无机磷组分的年际变化有不同的影响。

摘要

磷在酸性水稻土上的双季稻种植系统中起着重要作用。为了提高我们的知识并提高水稻土中施用磷肥的农作物利用率，我们调查了长期施用化学和有机磷肥后土壤无机磷组分含量的变化。在这个长达35年的实验中，双季稻种植系统中的稻田接受了以下三种不同的肥料处理之一：（1）牛粪，M；（2）氮，磷，钾钾，氮磷钾的化学肥料；（3）每年两次结合NPK和M（NPKM）。结果表明，在35年中，M，NPK和NPKM中Olsen-P的最大含量分别稳定在12.9、31.7和52.7 mg / kg。相比之下，M，NPK和NPKM的总磷中土壤无机磷的比例分别从试验开始时的62.2％变为53.3％，61.9％和66.2％。在累积的磷剩余量相同的情况下，NPK中总无机磷含量和无机磷含量的增加速率远高于M和NPKM。在平均累积磷过剩量为100 kg / ha时，NPK和NPKM处理的总无机磷含量分别增加了39.6和21.6 mg / kg。施肥主要是降低有机磷与无机磷的比例，增加铝结合磷（Al-P）与无机磷的比例，特别是在NPK和NPKM处理下。冗余分析表明，总磷和Olsen-P与铁结合磷（Fe-P），钙结合磷（Ca-P）和Al-P组分更紧密相关。这项研究表明，与肥料施用相比，NPK和NPKM处理增加了磷的供应和无机磷的比例。因此，为避免积累过多的未吸收磷，并使酸性稻田中磷的淋失风险降到最低，应减少无机磷的施用量，例如肥料和无机磷肥的联合施用。