黄河上游泥沙中氮磷形态及其生物有效性

As we all know, there are high sediments content in the Yellow River, and lots of nitrogen and phosphorus nutrients input in the farming fields by the Yellow River water irrigation; it has been confirmed that amounts and particle size of sediments from the Yellow River were seasonal changed. However, there were rather less researches on the spatial-temporal differentiation of nitrogen and phosphorus in sediments and its bioavailability in the upper Yellow River, it is very important to make clear that the role of nitrogen and phosphorus from the sediments input in farming fields soil and increase the sediment nutrients use efficiency. Therefore, nitrogen and phosphorus in sediments from the upper Yellow River are taken as the investigation object, and the quiescent sedimentation test will be conducted to discuss the spatial-temporal differentiation of nitrogen and phosphorus in sediments. The method for classification of soil particles is used to reveal the particle sizes classification of sediments from the upper Yellow River and the characteristics of nitrogen and phosphorus forms distributing in different particle sizes of sediments. These experiments with the simulated incubation under controlled conditions and field-pot will be carried out to evaluate the bioavailability of nitrogen and phosphorus in sediments under different crops cultivation, and make sure the role of sediments nitrogen and phosphorus from the Yellow River input in farming fields soil. The research results of this project can provide theoretical basis for the improvement of soil fertility and substitution of fertilizer nitrogen and phosphorus by sediments nutrients.

众所周知，黄河泥沙含量高，农田引黄淤灌输入大量泥沙氮磷养分，黄河泥沙输入量和颗粒大小具有明显的季节变化性已经得到证实。有关黄河泥沙中氮磷赋存形态的时空分异性以及其生物有效性大小评价的研究少见报道，明确泥沙氮磷在引黄灌溉农田土壤养分输入中地位对高效利用黄河泥沙中养分资源具有重要意义。本项目以黄河上游泥沙中氮磷为研究对象，采用静水沉积试验，探讨引黄灌溉农田输入泥沙中氮磷形态的时空分异性；借鉴土壤颗粒分级方法，阐明黄河上游泥沙颗粒组成及其氮磷形态分布特征；利用控制条件下室内培养与田间盆栽试验，评价黄河泥沙中氮磷养分对不同作物的生物有效性大小，明确黄河泥沙中氮磷在引黄灌溉农田土壤养分输入中的地位；本项目的研究结果为黄河上游引黄灌溉农田土壤培肥和泥沙氮磷对肥料氮磷的替代作用提供理论依据。

黄河入海年输沙量位居世界第二位，占我国大陆境内入海河流输沙量的46%。黄河泥沙不仅对流域水体的水质有着重要影响，其对引黄灌溉农田土壤培肥和土壤环境效应也有重要作用。以黄河上游泥沙为研究对象，采用静水沉积、筛分法、室内培养与田间盆栽试验方法，分别探讨了引黄灌溉农田输入泥沙质量分数及氮磷形态的时空变异性，明确了黄河泥沙颗粒组成的分级特征，评价了水稻和春小麦对黄河泥沙中氮磷养分的生物有效利用大小，揭示了黄河泥沙中氮磷在引黄灌溉农田土壤养分输入中的地位。取得主要研究结果如下：（1）黄河泥沙质量分数总体变化趋势是先增后减，8月份达最高峰值。表现为中宁（上游）＞青铜峡（中游）＞平罗（下游），同时期越靠近黄河上游的泥沙含量越高，但最高不超过1%。溶解性总N和颗粒态P分别为黄河水氮磷主要赋存形态；有机态N是泥沙氮素的主要赋存形态（占98%以上）。泥沙中速效磷（Olsen-P）占全磷比例为1.80%-1.93%。（2）黄河泥沙中不同粒级颗粒具有较大的时空变异性，总体以＜0.1 mm粒级颗粒为主（占比55.7%-82.0%）。黄河泥沙质地为砂质壤土，泥沙输入对灌淤土砂质特性形成起重要作用。黄河沉积泥沙各粒级颗粒中无机氮以硝态氮为主（占77.4%-99.1%）。（3）水稻和春小麦对黄河泥沙养分吸收利用都表现为N＞P2O5＞K2O，利用能力水稻远高于春小麦。（4）宁夏灌区单位面积农田引黄灌溉水沙平均分别输入N 31.76 kg/hm2、P2O5 8.86 kg/hm2，其中泥沙等颗粒物分别输入N 10.82 kg/hm2、P2O5 7.40 kg/hm2，泥沙输入氮磷养分比例分别占36%-37%和88%-91%。（5）发表中文期刊论文4篇，申请国家专利2件。研究结果为黄河上游引黄灌溉农田的化肥减施替代和氮磷养分平衡研究提供了数据参考和理论指导。