摘要
磷肥管理与土壤磷素赋存息息相关,选取杭嘉湖地区典型稻田定位实验,研究磷肥输入下稻田土壤剖面胶体磷含量的变化,分析不同施肥管理下胶体磷在土壤中的分布规律。结果表明,(1)胶体磷是磷素在土壤中赋存的重要形式,能够占到土壤胶体溶液(<1μm)总磷的85%以上,土壤全磷的0.1%—2%;(2)磷肥施用增加了土壤胶体磷含量,特别是在有机肥处理下0—5 cm土壤胶体磷含量达到了8.0 mg/kg;(3)随着土壤深度的增加,胶体磷含量减少,有机肥输入下对深层土壤胶体磷含量的影响较无机肥明显;(4)水稻收割后表层土壤胶体磷含量与油菜收割后相比减少明显,0—5 cm土壤胶体磷含量减少了90%左右,但有机肥施用下胶体磷含量减少较小;(5)水稻收割后30—60 cm土壤胶体磷含量有所增加,可能与胶体磷发生的纵向迁移有关。了解磷肥输入对稻田土壤剖面胶体磷含量的影响,为研究土壤磷素赋存形态及迁移变化提供科学依据,对有效评估胶体磷的环境风险起到指导作用。
Phosphorus （P） fertilization must be conducted with a clear understanding of P forms and their distribution in the soil profile. Excessive application of P fertilizers could eventually cause P accumulation, especially in the topsoil. P loss from a nutrient-enriched agricultural field can lead to eutrophication of water bodies, which has been a recent global concern. Traditionally, the P obtained after filtering a soil solution by using a 0.45-μm microporous membrane is defined as ＂particulate＂ or ＂dissolved＂ P species. Compared to the immobile soil matrix, colloidal particles （size, typically, between 1 nm and 1 μm） have larger surfaces and stronger sorption capacities. Colloid-facilitated P transport in agricultural soils has received much attention in recent decades because the binding of P species to colloidal particles can largely enhance its mobility. Therefore, colloidal P is an important contributor of P according to soil particle size fractionation, and it plays a significant role in the distribution, transformation, and variation of P in the soil environment. However, to date, few studies have shown the changes in soil colloidal P under long-term P fertilization. This study was based on long-term field experiments conducted in Hangjiahu Plain. We measured the changes of soil colloidal P contents and analyzed its distribution characteristics in a paddy soil profile, under different fertilization managements. Four P fertilizer treatments were applied： no fertilizer control （CK）, low P fertilizer （P1, 26 kg P/hm2） , high P fertilizer （P2, 39 kg P/hm2） and manure treatment （M, 26 kg P/hm2）. Soil samples were collected ＇after oilseed rape and rice harvests, and the soil profiles were divided into four layers, 0--5, 5--30, 30--60, and 60--100 cm. Soil total P concentration, mass of soil colloidal particles, and colloidal and truly dissolved P in water extraction were determined. Soil colloidal and truly dissolved P were determined using extraction with water, centrifugation, and ultra-centrifugation at 300000r/rain ibr 2 h to remove the colloids; P concentrations were determined using spectrophotomet~ based on binding with molybdenum and antimony. The mass of soil colloidal particles and colloidal P was calculated as the difference between non-ultracentrifuged and uhracentrifuged samples. Our results showed that colloidal P occupied at least 85% of the P in a soil colloidal solution and 0.1%--2% of the total P in the soil. P fertilization increased soil colloidal P concentration in all treatments, especially in the 0--5 cm layer in the M treatment, in which colloidal P was 8.0 mg/kg. Furthermore, soil colloidal P decreased with soil depth, except in the 0--5 cm and 5--30 em layers after rice harvest. Colloidal P decreased significantly in these two layers after rice harvest, which might have resulted from the anoxic conditions during the flooded period of rice production. At 0--5 cm depth, soil colloidal P after rice harvest was 90% lower than that after oilseed rape harvest; the reduction was less for the manure treatment. In general, compared to inorganic P fertilizer treatments, manure treatment had a more significant influence on soil colloidal P content. Colloidal P increased from 5.9% to 18.3% in the 30--60 cm layer after rice harvest compared to that after oilseed rape harvest, mainly because of the vertical transport of colloidal P. Our results provide scientific evidence tbr the existing P forms within the soil profile and the transformation characteristics of P. Our study also ofi^rs guidance for evaluating the environmental risk of yawing levels of colloidal P.
出处
《生态学报》
CAS
CSCD
北大核心
2015年第24期8251-8257,共7页
Acta Ecologica Sinica
基金
国家自然科学基金面上项目(41271314)
国家水体污染控制与治理科技重大专项(2012ZX07506-006-03)
关键词
磷肥管理
土壤剖面
胶体磷
phosphorus addition
soil profile
colloidal phosphorus
