紫色水稻土硅有效性的研究

STUDY ON AVAILABILITY OF SILICON IN PADDY SOILS FROM PURPLE SOIL

通过田间试验和土壤培养试验研究了紫色水稻上有效硅含量的概况，影响因素及施硅效应。结果表明:紫色水稻土施硅肥有不同程度的增产效应，增产幅度＞10％的土壤占55％。土壤有效硅含量为红紫泥田（SiO2:45.4mg／kg）＜灰棕紫泥田（SiO2:89.8mg／kg）＜红棕紫泥田（SiO2147.mg／kg）。水稻产量与土壤还有效硅含量及水稻茎叶硅含量呈显著正相关（r=0.781**和r＝0.804**，n=20）。影响紫色水稻上有效硅含量的因素主要是土壤pH和土壤质地;其次是Eh;铁铝氧化物含量和有机质含量也有一定的影响;有效硅与土壤全硅无明显相关性（r=0.196，n=22）。强酸性土、酸性土，质地偏砂土壤常是缺硅土壤;提高酸性土的pH，硅的有效性下降，降低碱性土的pH，土壤硅的有效性增强。有机酸能显著地促进土壤硅的释放，提高有效硅的含量。应用Elovich、抛物线扩散方程和权函数方程能很好描述土壤硅的释放。动力学方程参数b值比直观分析更能综合地反映土壤的硅释放。

Available Si content, its affecting factors and effect of Si fertilization in paddy soils from purple soil in Sichuan province were studied by using fields experiments and soil incubation experiments. The results are summarized as follows:(1) Si fertilization increased rice yield to varying degrees on the soils, that tallied with the state of contents of available Si: red purple paddy soil (SiO2 45.4mg,kg)<grey brown pruple paddy soil(SiO2, 89.8mg/kg)<red brown purple paddy soil(SiO2,147. 9mg/kg) The ranges of yield increased by more than 10% accounted for 50% of the soils. The content of available Si in the soils was positively correlated with the yield of rice and the content of Si in leaf and stem of rice (r=0. 804** and r=0. 781**,n=20).(2) Factors affecting available Si in the soils were in the sequence of soiI pH and soiil texture>Eh>Fe, Al oxides and organic matter. The total Si was insignifficantly correlated with the content of avallable Si in the soils. Strong acid soil. acid soil and sandy soil were Si-deficient soils. The availability of Si in acid soil was decreased by increaslng soil pH, and that in alkaline soil was increased by decreasing the soil pH.(3) The release of soil Si was accelerated and the content of soil available Si was increased by organic acids. The mechanism of Si release in the soils could be described with the following kinetic equations: Elovich equation, parabolic diffusion equation and power equation and be more comprehensively delineated by the parameter b value in the equations than the direct analysis.