【摘要】 本试验以禾谷类作物(大麦)为对象进行盆栽耗竭试验,结果说明:缓效性钾是禾谷类作物(大麦)钾素的主要给源。电超滤法(EUF)在一轮测定中能同时测得土壤钾素等养分的浓度、容量、缓冲容量和固定能力,电超滤法是研究和评定土壤钾素供应状况较好的方法。更多还原

【Abstract】 Pot experiment with barley as the indicator crop was carried out by using chemical methods and kinetic electroultrafiltration technique to study the relationship between the uptake of K by barley and the potassium status of the different soils. We hope that this investigation will lead to the development of a method for quick test of K and its recommendation particularly suitable for graminaceous crops, and that it will lay foundation for the study of the Ksup plying status of rice soils.The results from the pot experiment indicate that the total uptakes of K by barley from the soil in the form of exchangeable K and of slowly available K were 19.9—39.0% and 61—80.1% respectively. The total amount of K taken up by barley is 1.6—2.7 times that of soil exchangeable K. The correlation between the growth of barley as well as its total uptake of K and the amount of K absorbed from slowly available soil K is highly significant (0.9908 and 0.9884 respectively). All this shows that the slowly availbale K is the main source of K taken up by the graminaceous crop (barley).The conventional chemical methods give only the amount of available nutrient present in the soil, whereas the electroultrafiltration (EUF) technique cangive the K concentration, quantity, buffer capacity and K fixation in a single run.The correlation between the EUF value in mgK/100g soil/35min, and the total growth of barley as well as its total uptake of K is very high. By regulating the voltage applied and the duration of time, EUF technique gives very useful information about the K status of the soil.From the experiment, we come to the following conclusion: the K supplying intensity, quantity and buffer capacity of Xinghua clay and Nanjing yellow clay loam are all high and these soils are not deiicient in available K. However,Nanjing yellow clay loam has the highest fixation capacity of K. The supply power of Hanjiang soil is lower than the average. The supplying intensity,quantity and buffer capacity of Yixing silty-soil are the lowest and this soil is deficient in available K.更多还原