华北与西北地区典型土壤固钾能力差异研究

试验在我国华北和西北小麦玉米种植地区进行,研究了几种典型土壤在连续13年的K肥施用及小麦秸秆还田条件下耕层土对外源K素的固定能力差异.结果表明:相比常年只施NP肥处理,连续施用K肥或秸秆还田可显著降低土壤对外源K素的固定量,土壤固K量随环境溶液中K素浓度的增加而增加,但固定率下降.随土层变深,各定位点土壤固K量和固K率均随之增加,华北两定位点相对明显.轮作地区各处理0 ～ 20 cm土层土壤对外源K素的固定量(率)均远高于原始土壤,而单作区土壤的固K量(率)稍高或低于原始土.土壤固K能力表现出地带性规律,整体看取自华北两个定位点的土壤对外源K的固定能力强于取自西北两个定位点的土壤.

Study on Difference of Potassium Fixation Capacity of Soils in Northern and Northwestern Regions of China

Experiments were conducted to study the difference of potassium fixation capacity of soils under 13 year application of K fertilizer and wheat straw return in the northwestern region and northern region of China. The results showed that continuous application of K fertilizer and wheat straw return could reduce fixation rate of added K significantly compared with NP treatment. With the increase of K concentration in the surrounding solution, K fixation capacity of soils increased but the percentage of the total K in the solution fixed by soils reduced. K fixation rate in subsoil layer (20 ~ 40 cm) was greater than that in the top layer soil (0 ~ 20 cm), and it was more obvious in the northern region. K fixation rate by soils under double cropping region was higher than original soil but contrary under sole cropping region. K fixation capacity increased from the northwestern region to the northern region.