不同试剂提取紫色土溶解性有机碳含量研究

Study on Concentration of Dissolved Organic Carbon by Different Extractants in Purple Soil

本试验选取了不同浓度的KCl、K2SO4和CaCl2试剂,以6种不同耕作方式下的紫色土为对象,研究其提取土壤溶解性有机碳(DOC)的浸提效果。结果表明,各试剂提取土壤DOC含量均随生育期变化,呈现先增加后减弱的趋势,在拔节期达到峰值。同一生育期下,2.00 mol·L-1KCl和0.25 mol·L-1K2SO4提取DOC平均含量相对最高,0.05 mol·L-1KCl和0.15 mol·L-1CaCl2提取DOC平均含量相对较低。几种试剂中0.25 mol·L-1K2SO4提取的成熟期土壤DOC量占总有机碳比例最大(2.67%),同时,0.25 mol·L-1K2SO4测定各时期结果重复间的平均变异系数也最小(10.00%),2.00 mol·L-1KCl次之。0.15和0.25 mol·L-1K2SO4提取的成熟期DOC与土壤有机碳、全氮、速效磷、全磷呈显著(P<0.05)或极显著(P<0.01)相关关系。因此,综合试剂提取土壤DOC的浸提率、稳定性及其与土壤性质的关系得出,0.25 mol·L-1K2SO4为提取紫色土DOC的最佳试剂,2.00 mol·L-1 KCl和0.15 mol·L-1K2SO4次之。

In this trial, the extracting effect of different concentrations of KCI, K2 SO4 , CaCl2 on the dissolved organic carbon （DOC） of purple soils under six different tillage forms were studied. The results showed that soil DOC content firstly appeared increase, and then weake- ning trend with the growth period by different extractants, and reached its peak in the jointing stage. Under the same growth period, average DOC contents were relatively high by 2.00 mol ·L^-1 KCl and 0.25 mol ·L^-1 K2 SO4 , and relatively low by 0.05 mol ·L^-1 KCI and 0.15 mol ·L^-1 CaCl2. Comparing of the efiiciencies of extractants, the highest was 0.25 mol ·L^-1 K2 SO4 （2.67 % ） with the least variation coefficient of 10.00 %, then the second was 2.00 mol ·L^-1 KCl. The concentrations of DOC by 0.15 mol ·L^-1 and 0.25 mol ·L^-1 K2 SO4 extracting had a significant correlation （ P 〈 0.05 ） or highly significant correlation （ P 〈 0.01 ） with soil organic carbon, total nitrogen, available phosphorus and total phosphorus at maturity. Therefore, taking the reagents＇ extraction rate, stability and it＇s correlation with soil properties into account, 0.25 mol ·L^-1 K2 SO4 was the best suitable reagent to extract the DOC concentration of purple soil, and 2.00 mol ·L^-1 KCl and 0.15 mol ·L^-1K2SO4was the second.