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在美国西部许多土壤实验室用DTPA法评价Zn和Fe的速效值,也有用来估价Cu、Mn的速效值。关于样品的处理,一般从田里取来样品后,应尽快地风干,但有时潮湿样品送至实验室后,要搁置一周或更长时期才能风干进行分析。这样对土壤中微量营养元素速效值有无影响开始是不清楚的。通过统计分析表明,经湿润培养的土样与立即风干的土样比较,DTPA浸提的Fe、Mn、Cu为1%的显著降低,Zn为10%的显著降低。这样土样经湿润培育后
In many soils laboratories in the western United States, the quick and effective values of Zn and Fe evaluated by DTPA method are also used to estimate the quick-acting values of Cu and Mn. With regard to sample handling, the sample should be air-dried as soon as possible after it is taken from the field, but sometimes after a wet sample is sent to the laboratory, it can be allowed to stand for a week or longer to be air-dried for analysis. It is unclear how this affects the availability of micronutrients in soils. The statistical analysis shows that compared with the immediately air-dried soil samples, the DTPA-leached Fe, Mn, Cu is significantly reduced by 1% and the Zn is significantly reduced by 10%. This kind of soil samples after moist incubation