旱地土壤易分解与耐分解碳氮组分的高效筛分方法

The efficient sieving method of the upland soil liable and recalcitrant carbon and nitrogen component

土壤易分解与耐分解碳、氮组分是表征土壤有机碳、氮转化特征的一项重要指标,但如何高效获得该组分的大量样品是当前的一个难题。本文改进传统少量筛分法,设计一次性大量筛分设备,对我国两种典型旱地土壤黑土与潮土的不施肥（CK）、化肥（NPK）、化肥配施秸秆（NPKS）和化肥配施有机肥（NPKM）4个处理土壤分别进行一次性大量（100、200和300 g）筛分,并比较与传统（50 g）筛分法的差异,了解该设备大量筛分样品的工作效率与可行性。结果表明：黑土或潮土大量（300 g）筛分时,与筛分量200和100 g的质量、全碳和全氮回收率无显著差异,均在97%以上;3个筛分量下同一处理的黑土或潮土的易分解碳、氮或耐分解碳、氮含量基本无显著差异。与传统筛分法相比,黑土或潮土筛分量为300 g的质量回收率比50 g的质量回收率提高1%～3%,全碳和全氮回收率提高1%～8%;易分解碳、氮或耐分解碳、氮含量基本无显著差异,以黑土CK处理为例,筛分量为300 g与50 g的土壤易分解组分氮含量分别为0.12和0.14 g/kg,两者无显著差异;与传统筛分法相比,筛分量由50 g提高到300 g,单位时间获得土壤易、耐分解碳、氮组分样品的效率提高了5倍。因此,改进设备后的筛分法可以一次性筛分300 g旱地土样,且土壤质量、全碳和全氮回收率提高1%～8%,是一种获取旱地土壤易、耐分解碳、氮组分较为简单高效的方法。

Soil liable or recalcitrant organic carbon and nitrogen components are two important indicators of soil organic carbon and nitrogen turnover property. But it is a problem to obtain the components of the samples in a large number. So the original sieving method was improved and a new machine that could sieve more at one time was invented in this study. Two typical soils of upland（ black soil and fluvo-aquic soil） were chosen to sieve under three mass gradients of 300,200 and 100 g,and each kind of the soil contained four treatments,namely no fertilizer（ CK）,chemical fertilizer（ NPK）,chemical fertilizer combined with straw（ NPKS）,and chemical fertilizer combined with manure（ NPKM）. Then the differences between the new（ 300 g） and original（ 50 g） sieve method were compared to determine the efficiency and feasibility of the new method. The results showed that the average recovery rate of mass,organic carbon or total nitrogen recovery rate,which all above 97%,had no significant differences under three mass gradients of 300,200 and 100 g. There were also no significant difference in liable or recalcitrant carbon（ or nitrogen） content. Compared with the results that sieved at mass of 50 g,the mass recovery rate of the black soil or fluvo-aquic soil sieved at mass of 300 g increased by 1% ～ 3%. Organic carbon or total nitrogen recovery rate improved by 1% ～ 8%. There were also no significant difference in liable or recalcitrant carbon（ or nitrogen） content between the two sieving mass. For example,the liable nitrogen content of black soil under CK treatment,sieved at mass of300 g,was 0. 12 g / kg,which had no significant difference with 0. 14 g / kg that sieved at 50 g. The work efficiency of the new method,which increased the sieving mass from 50 g to 300 g,was five times of that of the old method to obtain the liable or recalcitrant carbon and nitrogen components. In conclusion,the new machine could sieve 300 g upland soil sample at one time,and it also improved the average recovery rate of mass,organic carbon and total nitrogen by 1% ～ 8%,compared to the original equipment. So it could be a simple and efficient way to get upland soil liable or recalcitrant carbon and nitrogen components.