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土壤有机质的测定,我国广泛应用的为丘林法,此法比干烧法快速而且设备简单,但是与 Walkley Black提出的铬酸氧化还原测定水合热法相比,因其需要油浴或磷酸浴加热,手续就比较麻烦,加之取样量少,加热温度及时间不易精确控制一致,精密度不及水合热法。但在实践中,一般水合热法受室温影响较大,要求室温在20℃以上这一条件限制了它的使用,同时,一般水合热法的温度较低,最高温度在120℃左右的时间极短,因此土壤有机质的氧化率较低,对不同类型的土壤,有机质氧化率的差异也就更加明显,因此,Walkley和Smith、Weldon等提出的不同土壤氧化校正系数各不相同。为了对一般水合热法采取一定的改进措施,使之既不失其快速简便的优点,而又与丘林法有良好的相关性,还能克服其受室温影响而限制了适用时间的缺点。为此,需要找出的氧化率校正系数能似丘林法那样更广泛地适用于各类土壤。我们用全国14个土壤样品设计了以下试验。
Determination of soil organic matter, our country is widely used for the method of hill, this method is faster than the dry method and the device is simple, but with the Walkley Black chromate redox determination of hydration heat compared to its need for oil bath or phosphoric acid bath heating , Procedures are more troublesome, combined with less sampling, heating temperature and time is not easy to accurately control the same precision than hydration heat method. However, in practice, the general hydration heat method is greatly affected by the room temperature, requiring room temperature above 20 ℃ this condition limits its use, while the general hydration heat temperature is low, the maximum temperature of about 120 ℃ pole Therefore, the oxidation rate of soil organic matter is low, and the difference of oxidation rate of organic matter becomes more obvious for different types of soils. Therefore, the different soils oxidation correction coefficients proposed by Walkley and Smith and Weldon et al. Are different. In order to take some improvement measures to the general hydration heat method, it not only has the advantages of quickness and simplicity, but also has good correlation with the method of coursing, and also overcomes the shortcoming that the application time is limited by the influence of the room temperature. For this reason, it is necessary to find out that the correction coefficient of the oxidation rate can be applied to various types of soil more broadly like the Qiu Lin method. We used the following 14 soil samples throughout the country.