论文部分内容阅读
三、贮备钾(Kc)和镁(MgR) (一)贮备钾(Kc)的测定引言由Metson等(1956)提出的这项测定值表示土壤的长期供钾能力。本项测定不包括易于提取的非交换钾,接近于代表几经抽提后的稳定释放量。它是土壤中现存矿物贮备的函数,不受归还土壤的有机质和施肥等因素的影响。为测定本项数值,以1MHNO_3(较宽的酸液∶土)一次提取的较易溶的缓效钾应弃去。然后再以1MHNO_3(酸液∶土的比值较窄)连续提取2～3次,测定浸提液中钾浓度,这两
Determination of Potassium (Kc) and Magnesium (MgR) (i) Potassium Reserve (Kc) Introduction This measure proposed by Metson et al. (1956) indicates the long-term potassium availability of the soil. This test does not include easy to extract non-exchangeable potassium, close to the representative after several extraction steady release. It is a function of the existing mineral reserves in the soil and is unaffected by such factors as soil organic matter and fertilization. In order to determine this value, the more soluble, slowly acting potassium extracted once with 1MHNO 3 (broader acid: soil) should be discarded. And then 1MHNO_3 (acid: soil ratio narrow) continuous extraction 2 to 3 times, the determination of potassium concentration in the extract, these two