磷酸根解吸作用与土壤磷植物有效性的关系(英文)

盆栽试验配台室内分析研究了浙江省四种代表性土壤的磷根摈解吸作用与植物吸收磷之间的关系,结果表明:0.02mol/l KCl溶液或去离子水解吸的磷十分接近于第一个月黑麦吸收的磷;而在0.001 mol/l柠檬酸根溶液中释出的磷相当于头三个月黑麦吸收的磷。在稀电解质溶液或水溶液中释放的磷主要是静电吸附态磷,这部分磷通过扩散作用解吸出。在含竞争性阴离子(柠檬酸根)的溶液中解吸的磷还包括可交换的化学吸附态磷。可见,物理吸附态磷和部分具交换活性的化学吸附磷是土壤中植物速效磷的主要来源。与常规化学提取法(Olsen法和Bray法)比较,本文提出的方法所测得的磷不仅与植物吸收磷相关性较好,而且在数量上比较接近。

Phosphate Desorption and Its Relation to Plant-availability of Phosphorus in soils

Both laboratory and greenhouse experiments were conducted to study phosphate desorption and its relation to P uptake of plant.The results showed that the amount of phosphate desorbed from soil by 0.02 molL-1 KCl solution or deionized water was very close to that uptake by rye plant during its first month ot growth and(hat desorbed by 0.001 mol L-1 citrate solution(pH 7.0)approximate to the rye-uptake P of three months growth under various levels of P supply intensity.Soil phosphate released in 0.02 mol L-1 KCl solution or deionized water mainly involved the electrostalically-sorbed P which is desorbed through diffusion while 0.001 mol L-1 citrate solution could release much more of the adsorbed phosphate through ligand exchange.Both mechanisms made contribution to the plant availability of soil phosphorus.The former prevails in bulk soil whereas the latter may be more important in rhizospheric soil.In comparison with extracted P by chemical reagents,the desorbed phosphate not only had better correlation but was more comparable in quantity with the plant uptake phosphorus.