有机肥对磷的吸附-解吸的影响及在红壤发育成的水稻土上的有效性

A field test with the traditional rotation of paddy rice/upland crop (wheat) was carried out on a paddy soil derived from red earth to elucidate the effect of organic manure on the phosphorus adsorption-desorption by soil and its P availability. Soil samples were taken from different treatments at rice harvesting stage and analysed. The isothermal adsorption of P by the samples fitted very well with Langmuir equation, and hence, the parameters in the equation, i.e., maximum adsorption (qm), constant related to bonding energy (k) and their product (k × qm) could be used as a comprehensive index to characterize the potential P adsorptivity of the soil. Organo-inorganic fertilization and organic manuring could decrease qm and k, while mineral P application had little effect on them. The isothermal desorption of P was significantly correlated with initially added and isothermally adsorbed P. Part of P added was fixed, which represented the P fixation capacity of soil, and organic manuring could obviously lower the P fixation. The content of soil available P had a significant negative correlation with qm, k and fixed P. It is concluded that organic manure could increase the P availability of paddy soil derived from red earth by decreasing qm, k, maximum buffering capacity (MBC=k × qm) and fixation capacity.

Effect of organic manure on phosphorus adsorption-desorption and availability in paddy soil derived from red earth

A field test with the traditional rotation of paddy rice/upland crop (wheat) was carried out on a paddy soil derived from red earth to elucidate the effect of organic manure on the phosphorus adsorption-desorption by soil and its P availability. Soil samples were taken from different treatments at rice harvesting stage and analysed. The isothermal adsorption of P by the samples fitted very well with Langmuir equation, and hence, the parameters in the equation, i.e., maximum adsorption (qm), constant related to bonding energy (k) and their product (k × qm) could be used as a comprehensive index to characterize the potential P adsorptivity of the soil. Organo-inorganic fertilization and organic manuring could decrease qm and k, while mineral P application had little effect on them. The isothermal desorption of P was significantly correlated with initially added and isothermally adsorbed P. Part of P added was fixed, which represented the P fixation capacity of soil, and organic manuring could obviously lower the P fixation. The content of soil available P had a significant negative correlation with qm, k and fixed P. It is concluded that organic manure could increase the P availability of paddy soil derived from red earth by decreasing qm, k, maximum buffering capacity (MBC=k × qm) and fixation capacity.