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Journal of Plant Nutrition and Soil Science, vol.172, no.3, pp.336-345, 2009 (SCI-Expanded)
Organic amendments considerably affect nutrient balance and interfraction mobility of nutrients by influencing the chemical, physical, and biological environment in soils. In this study, the effects of five amendments including: two composts, farmyard manure, packaging-industry byproduct, and olive-mill waste on time-dependent interfraction mobility of P among mineral P fractions in two semiarid-region soils differing in carbonate content and texture were investigated. Organic materials were applied at the rate of 0, 25, 50, and 100 g (kg soil)-1 soil thoroughly mixed and incubated at 27°C - 2°C for 110 d. Phosphorus fractions were sequentially extracted by 0.1 M NaOH + 1 M NaCl (NaOH-P), citrate-bicarbonate-dithionite (CBD-P), and 0.5 M HCl (Ca-P). Results showed that organic amendments especially farmyard manure significantly influenced NaOH-P, CBD-P, and Ca-P. In addition, higher application rates of organic residues increased NaOH-P fraction. NaOH-P and CBD-P fractions were increased after addition of organic residues and then converted to Ca-P fraction within the end of incubation period. Increasing application rate of organic residues allowed P to be retained in more labile fractions for a longer period. The amount of Ca-P was found to be related with carbonate content of soils. It can be concluded that organic residues applied to calcareous soils may enhance P nutrition of agricultural plants. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.