摘要
Phosphate mineral fertilisers are manufactured from non-renewable resources. Soil fertilisation with composts is considered a good source of reuse nutrients such as phosphorus (P). The aim of this work was to evaluate the effect of compost fertilisation on soil P sorption and consequently on P availability. It was done an incubation experiment followed by a sorption experiment in a low-P acid soil fertilised with compost (CP) or single superphosphate (SSP). The P application rates were: 0, 6.5, 13, 26 and 52 (kg•P•ha−1). In CP treatments, the rates 26 and 52 kg•P•ha−1 were achieved by adding SSP to CP since it was not allowed to incorporate into soil more than 170 kg•N•ha−1?from organic amendments. Although SSP has a higher proportion of easily available P than CP (86% vs 50%), the results showed that after 140 days of soil incubation, the available P was higher in CP treatments compared with SSP at the same rate of P application. The sorption experiment showed that after incubation of the fertilised soils, the P sorption maximum had lower values in treatments with CP in combination with SSP compared with only SSP fertilisation and the bonding energy had a deeper decrease in the same treatments. Also, the Standard Phosphate Requirement decreased in the CP in combination with SSP treatments. The reduction of soil P sorption capacity after compost addition to soil highlights the need of reducing P fertilisation rates to achieve similar levels of available P compared with only SSP fertilisation.
Phosphate mineral fertilisers are manufactured from non-renewable resources. Soil fertilisation with composts is considered a good source of reuse nutrients such as phosphorus (P). The aim of this work was to evaluate the effect of compost fertilisation on soil P sorption and consequently on P availability. It was done an incubation experiment followed by a sorption experiment in a low-P acid soil fertilised with compost (CP) or single superphosphate (SSP). The P application rates were: 0, 6.5, 13, 26 and 52 (kg•P•ha−1). In CP treatments, the rates 26 and 52 kg•P•ha−1 were achieved by adding SSP to CP since it was not allowed to incorporate into soil more than 170 kg•N•ha−1?from organic amendments. Although SSP has a higher proportion of easily available P than CP (86% vs 50%), the results showed that after 140 days of soil incubation, the available P was higher in CP treatments compared with SSP at the same rate of P application. The sorption experiment showed that after incubation of the fertilised soils, the P sorption maximum had lower values in treatments with CP in combination with SSP compared with only SSP fertilisation and the bonding energy had a deeper decrease in the same treatments. Also, the Standard Phosphate Requirement decreased in the CP in combination with SSP treatments. The reduction of soil P sorption capacity after compost addition to soil highlights the need of reducing P fertilisation rates to achieve similar levels of available P compared with only SSP fertilisation.
