Assessment of the Mineralization of Composts and the Availability of the Fertilizing Elements in Two Soils in Niger

Abstract

The work aims to study the mineralization of compost in soils and the availability of the fertilizing elements to plants. A silty sandy soil S1 and a sandy soil S2 have been used to study the elaborated compost mineralization. Soils-compost mixture (100:1) are incubated to 2/3 the humidity of field capacity during 30 days to follow-up the mineralization of the organic matter and during 30 days for the availability of soil fertilizing elements and the temperature to 28°C. Results in a first incubation showed curve of mineralization a slope at beginning and offers to be constant after 20 to 30 days of incubation. Then, the incorporation of compost to soils, leads to an increase of the mineral nitrogen of soil at the end of 28 days of incubation. The analysis of the physico-chemical parameters from the beginning to the end of the incubation, revealed an increase of the content in available phosphorus of 120.6 mg/kg for S1C, and 128.4 mg/kg for S2C. The content of the assimilated phosphorus in soils (control) is 10, 65 mg/kg for S1 and 9, 21 mg/kg for S2. The contents in assimilated phosphorus didn't vary meaningfully during 28 days in soils without composts. During this incubation, the values of pH for the control soil are lower than those of mixture soils + compost; the pH at the end of the incubation period is lower compared to one at the beginning. This organic contribution improved the cation- exchange capacity of soils of more than 96.33% for the treatments with S2C and more than 92.24% with S1C. The sum of the three cations (K+, Ca2+, Mg2+) measured out is higher in treated soils with compost than soils without compost.