Impacts des amendements organiques sur les caractéristiques physico-chimiques d’un sol ferrallitique du Sud-Bénin

Impacts of organic amendments on the physico-chemical characteristics of a ferrallitic soil in southern Benin Urban and peri-urban agriculture is now faced with the problems of soil depletion, especially in organic matter, and water loss through evaporation. To help farmers cope with these hazards, this study proposes to evaluate the importance of Ramial Chipped Wood (RCW) and poultry litter (PL) amendments in terms of water saving and soil fertility improvement. To this end, an experimental design of eight randomized treatments in four blocks was set up and soil temperature, water content and suction measurements were carried out in situ . The treatments included two volumes of irrigation water (V1 and V2=0.5V1) and soil amendments or not (45t.DM/ha of RCW and/or 15t.DM/ha PL). In parallel, composite soil samples were taken from each plot at a frequency of three months, and analyzed in the laboratory to determine the evolution of some chemical properties characterizing soil fertility. The results show that for the V1 trials, RCW-PL and PL amendments slightly limit evaporation by maintaining the water content higher than those with RCW alone and control. However, for the V2 trials, RCW and RCW-PL amendments limited evaporation more since the water content was maintained higher compared to the control and PL for the trials with limited watering volume (V2), and this throughout the 9 months of the study. However, soil temperature did not show a marked difference between treatments. Soil chemical characteristics show that organic matter content and phosphorus concentration increase from the 3rd month onwards, indicating an improvement in soil quality. Long-term monitoring of soil physical characteristics and a study in a controlled environment would confirm the advantages of this type of amendment.