Amending Soils to Decrease Salinity and Acidity for Improved Rice Production in Casamance/Senegal.

Thioro Fall

 

Amending Soils to Decrease Acidity and Salinity for Improved Rice Production

in Casamance/Senegal

 

Rice production in lowland is exposed to periodic flooding or waterlogging. The source and length of the flood dictate the soil chemistry state. Salinity is one of the primarily rice yield limiting factors in Casamance along with acidity. Before 1970, families in Casamance/Senegal could grow and harvest enough rice to last almost the entire year, and use imported rice only in occasional circumstances. Today, the locally grown rice does not last more than three months. In that South region particularly in Djibelor the saline-sodic nature of the soils, their acidity, low nutrients and organic matter content restrict the growth potential of lowland rainfed rice (Mangrove). The salt tolerant variety used in this experiment is WAR1/ROK22 and 2013 yield in the Djibelor was 3.4 t/ha. The goal of this study is to increase soil pH and nutrients, reduce the EC and SAR levels by adding amendments and testing two different types of planting methods “raised” and “flat” beds. Planting methods, raised beds versus flat beds were adopted to test the potential leaching of salt from the root zone. Application of soil amendments included biochar 20 t/ha to increase soil organic carbon and organic matter, crushed oyster shell was applied at 7.2 t/ha to raise the soil pH. The biochar and shell were combined to test their interaction in soil properties and yield improvement. Soil samples were taken before and after amendments for analysis. The results show that EC dS/m has decreased by 76.5% in flat and 45.5% in raised beds compared to initial. Soil pH has increased by > 50% flat and raised beds where biochar+shell and shell were applied. The highest yield, 5.8 t/ha was observed in the interaction between biochar and flat beds even thought there was not treatment difference.