Availability of nitrogen and organic matter in soil treated with calliandra calothyrsus compost in Rwanda. a case of Ruhande Hill, Huye District

Food insecurity is becoming an issue both nationally and internationally due to rapid population growth. One way to deal with this problem is to improve soil fertility using organic fertilizers in order to increase soil productivity in a sustainable way, thus rise crop yield and feed the growing population. Compost is one of the proposed suitable organic fertilizers increasing soil nutrients in a regular basis. The compost produced from Calliandra calothyrsus biomass can be used as organic fertilizer to provide basically Nitrogen as a primary nutrient and increase soil organic matter as a soil nutrients holder and reservoir. This study assessed the organic matter and the availability of Nitrogen to crops in soil treated with compost from Calliandra calothyrsus biomass. To evaluate organic matter and the availability of Nitrogen, plots were designed in Randomized Completely Block Design (RCBD) with four blocks, using Amaranthus retoflexusas a reference crop. Each block had two treatments, Amaranthus retoflexus + Compost as T1 and Amaranthus retoflexus only as T2.The results revealed that plots with compost has a higher mineral nitrogen content of 9.33 ppm (3.23 ppm for NO- 3 and of 6.11ppm for NH+ 4) than the control 6.48 (Mineral Nitrogen of 1.23 ppm for NO- 3 and of 5.23ppm for NH+ 4).Moreover, the mean soil organic matter in soil treated with compost was higher (2.48 %) than in the control (1.70%). To sum up, the compost from Calliandra Calothyrsus residues is a source of Nitrogen and organic matter to crops.