CHEMICAL FERTILITY OF GARDEN SOILS IN SOUTH TOGO: ANALYSIS, CORRELATIONS AND REASONED PROPOSAL OF FERTILIZERS RATE FOR EFFICIENT PRODUCTION OF SPINACIA OLERACEA L.

摘要

In this study, a sample of 12 garden soils were analyzed and compared to quality standards. A reasoned fertilization method was developed using online software "Fertilizer Rate Calculator". Results indicate that among macronutrients, those of potassium are very high and even tend to exceed standard. Moreover, 92% of soils studied are poor in nitrogen, 8% in phosphorus, 0% in potassium and 25% in organic matter. In? a reasoned fertilization method developed for spinach production,? 800 Kg/Ha and 567 Kg/Ha of NPK have been proposed for sustainable production of this vegetable on soils poor in nitrogen and phosphorus while a mixing of NPK 15-15-15 (340 Kg/ha) and compost 173-313-1328 (4000 T/Ha) would be suitable for soils poor in nitrogen and organic matter. The study of correlations between the different parameters through PCA allows to conclude that contents of total and available nutrients in soils are independent of organic matter, pH and particle size. Contrary, those of total organic matter and the pH would be the most impacted by the particle size types. This aspect earns to be considered in any fertilization processes of soils to prevent elevation of C/N ratio and consequently hunger of nitrogen in these soils. These results may contribute to future soil’s chemicals changes model and suitable fertilization methods development.