Impact of agronomic and organic characteristics of waste composts from Togo on Zea mays L. nutrients contents under water stress

Drought and soils poverty considerably decreased agriculture yields in Togo. In this context, the use of wastes' composts as organic amendments presents the advantages to increase crops' yields and improve the fertility of soils while valorizing wastes. However, the effects of wastes' composts on the growth of plants highly depend on their quality, specifically on their chemical properties and the organic matter maturity. In this study, three different wastes' composts were prepared by mixing household wastes and food wastes with admixtures as natural phosphate and manure. The composts produced were analyzed according to agronomic parameters before applying a leaching test to specially assess the organic matter maturity by considering its hydrophobic and aromatic characters. Whatever the compost, the contents in organic matter and nutrients were comparable to composts usually commercialized in Togo. Their characteristics depended on their initial chemical composition. The higher the food wastes percentage, the higher the organic matter content and the addition of admixtures considerably increased the percentages in nutrients in the final product. Besides, a slightly acidic pH, a high redox potential and a low aromatic and hydrophobic organic matter were recorded for compost of food wastes unlike household wastes and mixed composts and the highest concentrations in trace metals were quantified in compost of household wastes. Agronomic tests were performed on maize (Zea mays L.) under two water regimes to evaluate the impact of the characteristics of composts on both maize's nutrition and adaptation to water stress. The chemical characteristics of composts and the maturity of organic matter highly impacted the absorption of macronutrients by plants. A slightly acidic pH and a high redox potential improved the transfer of nutrients from soils to plants under normal irrigation conditions. On the contrary, a higher aromaticity of organic matter promoted the absorption of nutrients under water stress. Wastes' composts can thus be relevantly used to improve the nutrition of plants in function of the irrigation conditions.