Evaluation of the composition, properties and fertility of Haplic Ferralsol on the fields abandoned for five years in the Republic of Chad

The article deals with the fertility of red ferralitic soils in the Republic of Chad. The studies were carried out in the period between 2016 and 2018 in the southern part of the province of Moundou on the red ferralitic soils (Haplic Ferralsol)of the Cotton-Chad farm, which cultivates cotton first of its formation. Haplic Ferralsols are characterized by significant reservoir thickness and are not rich in nutrients. The aim of our research was to study the composition and properties of the Haplic Ferralsols of the fields abandoned for five years for their use under cotton export culture. We have evaluated the morphological structure of the soil on neglected fields and its description by genetic horizons, studied the particle size distribution of the soil profile, its gross composition, cation exchange capacity, the content of exchangeable cations, and also considered the agrochemical and agrophysical properties of soil horizons. It has been established that Haplic Ferralsols have their own characteristics: red color, thick soil profile and a gradual transition between genetic horizons, and lightweight granulometric composition in the upper part of the profile. The basis of the gross chemical composition of Haplic Ferralsols is SiO2, Fe2O3 and Al2O3, the content of which varies depending on the depth of the soil profile within the ranges of 61.83–82.73 %, 3.50–6.40 % and 11.46–29.25 % correspondingly. Haplic Ferralsols are characterized by a high cation exchange capacity (6.6–11.1 сmol (eq)/kg). Among the exchangeable cations, calcium (Ca2+) is the most essential. Haplic Ferralsols are moderately provided with humus. In the upper soil layers (up to 42 cm), its content varied within 1.53–1.66 %. Soils are characterized by acidic reactions – from moderately acidic in the upper horizons to very strongly acidic in the lower horizon. The content of mobile compounds of phosphorus and potassium in the profile is low and very low, respectively, 0.76–1.09 mg/100 g and 0.05–1.48 mg/100 g. According to its agrophysical properties, the soil may be used for cotton growing. In the upper soil layer (0–42 cm) the bulk density is 1.36–1.45 g/cm3, the total porosity is 45.9–48.9 % and the field water-holding capacity is 22.4–25.7 %