Contribution to the Assessment of the Fertility Status of the Soils of Kouh-East in the Eastern Logone in Southern Chad

Agriculture is the main source of income and survival for the population of East Kush. Population growth has led to an increase in the area available for cultivation, a reduction in set-aside time, migrations in search of cultivable soils, with the corollary of soil degradation and a reduction in fertility levels. The objective of the study is to assess the fertility status of soils in Kouh-East. Physicochemical characterization of soils from twenty-five localities has shown that soils are clay-sandy to sandy-clay with a clay content of 7 to 47.50%, MO ranges from 0.41 to 4.62%, pH ranges from 5.10 to 7.60, nitrogen content ranges from 0.00 to 0.11%, Ca2+ content ranges from 0.72 to 28.88 cmol+/kg, Mg2+ content ranges from 0.2 8 to 6.56 cmol+/kg, K+ ranges from 0.01 to 20.09 cmol+/kg, Pass ranges from 0.02 to 212.83 ppm, Na+ ranges from 0.03 to 0.24 cmol+/kg, CEC ranges from 11.20 to 42.32 cmol+/kg, SBE ranges from 1.44 to 39.82 cmol+/kg, V ranges from 11.02 to 1.02 16, 29%. Statistical treatment correlated soil fertility variables. Thus, a bilateral relationship is observed between clay and CEC (R2=0.711), between Limon and CEC (R2=0.707), nMO and Ca (R2=0.564), between SBE and MO (R2=0.429), between SBE and silt (R2=0.520), between SBE and Ca (R2=0.812), between SBE and Mg (R2=0.542), between SBE and K (R2=0.720), between SBE and Na (R2=0.689), between V and Ca (R2=0.713), between V and K (R2=0.748), between V and Na (R2=0.687) and between V and SBE (R2=0.949). Four soil fertility classes are identified. Soils have good physical properties but organic and mineral soil improvers are essential for chemical fertility