Overall, the proportion of soils with a stable humus status declined from 57% (2016) to 22% (2022), emphasizing widespread soil organic matter degradation in the Republic of Kazakhstan. The following study aimed to evaluate the humus balance of arable soils and substantiate approaches for restoring soil fertility. Humus balance calculations for 2022–2024 were according to yield statistics, the normative coefficient of organic matter removal, and the humification coefficient of crop residues. The results showed a consistently negative humus balance across major crops, ranging from –0.6 to –1.4 t ha⁻¹ yr⁻¹. The greater losses emerged under row crops, vegetables, and cotton, while maize, rice, and perennial grasses exhibited lower depletion rates. The results highlighted the urgent need for organic matter replenishment through crop residue retention, organic fertilization, green manures, and soil-conserving technologies.
Humus balance, soil organic matter, soil fertility, sustainable agriculture, Kazakhstan
In Kazakhstan’s agriculture, the negative humus balance was evident under most primary crops, except for perennial grasses, which ranged from –0.6 to –1.2 t ha⁻¹ yr⁻¹. The greater humus losses occurred under row and vegetable crops, reaching –1.4 t ha⁻¹ yr⁻¹, whereas under maize and rice crops, the lowest recorded loss was –0.6 t ha⁻¹ yr⁻¹.