Аңдатпа
Tomato production under organic and low-input systems requires soil fertility strategies that sustain nutrient availability, plant growth, yield and fruit quality, particularly under warm and dry conditions. This study evaluated the effects of World Illite, a natural illite-based mineral amendment compatible with organic production, on soil fertility status, vegetative growth, yield and fruit quality of tomato in southeastern Kazakhstan. The experiment was conducted in 2025 on an alkaline, medium-loamy dark chestnut soil. World Illite was applied at a total seasonal rate of 4670 kg ha⁻¹ and compared with an untreated control. Biological seed treatments, the biofungicide Obogi and selected bioinsecticides were also evaluated as complementary components of an organic tomato production system. At the sampling time, World Illite-treated plots had higher humus, easily hydrolyzable nitrogen, available phosphorus and exchangeable potassium contents than the control, by 40.6%, 77.8%, 20.0% and 9.1%, respectively. These differences were accompanied by significant increases in plant height, total plant weight, fruit number and mean fruit weight, by 48.5%, 54.9%, 37.7% and 38.1%, respectively. Tomato yield increased from 34.2 to 61.5 t ha⁻¹, corresponding to a 79.82% increase. World Illite also increased soluble dry matter by 14.5% and total sugar content by 50.8%. Nitrate concentration increased significantly but remained below the maximum permissible concentration used in the study. Among the complementary biological inputs, Trichodermix produced the highest final seed germination, Obogi reduced late blight severity by 71.73%, and Actarophyt showed the strongest biological effectiveness against Colorado potato beetle larvae. The results indicate that natural illite-based mineral amendments may improve the soil fertility–plant nutrition–yield–quality relationship in organic tomato production. However, multi-year studies including pre- and post-application soil analyses, plant nutrient uptake measurements and different amendment rates are needed to clarify the mechanisms of response.