The role of organic matter and green manure in increasing the fertility of typical grey soils and cotton yields

In conditions of soil degradation and reduction of organic matter during intensive cotton cultivation, the search for environmentally sustainable ways to restore soil fertility and increase crop yields is becoming particularly relevant. The aim of this study was to assess the effect of various organic fertilisers and green manure crops on the fertility indicators of typical grey soils in the southern regions of the Kyrgyz Republic and on cotton yields. Field studies were conducted with two cotton varieties, ‘Fergana-3’ and ‘K 43’, including the application of manure, winter rye as green manure, and crushed cotton stalks (guzapai). The results showed a significant improvement in the agrochemical indicators of the soil, expressed in an increase in the content of humus, total nitrogen, gross phosphorus and potassium. The most effective method of increasing yield was the application of manure at a dose of 30 t/ha, which ensured a yield increase of up to 107.2% for the ‘Fergana-3’ variety and 98.3% for the ‘K 43’ variety. The use of green manure also contributed to a significant increase in yield (up to 73.8%) and the accumulation of organic matter and nutrients in the soil. The use of crushed cotton stalks had a positive but less pronounced effect, increasing the yield by 50-59%. It was found that both varieties respond positively to the application of organic fertilisers, with the ‘K 43’ variety characterised by higher absolute productivity. The results confirm the advisability of the systematic use of organic fertilisers and soil-conserving technologies in cotton production in southern Kyrgyzstan and are of practical importance for the development of effective agronomic recommendations aimed at improving the environmental sustainability and economic efficiency of cotton production