Response of Cotton (Gossypium hirsutum L) Yield to Fertilization in Titanium-Mined Reconstituted Soils, Kenya

Abstract

Cotton has historically played a vital role in Kenya’s agricultural economy, supporting smallholder farmers and supplying raw material for the textile industry. However, recent years have seen a troubling decline in cotton yields, threatening rural incomes and the sustainability of the cotton value chain. A field experiment was conducted in Kwale County’s at base titanium mining company during May–August 2022 and September–December 2023 to assess how combinations of sunnhemp (a green manure), farmyard manure (FYM), and inorganic fertilizers affect cotton yield in different soil conditions. Using a Randomized Complete Block Design with 10 treatment combinations replicated three times across four soil conditions (undisturbed, mined with topsoil, reconstituted without topsoil, and reconstituted with topsoil), the study involved 120 plots. Treatments included various rates of FYM, sunnhemp, and NPK fertilizer. Key data collected included initial soil properties and cotton yield traits such as boll weight, lint weight, and seed characteristics. Results showed that the combination of 200 kg NPK fertilizer and sunnhemp significantly increased the number of bolls (by 77.3%), lint weight (by 86.6%), and overall yield (by 72%) compared to control. The study recommends integrated nutrient management using sunnhemp, FYM, and inorganic fertilizers for rehabilitating mined lands and boosting cotton productivity, emphasizing the need for long-term, site-specific research.