Soil pH influence on cotton lint yield and quality

Abstract

Increases in cotton (Gossypium hirsutum L.) production across Oklahoma due to various circumstances have led to cotton planted on soils that have been traditionally managed for differing crops, specifically winter wheat. Many of these soils are possibly acidic in nature due to natural and anthropogenic activities such as excessive ammonia-based fertilizer applications. Common wheat production practices such as banding phosphorus fertilizers with seed and planting aluminum (Al) tolerant varieties may have masked potential problems associated with crop performance in acidic soils. In response, this study was initiated to evaluate the impact of soil acidity on cotton production. This experiment was conducted in central Oklahoma in the 2019 and 2020 growing seasons. Cotton lint yield and lint quality were evaluated across a range of soil pH levels and associated potassium chloride extractable Al across a soil pH gradient of 4.0–8.0. Two cotton cultivars were planted to identify possible differences in response between genotypes. Soil acidity negatively impacted in-season growth parameters such as plant height, node count, and boll count, as well as the primary variable of lint yield. A critical threshold at a soil pH level of 5.2 was identified as detrimental to cotton lint yield, corresponding with a lint yield loss of approximately 4.5% per pH unit decrease below the critical soil pH level of 5.2. This equates to a lint yield loss of 44.5 kg ha⁻¹ per 0.1 change in soil pH, assuming 100% yield potential is approximately 989 kg ha⁻¹ of lint for this specific growing environment.