Abstract

Fertilizers are used to increase crop yields and also to improve crop quality. Nutrients removed from the soil by crops, lost by leaching, erosion, fixed or immobilized by micro-organisms or volatilized due to high temperature should be replaced to ensure optimum crop performance. One of the most important pre-requisites for formulating a sound fertilizer recommendation for a given crop in a given area, therefore, is the knowledge of the nutrient status of the soil, which is realizable only through a rational and systematic soil fertility evaluation. The requirement for organic and synthetic amendments to increase yield and facilitate crop growth has long been recognized by farmers. Synthetic N fertilizer produced via the Haber-Bosch process was a key component of the green revolution that increased agricultural productivity and alleviated hunger for many across the globe. Inadequate N reduces the number of fruiting sites and potential yield, whereas excessive N can create rank growth, actually lower yields and quality, delay maturity, increase problems with disease, insects, and defoliation, and pollute ground and surface water resources. When soil analysis calls for additional K, the cotton crop is usually fertilized with a single preplant broadcast application of K fertilizer. Mid-season applications are infrequently applied, and foliar applications are used occasionally to correct K deficiencies during fruiting. However, despite soil analyses and subsequent soil applications of fertilizer prior to planting, K deficiencies have occurred sporadically and somewhat unpredictably across the US Cotton Belt. This has prompted a renewed focus on K management in cotton with some emphasis on understanding K fertilizer requirements and use by the cotton plant. Hence this paper tends to address the use of Nitrogen and Potassium fertilizer for cotton production in the tropics.