Cotton is a natural fiber deeply integrated into daily life, recognized for its comfort, durability, and versatility. It forms the basis for numerous fabrics like denim and flannel, making it a foundation of the global textile industry. Beyond apparel, cotton derivatives are found in items like coffee filters and banknotes. The journey of this ubiquitous fiber from a tiny seed to usable material involves a precise and carefully managed agricultural process.
Preparing for Cultivation
Cultivating cotton begins with selecting an appropriate environment and preparing the land thoroughly. Cotton thrives in warm, humid climates, requiring a long frost-free period and abundant sunshine. Ideal temperatures for active growth range between 21 and 37°C (70 to 100°F); prolonged exposure above 37°C harms the plant. The plant benefits from 10 to 12 hours of daily sunlight during its developmental stages.
Well-drained, loamy soils with good moisture retention are preferred for cotton, maintaining a pH between 6.0 and 7.5. Soil preparation starts in autumn with deep plowing, reaching depths of 35 cm (14 inches). This practice ensures proper drainage and aeration. Before planting, farmers conduct soil analyses to identify nutrient deficiencies and adjust soil composition as needed.
Cotton seeds are planted in spring (April-May) when soil temperatures at planting depth consistently exceed 15°C (60°F). Optimal germination requires soil temperatures above 18°C (64°F) and adequate moisture. Seeds are placed 2.5 to 6.3 cm (1 to 2.5 inches) deep, with plant spacing of 38 to 102 cm (15 to 40 inches) depending on the cultivation method.
Growth and Development
After planting, the cotton plant undergoes a life cycle spanning 140 to 220 days to maturity. Seedlings emerge within 5 to 10 days (or 50-60 DD60s), with cotyledons appearing above the soil. The radicle forms the taproot, rapidly penetrating the soil. True leaves develop, shifting the plant’s energy source from stored reserves to photosynthesis.
Vegetative growth accelerates, with the main stem producing new nodes and leaves every three days. From 35 to 60 days after planting, small floral buds, “squares,” form on fruiting branches. Squares develop into flowers, initially white or creamy yellow, turning pink or red within a day of pollination. Cotton is self-pollinating, though insects can increase yields.
After pollination, the flower becomes a boll, a capsule containing developing seeds and fibers. Boll development takes 50 to 60 days to mature. Fibers elongate for 21 days, then thicken for 14 days as cellulose is deposited. Care during these stages includes consistent irrigation, especially during flowering and boll formation, to prevent water stress. While cotton is drought-tolerant, supplemental irrigation (drip or sprinkler) optimizes moisture. Fertilization with nitrogen, phosphorus, and potassium, guided by soil tests, supports vigorous growth and fiber quality. Pest management protects the crop.
Harvesting the Crop
Cotton bolls signal their readiness for harvest when they naturally crack open, revealing the fluffy white fibers inside. This maturation occurs between 150 and 180 days after planting, usually from late summer to early fall, depending on the region and climate. Harvesting proceeds during dry, sunny weather when the cotton’s moisture content is low, around 12%.
Before mechanical harvesting, a chemical defoliant is applied to cause leaves to drop, which minimizes staining and debris in the harvested cotton. The two primary mechanical harvesting methods utilize specialized machines: pickers and strippers.
Spindle pickers use rotating spindles to gently pull the lint from open bolls, leaving the plant largely intact. Stripper harvesters, conversely, remove both open and unopened bolls along with some leaves and stems, requiring more intensive cleaning later. While mechanical harvesting is prevalent due to its efficiency, manual harvesting is still practiced in some regions, allowing for selective picking of only mature bolls.
Initial Processing
After harvesting, the raw cotton, still containing seeds and plant debris, undergoes its first significant transformation at the cotton gin. Ginning is a mechanical process separating the cotton fibers, known as lint, from the seeds and other foreign matter. This separation is necessary because the seeds constitute about half the weight of the picked cotton.
The gin operates by feeding the raw cotton into a machine with rotating cylinders or saws with wire teeth. These teeth catch the cotton fibers and pull them through narrow grates, which are too small for the seeds to pass through. As the lint is pulled away, the seeds are left behind and can be collected for other uses, such as producing cottonseed oil or for replanting. This initial processing prepares the cleaned cotton lint for baling, making it ready for transport to textile mills for further manufacturing into yarn and fabric.