Soil and nutritional summary

Liming will increase pH, neutralize exchangeable aluminum and increase base saturation. The crop will also benefit from increases in cation exchange capacity (CEC) and the availability of N, S, P, B and Mo. It promotes improvements on root growth, allowing better nutrient use efficiency. Liming should be performed at least two months prior to planting with subsequent incorporation by plowing and harrowing.

Considering that exported nutrients by fiber and cottonseed is relatively small compared to other crops, cotton should not be considered an exhausting crop. However, removal and burning of crop residues in order to control pests and diseases cause several nutrient losses. 

After destroying crop residues in addition to intensive plowing at planting, fertilizer recommendations are higher than nutrients removed by fiber and seed, in order to replace losses and avoid soil degradation. Crop rotation, nutrient recycling and conservation tillage are very desirable because, in addition to avoid soil erosion and nutrient losses, they maintain and/or improve soil productivity.

In order to assess the nutrient requirements of the cotton crop, soil and leaf analysis are important tools and must be used. Of the specific nutrients, particular attention should be paid to potassium and calcium that both are key elements in order to improve yield and quality.

Nitrogen prolongs growth and increases the number of bolls set. It can also increase the boll size. 

Potassium is integrally involved in metabolism and plant water relations, it is an enzymatic activator and is essential to photosynthesis, among other functions. Apart from its enzymatic functions, in cotton potassium plays a particularly important role in fiber development and a shortage will result in poorer fiber quality and lowered yields. K also reduces the incidence and severity of wilt diseases. 

Calcium strengthens the cell walls and improves the membrane integrity hence adequate calcium nutrition is necessary for normal cell wall development. In cotton, the fruiting activity is influenced by the level of calcium in the growth media. Calcium also serves to increase the salt tolerance. In experiments where cotton was grown under varying levels of calcium, the fruiting index increased with each increment of added calcium. 

Cotton is especially vulnerable to boron deficiency during drought that is preceded by heavy rainfall. And then again, after a drought is broken, when there is sudden flush of growth and fruiting – especially if nitrogen is plentiful. Boron is an essential element that cotton needs during all stages of growth and fruiting. Supplying adequate boron will help cotton: 

• Develop and retain more squares
• Increase bloom pollination and boll set
• Move nutrients and sugars from leaves to the fruit
• Produce strong, well developed fibers
• Speed maturity