Optimizing Cotton Yields with Effective Nitrogen Application

Understanding Nitrogen Deficiencies

Nitrogen deficiencies in cotton can lead to various challenges. Firstly, they can disrupt the rate of photosynthesis, hindering the plant's ability to produce energy. Additionally, nitrogen deficiencies can cause a determinate bloom pattern, decrease water transportation efficiency, promote fruit shedding, and suppress fruiting branch development. These deficiencies manifest through smaller leaves and less vigorous vegetative growth.

Split Application Approach

To address nitrogen needs effectively, a split application approach is recommended. Apply 1/4 to 1/3 of the recommended nitrogen at planting, with the remaining amount applied as a side-dress later in the season. The preplant or at-planting nitrogen application is critical for providing the crop with a strong start and sufficient nitrogen nutrition. Timely side-dress application is crucial, especially during shortened or stressful years, to meet cotton's nutrient demands at peak growth stages. Monitoring plant growth helps determine the optimal timing for side-dress application. Avoid applying nitrogen after the third week of bloom.

Timing nitrogen applications in cotton is critical because demand increases during squaring and reaches its peak during bloom. Alongside nitrogen, the demand for sulfur also rises. Since nitrogen and sulfur move primarily by mass flow into the plant, having these nutrients applied before demand hits is crucial. Thio-Sul (12-0-0-26S), a soluble fertilizer which can be blended with UAN, offers available nitrogen and sulfur for promoting optimal cotton growth.

Protecting Your Nitrogen Investment

Protecting your nitrogen investment is essential. Side-dress applications with UAN solutions are favorable, allowing concentrated nitrogen application between rows. Applying UAN below the soil surface minimizes the risk of nitrogen loss through volatilization. With any nitrogen application, once in the nitrate form, nitrogen is prone to leaching through the soil profile and becoming unavailable for plant uptake. Incorporating thiosulfate sulfur from Thio-Sul and/or KTS into liquid UAN solutions can mitigate nitrification and maintain nitrogen stability for improved plant uptake. Combining effective nitrogen and nutrient management practices contributes to maximizing cotton yields.

These practices also apply to foliar applications through irrigation systems as well.

Written by Spencer McCown, Tessenderlo Kerley Crop Vitality Agronomist