Physiological and yield responses of field-grown cotton to application of urea with the urease inhibitor NBPT and the nitrification inhibitor DCD

Nitrogen deficiency and poor N use efficiency adversely affect cotton (Gossypium hirsutum L.) growth and yield. The objective of this study was to evaluate the performance of the urease inhibitor NBPT and the nitrification inhibitor DCD with urea fertilizer on the physiology and yield of irrigated cotton. Field experiments were conducted in 2009 and 2010 with the following treatments: untreated control, full recommended N rate with urea, 75% recommended N rate with urea, 75% recommended N rate with urea + NBPT, and 75% recommended N rate with urea + NBPT + DCD. The treatment Urea-75% plus NBPT improved cotton N uptake by 17% and N use efficiency by 41% when compared to the Urea-75% alone. NBPT addition to urea also positively affected leaf chlorophyll content, plant growth and fiber quality. The use of NBPT improved cotton lint yield by 14% compared to a similar urea application rate without NBPT. However, addition of DCD to urea fertilizer limited NBPT performance. The use of DCD resulted in decreased N uptake, N use efficiency, leaf chlorophyll, plant growth and yields. Under the field conditions of the current study, it is concluded that addition of NBPT to urea, but not DCD in combination with NBPT, improved N fertilization in cotton.

► We observed differences in the performance of the urease inhibitor NBPT and the nitrification inhibitor DCD with urea fertilization in cotton.
► The use of NBPT improved cotton N uptake and N use efficiency.
► Addition of DCD to urea was detrimental to the performance of NBPT, possibly due to an increase in ammonia volatilization.