|KAWAKAMI, EDUARDO - University Of Arkansas|
|OOSTERHUIS, DERRICK - University Of Arkansas|
Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2011
Publication Date: N/A
Interpretive Summary: Nitrogen fertilization is one of the most expensive agricultural practices and crops are known to recover only about a third of the N fertilizer applied, where two major factors that limit efficiency of fertilizer N recovery from urea are nitrogen losses through ammonia volatilization and nitrate leaching. In the current growth chamber study the effect of including N fertilizer additives to limit ammonia volatilization and nitrate leaching on the physiology and growth of cotton under normal and high temperatures was evaluated. Only the use of an additive to limit ammonia volatilization improved cotton urea utilization. Improving fertilizer N use efficiency by incorporating an ammonia volatilization inhibitor into urea has the potential to decrease input costs by maintaining productivity with lower fertilizer application rates.
Technical Abstract: Nitrogen fertilization is one the most expensive agricultural practices and crops are known to recover only about a third of the N fertilizer applied. A practice commonly recommended to improve N use efficiency is the incorporation of urease and/or nitrification inhibitor into N fertilizers. The objective of this growth chamber study was to evaluate the effect of adding N-(n-butyl) thiophosphoric triamide (NBPT) and Dicyandiaminde (DCD) to urea fertilizer, on the physiology and growth of cotton (Gossypium hirsutum L.) under normal and high temperatures. Treatments consisted of two day temperature regimes, 30oC and 38oC, and five nitrogen fertilization applications: (T1) unfertilized control, (T2) 125 kg/ha of urea, (T3) 93 kg/ha of urea, (T4) 93 kg/ha urea with NBPT, and (T5) 93 kg/ha urea with NBPT and DCD. The addition of NBPT to urea fertilizer showed positive results on leaf chlorophyll, leaf area, dry matter, N uptake, and N use efficiency. On the otherhand use of DCD was detrimental for leaf chlorophyll, N uptake, and N use efficiency. No two way interaction effect between temperature regime and N treatment was observed, indicating that N fertilization was not influenced by temperature conditions. Deficiency of N significantly decreased leaf chlorophyll, increased glutathione reductase activity, decreased protein and increased leaf nitrate reductase. The high day temperature (38oC) regime significantly increased plant N uptake, glutamine synthetase, leaf chlorophyll, protein content, plant height and leaf area. We conclude that use of NBPT but not DCD improved cotton urea utilization, N deficiency affected the physiology and N assimilation of cotton plants, and that the physiological changes in cotton under high temperature were due to higher N uptake and utilization.