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Acala Cotton Responses to Limiting Nitrogen: Plant and Soil N Status, Growth

R.B. Hutmacher, S.S. Vail, K.R. Davis, M.S. Peters, C.A. Hawk, T. Pflaum, D. Clark, D.A. Ballard, N. Hudson, B. Weir, M. Keeley


Concern for the potential impact of nitrogen (N) fertilization practices on nitrate contamination of groundwater and changes in predominant cotton varieties in California spurred interest in a joint project of the USDA-ARS and University of CA to assess growth, yield and N uptake responses of cotton to a range of nitrogen applications. Plants were grown under subsurface drip irrigation and irrigated daily to avoid water deficits. Phosphorus, potassium as well as nitrogen fertilizers were injected into the water. Nitrogen treatments were 0, 60, 120 or 180 kg N per hectare (ha) combined with pre-plant applications of 0 or approximately 53 to 56 kg N per ha. Soil NO3-N levels in the upper 1.2 m of the soil profile were in the 10 to 30 mg N03-N kg-1 range in the first and second years of the study. In the third year, soil N levels were significantly lower, and petiole nitrate-N levels in 120 kg and lower N application treatments were in the borderline deficient or deficient range of University of CA recommendations for cotton. Leaf area and height were reduced in all treatments receiving 60 kg N or less (even with pre-plant N). Peak lint yields (between 1600 and 2100 kg lint per ha) occurred in 120 and 180 kg N treatments, with no difference in yields with applications in excess of 120 kg N ha-1 and significant differences in treatment yield levels across years. Residual soil N levels have significantly influenced the response to amounts of applied N over the three years. Results indicate that when residual soil N is accounted for, high cotton yields can be achieved with between 120 and 180 kg of applied N per ha.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 1366 - 1373
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998