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This article in AJ

  1. Vol. 96 No. 1, p. 48-62
     
    Received: Dec 17, 2002


    * Corresponding author(s): rltravis@ucdavis.edu
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doi:10.2134/agronj2004.4800

Response of Recent Acala Cotton Varieties to Variable Nitrogen Rates in the San Joaquin Valley of California

  1. R. B. Hutmachera,
  2. R. L. Travis *b,
  3. D. W. Rainsb,
  4. R. N. Vargasc,
  5. B. A. Robertsc,
  6. B. L. Weirc,
  7. S. D. Wrightc,
  8. D. S. Munkc,
  9. B. H. Marshc,
  10. M. P. Keeleyd,
  11. F. B. Fritschie,
  12. D. J. Munierc,
  13. R. L. Nicholsf and
  14. R. Delgadog
  1. a Univ. of California Coop. Ext., Shafter, CA, and Univ. of California, Davis, CA
    b Dep. of Agron. and Range Sci., 1 Shields Ave., Univ. of California, Davis, CA 95616
    c Univ. of California, Madera, Kings, Merced, Tulare, Fresno, Kern, and Glenn Counties, respectively
    d Univ. of California, Shafter, CA
    e Dep. of Agron. and Range Sci., Univ. of California, Davis, CA (currently USDA, Stoneville, MS)
    f Cotton Inc., Cary, NC
    g Univ. of California, Shafter, CA

Abstract

Nitrogen fertilizer is routinely applied to crops grown in rotation with upland cotton (Gossypium hirsutum L.) in the San Joaquin Valley (SJV) of California. However, increasing N fertilizer costs, the potential overuse of N resulting in excessive vegetative growth and harvest delays, increasing pest pressure, and concern for nitrate contamination of groundwater support a reassessment of current N fertilization practices. The primary goal of this research was to provide information that would assist SJV cotton growers in updating and improving N management practices. Plot site selection included two university field stations and six on-farm locations representing all SJV cotton-producing counties. Nitrogen treatments of 56 to 224 kg N ha−1 were over a 5-yr period. Cotton lint yield responded positively to increasing N applications in only 41% (16 out of 39) of the test sites. Yield response to fertilizer N was related to residual soil N in the upper 0.6 m of soil as follows: below 70 kg ha−1 residual NO3–N, 9 of 17 sites responded positively to increasing applied N; at 70 to 125 kg ha−1, 5 of 11 sites responded; and at greater than 125 kg ha−1, only 2 of 11 sites responded. Changes in soil NO3–N levels from postplanting to postharvest were generally larger within the upper 1.2 m of soil than at lower depths. However, net increases in soil NO3–N also occurred in the 1.2- to 2.4-m range at sites prone to leaching.

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Copyright © 2004. American Society of AgronomyAmerican Society of Agronomy