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This article in AJ

  1. Vol. 80 No. 3, p. 498-502
     
    Received: Apr 27, 1987
    Published: May, 1988


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doi:10.2134/agronj1988.00021962008000030021x

Nitrogen Application to Cotton on Clay Soil: Timing and Soil Testing

  1. G. A. Constable  and
  2. I. J. Rochester
  1. New South Wales Dep. of Agric., Agric. Res. Sin., PMB Myall Vale, Narrabri 2390, Australia

Abstract

Abstract

With the aim of improving utilization of N fertilizer and the flexibility of N application strategies in cotton (Gossypium hirsutum L.), five field experiments examined the response of cotton to N fertilizer, either applied before sowing or as applications before or after sowing, or both. The soils were Pellusterts with a high pH. Anhydrous ammonia was used as the N fertilizer throughout. Soil nitrate N, N uptake, and lint yield were measured in all experiments. There was a linear increase in N uptake with increased application of N fertilizer, with an average of 30% of applied N being taken up by the crop 120 d from sowing. Compared to a single presowing application, N recovery was increased by split application on two occasions, but on a further two occasions it was decreased. Split application increased lint yield on one occasion only—when compaction, waterlogging, and a long growing season allowed better utilization of sidedressed N. On all other occasions the two methods of N application produced similar yields. Therefore, sidedressing can be considered a viable practice on these soils and in this climate. Maximum yield was obtained when crop uptake was about 108 kg N/ha at 120 d from sowing, and was only partially affected by yield level. Soil nitrate N, sampled to a depth of 30 cm 4 wk before sowing, was closely correlated (r=0.86) with subsequent plant N uptake in nil fertilizer treatments. Therefore, N fertilizer requirement can be accurately determined by applying moderate levels of N before sowing, then subsequently testing for soil N on nil fertilizer strips to determine if any sidedressing is necessary. It was concluded that recovery of N fertilizer was generally poor, and improvement of this parameter has the potential to increase fertilizer use efficiency and productivity of cotton in this environment.

Contribution from the Univ. of California, Davis.

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