Fertilizer Nitrogen Requirements for Cotton Production as Affected by Tillage and Traffic
- H. A. Torbert and
- D. W. Reeves
Soil compaction and its associated problems have led to interest in investigating the interactive effects of traffic and tillage systems on fertilizer N requirement for cotton (Gossypium hirsutum L.). In 1987, a study was initiated on a thermic Typic Hapludult soil complex with a cropping system of wheat (Triticum aestivum L.)-cotton double cropped. The experimental design was a split-split plot with four replications. Main plots were two traffic treatments (conventional and no-traffic), subplots were four tillage systems for cotton (surface tillage without subsoiling [surface-only], surface tillage and annual in-row subsoiling [subsoiling], surface tillage with one-time-only complete disruption of the tillage pan [complete], or no surface tillage and in-row subsoiling [strip-till]), and sub-subplots were four N rates (0, 45, 90, and 135 kg N ha−1). In addition, application of 15N-labeled NH4NO3 was made to microplots inside each tillage-traffic-90 kg N ha−1 plot. In 1990 and 1991, increasing N application increased cotton biomass and decreased lint percentage. In the dry year of 1990, no-traffic decreased seed cotton yield from 1500 to 1360 kg ha−1, while tillage had no significant effects on cotton yield components. Above-normal rainfall in 1991 resulted in the strip-till with no-traffic treatment having the highest seed cotton yield (2749 kg ha−1) and the greatest fertilizer N uptake efficiency (35%). Results indicate that the detrimental effects of traffic on N uptake efficiency may be reduced with conservation tillage systems and that higher fertilizer N application rates may not be needed for conservation tillage practices such as strip-till in Coastal Plain soils.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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