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Nitrogen Fertilization of Maize on an Oxisol of the Cerrado of Brazil 1

1980; Wiley; Volume: 72; Issue: 2 Linguagem: Inglês

10.2134/agronj1980.00021962007200020004x

1435-0645

Thurman L. Grove, K. D. Ritchey, G. C. Naderman,

Soil Carbon and Nitrogen Dynamics

Abstract Information about N management for crop production on the highly weathered, tropical Oxisols is limited. Six crops of ‘Cargill 111’ maize ( Zea mays L.) were planted on an Oxisol (Typic Haplustox, fine, kaolinitic, isohyperthermic) of the Cerrado of Brazil to 1) define the N fertilizer response curve; 2) estimate increase in N content of aboveground dry matter per unit fertilizer; 3) estimate soil N supply; 4) determine the effects of timing of application on yield and N recovery; and 5) compare conventional and S‐coated urea. Treatments included sidedressed urea at 0, 60, 80, 100, and 140 kg/ha with 20 kg/ha applied at planting and the remainder 30 days later, sidedressed urea at 100, 140, and 220 kg/ha with 20 kg/ha applied at planting and the remainder equally split and applied 20 and 60 days later, 100 kg/ha lime‐coated NH 4 NO 3 and 140 kg/ha sulfur‐coated urea. Grain and stover yields were measured for each crop and subsamples collected for N analysis. Soil samples were collected throughout the experiment and analyzed for organic N. Yield increased significantly with N fertilization. Average maximum grain yield of 6.1 metric tons/ ha resulted from application of 203 kg/ha N. Recovery of fertilizer N varied with application rate from 60% at 60 kg/ha to 35% at 220 kg/ha. A single application of fertilizer 30 days after planting produced the same yield and N recovery as split applications at 20 and 60 days. Neither Scoated urea nor lime‐coated NH 4 NO 3 produced greater yield or N recovery than conventional urea. Average N content of above‐ground dry matter at maximum yield was 1.18%. Average uptake of soil N was 70 kg/ha/crop. There appears to be no fundamental difference in response of maize to N fertilizer between Oxisols and soils of the temperate regions.