Stubble Burning Effects on Winter Wheat Yield and Nitrogen Utilization under Semiarid Conditions
1988
Rasmussen, P. E. | Rohde, C. R.
Although cereal residues are reportedly burned to accelerate vegetative growth, reduce disease or weed competition, or prevent microbial immobilization of N, there may be no yield enhancement in semiarid regions where drought stress limits yield. Experiments were initiated in 1979 and 1980 in a winter wheat (Triticum aestivum L.)—fallow rotation to determine burning effects on wheat yield and N utilization on a Walla Walla silt loam soil (coarse-silty, mixed, mesic Typic Haploxeroll). Burning versus not burning wheat stubble was examined at three N levels (0, 45, and 90 kg ha⁻¹) over 6 yr (three crops in each wheat-fallow secquence). Wheat stubble was burned on designated plots in the spring of the fallow year, then all plots were plowed 0.22 m deep. Nitrogen as NH₄NO₃ was applied in October prior to wheat seeding. Stubble burning had no effect on grain yield or grain N uptake in any of the 6 yr. Burning tended to increase straw yield when wheat was fertilized with N but had no effect on straw N uptake. Overall, burning did not increase total N uptake. Nitrogen fertilization increased yield and N uptake in all years. Six-year grain yield averages for 0, 45, and 90 kg N ha⁻¹ were 3.1, 4.7, and 5.3 Mg ha⁻¹. Stubble burning did not decrease foot rot (Pseudocercosporella herpotrichoides) incidence or severity in either of the 2 yr that it was present. Burning did reduce downybrome (Bromus tectorum) density in the 1 yr that it was not effectively controlled by mechanical tillage. Joint contribution of the USDA-ARS and Oregon State Univ. Agric. Exp. Stn., Technical Paper no. 8387.
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