The effect of varieties, nitrogen and stubble treatments on successive cycles of grain and forage sorghums in the Ord River valley

Abstract

Two exploratory experiments with re-cycled (ratooned) grain sorghums (hybrid Texas R.S. 610 and standard variety Alpha) and forage sorghums (hybrid Sudax and standard variety Sugardrip) were carried out at Kimberley Research Station to provide data for the initial assessment of sorghum production possibilities in the Ord River area. Re-cycling of sorghum led to progressive reduction in grain and dry matter yields. Grain yield reduction was greater when stubble was cut at the header height (approximately 40 inches) than when it was cut at 6 to 8 inches above ground level and removed. Grain and dry matter yields were higher for Texas R.S. 610 than for Alpha, while dry matter yield of Sudax was also higher than that of Sugardrip. Nitrogen application at 50 lb N an acre and 100 lb N an acre increased grain yields of Texas R.S. 610 and Alpha. It also increased dry matter yields of these two varieties and of Sugardrip, while dry matter yield of Sudax did not respond above the 50 lb N an acre rate of application. Relative, but not absolute, reduction of grain and dry matter yields in successive cycles was diminished by nitrogen application.