M G. Mason

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Aspects of the effect of nitrogen fertilizers on cereal hay production in twenty-one experiments carried out over eight seasons were investigated.Areas investigated include the effects of rate and time of application of nitrogen fertilizer, sowing rate, date of sowing, crop species and variety and time of cutting on cereal hay yield, nitrogen content and digestibility.Response to nitrogen fertilizers in hay and grain production varied but profitable responses were more common, and optimum rates were higher for hay than for grain. Average optimum rates for hay were 51 to 88 kg nitrogenha-1 and for grain 0 to 44 kg nitrogen ha-1. Results showed 4 to 8 weeks after sowing to be the best time of application.Increasing sowing rates above the normal rate of 50 kg ha-1 for grain production increased hay yields in 2 of 3 trials, but there were no interactions with nitrogen. In two trials higher hay yields were obtained with earlier than with late planting, but there was no clear interaction with nitrogen. More hay was generally produced from the oat varieties used than from wheat and there was little interaction of species with nitrogen, in four experiments. No consistent interaction between oat varieties was found in six experiments.Protein levels in hay increased with higher rates of nitrogen and late applications and were higher for early cuts than for later cuts. There were no consistent effects on in vitro digestibility of the hay.

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Western Australia, Farming Systems