STUBBLE MANAGEMENT OF HAY AFTERMATH

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Possible management strategies for areas of stubble left after hay had been harvested from a ryegrass/white clover pasture were studied in a trial on an irrigated Wakanui silt loam at Lincoln College, Canterbury. Following a hay crop cut in late December, the stubble was either trimmed to 2 cm (920 kg DM/ha) or left intact at 8-12 cm (2200 kg DM/ha) and spelled for either four or eight weeks. Subsequent regrowth herbage yield, botanical composition and digestibility were measured. The highest live herbage mass of 5380 kg DM/ha resulted from leaving the stubble intact and cutting the regrowth at four weekly intervals. The other treatments gave herbage masses from 4120 kg DM/ha to 4350 kg DM/ha but did not significantly differ from one another. However while 1220 and 1650 kg DM/ha of dead material was present in the "stubble intact" treatments, only 470 and 880 kg DM/ha occurred where the stubble was trimmed to 2 cm. The amount of dead material was the main determinant of overall digestibility, as the digestibility of the green herbage was similar (79-80%) for all treatments. As a result of differing amounts of dead material therefore, the herbage mass from trimmed stubble was from 4 to 10% higher in digestibility than that from the stubble left intact treatment. Clover proportion was high throughout the treatments, ranging from 50% in the long spelled treatment to 70% in the short spelled treatment. The results of this trial suggest that hay stubble should be left intact but regrowth should be closely defoliated after four weeks to maximise production and return the sward to a leafy state as quickly as possible.