Grass establishment and performance on a high country soil fertilised with nitrogen

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Abstract
Slow release sulphur-coated urea (SCD) was drilled with seed of ‘Grasslands Nui’ ryegrass (Lolium perenne L.), ‘Grasslands Roa’ tall fescue (Festuca arundinacea Schreb.), ‘Grasslands Wana’ cocksfoot (Dactylis glomerata L.), ‘Grasslands Maru’ phalaris (Phalaris aquatica L.), and ‘Massey Basyn’ Yorkshire fog (Holcus lanatus L.) in glasshouse and field trials to improve establishment on a low fertility high country soil. In the field trial, SCU (50 kg nitrogen(N)/ha) was also broadcast at sowing and uncoated urea (50 kg N/ha) was broadcast after seedling emergence. In the second year, one half of each field plot was given 125 kg N/ha in five applications and in the third year all field plots received 125 kg N/ha in three applications. Grass establishment was greatly enhanced by 25-75 kg N/ ha. SCU, drilled with the seed at rates above 25 kg N/ha,. caused germination injury but surviving seedhngs responded well to any additional N. At the highest N rates (100 kg/ha or more) individual grass plants grew vigorously but their patchy cover allowed the resident hawkweed (Hieracium pilosella L.) to grow vigorously in the intervening spaces. SCU broadcast at sowing or uncoated urea broadcast after emergence were generally less effective than the same rate of drilled SCU. Although Nui and Roa had the most uniform establishment, the second year yields were best overall for Wana and Basyn where N had been applied in both the first and second years. Without N in the second year there was little growth in any plots. Maru seedlings did well initially but appeared to suffer from aluminium toxicity in the second year. Third year yields were highly dependent on the application of N in the second year and to a lesser extent on the first year's application. The cultivarresponse varied, withNui being most affected by lack of N in the second year and Basyn the least. The need to supply N in a manner which minimises germination injury yet maximises uptake by the seedling is discussed. The option of applying N fertiliser is compared with liming, and with using a legume-dommant phase to improve N availability.

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