An account is given of three experiments conducted on uncultivated grasslands in the fescue tussock zone of the Broken River Basin. Where other nutrients were not limiting, constant returns in grass yield were shown to increments of nitrogen up to 200 lb N per acre. On both poor and good sites grass yield was increased fivefold with applications of nitrogen at the level of 200 lb N per acre. Increases were shown to persist for at least two years after fertiliser application on the poor sites.
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