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A lime recommendation scheme for established pastures on mineral soils is described. The scheme is based on a simple model, using soil pH, to estimate the size of pasture responses to lime at 3 rates of application (1.25, 2.5, and 5.0 t/ha), The estimated pasture production responses to lime are converted to increases in animal production, from which the potential economic benefits of Iiming are calculated. The limitations and accuracy of the model are discussed. The importance ofliming relative to fertiliser nutrient inputs is also discussed and, in particular, it is concluded that lime and fertiliser inputs should be assessed independently. Recommendations for the use of lime on organic soils are also presented.

The literature on the use of lime (ground limestone) in New Zealand pastoral agriculture is reviewed, and the need for an objective assessment of accumulated results from Ministry of Agriculture and Fisheries field experiments is established. A data base consisting of records from 126 pastoral lime trials in the North Island of New Zealand is described.

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The occurrence of interactions between lime and phosphorus (P) on pasture yield was examined in field trials conducted on a range of soil types in the North Island of New Zealand. The results showed that negative lime X P interactions occurred in most of the trials (19 out of 25). The size of the interaction was negatively related (r 2 = 0.32, P < 0.05) to the size of the lime response. For soils derived from sedimentary parent material, the sign and size of the interaction was positively related {r 2 = 0.36, P < 0.05) to soil pH. Interactions were not related to seasons. The P-sparing effect of limewhich is a particular type of negative lime x P interactionis defined. Of the 25 trials examined, only 11 showed a P-sparing effect, and of the&e, only 4 gave interactions which were large enough to indicate possible economic savings of P fertiliser by liming. The P-sparing effect can occur on both sedimentary and volcanic soils. Implications of these results for predicting lime responses and for making fertiliser P and lime recommendations are discussed.