Effects of lime on pasture production on soils in the north island of new zealand: 3. Interaction of lime with phosphorus

Abstract

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 × 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 lime — which is a particular type of negative lime × P interaction — is defined. Of the 25 trials examined, only 11 showed a P-sparing effect, and of these, 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. © Crown copyright 1984.