Poor incorporation of lime limits grain yield response in wheat

Abstract

Thorough mixing of lime with the soil is a standard recommendation for lime application. However, the implements and passes that may be used to achieve this in Australian cereal farming are unclear. Therefore, 2 experiments were conducted to examine the incorporation of lime applied at 0, 2 and 5 t/ha using a range of different agricultural implements and numbers of cultivation events. Shoot dry matter and grain yield of wheat were measured in the year of lime application in both experiments. The plots were resown to wheat in the following season by direct drilling, and measurements were repeated. In a dry season, high soil disturbance (rotary hoe and disc harrow) improved the response of wheat to lime in the first year of experiment 1. In experiment 2, rainfall was higher, and the advantage from thorough incorporation was less clear. However, the rank order of incorporation methods and lime responsiveness was positively correlated with that in experiment 1 for both dry matter and grain yield; thorough incorporation tended to give better responses to lime than ‘poor’ incorporation (light harrowing). In the second year of experiment 1 there was limited evidence of the influence of incorporation method on lime response. In the second season of both experiments the effects of incorporation method on lime response had dissipated or other effects were more important. We found that to maximise grain yield responses to lime, the most effective incorporation was achieved with a disc harrow or with multiple passes with a tined implement (scarifier). Incorporation limited to a light harrow was inadequate. However, any effects of method of incorporation reduced or disappeared in the following season, even when direct drilling was used and there was limited further soil disturbance.