Meta-Analysis On Yield and No-Tillage: I. Climate, Water, and No-Till Duration.

It is well established that no-till practices have the potential to provide numerous soil and cropping system benefits, particularly in terms of reducing environmental impacts associated with intensive (conventional) cultivation. However, the effects of no-till on crop productivity remain less well understood with reports of yields increasing, decreasing, or being maintained depending on a range of factors. We conducted a global meta-analysis to comprehensively evaluate the relationship between no-till and yield. Peer-reviewed studies containing side-by-side comparisons of yield under no-till and conventional tillage practices were compiled through an exhaustive literature search. Studies with confounding factors in addition to tillage effects were not included. The established database contained several thousand observations and the following variables: crop type, duration of no-till practices, rate and source of fertilizer N input, residue management practices, irrigation (presence or absence), and aridity index. In this presentation factors governing the response of yield to no-till practices will be discussed with an emphasis on duration, climate, and irrigation practices.