Meta-Analysis On Yield and No-Tillage: II. Management of Crops, Residue, and Nitrogen.

No-till (NT) practices often allow growers to reduce energy, labor, and machinery inputs as well as potentially manage more land. NT has increasingly been promoted world-wide, particularly in agricultural intensively developed countries such as America, Argentina, Australia, Brazil, Canada, and some European countries. However, there is some concern whether crop productivity increases or decreases following NT adoption, which may have major consequences regarding the challenge of meeting projected increases in global food demand. Here, we established a global database with several thousand side-by-side comparisons of NT and conventional tillage under a range of crops, climatic zones, and residue, nitrogen, and irrigation management practices to investigate the extent to which NT affects yield. We quantified the effect of tillage on yield by calculating the natural log of the response ratio between NT and conventional tillage treatments and performed meta-analyses using non-parametric weighting functions and generated confidence intervals on weighted effect sizes using bootstrapping. This presentation will address the main objectives of this study with a focus on yield as influenced by crop types, residue, and N management.