Does shifting from normal to early or late sowing dates provide yield benefits? A global meta-analysis

Shifting the sowing date has been proposed as a simple agronomic lever to enhance crop establishment, growth, and yield, which could be a climate change adaptation strategy. Previous research showed that the experimental data assessing the effect of sowing date are not consistent and vary between trials and publications. We hypothesized that the difference in pedoclimatic conditions and management practices may be responsible for the contrasting impact of sowing dates on crop establishment, growth, and yield. A global meta-analysis of 94 studies and 3145 observations was conducted to quantify the effect of covariates related to crop types and pedoclimatic conditions in relation to early and late sowing dates compared to normal sowing dates. On average, early sowing significantly increased seedling emergence vigor (53 %, confidence interval (95 %) = 49 %,58 %) and disease and pest control (88 % 20 %,195 %) without significant effect on plant biomass (2 % -2 %,5 %) and yield (-10 % -20 %, +0.8 %) compared to normal sowing date. In contrast, late sowing had no significant effect on seedling emergence vigor (28 %-4 %,72 %) or disease and pest control (14 %-1 %,31 %) while it significantly decreased plant biomass (-21 %-21.42 %,-21.12 %) and yield (-24 % -28 %, −19 %) compared to normal sowing date, in particular when the sowing delay exceeded three weeks and when the average minimum temperature was above 13°C during the growing season. Early sowing does not affect crop productivity while late sowing reduces crop yield. Shifting from normal to late sowing dates may lead to yield losses exceeding 20 %, especially in warm conditions. This study offers an important insight into the potential of crop yield improvement by adjusting sowing dates to aid decision-making in relation to specific pedoclimatic conditions and cropping practices. • Shifting the sowing date is a simple adaptation strategy. • No study quantified the effect of early and late sowing vs. normal sowing. • A global meta-analysis of 94 studies and 3145 observations was performed. • Early sowing increases seedling emergence vigor, disease, and pest control compared to normal sowing. • Late sowing decreases plant biomass and crop yield compared to normal sowing.