Comparative Evaluation of Tillage Methods on Maize Biomass and Yield Performance across Agroecological Zones in Rwanda: Towards Efficient and Sustainable Use of Mineral Fertilizers

Although the effect of tillage methods on agricultural productivity is among the most researched topics in agriculture, conservation tillage counterparts are poorly reported, more so their systematic effect on crop yield. This study evaluated the effects of four tillage methods—continuous cover (CC), flat till (FT), ridge till (RT), and minimum till (MT)—and four fertilizer treatments—nitrogen (N), farmyard manure (FYM), a combination of nitrogen and farmyard manure (N+FYM), and a control with no fertilizer (NF)—on maize biomass and yield over three consecutive growing seasons. The experiment was conducted for three consecutive seasons (S1–S3) at two contrasting sites (Eastern Savannah and Volcanic Highland) using a two-factor factorial arrangement in a randomized complete block design (RCBD) with three replications. Continuous cover increased biomass accumulation by 133 and 125% in Eastern Savannah and Volcanic Highland Agroecological zones, and yield by 83 and 46%, respectively. Across seasons, yield was highest in season 3 while there was no interaction effect between tillage methods and fertilizers application. In conclusion, results indicate that CC has huge advantage over other tillage methods investigated in this study in terms of biomass accumulation and yield of maize.