Acidification of Biogas Residues Stimulates Manganese Uptake in Wheat

ABSTRACT Background Efficient application of organic fertilizers contributes to resource‐efficient agriculture. Acidification of liquid manure effectively reduces ammonia (NH 3 ) emissions. However, the effect of acidification on other plant nutrients, such as Mn, often a yield‐limiting nutrient in cereal production, is not well understood. Aims This study aimed to investigate the effect of fertilization with acidified biogas residues (ABGR) on yield, Mn concentration, and Mn uptake from winter wheat. Methods A fully randomized field trial with winter wheat was established on a sandy/loam soil in northern Germany in 2016 and 2017, with sowing each September and harvest in the following year. Fertilizer treatments of untreated biogas residues (UBGR) and ABGR, respectively, were applied on NH 4 + ‐N basis. The effects of UBGR application at three NH 4 + fertilization levels were compared with each other and with three corresponding ABGR fertilization levels. Yield, Mn concentration, and Mn uptake were determined at the early milk stage during intermediate sampling and again at final harvest before the early dough stage. Results Fertilizing with ABGR increased yield and Mn uptake at early dough stage under low fertilizer rates in both years. However, grain yield was significantly increased by ABGR application in the first year only. Significant increases in Mn concentrations were observed at the two higher fertilizer levels as a result of ABGR application. Conclusions Fertilizing with ABGR has the potential to improve Mn uptake by cereals. This yield‐limiting factor could therefore be minimized by acidification, especially in years with low rainfall, when Mn deficiency is frequently observed.