Manganese and phosphorus maize shoot concentrations are differently affected by nitrification inhibitor‐driven rhizosphere acidification

Abstract High soil pH can lead to Mn 2+ and P deficiency and yield losses. In addition, it is unclear which process, nitrification‐induced acidification of bulk soil or nitrification inhibitor‐driven rhizosphere acidification, is more effective in increasing Mn 2+ availability and shoot concentration. Thus, this topic was investigated in this study. Moreover, we also evaluated if applying NIs can avoid P deficiency in soil with high pH and high buffering capacity. Two greenhouse experiments were carried out to investigate the impact of applying 3,4‐Dimethylpyrazole phosphate (DMPP) in sandy soil subjected to the application of different lime rates, simulating several soil pH and buffering capacity conditions. The utilized lime rates were 0, 0.5, 1, 2 and 4 g CaCO 3 kg −1 . The measured variables were bulk and rhizosphere soil pH, Mn 2+ and P availability, maize biomass production, as well as Mn and P shoot concentrations. DMPP significantly reduced shoot biomass by 10% in unlimed soil; however, it promoted the overall shoot biomass by 30% in limed soil in both experiments. In addition, DMPP decreased the overall Mn shoot concentration by 24 and 21% in experiments I and II, respectively. In contrast, DMPP increased the overall P shoot concentration due to rhizosphere acidification by 24 and 17% in experiments I and II, respectively. The DMPP application did not avoid P deficiency under the highest lime rate (4 g CaCO 3 kg −1 ) despite alleviating it. In conclusion, the application of NIs is not beneficial for increasing Mn 2+ shoot concentration and, when performed to increase P availability in high pH soils, should consider the likelihood of causing Mn deficiency.