Does Drought Regulate DMPP Effectiveness in Alleviating Maize Manganese and Phosphorus Deficiencies in High-pH Soils?

Drought will likely become more frequent and intense in Europe due to climate change, which may worsen Mn2+ and P deficiencies found in high pH soils. In this context, research investigating the effectiveness of ammonium-based nitrogen fertilizers treated with nitrification inhibitors (NIs) in alleviating Mn2+ and P deficiencies in such soils has been done. However, studies considering the impact of drought periods and soil texture on this topic are lacking. Therefore, we carried out a study addressing this research gap. Maize plants were grown in a greenhouse experiment, and the experimental setup comprised three factors consisting of soil texture (sand and silt loam), soil moisture (sufficient and drought), and DMPP application (with and without DMPP). The measured variables were bulk and rhizosphere soil pH, Mn2+ availability, maize biomass yield, and shoot concentration of selected macro- and micronutrients. DMPP increased shoot biomass production by 60% in silt loam under drought but not in sand soil texture. In addition, DMPP increased Mn2+ and P shoot concentrations by 38% and 21%, respectively, in the silt loam soil texture under drought. In contrast, DMPP did not alleviate the negative impact of drought on plant biomass production, Mn2+ and P shoot concentration in the sand soil texture. In conclusion, DMPP application is effective in alleviating Mn2+ and P deprivation in high pH soil subjected to drought. However, this effect was soil texture-dependent and observed in the silt loam rather than in the sand soil texture.