Grain Mineral Concentrations in Maize (Zea Mays L.) and Nutrient Use Efficiency as Affected by Fertilizer Management on a Nitisol in Southwestern Ethiopia

Abstract

ABSTRACT The combined application of organic and mineral fertilizers is an appropriate agronomic measure and is particularly important for smallholders who have limited access to mineral fertilizers. However, fertilizer recommendations in terms of crop nutritional value and nutrient efficiency strongly vary in dependence of site-specific conditions. In this study, seven different ratios of bio-waste compost (comp) and mineral fertilizers (MF), consisting of nitrogen (N), phosphorus (P), and sulfur (S), were tested in a two-year field experiment on a Nitisol soil in order to assess their effects on nutritionally important minerals in maize (Zea mays, L. Bako-hybrid) grains as well as the nutrient use efficiency. The application of fertilizers corresponded to an N supply of about 100 kg ha−1, whereby the application of only MF (100 MF) was gradually replaced by compost. Compared to 100 MF the treatments with 40 to 70% of N supply given with compost had a higher concentration of most grain minerals. The most pronounced elevations were found for Fe (570 vs. 304 mg kg‒ 1) and Mn (70.1 vs. 36.3 mg kg‒ 1) when 50% of the N was given with compost in comparison to the 100 MF treatment. The P use efficiency increased particularly when compost was part of the nutrient supply. The results suggest that replacing mineral fertilizer with compost accounting for 40 to 70% of the total N supply would be a suitable option for increasing the nutritional quality of maize grains and to efficiently use fertilizers on this Nitisol.