Genotype x management interaction for nutrient use efficiency (NUE) of maize varieties tested under different tillage and fertilization regimes

Summary

Most varieties have been selected under high input conditions, including seed treatment, herbicide applications, as well as optimal levels of fast releasing fertilizers. Under organic farming nutrient release is dependent on the temperature and biological activity of the soil and its interaction with the declining residues from previous crops and applied quantity of farmyard manure. As a consequence it is not always possible to match nutrient release with crop demand over time. This effect is even more severe under conservation tillage. To promote conservation tillage in organic farming, it is necessary to identify cultivars that show high nutrient use efficiency (NUE) under these conditions. While there is substantial evidence that breeding for low N input conditions selection is more efficient under severe N stress than under high input conditions only few studies have been conducted to demonstrate the difference in selection gain between organic and inorganic fertilization or between different soil tillage management. The objectives of the study were (i) to quantify the NUE of maize (Zea mays L.) genotypes under different tillage regimes and fertilization levels, (ii) to compare the effect of slow releasing organic versus inorganic fertilizer, and (iii) determine genotype x management interaction.