Variable rate nitrogen fertilisation to improve silage maize yield and crude protein using APSIM modelling

Iris Vogeler; Christof Kluß; Friedhelm Taube

Just Accepted

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Variable rate nitrogen fertilisation to improve silage maize yield and crude protein using APSIM modelling

Iris Vogeler , Christof Kluß, Friedhelm Taube

Abstract

Context: Precision nitrogen (N) fertilization, which considers variability in both near-future soil nitrogen supply and crop nitrogen demand, enables reductions in fertilizer use at the field level, while maintaining high yields, high crude protein (CP) content, and minimizing nitrogen losses Aims: To determine optimum N fertilization rates for silage maize (Zea mays) based on variability in soil organic carbon (SOC) and plant available water (PAW) of a 20-ha field, a simulation study using the APSIM model was set up Methods: APSIM was initially tested under northern European conditions using measurements of biomass, crude protein (CP), and nitrogen leaching losses. The model was subsequently applied to determine optimal nitrogen rates, taking into account variability in soil organic carbon (SOC) and plant available water (PAW) through different fertilization scenarios. Model outputs were then used to calculate the required nitrogen rates to achieve a target CP of 6.6%, which is the critical value for maximizing yield. Key results: Compared to a blanket N application across the field, variable nitrogen rate application generally increased the proportion of the field achieving the target crude protein (CP) and reduced overall field-scale nitrogen leaching Conclusions: Process-based models like APSIM offer a valuable tool for determining optimal nitrogen fertilization rates based on variability in soil properties. However, field testing is essential to validate the effectiveness of this approach under real conditions. Implications. The simulations highlight that in sandy soils with high mineralisation potential due to past high organic matter inputs, N fertilisation should be avoided to meet the requirements of given environmental standards for water protection in the European Union.

SR24180 Accepted 14 May 2025