Communicating Nitrogen Loss Mechanisms for Improving Nitrogen Use Efficiency Management, Focused on Global Wheat

Abstract

Nitrogen (N) losses are a major environmental issue. Globally, crop N fertilizer applications are excessive, and N use efficiency (NUE) is low. N loss represents a significant economic loss to the farmer. NUE is difficult to quantify in real time because of the multiple chemical–biological–physical factors interacting. While there is much scientific understanding of N interactions in the plant–soil system, there is little formal expression of scientific knowledge in farm practice. The objective of this study was to clearly define the factors controlling NUE in wheat production, focusing on N inputs, flows, transformations, and outputs from the plant–soil system. A series of focus groups were conducted with professional agronomists and industry experts, and their technical information was considered alongside a structured literature review. To express this understanding, clear graphical representations are provided in the text. The analysis of the NUE processes revealed 16 management interventions which could be prioritized to increase farm nitrogen use efficiency. These management interventions were grouped into three categories—inputs, flow between pools, and outputs—and include management options through the range of application errors, fertilizer input choice, root development, pests and disease, soil structure, harvesting and storage errors, and soil resources of water, micronutrients, carbon, nitrogen, and pH. It was noted that technical solutions such as fertilizer formulation and managing organic matter require significant supply chain upgrades. It was also noted that farm-scale decision support would be best managed using a risk/probability-based recommender system rather than generic guidelines.

Modeling canopy water content in the assessment for rainfall induced surface and groundwater nitrate contamination: The Bilate cropland sub watershed

“… where CCWC is the water content of the crop canopy for the monthly average rainfall of the crop season in mm and RZ_SWC is the observed soil water content of the crop root zone for classified cropland sampled from African soil grids. Root depth data [ 139 , 140 ] observation for the average root zone depth was 30 cm–50 cm for seasonal N input in kgNha-1 year-1. The annual average water content of the tree canopy of the growing areas ( Fig.…”

Continuous no‐tillage winter wheat response to nitrogen fertilizer by yield environment

“…One probable reason why the agronomic optimal rates are relatively greater in LY environments than in HY environments is that higher rate brings N much closer to plant, which shortens the transport of nutrient in water‐limited environments (Assefa et al., 2010; Boulelouah et al., 2022). The other possible reason for a relatively greater optimal fertilizer rate in low‐yield environments could be vulnerability to environmental losses due to prolonged dry spells (Whetton et al., 2022).…”

Post-Intensification Poaceae Cropping: Declining Soil, Unfilled Grain Potential, Time to Act

“…Given the complexity of nitrogen reactions and pathways in soil [ 54 ], losses of mineral N are best reduced through what is termed a ‘portfolio approach’ to low nitrification management, in which a range of interventions are introduced to cover for unexpected variation in the growing environment [ 20 , 55 , 56 ]. Interventions include diversifying cropping systems, minimum tillage, applying nitrification inhibitors, and perhaps most effectively, introducing a grain or forage legume in a cereal rotation [ 57 ].…”