Work

Spatiotemporal dynamics of cropland N balance reveal rising N surplus and poor crop response in the Lake Victoria Basin (2000–2020)

Year: 2026

Type: article

Abstract: Understanding spatiotemporal dynamics of nitrogen (N) balance is essential for improving food security and mitigating environmental risks. Yet long-term, high-resolution assessments remain scarce in the Lake Victoria Basin (LVB), despite rising production demands and worsening water quality. In this study, we estimated four major N inputs (fertilizer, manure, atmospheric deposition, and biological fixation) and crop N outputs from 36 species for the period 2000–2020 to calculate nitrogen use efficiency (NUE) and N surplus. Regression and spatial analyses were further conducted to identify the drivers influencing their spatiotemporal patterns. During the two decades, N inputs increased from 10.01 to 17.49 kg N ha −1 (a 75% rise), while N outputs increased from 7.57 to 10.05 kg N ha −1 (33%), leading to a decline in NUE from 76% to 61% and a doubling of N surplus from 3.85 to 8.38 kg N ha −1 . The rising N surplus was mainly driven by greater fertilizer and manure applications, low crop responsiveness to N, cropping patterns, and climatic factors. This first spatially explicit, long-term N balance dataset for the LVB offers insights into N management and regional environmental degradation, supporting targeted strategies to improve productivity and reduce pollution in line with SDG 2 (Zero Hunger) and SDG 6 (Clean Water and Sanitation).

Source: Environmental Research Letters

DOI: 10.1088/1748-9326/ae5316

Authors: Siyue Sun, Sophia Shuang Chen

Institution: Nanjing University of Information Science and Technology

Language: English

Topic: Soil and Water Nutrient Dynamics

Subfield: Environmental Chemistry

Field: Environmental Science

Domain: Physical Sciences

SDGs: Zero hunger, Clean water and sanitation, Climate action

Open Access status: gold

Estimated APC paid: $3,045