Abstract:
Maize (Zea mays L.) is the most vital upland cereal and a cornerstone of food security
in Sri Lanka. Despite its extent of cultivation within the dry zone, a region highly
vulnerable to climate change vulnerabilities, the current nitrogen (N) fertilizer
recommendations often lack climate-specific optimization, leading to inefficiencies
in yield and environmental impacts. The objectives of this study were to model and
optimize N fertilizer rates for maize, under current and projected climate conditions
for 2050 and 2100 by testing different nitrogen management scenarios by utilizing
the agricultural production systems simulator (APSIM). The analysis incorporated
Department of Agriculture recommendations, present-day data, and climate
projections, for examining yield, nitrogen leaching, and fertilizer rates across the
Maha and Yala seasons under rain-fed conditions. Findings indicated that under
current conditions, applying 345 kg ha-1 of N in the Maha season yields 2,625.10 kg
ha-1 with a median leaching value of 11.3 kg ha-1. In Yala, 435 kg ha-1 of N achieves
3,174.46 kg ha-1 yield and 0.4 kg ha-1 leaching. As per anticipated alterations in
climate scenarios for 2050, a slightly increased optimal yield is expected with similar
N rates. In 2100, particularly in Yala, the simulated yield increased with higher N
rates (375 kg ha-1 in Maha and 465 kg ha-1 in Yala), despite increased leaching. The
study emphasized the importance of climate-responsive N management to sustain
yield optimization and mitigate environmental impacts over time. This research
provides data-driven insights for policymakers and extension services, highlighting
the value of climate-resilient N management strategies for sustainable maize
production. These tailored recommendations would help Sri Lankan farmers to
navigate the challenges of climate change, promoting agricultural productivity and
environmental sustainability in the dry zone of Sri Lanka.
