Enhancing Efficiency of Water–Energy–Food Nexus Through Irrigation and Phosphorus Management in Maize Production: A Case Study of Semi-Arid Region

The declining productivity, fertilizer inefficiencies, and rising energy cum production costs are the key issues in crop production, especially in semi-arid regions with alkaline soils. Integration of crop management strategies needs to be adopted to address these issues within the water–energy–food nexus (WEFN). For this purpose, a case study was conducted in semi-arid region of central Punjab, Pakistan, to evaluate the interactive effects of irrigation water source canal water (CW) and tubewell water (TW), phosphorus fertilizer source diammonium phosphate (DAP) vs. phosphoric acid₂5% (PA), and fertilizer application levels 100% and 80% of recommended dose of fertilizer (RDF) on maize productivity, energy efficiency and economic performance. The experiment comprises eight treatments under raised bed planting (RBP) and one control treatment under ridge-furrow sowing (RFS). Each treatment had three replicates, and the experiment was laid out under a randomized complete block design (RCBD). Maize growth, yield, water productivity, energy efficiency, and economic performance were analyzed using field measurements, energy equivalents, and partial budget analysis. The T1 (RBP+CW+PA+100%RDF) produced the highest maize yield, and it varied from 6. 36 to 7. 90 t ha−1 under other treatments. CW significantly showed better water productivity (1. 14–1. 37 kg m−3) than that under TW (1. 13–1. 31 kg m−3) ; however, total energy input was higher under TW-based treatments (29, 269–41, 033 MJ t ha−1) than that under CW-based treatments (24, 129–29, 681 MJ ha−1). This results in lower energy productivity under TW-based treatments compared with CW-based treatments (0. 17–0. 23 kg MJ−1 vs. 0. 25–0. 31 kg MJ−1, respectively). Moreover, T2 (RBP+CW+PA+80%RDF) produced the highest energy use efficiency (0. 59). Economic analysis revealed that production costs were nearly 15–17% higher under TW-based treatments, mainly due to the cost associated with groundwater pumping, and it reduced net profit to USD 1134–1385 ha−1. Better net profits were achieved by CW-based treatments (USD 1244–1593 ha−1), while those produced by BCR ranged from 3. 11 to 3. 69, with the highest value under T2 (RBP+CW+PA+80%RDF). Overall, irrigation water source emerged as the dominant driver of WEFN performance, while phosphoric acid significantly improved phosphorus availability, energy productivity, and economic returns, particularly under reduced fertilizer input. This study evidenced better maize productivity, less energy consumption, and improved farm profitability in semi-arid irrigated systems through the integration of canal water irrigation with optimized phosphorus management.