Precision Nitrogen Management in Spring Rice (Oryza sativa L.) using Decision Support Tools in Chitwan, Nepal

The blanket prescription of nitrogen (N) fertilizer often results in irrational fertilization. To address this issue and align the application of nitrogen fertilizers with the crop-specific demand, it is imperative to save nitrogen resources, maximize the uptake and net income, and subside environmental pollution. In this context, a field experiment was carried out in Kumroj, Chitwan, Nepal during 2022 to assess the growth, yield, and profitability of rice production by comparing different precision nitrogen management practices. The study was carried out in a randomized complete block design with seven treatments and three replications. The treatments included decision support tools for nitrogen management such as the Green Seeker (GS), the Soil plant analysis development Development (SPAD) meter, and the Leaf Color Chart (LCC) combined with basal application of nitrogen at 30 kg ha–1 and the Urea briquette Deep Placement (UDP), the Polymer Coated Urea (PCU), and the Recommended Dose of Fertilizers (RDF, 120 kg N ha–1). The growth, yield, yield attributes, and financial data were taken. Precision nitrogen management techniques significantly enhanced rice growth and yield parameters. GS–guided application required the highest nitrogen demand (155 kg ha–1), while SPAD (80 kg ha–1) and UDP (78 kg ha–1) resulted in lower usage. PCU and UDP enhanced plant height, leaf area index, and above–ground dry matter. Higher grain yield (6.64 t ha–1) was attained with LCC, SPAD (6.44 t ha–1), and UDP (6.41 t ha–1) treatments. GS application exhibited the highest straw yield (11.17 t ha–1), while LCC demonstrated the highest benefit–cost ratio (1.96). This study concluded that SPAD and UDP demonstrated the potential to save nitrogen resources, while LCC and UDP were found profitable.