Impact of nutrient management strategies on cassava performance, nutrient uptake, and economic returns in Agusan del Sur, Philippines

This study explores the efficiency of fertilizer management strategies on the yield, nutrient uptake, and economic returns of cassava varieties (Lakan 1 and Golden Yellow) grown in two sites in Agusan del Sur, Philippines. The study employed a split-plot randomized complete block design to assess eleven fertilizer treatments, including site-specific nutrient management (SSNM), full (NPK) application, nutrient omission (N, P, and K omission), adjusted nutrient (N, P, and K adjusted), national fertilizer recommendation (NFR), and farmers’ fertilizer practice (FFP) conducted over 12 months. The results revealed that full NPK fertilization consistently produced the highest yields, with Lakan 1 and Golden Yellow reaching 47.61 t/ha and 47.89 t/ha, respectively. However, the SSNM treatment unexpectedly delivered the highest return on investment (ROI), with 128.61% for Lakan 1 and 126.75% for Golden Yellow, outperforming full NPK in economic efficiency. Despite differences in varietal growth characteristics, both varieties showed similar nutrient uptake patterns, indicating a uniform response to the nutrient management strategies applied. Additionally, NPK fertilization enhanced overall tuber yield; it also led to higher non-marketable yields compared to other treatments, particularly in nitrogen and potassium omission plots. SSNM was a cost-effective nutrient management approach, balancing productivity and economic returns and optimizing fertilizer strategies for cassava production, emphasizing the importance of tailored nutrient management for maximizing profitability.