Rice–fish coculture and its ecological indicators: Insights from Ziro Valley using LASSO regression model

This study evaluates ecological and productivity outcomes of three rice-based farming systems in the Ziro Valley, Arunachal Pradesh: rice monoculture with irrigation (RMI), rice–fish integration with irrigation (RFI), and rice–fish integration using irrigation and household-livestock wastewater (RFIW). Soil, water, and plankton parameters were measured across 30 plots. A total of 23 variables were analyzed using t-tests, principal component analysis, and Lasso regression to identify the most influential indicators linked to rice yield. RFI fields recorded the highest rice yield (average 1626 kg/ha) and demonstrated a well-balanced ecological profile, with lower soil specific conductance (mean 142 μ S/cm), moderate nutrient levels, and greater zooplankton diversity. In contrast, RFIW plots had higher nutrient loads, particularly ammonia in water (mean 2.10 mg/L), and slightly reduced rice productivity (average 1252 kg/ha), likely due to ecological imbalances and eutrophic stress. RMI fields showed reduced rice productivity (average 1510 kg/ha) and less diverse plankton structure, reflecting nutrient limitations and lack of biological interactions. Rotifera, Copepoda (both adult and naupli), and Cyanophyceae emerged as key biological indicators across systems, and Lasso regression models explained up to 98 percent of yield variation. The results suggest that the fish can influence rice growth and nutrient dynamics and planktonic assemblage in Ziro’s rice field, while maintaining baseline ecological stability would be necessary for the best results. These findings highlight the need for nutrient balance over intensification and demonstrate how plankton-based indicators can exhibit ecological performance and nutrient management in integrated rice and fish landscapes. • Rice–fish integration using irrigation water (RFI) outperformed rice–fish integration using irrigation and household-livestock wastewater (RFIW). • Rotifera, Copepoda, Cyanophyceae, and soil-specific conductance emerged as key indicators. • Fish presence improved nutrient recycling and plankton diversity. • Soil-specific conductance was lowest in RFI, indicating system health. • Ammonia levels were highest in RFIW, signaling eutrophication.