A Cost-Benefit and Optimization Analysis for Low-Emission Rice Production Systems in Bac Lieu, Mekong Delta, Viet Nam

This study compares the economic performance and trade-offs of triple-rice and rice–shrimp farming systems in Bac Lieu Province, Viet Nam's Mekong Delta, using season-specific household survey data from 193 farming households across three ecological zones. The analysis combines a cost–benefit analysis with a risk-adjusted household optimization model to assess how farmers' choices and outcomes respond to policy incentives under ecological feasibility constraints. Results show that while rice–shrimp rotation generates higher average net income compared to triple-rice, mean profitability tells only part of the story. Risk burdens are highly spatial: freshwater zones face risk penalties of just 2.2%, while brackish and transition zones bear 12.6%, and the aggregate risk penalty across Bac Lieu reaches 9.9%, narrowing the welfare advantage of rice–shrimp considerably once income volatility is accounted for. Policy simulations indicate that cost-side instruments generate the largest welfare gains. A 20% input subsidy raises certainty-equivalent income to 1.44×10⁸ VND and soft credit to a comparable level (1.47×10⁸ VND), while a bundled package of price premiums, carbon payments, soft credit, and input subsidies raises it to 1.83×10⁸ VND. Carbon payments also stimulate measurable mitigation, reducing average emissions from 26.6 to 18.2 tCO₂e per farm per year. These findings support spatially targeted policy packages that jointly address profitability, liquidity constraints, and risk exposure while aligning climate incentives with agro-ecological suitability.