Optimizing Rice-Potato Systems through Circular Economy
This work demonstrates how mechanized rice straw composting and the 4R nutrient management principles can transform agricultural byproducts into high-value assets, significantly boosting farmer incomes while providing safe, organic produce for local school feeding programs in Vietnam.
CIP–IRRI Collaboration in Yen Cuong, Vietnam
The integration of rice straw-based circular economy models into intensive cropping systems offers a sustainable pathway to enhance soil health and farmer livelihoods in Southeast Asia. At the Nam Cuong Agricultural Production, Business, and Service Cooperative in Ninh Binh Province, a strategic partnership between the International Rice Research Institute (IRRI), the CGIAR Science Program on Scaling for Impact (S4I), and the USDA-funded Fertilize Right (FerRight) project has implemented a precision nutrient management model centered on the use of rice straw as fertilizer. This work leverages the farmers' structured 12-month cycle, which integrates a four-month nitrogen-fixing peanut crop, a three-month rice crop for biomass production, and a three-month high-value potato crop.
The primary objective of this initiative is to provide safe, organic produce for school feeding programs across 20 local schools. By utilizing high-quality potato varieties known for consistent tuber quality and strong market acceptance, the cooperative has successfully aligned agricultural productivity with regional food security and nutrition goals.
Effect of Compost in Rice Production
The technical core of this model is the systematic transformation of rice straw into high-quality organic fertilizer, effectively closing the nutrient loop. Traditionally, one hectare of rice field produces approximately 2 tons of straw; when co-composted with cow dung, this biomass is converted into 2 tons of stabilized organic input. This process mitigates straw burning, a common practice that contributes to atmospheric pollution and carbon loss.
Mechanization and Process Efficiency
A critical challenge in intensive multi-crop systems is the time required for organic matter decomposition. Traditional composting methods typically require 90 days—a duration that exceeds the fallow period between rice harvest and potato planting. To address this, IRRI introduced mechanized compost turner technology to the Nam Cuong Cooperative in 2024.
By combining physical aeration with the application of biochemical probiotics, this technology shortens the decomposition period from 90 days to just 45 days. To ensure high-quality output, farmers are trained to monitor critical parameters, including temperature, pH levels, and moisture content, through regular mixing.
In contrast to the success of stabilized compost, field observations noted that raw rice straw mulching (typically sourced after the June harvest) appears to have no significant effect on potato productivity. Furthermore, it requires careful monitoring to avoid tuber exposure to sunlight, which causes "greening." Farmers reported that potatoes grown with rice compost application (19–28 t/ha) exhibited superior tuber quality and taste. Additionally, non-composted plots often faced nutrient competition, requiring an additional 20% of potassium and nitrogen to stabilize the nutrient profile and maintain yield targets.
Socio-Economic Implications and Scale
The Nam Cuong Cooperative involves approximately 1,600 farming households managing 300 hectares of land. Of this total, 130 hectares are dedicated to potato production, reflecting the crop's superior economic performance. The transition to a potato-based rotation has provided a substantial increase in household income compared to traditional monocultures.
The profitability hierarchy among regional crops clearly favors potatoes as the most lucrative commodity. Specifically, potato cultivation generates a gross income of 6,500,000 VND (approx. 255 USD) and a net profit of 4,500,000 VND (approx. 176 USD) per sao (360 m²). This significantly outperforms peanuts, which yield a 2,000,000 VND (approx. 78 USD) net profit from a 4,500,000 VND (approx. 176 USD) gross. In contrast, rice production offers the lowest returns with a gross income of only 200,000 VND (approx. 8 USD) and highly variable net margins, further justifying the cooperative’s strategic shift toward diversified potato systems.
Toward High-Productivity and Low-Emission Systems
By adopting the 4R principles of nutrient management—Right Source, Right Rate, Right Time, and Right Place—the cooperative ensures the system remains both ecologically sustainable and financially viable. In the Red River Delta, farmers grow potatoes in paddy fields that would otherwise be left fallow during the dry winter season. While previous efforts focused on minimum-tillage mulch as a low-emission alternative, that approach declined with the expansion of mechanized rice harvesting.
Today, rice straw compost offers a practical and renewed opportunity for a low-emission rice-based cropping system. IRRI and CIP continue to collaborate to identify best practices and promote sustainable land-use systems that benefit smallholder farmers and the environment alike.
*sao: A traditional Northern Vietnamese unit of area measurement (360 m²).
