From a single paddy, both organic rice and a premium delicacy can be harvested. In northern Vietnam's Red River Delta, across Hai Phong City and Hung Yen province, the combined cultivation of 'organic rice \u00d7 r\u01b0\u01a1i (ruoi, a ragworm)' is generating 500 million to 600 million dong per hectare a year (about 3.09 million to 3.7 million yen; rough estimate at 1 yen = about 162 VND as of July 2026). For Japanese food and agriculture buyers, what deserves attention is less the amount itself than the design of how it earns. By raising r\u01b0\u01a1i, which cannot grow in paddies where chemical pesticides or fertilizers remain, in the same paddy, the harvest itself shows that 'a near-pesticide-free water environment is maintained.' The living things speak for the condition of the land.<\/p>\n
What the Vietnamese agricultural media D\u00e2n Vi\u1ec7t reported is the results of a combined organic-rice-and-r\u01b0\u01a1i cultivation model advancing in Hai Phong City and Hung Yen province. The project's total demonstration area is 56 hectares. In participating farmers' paddies, specialty rice is grown without chemical pesticides or fertilizers while r\u01b0\u01a1i is raised in the soil of the same paddy. Pham Xuan Sau of Chi Minh commune (x\u00e3 Ch\u00ed Minh) in Hai Phong City earned a profit of 350 million dong (about 2.16 million yen) a year from nearly one hectare of paddy, taking more than 600 kilograms of r\u01b0\u01a1i over two harvests. Compared with conventional single-crop rice, profit has more than doubled.<\/p>\n
R\u01b0\u01a1i is a polychaete creature caught in the brackish waters of the Red River Delta, a delicacy that in northern Vietnam appears only in a season centered on autumn. 'Ch\u1ea3 r\u01b0\u01a1i (cha ruoi),' made by binding it with egg, is known as a Hanoi specialty dish, and its producing areas are limited to Hai Phong, Hai Duong, Hung Yen, Thai Binh, Quang Ninh, and the like.<\/p>\n
This r\u01b0\u01a1i is the linchpin of the combined cultivation. R\u01b0\u01a1i is so sensitive that it cannot live once chemicals mix into water or soil, and it will not breed in paddies that have used pesticides or chemical fertilizers. Turned around, a paddy where r\u01b0\u01a1i grows becomes a visible indicator that 'a water environment free of chemical residue is maintained.' Farmers improve saline soil, manage water, and use biological preparations to ready r\u01b0\u01a1i's habitat, and in extension of that the conditions for organic rice are also readied. The economic motive to stay pesticide-free is born not from outside certification but from inside the paddy. This point differs from the type of organic cultivation that merely cuts chemical inputs.<\/p>\n
The economics of combined cultivation hold only on the two-track of rice and r\u01b0\u01a1i. Looking at rice alone, yield is about 5 tonnes per hectare, not especially high. The thickness of the earnings comes from the combination of high-unit-price r\u01b0\u01a1i and specialty rice that sells high because it is pesticide-free. Below are the project's demonstration values; rice and r\u01b0\u01a1i yields vary by area (Hai Phong \/ Hung Yen).<\/p>\n