Wider spacing for more efficient rice production

Two machine-sown panicles outperform three hand-sown ones

Standing in the middle of his rice field in Yen Cuong Commune, Ninh Binh Province, Nguyen Van Cac bends down to pull up a clump of ripe golden rice and separates the panicles for comparison. On one side is a field traditionally broadcast by hand; on the other is a machine-sown field managed under a low-emission rice production model introduced by the International Rice Research Institute (IRRI).

Cac remarks that the difference is obvious even to the naked eye. The hand-broadcast field appears denser, with more panicles, but the panicles are shorter, with fewer grains and weaker stems. By contrast, the machine-sown field has much wider row spacing, yet its panicles are longer, fuller, and sturdier.

That observation runs counter to the long-held beliefs of many rice farmers in northern Vietnam. In Ninh Binh, one of the Red River Delta's largest rice-producing regions, dense sowing has traditionally been regarded as the safest way to ensure a good harvest. Farmers often increase seeding rates on the assumption that fewer plants will mean fewer panicles and lower yields.

However, the low-emission rice model introduced in Yen Cuong during this year's spring crop began by cutting the seeding rate by nearly half.

Immediately after sowing, the field looked unusually sparse, with patches of gray mud still visible between the young rice seedlings. Whenever neighbors passed by, they seemed to slow down. Some bent over to inspect the field and asked Cac whether he had accidentally used too little seed. Others simply stood in silence for a few seconds before walking on, clearly unconvinced.

Even Cac himself was not entirely confident. Although he committed all four sao of his land to the pilot model, the benefits became evident only when the rice reached the stem elongation and heading stages.

Yen Cuong has a long tradition of rice cultivation, but like many rural areas, it is facing a rapidly aging agricultural workforce. Younger people have largely moved into factory jobs, leaving older residents to manage the fields, while finding labor for farm work has become increasingly difficult.

For the local cooperative, the most immediate value of the low-emission farming model is not the prospect of carbon credits but its potential for mechanization.

The project's seeding machine performs row sowing while simultaneously placing fertilizer beneath the soil surface. It completed Cac's entire field in about two hours. Farmers also no longer need to apply fertilizer multiple times as they did under conventional practices. In traditional fields, fertilizer is typically spread two or three times during the season, roughly twice as much as under the new model.

Convincing farmers from the ground up

Listening to farmers' experiences is one thing, but seeing firsthand how rice plants respond to the new cultivation method leaves little room for doubt about the effectiveness of low-emission farming.

In conventionally managed fields, rice plants tend to grow in uneven flushes, producing waves of tender leaves and soft stems. By contrast, machine-sown fields maintain a consistent green canopy throughout most of the growing season. As harvest approaches and the grains begin to fill, the crop gradually turns golden uniformly, rather than showing premature yellowing in the lower leaves.

A visit to Cac's field in early June, just before harvest, makes it easy to understand why local farmers have been so impressed. The field surface is dry and well-aerated, and in most cases, only a single application of crop protection products is needed to protect the flag leaf before heading. Additional treatments for common pests and diseases, such as sheath blight, rice blast, and planthoppers, are rarely required.

Behind these visible changes is a technical package that farmers in the area had rarely adopted before. According to Ngo Duc The, an IRRI technical officer in Vietnam, the Yen Cuong model combines row sowing with deep fertilizer placement and water management based on the alternate wetting and drying (AWD) principle.

Periodic drainage during the growing season encourages deeper root development, strengthens plant stems, reduces the risk of lodging, and limits the anaerobic conditions that generate methane emissions.

That is precisely why Nam Cuong Agricultural Cooperative chose one of its lowest-lying and most challenging fields for the pilot model. “If this method works on this plot, it can work on any of our other rice fields,” said Nguyen Van Du, Chairman of the Cooperative's Board of Directors.

This model is not only about reducing emissions but also serves as a test of a different way of organizing production. Instead of each household farming in its own way, individual plots are managed more uniformly, with synchronized sowing schedules, shared machinery, and standardized irrigation and fertilization practices.

This level of coordination has long been an aspiration for northern Vietnamese agriculture, but it has been difficult to achieve due to highly fragmented landholdings.