Smart water use: [3] Saving peanut season with efficient irrigation

Protecting groundwater

Peanuts are one of the key crops for Gia Lai farmers, especially in the eastern part of the province (formerly Binh Dinh), where the planted area has grown steadily in recent years. From just 8,300 hectares in 2010, the area expanded to 8,700 hectares by 2015, jumped to 9,600 hectares by 2017, and now exceeds 10,000 hectares, concentrated mainly in the former Phu Cat district (now the communes of Phu Cat, Xuan An, Ngo May, Cat Tien, Hoa Hoi, and Hoi Son) and the former Tay Son district (now Tay Son, Binh Khe, Binh Hiep, and other communes).

This growth has placed heavy pressure on irrigation water, since peanuts are considered the most water-hungry of all short-term industrial crops. In eastern Gia Lai, peanuts are grown mainly on nutrient-poor, drought-prone coastal sandy soil, and farmers rely largely on drilled wells to tap groundwater for irrigation. Due to limited awareness, most farmers have used flood irrigation, judging water volume and timing by instinct, which wastes large amounts of water and washes away soil nutrients.

In recent years, the South Central Coast region, including eastern Gia Lai, has seen below-average rainfall, with totals declining further under the effects of climate change. The rainy season lasts only three to four months, while the dry season stretches eight to nine months, leaving surface water in the region very limited. Since peanut cultivation is concentrated in the dry season, farmers must rely on groundwater for production, a reality that has pushed authorities and related agencies to research and quickly develop water-saving irrigation solutions for peanuts to protect groundwater resources.

Under the Project on Integrated Water, Soil, and Nutrient Management for Sustainable Agricultural Systems in the South Central Coast, run by the Duyen Hai Nam Trung Bo Agricultural Science and Technology Institute (ASISOV) in partnership with the Australian Centre for International Agricultural Research, researchers successfully developed a method for determining irrigation timing and volume for peanuts on sandy soil using evaporation pans (minipans), which was quickly put into practice.

A sprinkler head delivers water to plants as fine droplets spread evenly, saving water compared to traditional irrigation. A minipan tray, placed in the field, measures evaporation to help determine precisely when a crop needs water and how much, rather than relying on guesswork.

Nguyen Dinh Phi, 50, of Hoi Van village (Hoa Hoi commune, Gia Lai), who has grown peanuts for nearly 30 years, recalled: "I used to drill a well and drag a soft plastic hose across the field to water the peanuts. When the plants started to wilt, or when I grabbed a handful of topsoil and squeezed it and the soil crumbled apart in my palm, I knew it was dry and time to water. While irrigating, I'd press my toes into the soil, and once water had soaked in about 5 centimeters, I'd stop.

In the 2025-2026 winter-spring crop, Duong Van Minh of Binh Hiep commune (Gia Lai) planted nearly 40 sao of peanuts (500 square meters per sao), yielding 300 to 350 kilograms per sao. In the 2026 summer-autumn crop, he planted another 10 sao, not yet harvested, expected to yield 200 to 250 kilograms per sao. This is his sixth year using water-saving irrigation for peanuts.

Saving water, raising yields

Before planting, farmers using the minipan method are guided by local agencies to set up evaporation pans in the field. By tracking evaporation rates alongside the peanut plant's growth stages, farmers can determine exactly when to irrigate and how much water to apply, avoiding waterlogged soil.

According to Dr. Ho Huy Cuong, Director of ASISOV, farmers previously applied more water through flood irrigation than the soil could hold, wasting irrigation water and washing away soil nutrients, which affected groundwater quality and peanut yields.

"Combining sprinkler irrigation with the minipan method cuts water loss through the root zone by more than 69 to 77 percent, equivalent to more than 613 to 614 cubic meters of water per hectare per crop. On top of that, this combined method raises peanut yields by 20 to 29 percent," Cuong said.

He added that sprinkler irrigation alone raises the number of well-formed pods in peanuts grown on sandy soil by nearly 15 percent, while combining sprinklers with the minipan method raises that figure by more than 19 percent compared to flood irrigation, a key factor behind the higher yields. Peanut yields decline when irrigation regularly exceeds the soil's moisture needs; waterlogged soil suppresses pod formation, and soil moisture levels of 70 to 80 percent can cut yields by 60 percent.

According to Huynh Viet Hung, Director of the Gia Lai Agricultural Extension Center, applying the minipan water-saving system together with sprinkler irrigation amid drought conditions saves water while still meeting peanut plants' needs for growth, development, and yield formation. It also reduces farmers' labor and electricity costs while raising productivity, delivering both economic and social benefits.

Peanuts are one of the key crops for Gia Lai farmers, especially in the eastern part of the province (formerly Binh Dinh), where the planted area has grown steadily in recent years. From just 8,300 hectares in 2010, the area expanded to 8,700 hectares by 2015, jumped to 9,600 hectares by 2017, and now exceeds 10,000 hectares, concentrated mainly in the former Phu Cat district (now the communes of Phu Cat, Xuan An, Ngo May, Cat Tien, Hoa Hoi, and Hoi Son) and the former Tay Son district (now Tay Son, Binh Khe, Binh Hiep, and other communes).

This growth has placed heavy pressure on irrigation water, since peanuts are considered the most water-hungry of all short-term industrial crops. In eastern Gia Lai, peanuts are grown mainly on nutrient-poor, drought-prone coastal sandy soil, and farmers rely largely on drilled wells to tap groundwater for irrigation. Due to limited awareness, most farmers have used flood irrigation, judging water volume and timing by instinct, which wastes large amounts of water and washes away soil nutrients.

In recent years, the South Central Coast region, including eastern Gia Lai, has seen below-average rainfall, with totals declining further under the effects of climate change. The rainy season lasts only three to four months, while the dry season stretches eight to nine months, leaving surface water in the region very limited. Since peanut cultivation is concentrated in the dry season, farmers must rely on groundwater for production, a reality that has pushed authorities and related agencies to research and quickly develop water-saving irrigation solutions for peanuts to protect groundwater resources.

Under the Project on Integrated Water, Soil, and Nutrient Management for Sustainable Agricultural Systems in the South Central Coast, run by the Duyen Hai Nam Trung Bo Agricultural Science and Technology Institute (ASISOV) in partnership with the Australian Centre for International Agricultural Research, researchers successfully developed a method for determining irrigation timing and volume for peanuts on sandy soil using evaporation pans (minipans), which was quickly put into practice.

A sprinkler head delivers water to plants as fine droplets spread evenly, saving water compared to traditional irrigation. A minipan tray, placed in the field, measures evaporation to help determine precisely when a crop needs water and how much, rather than relying on guesswork.

In the 2025-2026 winter-spring crop, Duong Van Minh of Binh Hiep commune (Gia Lai) planted nearly 40 sao of peanuts (500 square meters per sao), yielding 300 to 350 kilograms per sao. In the 2026 summer-autumn crop, he planted another 10 sao, not yet harvested, expected to yield 200 to 250 kilograms per sao. This is his sixth year using water-saving irrigation for peanuts.