In Tra Giang village, Quang Ngai province, a farming method of planting pineapples at the foot of an acacia plantation is taking shape. The man behind it is Pham Van On. He treats the trees' shade not as a nuisance but as an asset that lowers irrigation costs, and expects a profit of 200 to 300 million dong per hectare per year. Moving from the conventional model that depletes the land with a single crop to a multi-layered, multi-income operation—this idea offers lessons even for Japanese agriculture, which struggles with abandoned farmland and hilly, semi-mountainous areas.
The ground beneath the trees was not "unusable land"
On began trial cultivation on 4 hectares in early 2025. Acacia is a fast-growing tree planted for timber and biomass, but its understory (the space beneath the trees) is usually left idle. There he planted about 55,000 pineapple plants per hectare. Dappled sunlight and shade curb the drying of the soil, saving irrigation water and electricity. By On's estimate, electricity costs alone fall by around 7 to 9 million dong a month.
He expects a yield of about 55 tonnes per hectare, with an initial investment of 220 million dong per hectare (55 million for seedlings, 40 million for irrigation, 16 million for fertilizer, and more). In addition to pineapples, he combines bananas and biomass bamboo, diversifying his income sources.
| Item | Details |
|---|---|
| Growing region | Tra Giang village, Quang Ngai province |
| Farming method | Multi-layered pineapple cultivation in the understory of an acacia forest |
| Scale | 4 ha trial (from 2025) / about 55,000 plants per ha |
| Expected yield and profit | About 55 tonnes per ha / 200 to 300 million dong per year |
| Cost reduction | Electricity savings of 7 to 9 million dong per month |
Agroforestry that turns "shade" into a resource
Agroforestry—growing trees and crops on the same land—shows its strength on poor soils and slopes. Tree roots curb topsoil runoff, fallen leaves enrich the soil, and shade retains moisture. In Vietnam, similar ingenuity in "using land in layers" is spreading in many places, and a mixed operation in Da Nang that combines pineapples with bamboo rats and pigeons on barren hills is a representative example. The common thinking is not to chase yield per unit but to fatten the "bundle of earnings" per unit of area.
Lessons for Japan's hilly, semi-mountainous areas and abandoned farmland
Japanese agriculture is weighed down by the abandonment of sloped farmland, wildlife damage, and high fuel and material costs. What On's model shows is the reality that profitability can be built through the right combination even without prime land. Turning the understory of plantations and idle land into a source of side income, lowering irrigation costs with shade, and spreading risk across multiple crops—each of these could be a prescription for the challenges facing Japan's hilly, semi-mountainous areas. In fact, a northern farmer who takes on net melons in a highland greenhouse and earns 2.5 billion dong a year shows that the worse the land's conditions, the more directly "room for ingenuity" translates into profit.
Of course, this cannot simply be imported wholesale. The climate, the varieties, and labor costs all differ. But the design philosophy of "not letting the space under the trees go idle" and "the number of income sources over yield per unit" can be translated almost directly to Japanese operations.
Points to consider when weighing adoption
- Whether the harvest cycles of the main crop (timber and biomass) and the secondary crop (fruit trees) clash. Avoid overlapping labor peaks.
- The amount of shade changes with tree species and age. Estimate in advance whether it matches the amount of sunlight the crop needs.
- Initial investment tends to be weighted toward irrigation. If shade can lighten the irrigation load, that portion can be recovered sooner.
- Managing undergrowth, pests, and diseases adds labor specific to the understory. Settle on labor-saving varieties and a work plan first.
- Diversify sales channels across multiple crops. Build a mix so that even if fruit prices collapse, timber and biomass can provide a floor.
Multi-layered farming as "adaptation" to climate change
This farming method is not only about revenue. In central Vietnam, where dry seasons are lengthening and downpours intensifying, open-field monoculture takes the full brunt of weather risk. A multi-layered structure that grows crops under trees softens sunlight and drought and acts as a buffer that curbs topsoil runoff. The strength of this case lies in making adaptation to climate change stand on its own as a profitable business rather than relying on subsidies. In Japan too, quality decline in open-field vegetables due to extreme heat, and topsoil runoff from heavy rain, are challenges that growing regions across the country face. The idea of using the space of existing plantations and orchards in layers, taking in shading and water retention as "free infrastructure," offers a clue for building growing regions that adapt to warming. On's ability to hold down electricity costs by 7 to 9 million dong a month is one concrete result.
Summary
Quang Ngai's attempt to grow pineapples in the understory of acacia overturns the premise of "unusable land." It turns shade into reduced irrigation costs and bundles income across multiple crops. As single-crop, yield-first farming reaches its limits, this multi-layered design offers much to learn for Japanese growing regions that hold poor land.
Sources
- Nong nghiep & Moi truong, "Dua luon tan rung, da dang nguon thu" (August 26, 2026)
https://nongnghiepmoitruong.vn/dua-luon-tan-rung-da-dang-nguon-thu-d827239.html
