Date released
09 October 2023

An ACIAR-supported project to reduce erosion on steep upland slopes in the north-west Vietnam/north-east Laos border region has become a lesson in adaptability – for researchers as well as the smallholder farmers they have been working with.

This area is a remote region that struggles with endemic poverty and was long ago dedicated to poppy production.

Launched in 2017, the primary focus of the 6-year project was to improve maize-based farming systems on sloping lands along the Vietnam and Laos border, improving income stability and reducing soil degradation.

However, the start of the project coincided with low maize prices. Following a policy implemented as a result of the research outputs from an ACIAR-supported agroforestry project, provincial and district authorities in Vietnam provided incentives to encourage farmers to diversify from maize, which reduced maize plantings by 20%.

Farmers turned instead to tree crops: plums, longans and mangoes.

As ACIAR Research Program Manager, Soil and Land Management, Dr James Quilty explained, this change in crop type made the erosion challenge even more complicated.

‘The erosion issues in maize were actually exacerbated by the practice in Asia to keep the ground beneath fruit trees bare,’ said Dr Quilty. ‘None of the residue retention, minimum tillage-type practices that had been developed for maize were being carried forward during the transition into tree crops.’

Because it takes years for fruit trees to produce a marketable crop, the researchers found themselves not just with an erosion challenge, but also with the need to provide options to help farmers maintain cash flow during the transition.

This meant finding crop options to fill an income gap while also providing stable groundcover.

Project leader Dr Mike Bell from The University of Queensland said the project’s dynamics changed enormously. This was further compounded by farmers in Laos and Vietnam being at different stages of crop transition.

‘While many on the Vietnam side are transitioning out of maize, most on the Laos side are still looking to increase maize production. They are still learning about maize agronomy,’ explained Dr Bell.

Large group of people in field listening to a lady speaking about a crop
Smallholders in Vietnam learning that grasses planted between fruit trees can help to stabilise soil on slopes and provide fodder for livestock. Photo: The University of Queensland

Three-pronged approach

Dr Bell said the project’s priority was to find a way to stabilise farming systems on slopes with up to a 35% gradient. The team identified 3 options.

The first is an understory species Centrosema pascuorum, a low-growing, nitrogen-fixing perennial legume that is compatible with both maize and fruit trees, and can potentially provide forage for livestock to help diversify incomes.

The second option is a ‘relay crop’, such as rice bean, that is grown with maize and generates groundcover with ongoing agronomic and economic benefit. Rice bean has a small but growing market for its seeds.

The third option is to plant grass strips for erosion control, which can also be cut for fodder to feed cattle.

Local project scientist from the Northern Mountainous Agriculture and Forestry Science Institute (NOMAFSI) Mr Xuan Thao Hoang said experimental sites were set up to study these options and their economics, labour and fertiliser requirements.

‘The forage and groundcover options are easy for farmers to establish, have low input costs and quickly generate groundcover,’ said Mr Hoang.

‘The seeds of Centrosema and rice bean can be provided cheaply, while the high protein content in cover crop biomass provides good quality livestock feed and helps to build soil organic matter.

‘These species can fit with a diversity of cash crops and fruit trees, so should reduce erosion at the landscape level.’

Man standing in the middle of a bean crops
Rice beans provide an option to plant with both fruit tree crops and maize. Photo: The University of Queensland

Laos focus

In Laos, however, the project required a different focus. Here the project sought to lift farmers’ maize knowledge as well as stabilising the system with forage species.

Dr Bell said farmers started reporting, through consultation meetings, that they were pleased with the forage grasses and keen to diversify into cattle, but were reluctant to buy them because they did not know how to look after the animals.

As a result, the project team has initiated cross-border workshops on silage techniques to preserve forage for feeding over winter, while the greater need for animal husbandry training will form part of future project planning.

The project will conclude this year, and the results of the project to date are promising. However, Dr Bell and Dr Quilty hold concerns about both maize and the incoming fruit trees perpetuating a history of boom-bust cycles.

‘The demand for maize for animal feed has always been high, but the local maize price fluctuates with the world trade price,’ explained Dr Quilty.

‘A drop in maize prices occurred as the project began. This, combined with soil erosion concerns, helped to fast-track the fruit trees in Vietnam.

‘However, the rapid transition into tree crops has occurred with limited varietal options, with narrow harvesting windows for perishable products, resulting in lower-than-expected returns. The current upswing in maize prices highlights the benefits of maintaining income diversity through diverse enterprise mixes.’

ACIAR PROJECT: ‘Improving maize-based farming systems on sloping lands in Vietnam and Lao PDR’ (SMCN/2014/049)