For thousands of years, Pacific farmers adapted crops to drought and changing weather; now Samoa and Tonga are combining that ancestral knowledge with modern science to rebuild soil, manage weeds and make farms more climate-resilient

For thousands of years, farmers across the Pacific have learned how to work with their environment. Now, as droughts, irregular rainfall and declining soil health make farming harder, that traditional knowledge is being combined with modern agricultural research.

In Samoa and Tonga, farmers are testing practical ways to manage weeds, improve soil and reduce dependence on costly chemical inputs. The work is bringing ancestral farming knowledge and Sustainable Agriculture Intensification principles together in the fields where they matter most.

How are Pacific farmers adapting to climate change?

A three-year research project led by the University of Melbourne, together with the University of the South Pacific, MORDI-Tonga Trust and Lincoln University in New Zealand, has been working with farmers, researchers and government officials in Samoa and Tonga. The project is led by Associate Professor Dorin Gupta, Dr Viliamu Iese and Dr Sineka Munidasa of the University of Melbourne, Dr Leslie Ubaub of the University of the South Pacific, and Associate Professor Soane Patolo Jr. of MORDI-Tonga Trust.

The approach is based on Sustainable Agriculture Intensification, or SAI, which aims to increase productivity, use resources more efficiently and reduce agriculture's environmental impact.

Farmers are not simply being asked to adopt practices designed elsewhere. They are involved in testing them through farmer-managed trial sites, while controlled research sites collect detailed biophysical data using the same treatments.

That combination gives researchers a way to compare what works in controlled conditions with what happens on an actual farm.

The need is increasingly pressing. Farmers in both countries are dealing with prolonged drought, unpredictable rainfall and rising agricultural input costs, particularly for herbicides. The trials are therefore looking at methods that can improve weed management, plant water availability and soil health while reducing chemical use.

What is changing on farms in Samoa?

Taro is central to Samoan food and cultural identity and is also an important export crop. But conventional chemical weed control can be expensive and can affect soil health and the surrounding environment.

Farmers are now testing alternatives including mulching, sheep grazing and hand weeding.

Leguminous alley cropping is also being trialled. Fast-growing trees such as Gliricidia, Sesbania and Erythrina are planted to provide biological mulch that can help suppress weeds and enrich the soil.

Mr Sala Sagato, President of the Samoa Farmers Association, is hosting one of the trial sites and has supported mulching.

“Weed killers cost a lot, and sometimes they don’t even work."

He added, “With mulching and alley cropping, we keep the soil moist and healthy, and we don’t need to rely on chemicals anymore.”

At another site, Mr Tauiliili Polito Vili has been testing sheep grazing as a way to manage weeds in taro.

“Fencing keeps the sheep in and the pigs out, which used to be a big problem for my taro,” he says.

“Letting sheep graze means less hand weeding, less need for herbicide and an extra income from the sheep as well.”

The trials show how a farming practice can address several problems at once, from weeds and labour to chemical costs and additional farm income.

What are farmers learning in Tonga?

Farmers in Tonga are also testing mulching and intercropping within traditional production systems.

Yams and taro are being grown together on the same plots, while other trials combine bananas and root crops.

Mr Tevita Kata Finefeuiaki, a local Kauvai farmer, described the value of learning through the trials.

“One of the main advantages of this project and collaborative work is the knowledge gained, especially seeing how yams produced abundant planting material for future crops.”

Mulching was a new practice on his farm, and the mulched plots produced higher yields than herbicide-treated plots. During the first cycle of yam cultivation, mulched plots also produced noticeably larger tubers, providing evidence of improved soil nutrient availability and crop performance.

Mr Vitolio Ongolea, who hosts another experimental site, has focused on intercropping bananas and root crops.

“It allows us to earn from both taro and banana, blending traditional knowledge with modern methods for greater resilience,” he says.



Importantly, yields from farmer-led sites in Samoa and Tonga have been comparable with those recorded at the controlled research sites. That suggests the practices are not only promising under research conditions but can also work in farms managed by local farmers.

The findings point to possible economic benefits as well. Organic mulching and sheep grazing can reduce dependence on chemical herbicides and labour, while sheep grazing can provide another source of farm income.

However, wider adoption will require further work. The project's mid-project review found that scaled-up testing and capital support, including support for livestock and secure fencing, are important for expanding the practices.

The project is also focused on building the capacity of researchers, farmers and young graduates. Those efforts are intended to support future extension work, co-design and policy decisions.

The broader goal is straightforward: make farming more resilient without leaving local knowledge behind.

In Samoa and Tonga, farmers are showing how traditional knowledge and modern science can work side by side. Rather than treating the two approaches as opposites, the project is using both to address drought, weed pressure, soil health and the changing conditions farmers face.

FAQs

How are Pacific farmers adapting to climate change?
They are testing mulching, intercropping, sheep grazing and other practices alongside traditional knowledge.

Which countries are involved?
The project is working with farmers in Samoa and Tonga.