Growing maize in the Mekong: Perceptions from an Australian agricultural researcher

A guest blog


Anika Molesworth


The Mekong River Basin is known to be one of the most dynamic, productive and diverse in the world.

Just the mere mention of its name conjures images of fishing nets being thrown by weathered hands, brightly clad women stooped low transplanting rice seedlings, and barefooted children with broad grins riding rickety bicycles.

The mighty Mekong River provides life and livelihoods to over 65 million people. Most of the inhabitants who call it home are rural poor with livelihoods directly dependent on the availability of its water for their production of food. Poverty is widespread in the basin, with the people in Cambodia and Laos being among the poorest in the world. Within this, the agricultural labour force is the poorest sector of the population, many earning less than US$1/day, and constituting up to 34% of the national population.

•  The brick maker

The brick maker

Cambodia’s landscape is a scenic timeline of an erratic history; from the vestiges of mysterious god-kings, to colonial imprints left by the imperialistic French. Sweepers for landmines still work alongside the road verge as one gazes from a bus window travelling from palm-lined beaches, past mosaic rice paddies, and ending in present-day city mayhem. It is a country rapidly transforming – a tug-o-war between traditional beliefs and saffron robed monks versus prestigious cars and the latest phones. The younger generation speak of the future and of politics in hushed tones, and groups meet to discuss how deforestation is leading to changes in the weather and what can be done about it. It is in this complex and intoxicating place I have chosen to undertaken part of my PhD.


•  Anika Molesworth preparing field for planting trial maize

Anika Molesworth preparing field for planting trial maize

Today I am bent low over my field trial site at the Cambodian Agricultural Research and Development Institute (CARDI). I am planting maize. With a small stick I make a shallow hole in which I drop three small golden seeds. There are half a dozen Cambodians working alongside of me, persevering with the slow work without complaint as the temperatures creep to mid-thirties with 80% humidity.

Over the past few weeks I have been working with the CARDI Soil and Water team, preparing organic amendments such as rice straw, livestock manure and biochar. Our trials will determine how these treatments influence soil moisture retention and nutrient availability. We have leveled the ground and made beds for planting – this field layout designed to aid the application, movement and drainage of irrigation water. The equipment used here is synonymous with hard-yakka – pushed by hand with small motors rotating tillage blades to loosen the soil surface, then dragging wooden planks to level the soil.

•     Harvesting rice with scythe at CARDI

•   Harvesting rice with scythe at CARDI

Once our crop has emerged we fly a drone over the field to assess its development. From aerial imagery we can determine plant health and vigour in response to the organic amendment treatments. The Cambodian agricultural research team are keen to learn how the latest technology can be used to improve nutrient and water management, and give new insight into field characteristics.


•  Family travels in rural village

• Family travels in rural village

My PhD research is situated within a larger project by the Australian Centre for International Agricultural Research (ACIAR). This project – “Improving water and nutrient management to enable double cropping in the rice growing lowlands of Lao PDR and Cambodia” – addresses the questions; What are the key constraints limiting crop productivity? And, how can these be overcome to enable successful dry-season cropping? The support and guidance offered to me by the research team and local partners has been invaluable. My teachers are not found in stuffy lecture rooms, but wear sun-faded shirts, mud covered boots and quite often we share no common language.

•  Phnom Penh market place

• Phnom Penh market place

Every day I learn more of the complexity of agro-ecological systems – how each individual component is connected to another. If the rain doesn’t fall, then the soil here in Cambodia dries like cement, exacerbating its inherently low fertility and constraining crop development. This results in little grain yield to sell at market and less plant biomass to feed to livestock. Less money in the farmer’s pocket means they search for off-farm employment – it is often the men who leave first, or young family members sent to the factories or who head across the border to Thailand or Vietnam. Those left behind work longer and harder. The interrelationship between the environment and with those who live so closely with the land is clear – a healthy landscape is essential to produce healthy food, adequate livelihoods and sustain vibrant communities.

Improving in-field crop management practices holds the potential to increase grain yield, household income, the regional economy and food security. Doing this by incorporating agricultural residues into the soil means that nutrients are recycled, soil organic matter increases, and the need for synthetic fertiliser inputs is potentially reduced. It is well recognised that the nutrient- and water-holding capacity of soils can be increased by the addition of organic amendments, thereby enhancing soil fertility and increasing crop productivity. Crop residue mulches, livestock manures and biochars have been found to suppress weeds, elevate levels of beneficial trace metals and exchangeable cations, increase crop nitrogen uptake, lower soil temperature, and enhance soil surface aggregate stability and permeability which improves crop root movement for access to nutrients and water.

On hardsetting Cambodian soils, applying organic amendments can ease its cement-like characteristics by lowering soil tensile strength, reducing runoff and subsequently improving microbial conditions.

Farmers in both Australia and the Mekong Basin are facing environmental, social and political pressures to improve nutrient and water productivity. Farmers also have the desire to improve profit margins by reducing input costs whilst increasing yields. My research in both Australia and Cambodia is investigating two farming systems at opposite ends of the spectrum in terms of social capacity and access to technology and new information, however sharing similar production challenges related to water and soil management. Both systems are striving for improved production with reduced environmental footprint. By understanding the building blocks of any farm – the soils, nutrients, water, and their dynamics influencing plant growth – we can transfer knowledge between farming systems, and ensure the best interactions with them.

As climate change impacts become more pronounced and the global population rises, there will be changes to the way food and fibre can be produced and managed. The impacts will be felt across the globe in varying degrees, and are expected to affect managerial and enterprise efficiencies. Projected impacts of climate change include changes to rainfall and temperature patterns, carbon dioxide levels and other climatic variables, that if realised, are likely to affect forage, food and fibre yield, animal welfare, and proper ecosystem functioning. The magnitude of these effects emphasises the importance of developing a greater understanding of our natural world, of how the climate is changing, and finding adaptation strategies farmers can effectively and efficiently embrace.

After a long, hot day in the field, there is no greater reward than sitting under a shady tree with my Khmer colleagues – reflecting on the good work achieved and discussing the obstacles still to be overcome. With a cool drink in hand, a local dish to sample, and an ever-effervescent group laughing loudly at lost translations, it is hard for me not to love what I do. Although there is no misconception to the challenges that face the agricultural industry, I feel hopeful about the future when amongst this group of young Cambodian agriculturalists.

More information here.