The problem with N: greening rice farming systems in Laos

While essential for successful farming of high-volume crops such as rice, nitrogen-based fertilizers create multiple environmental harms. A collaborative research project is getting underway in Laos to find new methods of limiting nitrogen pollution without sacrificing crop yields.

Nitrogen (N) fertilizers in agriculture have dramatically increased crop yields since they were introduced in the 20^th century, but the resulting food security improvements come at the cost of serious unintended consequences in present-day environments.

About half of humanity is now supported by food grown through nitrogen fertilization, but its tendency to escape into the environment through volatilisation (loss of N from the soil as ammonia gas), leaching and runoff (as nitrate) and emissions (as nitrous oxide), causes it to cascade into the atmosphere, soils, forests, and waterways, with resulting multiple effects during its lifetime.

Additionally, analyses have revealed that emissions from all nitrogen sources account for 5 per cent of global greenhouse gases, and that more than 50 per cent of nitrogen release occurs after fertilizers are applied to crops, rather than during manufacturing.

In the atmosphere, nitrogen gives rise to smog and stratospheric ozone depletion. In terrestrial ecosystems it leads to soil acidification, forest dieback, and biodiversity loss. In marine and freshwater ecosystems, it contributes to groundwater pollution, ocean acidification and the stagnation of waterways from related algal blooms, a further factor in biodiversity loss.

In human society, the high levels of nitrogen in water and air have been directly and indirectly connected with human ailments, diseases and allergies which influence human health and welfare.

Finding solutions

In many parts of the world however, agriculture is a key component of the economy and populations are dependent on large yields of staple produce. Simply reducing the use of nitrogen fertilizers is therefore not a realisable solution to problems of nitrogen pollution.

A new research project (AU$3.08 million over five years funded by ACIAR) being led by University of Melbourne is focused on quantifying the impacts of nitrogen use and developing sustainable agricultural management strategies, using rice-based farming systems in Laos as the site of their investigations. They are working with primary producers, and official agricultural and research organisations to develop viable solutions to N management.

Project lead Dr Xia (Emma) Liang says the aspiration of Laos as a safe and “green” source of agricultural produce is part of the Lao Government’s strategy to expand exports in competitive markets.

“Our aim is to help improve the sustainability of Laotian rice farming and reduce environmental degradation caused by unnecessary and unsustainable use of N fertilisers.

“The project will develop knowledge and evidence to support the “green growth” ambitions of Laos, and improve the sustainability and resilience of farming systems, by improving N management in rice systems.

“In the longer term the project will lead to increases of farm-level and national incomes by improved resource use efficiency in the development of sustainably produced rice, build human capacity for research in environmentally sustainable rice production, and further Lao research in soil and environmental sciences.”

A capacity building approach

The University of Melbourne has extensive internationally recognised expertise in the management of N fertilisers, their use by crops, and the measurement and abatement of N losses to the atmosphere and ground and surface waters.

As part of the Soil Science research program led by Professor Deli Chen, it has established the ARC Research Hub for Smart Fertilisers and has successfully executed projects in Myanmar and China.

“This project aims to understand the N cycles in rice-based cropping systems in Laos and to assess the impacts of N fertiliser inputs on these processes,” Dr Liang explains.

“The project will also develop knowledge and practices for nutrient and systems management that will improve the productivity and sustainability of N use. It will form the base for the certification and green credentials of Lao rice, particularly for export markets. There are now good transport links between Laos and to China, and a growing middle class of consumers in China, offering the possibility of exports of high-quality Lao rice.”

The research team, which includes partners from the National University of Laos, the National Agricultural and Forestry Research Institute, and the Laos Department of Agricultural Land Management will initially work with farmers and extension officers through a co-design workshop to identify suitable locations for field work.

Additional focus groups with Laos smallholder farmers and farmer groups will be conducted, with a gender sensitive approach to ensure equitable representation of women.