But a more-extensive evidence base founded on rigorous and consistent research methods is needed before the findings can be generalised to other situations, according to the study published in the current issue of the International Journal of Agricultural Sustainability.
'The findings show at the farm level it [organic farming] appears to be very positive — more than many people think,' says Steve Franzel, an agricultural economist at the World Agroforestry Centre, Kenya, co-author of the study.
The review feeds into what Franzel describes as a 'polarised' debate between conventional agriculture and organic and resource-saving agriculture (ORCA) methods.
In an era of rising energy costs and greenhouse gas emissions, some researchers are questioning whether conventional agriculture's reliance on chemical fertilisers is sustainable, and point to its negative effects: pesticide residues, soil erosion and reduced biodiversity.
ORCA offers a possible solution, aiming to use natural goods and services without compromising their future use. Its practices include integrated pest and nutrient management, conservation tillage, agroforestry, aquaculture, water harvesting and livestock integration.
The review looks at 31 case studies of farms in Africa and South America, the majority of which were smaller than seven hectares, which switched to ORCA methods.
It found yields increased in 19 of the 25 cases that reported on it, food security improved in seven of eight cases, and income went up in 19 of 23 cases.
While the majority of farmers moving from an organic-by-default system — those without access to industrial fertilisers and pesticides — benefit from the change, farmers choosing to give up modern chemicals and techniques had more mixed results.
Yields decreased in five out of six cases, and farmers saw greater profits in only three out of five cases.
Market linkages also play a major role, the review finds, with farms with good access to markets more likely to profit from conversion to ORCA.
Furthermore, the complex integrated principles involved in ORCA encourage farmers to become better managers of natural, physical and financial resources, as well as members of networks such as farming organisations, the report finds.
This, it adds, strengthens farmers' capacity to adapt to changing farming and market conditions — a flexibility that will become increasingly important as the effects of climate change worsen.
But, as the sample size is small and the literature on ORCA sparse, the results should not be used to generalise, the report warns.
According to Franzel, ideology is inhibiting objective research on organic farming.
'What is missing is hard data on performance: there are so few case studies analysing objectively what is going on,' he tells SciDev.Net.
Without a good body of evidence across a wide variety of situations, determining if ORCA is a viable strategy to address worldwide food security is impossible, he adds.
President of the African Organic Farming Foundation, Ged Buffee, says the review offers little new to understanding the impact of organic agriculture and only serves to underline the inadequacies of scientific efforts in the area.
The relatively small-scale study is symptomatic of a research community that is not connected and lacks the 'critical mass' to make a persuasive case for ORCA's effectiveness, he adds.
'They just don't have the bullet-proof science they need compared to other areas such as pro-fertiliser, or pro-GMO,' he tells SciDev.Net. 'The science available and the way it is presented is not competitive.'