Smallholder farms may make up 40% of global agriculture area

November 29, 2018

A new global field size data set collected as part of a crowdsourcing citizen science project by International Institute for Applied Systems Analysis (IIASA) researchers has shown that the proportion of smallholder farms may be much larger than previously thought, contributing much more to global food production. The results are published in Global Change Biology.

Smallholder farms are classified as being made up of fields less than around 2 ha in size. Evidence is increasing that such farms make a substantial contribution to world food production, but until now, the data on the number and distribution of smallholder farms has been lacking. Previous estimates have suggested that smallholder farms make up between 12% and 24% of the global total. However, the new research led by IIASA researcher Myroslava Lesiv shows that smallholder farms in fact make up 40% of the global agricultural area.

The study is the first to estimate field sizes at the global, continental, and national level, and covers the entire world, rather than just 55 countries as in earlier studies. The crowdsourcing campaign began in June 2017 using the Geo-Wiki app. It lasted for four weeks and was focused on collecting field size data. The Geo-Wiki app takes high resolution satellite imagery from Google Maps and Microsoft Bing and allows users to visually assess those images, for example for land cover or human impact. In this case, users were asked to assess images of agricultural land.

A field was defined as any enclosed agricultural area, including arable and pasture land, which could be separated by roads, permanent paths, or vegetation, and users could choose one of five field size categories—very large (greater than 100 ha), large (16–100 ha), medium (2.56–16 ha), small (0.64–2.56 ha), and very small (less than 0.64 ha). The user was asked to define which field sizes were present, and if there was more than one field size, which was the dominant size, using either an estimation grid, or with an area measuring tool. Each image was checked by three users and they were trained in using the app with a video and slides before they began.

A previous Geo-Wiki study in 2011 collected 13,000 unique samples, but this latest survey collected 130,000 samples. The researchers used the 390,000 classifications (from three “visits” to each site) to create a map and calculate agricultural area proportions at the global, continental, and national levels.

“We have filled the gaps in available information on global field size distribution by covering countries where no statistical surveys were carried out and no mapping was done with the help of remote sensing. Therefore, the field size data set we developed provides full and accurate information on the distribution of field sizes to support policy decision making related to food security issues,” said Lesiv.