Globally, a wealth of local knowledge of soil biota exists

By Natasha Pauli, Lecturer in Geography in the UWA School of Agriculture and Environment, University of Western Australia

This is the third in a series of global perspectives on the concept of soil health. Read Part 1 and Part 2.

Categorisation of farmers’ knowledge of soil biota, based on the ‘knowledge-practice-belief’ complex in ethnoecology. From Pauli et al. 2016

The 2016 publication of the Global Soil Biodiversity Atlas presented a compelling depiction of soil biology to a wide audience. The need for the Atlas is reflected in the fact that soil biodiversity is undervalued by society, and rarely considered within policy frameworks to protect either soil quality or biodiversity. However, this relative lack of interest in soil biological health does not hold true across all segments of society. If you were to go and ask someone who makes their living from the land what they know about soil health and soil biology, you may get a far more informed answer (as discussed last month by Hannah Birgé).

My interest in what farmers know about soil biota was sparked in the hills of Central America, while investigating the spatial distribution of soil fauna in a smallholder landscape in remote Honduras. Ultimately, I wanted to know whether the soils beneath particular trees that were left within cropping fields attracted soil animals, with flow-on effects for soil quality. There were dozens of species of trees to examine and the topography and soils were highly variable - it was difficult to know where to begin! We decided to start by asking the farmers what they knew - and what they had to say was fascinating, reaching far beyond simple descriptions of which parts of their farm supported the greatest density of earthworms (read about it here).

As I soon learned, while these types of questions may be asked in the field, they are often not deemed worthy of in-depth investigation or publication. The volume of literature on farmers’ knowledge of soil organisms pales in comparison with that on scientists’ knowledge of the topic. Even the field of ethnopedology (which is concerned with local ecological knowledge of soils) has tended to emphasise the identification, mapping, management and use of different local soil types within agroecological systems, with little enquiry on the living components of soils. Historically, social scientists and soil biologists have worked together infrequently. So, does this lack of information on how farmers view and use soil biota reflect an actual dearth of knowledge, or simply an understudied field of enquiry?

To address this question, I worked with colleagues Professor Lynette Abbott at the University of Western Australia, Dr Simoneta Negrete-Yankelevich at INECOL Mexico, and Dr Pilar Andrés at CREAF, Spain to undertake a systematic, worldwide review of peer-reviewed and high quality grey literature on local knowledge of soil fauna in agriculture. Our review, published last year in the open access journal Ecology and Society, turned up 60 studies that highlighted some aspect of farmers’ understanding of soil fauna, drawn primarily from Africa, Latin America and Asia, with a handful from the USA, Europe and Australia. Our findings show that there is a potentially rich body of knowledge on soil biota, but one that is rarely elicited.

Illustration of farmers’ perceptions of the effect of soil invertebrates on components of a smallholder farming system in Honduras. Redrawn from Pauli et al 2012 for the Global Soil Biodiversity Atlas.

There was a very broad range of ways in which farmers understand and use soil fauna. The most common example was the use of particular taxa (usually earthworms and beetle larvae) as an indicator of soil quality, cited in around two-thirds of studies reviewed. There were also many instances of local observations of species’ ecology, behaviour and life history, as well as exquisitely detailed taxonomies of invertebrate life. Some authors documented management practices such as deliberately using the action of soil fauna to improve soils for cultivation, by encouraging the activities of ants and termites to improve soil structure and increase organic matter content on marginal land. Soil invertebrates can also have cultural and spiritual significance, which influences how people perceive these organisms.

Map of the location of 60 reviewed studies on farmer knowledge of soil biota. From Pauli et al. 2016

Farmers are rarely deliberately or deeply consulted by researchers on their knowledge of soil biota, soil ecology, or soil ecological processes. We encourage soil biologists to work together with social scientists to explore this important topic. In particular, researchers should explore not just observations of soil fauna, buthow these organisms are considered in agricultural activities, and the belief systems and cultural values that influence agricultural systems and perceptions of soil life. Our review found very few studies on local knowledge of fungi, rhizobia, or soil microbes, with most existing research limited to visible organisms - this is another area ripe for further exploration.

There are very important reasons why soil biologists should do more to understand how farmers use and value soil life. A deeper understanding of this topic can lead to more effective development of collaborative extension programs, policies and management initiatives directed at maintaining healthy, living soils. We give some examples in the paper of how this has occurred in smallholder and broadacre systems from Mexico, Nicaragua and Australia. Giving farmers the tools to measure elements of soil biological activity in their own fields can empower them to undertake their own experiments and analysis, and ultimately support adaptive and sustainable management of agricultural landscapes.