The Global Soil Partnership (GSP) endorsed a set of voluntary guidelines for sustainable soil management at its plenary conference at FAO this week, marking a step towards coordinated action to assure that the earth under our feet - a keystone of global food security - remains fertile.

The GSP has been set up as a coalition tasked with promoting efforts to improve the parlous state of the world's soils, a third of which are defined as degraded.

For prescriptions for improving soil health to succeed, much diagnostic work must be done, according to the GSP.

For example, in Malawi, an extensive new FAO-government survey of cropland detected topsoil losses on the order of 29 tonnes a year, leading to a 10 percent decline in farm output.

But despite troubling "hot spots" of increasing erosion there also "bright spots" where soil depletion is not only much lower than elsewhere in the country - less than 10 tonnes a year in the Rift Valley, for example - but has steadily declined as a result of active soil management, the study found.

"The bright spots where topsoil erosion is both low and declining show that sustainable soil management interventions such as mulching, minimal tillage, cover plants, contour ridges, and pitting do in fact work," said Ronald Vargas, a soils and land management officer at FAO. "This kind of mapping exercise can help monitor which measures work best."

The study also showed that increasing rates of soil loss in the past two decades often occurred where natural forests had been put to the plow. That appeared to be particularly problematic in areas northern regions whose soil tend to have high concentrations of clay, making them less suitable for agricultural activities.

The dynamics on display in Malawi play out on a planetary scale: Globally, 75 billion tonnes of soil are lost from arable land each year and an estimated $400 billion in agricultural production is lost.

"We need to replicate this kind of work in many countries in order to enable stakeholders to know how to be stewards of sustainable soil management," said Vargas.

"It illustrates what must to be done on a vast scale across the planet to promote sustainable management of the world's soils, which are used to grow 95 percent of the world's food and provide valuable services such as carbon storage," he added.

Voluntary Guidelines being crafted

The Voluntary Guidelines for Sustainable Soil Management, on track to be presented to the FAO Council for adoption in December, are meant to serve as a reference of sustainable soil management principles for an audience ranging from government officials and policy makers to farmers and pastoralists as well as development practitioners.

Minimizing soil erosion by water and wind is a top priority for the guidelines. Doing so entails careful management of land-use changes, such as deforestation or conversion of grassland ecosystems to cropland, as well as promoting land surface protection activities such as mulching and no-till farming or interventions such as terracing, windbreaks and riparian buffers.

The goals are to minimize unwanted loss of soil nutrients as well as reduce downstream runoff of agricultural inputs. The guidelines also emphasize the importance of enhancing soil organic matter, which not only makes cropland more fertile but has a critical role in efforts to mitigate and adapt to climate change through carbon sequestration.

The recommendations propose special actions to protect soils that provide significant ecosystem services -storing carbon, hosting biological diversity, boosting crop yields - from urban sprawl. Year-round crop cover is advised, not only to keep dirt from blowing away but also to reduce the pace of moisture evaporation, which can lead to salinization and ultimately eliminate the viability of growing any crops at all.

During it's plenary the GSP also endorsed the establishment of the Glinka World Soil Prize, named after the pioneering Russian scientist Konstantin D. Glinka.