Bean crop using direct seeding under cover. Experiment in Ponta Grossa (Brazil). © INRA, INRA, Stéphane de Tourdonnet

Conservation agriculture: blazing a trail through research

Erosion: the root of the problem

Conservation agriculture was invented in areas blighted by water or wind erosion. Initially, it aimed to protect land against the ravages of erosion, primarily by means of soil coverage.

By Pascale Mollier, translated by Inge Laino
Updated on 02/07/2014
Published on 11/08/2013
Dust Bowl. Plumes of dust from soil erosion. Dallas, South Dakota, 1936. © United States Department of Agriculture
Dust Bowl. Plumes of dust from soil erosion. Dallas, South Dakota, 1936. © United States Department of Agriculture

In the US, the ground lifted up in plumes of dust…

A brief historical overview of the origins of conservation agriculture is in order to understand why farmers turn to these practices.  

The first of the three core components (1) of conservation agriculture to develop was soil coverage. This was seen as a means to combat the devastating effects of soil erosion, which struck the US particularly hard in the 1930s. Alternating spells of severe drought and rain, combined with gale force winds, created the devastating phenomenon known as the Dust Bowl, admirably described by John Steinbeck in The Grapes of Wrath (see insert).

This traumatic experience, combined with government incentives, prompted US farmers to quickly change the way they farmed. Direct seeding techniques beneath soil coverage began to appear in the 1950s: seeds were planted directly into the ground beneath soil coverage without tilling, and weeds were kept in check by herbicides. This gave rise to the need for more efficient seed drills. Applying these protection practices to 37% of arable land resulted in a dramatic reduction in erosion of US soil.

Other advantages of this agricultural system quickly became apparent, especially on large farms: savings on fuel and time, and streamlined labour practices. The development of herbicide-resistant GMO crops (soy, maize, cotton) in the 1990s favoured the adoption of direct seeding on large farms specialising in cash crops that are resistant to glyphosate, a highly efficient non-selective herbicide which eliminates weeds in one fell swoop before planting without the need for tillage.

Direct seeding without tillage is now the norm for maize and soy crops in the US, but also in Brazil, Argentina, Canada and Australia. These countries use the three-pronged strategy of direct seeding, simplified crop rotation with GMO crops, and non-selective herbicides - a far cry from the concept promoted by the FAO.

Soil erosion cause for concern in Europe too

In France, the risk of soil erosion is particularly high in the Southwest, the Rhône-Alpes region, the centre and western regions of Brittany, and the marshy plains of the North.. © INRA GIS Sol
In France, the risk of soil erosion is particularly high in the Southwest, the Rhône-Alpes region, the centre and western regions of Brittany, and the marshy plains of the North. © INRA GIS Sol

Although Europe has not experienced the drastic climatic conditions described in the US, soil erosion is taken very seriously there as well. The European Commission, in its soil thematic strategy to protect EU soils (COM (2006) 231), cites erosion as one of eight serious threats to soil. In France, implementation legislation (2) in force since 2005 calls for measures to fight against soil erosion and requires prefects to oversee the designation of at-risk zones. Some negative factors have come into play there: during the re-parcelling of land in the 1960s, hedges, embankments and ditches were eliminated to increase the surface area of plots. Springtime crops (sunflower, maize, beet), which leave fields exposed in winter and even less protected during spring storms, have gained ground.

In 2011, the Scientific Interest Group GIS Sol (3), created in 2001 and headed by INRA, published the first comprehensive assessment of soil quality in France. According to this report, the percentage of soil in mainland France presenting an average to high risk of erosion (primarily water erosion) is nearly 18%. The report goes on to say that there are many ways to manage this risk; in addition to soil coverage, farmers can implement a myriad of other techniques, known as “soft irrigation”, locally: hedges, thickets, planted beds and ditches can be created to curb runoff and prevent erosion. On inclines, farmers can also follow the natural contours of the land to avoid grooves running along slopes, or create rough surfaces on flat areas so that water collects in micro-pools, preventing runoff.

(1)    The core principles of conservation agriculture are threefold: soil coverage, minimum soil disturbance, diversified crop rotations. Definition by FAO, 2001 (cf section 2).

(2)    French decree n°2005-117 of the law of 30 July 2003 (n°2003-699).

(3)    Gis Sol, a scientific research group, brings together the French Agricultural and Environmental ministries, INRA,  the French Institute for the Environment (IFEN) and the French Environment and Energy Management Agency (ADEME). 

 

Brief overview of the state of soils in France (in French):

State of soils in France

Presentation of the 2011 report on state of soils in France (in French):

Report of the state of soils in France

The Dust Bowl as seen by Steinbeck

In the first chapter of The Grapes of Wrath (1939), John Steinbeck gives a chilling account of the Dust Bowl:

“In the water-cut gullies the earth dusted down in dry little streams (…) Now the wind grew strong and hard and it worked at the rain crust in the corn fields (…)The rain crust broke and the dust lifted up out of the fields (…)The finest dust did not settle back to earth now, but disappeared into the darkening sky. (…) During a night the wind raced faster over the land, dug cunningly among the rootlets of the corn, and the corn fought the wind with its weakened leaves until the roots were freed by the prying wind (…) Men and women huddled in their houses, and they tied handkerchiefs over their noses when they went out, and wore goggles to protect their eyes”.

The rest of the novel describes the plight of a family travelling to California in a desperate search for land. Nearly three million people from the great plains of Oklahoma and Arkansas were likewise forced to take to the road to find viable farmland.

"The Grapes of Wrath", Copyright 1939, renewed 1967 by John Steinbeck.

At a glance

- Europe: 12% of soils (115 million ha) are exposed to water erosion and 42 million ha to wind erosion. (Source: European Environment Agency)

- France: water erosion affects approximately 18% of soils in mainland France. More than 40% of mainland France is highly susceptible and 30% moderately susceptible to landslides and runoff. Practically all communes in Brittany were affected by mudslides in the past 30 years.