Conservation agriculture is a farmland management method. It first appeared in the 1930s in the United States as a consequence of severe farmland erosion. Nowadays, it is practiced all over the world by all types of farmers. In 2015, it was estimated that conservation agriculture accounted for 100 million hectares of cultivated land worldwide.
Permanent soil cover, species diversification, and less tillage
The FAO (Food and Agriculture Organisation) defines conservation agriculture as " a farming system that can prevent losses of arable land while regenerating degraded lands". It has three main principles:
- Maintenance of a permanent soil cover.
- Minimum soil disturbance.
- Diversification of plant species.
The main objective of conservation agriculture is to preserve soil fertility and organic matter. This was defined in 2001 at the first World Congress on Conservation Agriculture, proposed by the FAO, in Madrid. However, the terms were first used in Mexico in 1997, at a congress sponsored by the FAO.
Conservation agriculture or minimum tillage: is it the same thing?
Conservation agriculture promotes a wide range of agronomic practices, often including direct drilling, minimum tillage, mulching, strip-till, etc. Even though they are often an integral part of conservation agriculture, the aim of these practices is simply to sow while using reduced tillage methods, in plant cover or residues. Soil regeneration and conservation would not be possible with these practices alone. It is necessary to take the whole cropping system into account. The key concept of conservation agriculture also encompasses aspects such as saving time and fuel, conserving natural resources such as earthworms, conserving moisture and nutrients in the soil, as well as soil structure, carbon fixing in the soil, etc.
Conservation agriculture is the concept, while tillage methods are a means to achieving it.
Seeding without tilling started in the United States
In the 1930s, after widely mechanising their farming practices in arid areas, American farmers observed severe erosion on their agricultural soils. It was due to the "Dust Bowl", or dust storms, where strong winds lifted fine silt particles from dry soils. This caused erosion on agricultural land in Oklahoma, Kansas, and Texas during droughts.
As a result, farmers reduced tillage by switching from ploughs to tine tools. They planted strips of fallow land on slopes (strip cropping), then developed direct seeding. Soil Conservation Tillage was created as agency of the US Department of Agriculture responsible for safeguarding natural resources and the environment. Today it is known as the Natural Resources Conservation Service.
Sources:
https://www.jswconline.org/content/jswc/70/5/103A.full.pdf
https://en.wikipedia.org/wiki/Dust_Bowl
https://www.fao.org/agriculture/crops/thematic-sitemap/theme/spi/agricultural-mechanization/agricultural-mechanization-technologies-and-equipment/conservation-agriculture/en/