Millions of hectares are lost every year due to soil erosion. Fertile soil is the basis for growing crops. Looking after the soil is paramount for sustainable food production. Conservation agriculture uses a basic set of principles to protect and conserve soil in best condition for productive cropping, now and in the future. Soil degradation affects many areas, particularly with sloping ground. Loss of soil quality often forces farmers to seek new ground. This leads to the clearing of forested areas and, consequently, habitat loss.
Conservation agriculture is based on the minimal cultivation necessary to successfully establish and grow crops. Zero tillage can be practiced on some soils; other soil types and some crops may require some cultivation to achieve a seedbed and remove soil compaction.
The three principles of Conservation Agriculture are:
Minimise soil disturbance
- Minimal soil disturbance achieved through techniques of Conservation Tillage improves soil structure and soil health, with more micro-organisms and soil fauna.
Carbon sequestration within the soil profile decreases greenhouse gases such as carbon dioxide by retaining the carbon in the soil profile.
Keep the soil covered
- A growing crop, green manure or dead mulch reduces wind and water erosion of soil.
- Soil cover retains moisture and improves water infiltration. There is a need to
- Manage cover crops and stubbles to avoid weed growth and setting seed and reduce competition with crop for water.
Diverse crop rotations to reduce reliance on inputs
Appropriate crop rotations can:
- reduce the need for inorganic fertiliser
- avoid the build up of pests and diseases thus minimising the need for pesticides
Minimising soil tillage reduces the amount of fuel energy and time required for crop sowing. Conservation Agriculture practices can also be adopted to manage the inter-row areas in perennial crops.
Example: Soil stability helps potato profits.
Colombia loses an estimated 20 tons of soil per hectare every year. In extreme cases this rises to 100 tons per hectare.
Through cultivation, Colombian potato growers traditionally move an estimated 2,000 tonnes of soil per hectare in order to achieve a yield of 15 tonnes of potatoes. Growers create a deep seedbed for planting seed tubers, and then continue to move the surface to control competitive weeds. The result leaves a fragile soil structure highly vulnerable to wind and water erosion. Colombia loses and estimated 20 tons of soil per hectare every year. In extreme cases this rises to 100 tons per hectare.
Falling yields and uneconomic production for growers has put the future of 17,000 families at risk in the Cundinamarcia Region who are dependent on potatoes for their livelihoods. Urgent action was needed to prevent further soil loss and improve the fortunes of growers. An ongoing project was developed jointly between Corporacion Autonoma Regional, the Environment Authority, and private enterprise. The project introduced a training programme of new non-tillage techniques, innovative direct sowing and the use of cover crops to protect soil structure.
The programme planned over 200 workshops reaching more than 4,000 small farmers across the region. Introducing growers to proven practical techniques that reduce costs, labour demands and deliver equal or improved yields creates an immediate physical benefit.
But longer term, these activities on around 8,000 hectares of potato cropping could decrease soil loss by 480,000 tonnes over the next three years. This also increases important water retention in the drainage basin by 360 million litres.