Cover crops for sustainable farming
Cover crops in sustainable farming.
Why are cover crops important? The use of cover crops has an array of benefits for sustainability and agricultural production. They improve soil health and structure by regulating moisture and providing a high level of organic material to the soil. Additionally, the presence of cover crops reduces the need for synthetic fertilisers, herbicides and insecticides and increases biodiversity.
Cover crops also prevent erosion and soil loss due to their root system. They offer habitats for beneficial microorganisms, which break down plant and animal matter to form humus, and are beneficial for the capture and storing of water. While improving soil fertility they also suppress weeds.
They can aid carbon sequestration and help re-establish natural nutrient cycles, allowing the planting of more sustainable, healthy crops in the future. The cover crops model of farming also promotes biodiversity, and ensures varied food sources for wildlife and insects.
This all adds up to an increased crop yield.
With such a variety of benefits, it's no wonder that cover crops are becoming an important part of sustainable farming in South Africa.
Examples of Cover Crops in South Africa
Cover crops are plants grown in rotation with major crops like maize, potatoes, wheat and barley. One of the key benefits is that they act as a form of “green manure” – their roots, shoots and other plant debris get incorporated into the soil, feeding the fertility of the ground for the next rotation of crops.
There are multiple varieties grown in South Africa.
- Legumes, such as clovers, peas and beans, are extremely common options due to the high levels of nitrogen they can introduce into the soil.
- Grasses, including rye, oats and sorghum, are also widely used as they improve water retention and prevent erosion.
Buckwheat, vetch and sunflowers also play a role as they support and attract beneficial insects - this can be vital in reducing the number of pests and diseases a farm might experience.
Cover crops are an essential and powerful tool on sustainable South African farms, helping with soil security, environmental protection and economic profitability.
Timing of Planting
Timing of planting is pivotal for any successful implementation of sustainable farming practices. Different crops require different timing, however, it is important to ensure that these are planted in accordance with the seasonal changes and other factors such as rainfall and soil fertility.
Planting needs to be carefully considered and should align with the ideal temperature and adequate moisture in the soil. Pre-plant burndown herbicides, if used, should be applied two weeks before sowing for optimum efficacy in controlling weeds while adhering to label recommended pre-plant intervals.
For examples of ADAMA herbicides, please visit our Crop Protection pages and use the herbicide filter.
According to GrainSA’s Conservation Agriculture Manual, “cover crops [generally] consist of mixtures of grasses and or grains and legumes to balance the need for inclusion of both carbon (C) and nitrogen (N) to build the soil. Both C and N are needed to form soil organic matter…
“The release of N depends on cover crop species, growth stage, management, and climate. For example: An early spring kill of grasses promotes a lower C:N ratio and a faster release of N. Legumes tend to have a lower C:N ratio but if either grasses or legumes are allowed to reach full maturity, N release is delayed. Slower N release occurs more in dry weather than in wet years due to decreased microbial activity needed to decompose residues and release N.
“N uptake of cover crops varies from 57 to 296 kg N/ha. If 50% of N is recycled, cover crops may supply 25 to 132 kg N/ha to the next crop. Late planted cover crops may not have as much vegetative growth but may impact soil and water quality through reduced soil erosion.”
(Source: Conservation Agriculture Manual)
(Source: Conservation Agriculture Manual)
Management
Despite their benefits, regular care and attention is required to ensure maximum effectiveness.
The first step to successful cover crop management is to start with high-quality seed. Farmers should select seeds that are adapted to the regional climate and soil conditions and are best suited to their crop rotation plans. Planting the seeds in well-prepared beds and keeping the soil well-watered can also go a long way in helping the crop reach its full potential.
Fertiliser use should also be tailored to the needs of the crop. Too much fertiliser can be harmful, so farmers should use test kits to check the nutrient content of their soil and then treat accordingly. Additionally, consistent weed control is necessary to allow the crop to grow unhindered.
Finally, it is important to take into account the intended purpose. Many cover crops are used as soil enrichers, and farmers should correctly time their harvest or leave a portion in the field to provide additional benefits such as increased nitrogen or weed suppression. Following these steps can help to ensure that the greatest possible benefits in sustainable farming.
According to Regenz, legume cover crops that are beneficial for nitrogen-fixing include:
- Red clover
- Crimson clover
- Vetch
- Peas
- Beans
Non-legume cover crops that are beneficial for scavenging nutrients include:
- Cereals: Rye, wheat, barley, oats, triticale
- Forage grasses such as annual ryegrass
- Broadleaf species: Buckwheat, mustards, brassicas
In conclusion, cover crops provide a valuable contribution to sustainable farming practices in South Africa, and can be a cost-effective solution for farmers. They provide a variety of benefits that help protect the environment and increase crop yield. But choosing the ideal cover crop or mix requires careful consideration.
For more in depth information on cover crops in South Africa, please read:
- Utilisation of cover crops: implications for conservation agriculture systems in a mediterranean climate region of South Africa
- The financial implications of cover crops in summer cereal systems in the Eastern Free State area over the long term
- Benefits of winter cover crops in a mixed farming system
- Cover crops and what are they used for (KZN)