Farming for the Future

Optimising soil health for a sustainable future in Kenyan broad acre cropping

Soil health is the linchpin of the entire agricultural sector. As Lloyd Noble once said, “No civilization has outlived the usefulness of its soils. When the soil is destroyed, the nation is gone” (Noble Research Institute, 2017).

By definition, sustainable and successful farming businesses depend upon the health of their soils. For many years, conventional farming practices have been degrading soils, creating issues such as erosion, and negatively affecting crop yields. Full-disturbance tillage of the soil and whole paddocks left bare to fallow, goes against the laws of nature. A recent shift in farming practices towards minimum tillage has seen many benefits – yield increases, reduced erosion, improved cover retention and better water infiltration to name a few. The zero-till revolution has been paving the way for the agricultural industry to further improve management practices, in a push towards biomimicry.

Farming in nature’s image is increasingly important to maintaining soil health in agricultural operations. Bio-diversity and ground cover retention are both key elements to obtaining optimal soil health. Multi-species cover cropping is an emerging innovation in soil health management proving to be extremely effective at incorporating both of these elements.

It is important to review the functions of multi-species cover crops as ground cover for weed suppression, erosion prevention, increasing soil organic matter levels, and improving water infiltration and moisture retention. There is also importance to investigate the effects of bio-diversity on soil function, with an analysis of the significant interactions provided, including microbial activity, the bacteria to fungi ratio, the carbon to nitrogen ratio, and carbon and nutrient cycling. Key findings indicate that the species-richness effect on soil health is predominantly related to root biomass production, which stimulates growth and diversity in microbial communities within the soil, balances the bacteria to fungi ratio, and generally creates synergy between all soil elements and processes to promote a healthy soil ecosystem.

The logistics, considerations and financial viability of incorporating multi-species cover crops into broad acre cropping rotations is also assessed. Research shows that despite initial financial deficits being possible in early cover-cropping seasons, the long-term soil health benefits prove to be profitable through increased yields and decreased costs on fertiliser and chemical inputs.

The sustainability of Kenyan broadacre dryland cash cropping operations, and the agricultural industry in general, hinges heavily on a soil health focus. Incorporating multi-species cover crops into cash crop rotations is the most effective way to improve soil health. Research has proved that multi-species covers can alleviate several environmental factors affecting soil health by:

  • reducing or preventing erosion.
  • increasing water infiltration.
  • inhibiting weed growth.
  • increasing SOM.

Further, emphasises should be made on the importance of bio-diversity within a cover crop, showing how a species-rich environment creates synergy between all soil components. Bio-diversity encourages:

  • effective carbon and nutrient cycling. 
  • a balance of C:N ratios. 
  • microbial growth and activity.
  • healthy bacteria to fungi ratios.

Though implementing diverse cover-crops can pose initial economic issues, the long-term environmental and economic benefits prove to outweigh the financial deficit associated with the transition phase.

Through careful management and mixselection, multi-species cover cropping can certainly be a viable option for Kenyan broadacre farmers seeking to improve soil health.

Recommendations

  • Employ zero-till farming practices wherever possible to lessen soil degradation.
  • Create a cover crop rotation schedule – based on soil test results and current cash crop rotations. It is imperative to have a plan, goal and strategy in place in order to be effective and efficient in any business venture.
  • Implement a business plan for the transition phase – expect that multi-species cover-cropping is a long-term investment, interim alternative income sources may be required to support the associated expenditure.
  • Conduct regular soil testing – knowing your soil and monitoring soil changes will ensure that appropriate actions can be taken e.g. which paddocks require attention, what soil health issues are arising, and which plant species are most suited for rectification.
  • Research plant varieties suitable for the region – understanding species for both their benefits and their required growing conditions is advisable. Consider contacting a local agronomist if necessary and remember, the more species the better!
  • Construct a “seed budget”. Seed will be the primary input cost. Pricing different varieties and options available and adhering to a budget will minimise any negative financial impacts in the initial season.
  • Decide which methods will be employed for planting and termination – performing an opportunity cost analysis may assist when considering alternatives.
  • Consider value-adding (such as livestock grazing). It is important to closely monitor and control any grazing to ensure the best results from plant growth benefits. 
  • Encourage neighbours to get involved – a local cooperative initiative could be an option for capital investment of plant and machinery, bulk seed purchases to obtain discounts and disseminating local knowledge, information and findings from trials.
  • Consider applying for government grants and subsidies associated with agricultural conservation practices.