OPINION
Grassroots
August 2017
Vol. 17, No.3
13
adopted by farmers which can help to restore and improve the quality of the soil. The role of agricultural scientists should be to assist farmers in doing this. Our research should find practical solutions to real, on-farm, challenges. In the farming community, there is consensus on the importance of soil health, but there is still uncertainty about the right methods of improving soil health. As a result, the implementation of management practices that improve soil health has been slow.
In my view, there are several methods which pasture farmers can adopt in order to start the journey towards healthier soil. The key lies in building soil carbon. Below are some management practices which will immediately contribute to the improvement of soil health on pasture farms. I believe we should be encouraging farmers to adopt these practices, and then carrying out further research to better understand the dynamics and influences of these practices.
Soil management practices to improve soil health
- Diversify pastures
Multiple species cropping is slowly being adopted in the pasteurization dairy industry as one of the methods of improving soil carbon. Multiple species are beneficial because of the diverse roots below ground. These roots are able to reach different soil depths which helps distribute soil carbon in the lower profiles. The diverse roots also encourage an accumulation of diverse microorganisms which are important in nutrient mineralisation processes (Chung et al. 2007, Eisenhauer et al. 2013). Apart from an improved soil microbial activity and diversity, a mixture of pasture species also provides opportunities to improve other soil properties such as soil structure, water storage and movement processes.
- Keep the soil covered
Soil erosion is one of the quickest ways to lose top soil, especially through wind erosion. It is estimated that over a billion tons of top soil can be lost within one year due to wind erosion and the top soil is where most soil carbon is found (UNCCD, 2014). In the words of Gabe Brown, a renowned conservation agriculture farmer, “if you can see your soil, then you are losing it”. Bare soil is a detriment to soil health, therefore maintaining soil cover all the time is a must. Ensuring the soil is covered also helps to regulate the soil temperature and protects the soil from losing water through evaporation. This further helps reduce the need for frequent irrigation because water is stored for longer periods.
- Disturb the soil as little as possible
Soil disturbance, such as ploughing, is one of the quickest ways to lose carbons from the soil. Tilled soil can induce temporal heightened mineralisation rates which lead to loss of carbon via soil respiration. Undisturbed soil builds biological, physical and chemical resilience.
- Manage pasture grazing rotations
The carbon that is stored in the soil is harvested by plants from the sun through the process of photosynthesis, converting carbon dioxide into carbohydrates which are then stored in the soil through plant roots. It is important that pastures are measured and allocated properly so as to avoid over or under allocating pasture which could lead to either wasting pasture or overgrazing (Findlay, 2016). Ryegrass pasture is best grazed at 3-3.5 leaf stage, whereas kikuyu pastures are advised to be grazed at 4-4.5 leaf stage (Clark, 2007; Botha, 2015; Findlay, 2016).
- Mob grazing is the way to go
This grazing method ensures proper distribution of livestock manure and resting periods for pasture allowing it to recuperate. It also allows for a longer rotation of pasture, which in turn allows for grass recovery and more root mass to form which contributes to soil carbon stocks (Findlay, 2016). Mob grazing further improves effective pasture utilisation and the trampling of manure and some pasture back into the soil also adds to the carbon reserves.
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