Agri Kultuur August / Augustus 2018 | Page 9

seed and seedling emergence. CA impact Conventional farming practices around the world has unfortunately been the culprit when it comes to poor soil and water preservation. This is due to improper soil use, practising monoculture and the reliance on tillage tools. These inadequate technologies, not adapted to site specific needs, leaves the soil bare and pulverized, exposing the soil to be carried away by heavy rains. This ultimately results in a gradual loss of soil and soil fertility, leaving the land unproductive. Eroded, unproductive and abandoned land, as well as the signs of desertification across the world, is a silent testimony. The question now is, how do we turn this around? Can it be reversed? The answer is yes and lies in the implementation of the three CA principles: low soil disturbance, residue retention and diversity through crop rotation. When the soil is covered by living plants and/ or plant residue, the plant biomass absorbs the impact energy of raindrops and the drops brake up into smaller droplets, which flow gently to the soil surface and here it infiltrates into porous and undisturbed soil. In this way the sealing-off of soil pores is prevented, erosion is minimised and even eliminated. Once disturbance of the soil is limited, soil structure can be rebuilt through the build- up of soil organic matter and carbon. The aim is to rebuild the soil structure, which we eliminated through tillage, in such a way that the porous aspect is returned. Think of it as building an apartment complex underneath your feet. Just like an apartment consist of rooms of varying sizes, soil has larger and smaller pores or spaces where water can AgriKultuur |AgriCulture be stored. This stored water, along with the cover provided by the biomass, prolongs the effective use of water by crops, especially in drier climates, drive the soil biology and some much more positive outcomes driving productivity. The effectiveness of infiltration and water holding capacity will increase over time as organic matter increases in the soil. Research conducted in Brazil showed that the percentage of soil covered with plant residues is the most important factor that influences water infiltration into the soil. They showed that soil with a 100% cover accepted nearly all the water from a rain simulator delivering 60 mm/hour, but in the case of bare soil, between 75 and 80% of the water was lost as runoff. Other researchers also obtained similar results (Derpch, 2004). Conclusion Soil erosion is not only caused by water, but wind also plays a huge role. Just think about the dust storms seen in the Free State. Conservation Agriculture, using no-till or zero till, offers the most effective and affordable way to control soil erosion and ultimately achieve sustainable agriculture. References Derpsch, R., 2004. Understanding the process of Soil Erosion and Water Infiltration. Special Publication. No-till on the Plains Inc. Lal, R., 1982. Management of clay soils for erosion control. Tropical Agric., 59 (2). 133 – 138. Meyer, L.L. & Mannering, J.V., 1967. Tillage and land modification for water erosion control. Amer. Soc. Agric. Eng. Tillage for Greater Crop Production Conference. Proc. Dec. 11-12, 1967, 58- 62. 9