Farmers Review Africa Nov-Dec 2018 Farmers Review November-December 2018-6 | Page 38

FEATURE Conservation Agriculture By Givemore Ndlezane, Agricultural crop and livestock extension officer ([email protected]) C onservation Agriculture is a farming system that promotes maintenance of a permanent soil cover, minimum soil disturbance (i.e. no tillage), and diversification of plant species. It enhances biodiversity and natural biological processes above and below the ground surface, which contribute to increased water and nutrient use efficiency and to improved and sustained crop production. The principles of conservation agriculture principles could be applied to all agricultural lands and practiced in all agro-ecological zones. It entails optimum usage of agrochemicals, organic and inorganic fertilisers in ways and quantities that do not interfere with, or disrupt biological processes, in addition minimizing or totally eliminating mechanical disturbance to the soil. Conservation agriculture (CA) facilitates good agronomy, such as timely operations, and improves overall agricultural land using both irrigation and rain-fed production. It counters the concept of soil tillage/ ploughing prior to planting, additionally marking it as being responsible for destruction of soil organic matter, a crucial element for the stabilization of soil structure. It is worthy to note that a soil left without tilling for long allows crops 36 |November - December 2018 residues/mulch to remain on the soil surface, as such protecting the soil from rainfall, heat from the sun and wind. It also stabilizes temperature and moisture which becomes conducive for beneficial small and large organisms that help in decomposition of the mulch for stabilizing the soil structure. Soils under conservation agriculture have significantly higher water infiltration capacities, with high reduction in surface runoff that causes soil erosion. PRINCIPLES OF CONSERVATION AGRICULTURE Minimum mechanical soil disturbance • Direct seeding or planting Direct seeding involves growing crops without mechanical seedbed preparation and with minimal soil disturbance since the harvest of the previous crop. The term direct seeding is understood in CA systems as synonymous with no-till farming, zero tillage, no-tillage, direct drilling, etc. Planting refers to the precise placing of large seeds (maize and beans for example); whereas seeding usually refers to a continuous flow of seed as in the case of small cereals (wheat and barley for example). The equipment penetrates the soil cover, opens a seeding slot and places the seed into that slot. The size of the seed slot and the associated movement of soil are to be kept at the absolute minimum possible. Ideally the seed slot is completely covered by mulch again after seeding and no loose soil should be visible on the surface.