NWU BSc Agriculture CSPP221 Conservation Agriculture Lecture Notes PDF

Faculty of Natural and Agricultural Sciences School of Geo and Spatial Sciences Programme: BSc Agriculture CSPP221 – 12 credits Module Name: Introduction into Agronomy LECTURE 10 – Conservation Agriculture (CA) Study Unit 9 Conservation Agriculture (CA)  Introduction Definition ❑It is a con...

Faculty of Natural and Agricultural Sciences School of Geo and Spatial Sciences Programme: BSc Agriculture CSPP221 – 12 credits Module Name: Introduction into Agronomy LECTURE 10 – Conservation Agriculture (CA) Study Unit 9 Conservation Agriculture (CA)  Introduction Definition ❑It is a concept for resource-saving agricultural crop production that strives to achieve acceptable profits together with high and sustained production while conserving the environment ❑CA is based on enhancing natural biological process above and below the ground ❑Interventions such as mechanical soil tillage are reduced to an absolute minimum ❑The use of external inputs such as agrochemicals and nutrients of minerals are applied at optimum levels and in a way and quantity that does not disrupt the biological process. Advantages of conservation agriculture ❑It provides a truly sustainable production system that enhances natural resources and increases the variety of soil biota. ❑Farmers applying this practice could be rewarded with carbon credits. ❑Soils under CA have very high water infiltration capacities, reducing surface runoff. ❑Conservation agriculture is not low-output and allows yields comparable to modern intensive agriculture. ❑Conservation farming is mostly attractive because it allows a reduction of the production cost, reducing time and labour. Three principles of conservation agriculture CA is characterized by three principles: ❑Continuous minimum mechanical soil disturbance. ❑Permanent organic soil cover. ❑Diversified crop rotation in the case of annual crops. Three principles of conservation agriculture 1. No mechanical soil disturbance ❑This include no till or zero tillage ❑Seeding is directly through the mulches ❑Crop residues are retained and fertilizer is normally broadcasted on the soil surface. The effects of no till on farming systems are: ❑Minimum destruction of soil structure through pulverization and compaction. ❑Slower mineralization of soil organic matter through less exposure to climatic elements. ❑No disturbance of worms or other soil inhabitants. ❑No breaking of roots. ❑Better infiltration and circulation of air and water through soil profile. ❑Improved nutrient retention and availability of plant growth. ❑Increased carbon sequestration reducing CO2 emission from soils Three principles of conservation agriculture 1. No mechanical soil disturbance ❑No till reduces CO2 flux by about 20%, compared to conventional tillage 4.00 (b) CO2 fluxes (µmolm-2 s-1) CT 3.00 No-till 2.00 1.00 0.00 04/Mar/15 04/Apr/15 04/May/15 04/Jun/15 04/Jul/15 04/Aug/15 04/Sep/15 04/Oct/15 Three principles of conservation agriculture 2. Permanent soil cover ❑Done through retention of crop residues and cover cropping ❑Permanent soil cover protects the soil against the effect of exposure to rain and sun. The effects of soil cover on farming system are: ❑Improves infiltration and retention of soil moisture resulting in less crop water stress. ❑Increased humus formation. ❑Reduction of impact of rain drops on soil surface that result in crusting. ❑Consequential reduction of run off and erosion. ❑Better conditions for the development of roots and seedling growth. ❑Reduces weeds Three principles of conservation agriculture 2. Permanent soil cover R+ R- R- R+ Three principles of conservation agriculture 3. Crop rotation ❑The rotation of crops is necessary for the development of roots at different soil depths and capable of exploring different soil layers for nutrients. ❑Crops rotation has phytosanitary function, since it prevents carry over of pests and diseases. Effects of crop rotation on farming system are: ❑Higher diversity in plant production, which contribute to human and livestock nutrition. ❑Reduction and reduced risk of pest and weed infestation. ❑Better distribution of water and nutrients through the soil profile. ❑Increases nitrogen fixation through certain plant-soil biota symbionts. ❑Increases humus formation. Economic, agronomic and environmental benefits of CA 1. Economic benefits of CA ❑Time saving and reduction in labour requirement, ❑Reduction of costs e.g. fuel, machinery costs. ❑Higher efficiency in the sense of more output from a lower input. ❑Farmers applying this practice could be rewarded with carbon credits (http://www.treasury.gov.za/public%20comments/CarbonOffsets/2014042901%20- %20Carbon%20Offsets%20Paper.pdf) 2. Agronomic benefits ❑Organic matter increases. ❑Soil water conservation-reducing evaporation and increasing water infiltration ❑Improvement of soil structure. Economic, agronomic and environmental benefits of CA 3. Environmental benefits ❑Reduction in soil erosion. ❑Improvement of air and water quality. ❑Carbon sequestration.  Limitation of CA ❑Initial lack of knowledge of CA is a major limitation ❑Information about locally adapted cover crops that produce high level of biomass is often lacking ❑Poor implementation that result in high weed infestation, higher labor requirement, low yield and low profit is also limitation to adopt CA ❑ Lack of markets for specialised equipment ❑Residue destruction by livestock ❑ High managerial requirement What is required to start CA ❑Change in crop management system. ❑A tool that can manage the crop residues or cover crops. ❑Consider the soil biological and self sustainable productive system. ❑Adopt a new way of thinking as far as weed management and crop production are concerned. ❑Improve the capacity to tackle new challenges and find a solution. Guidelines for farmers to start practices of CA ❑Concentrate on achievable objectives ❑Start on a small portion of the farm to gain experience ❑Start in an area where there is enough cover and use a tool that can do the job easily. ❑Before starting CA bring soil up to a condition where life can develop. ❑Plan a good crop rotation. ❑Take a time to learn to identify and use the herbicides in a correct way. ❑Learn to identify and manage different problems. END