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Agricultural and Environmental
DMCs provide many environmental and agricultural benefits,some of which may be noted in the field and others that have an indirect impact on farmers. Some of these benefits are not yet clearly understood, especially those only perceptible when DMCs are implemented on a very large scale (an entire agrarian region, for instance) (boosting water table levels, etc.).
SOILS BETTER PROTECTED FROM EROSION Featured
Erosion (water, wind) is triggered by a combination of factors: slopes, climatic hazards, poor landuse, bare soils, etc. It is limited by the presence of live or dead plant cover and the absence of tillage. Plant cover decreases the mechanical impact of raindrops on the soil and improves water infiltration, thus reducing runoff and soil loss. Decomposition of this cover by live soilborne organisms produces humus, which is essential for stabilizing the soil structure (less compacted). Moreover, the presence of plant cover limits drying of the surface layer (better moisture and lower temperatures).Effects on the plot scale: reduced runoff, better soil stability and fertility, better water management and efficiencyEffects on the landscape unit scale: improved soil protection and fertility regeneration, better protection of downstream structures (dams, roads, etc.)
ENHANCED SOIL STRUCTURE AND BIOLOGICAL ACTIVITY Featured
Plant residue accumulation and no tillage leads to an increase in organic matter on the soil surface (0-10 cm), and then in deeper layers. The root systems of crops associated with cover plants, along with microorganisms and soil fauna, fulfill the soil tillage function and enhance the soil nutrient balance (‘biological tillage’). Soil fauna (worms, arthropods, etc.) break down the organic matter, which is then degraded by microorganisms and transported to deeper and more stable soil horizons. In the most efficient DMCs, organic matter levels can thus be as high as in natural ecosystems, even when starting from highly degraded conditions, within a timeframe that is as short as that which led to their degradation!Chemical products (pesticides and chemical fertilizers) should be rationally used to avoid altering the essential biological activity in the soil. Soils under DMCs are always protected from pollutants by the permanent litter cover. During biological digestion of this litter, intercepted pollut ...
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REDUCTION IN DISEASE AND PEST PRESSURE Featured
DMCs are based on integrated pest and disease control methods, i.e. crop rotations represent a key element of this new strategy to break the cycle of diseases and weeds. DMCs also improve crop nutrition regulation by avoiding losses via leaching to the water table and reducing excess soluble nitrogen and sugars in plant tissues, which are the main foods of pathogenic fungi and pests. The presence of permanent plant cover also helps control weeds (effect of shade and allelopathy). Pesticide treatments are also reduced.Effects on the plot scale: reduced fertilizer and pesticide dosages (input savings)Effects on the landscape unit scale: reduced impact on soil pollution and the water table, enhanced food quality and security
BETTER WATER MANAGEMENT Featured
In dry climates, the soil is more humid under DMC (elimination of surface runoff, limited evaporation, increased water retention capacity). The roots of cover plants also capture deep moisture via their roots, thus improving the water balance. In wet climates, the greater infiltration and drainage in the soil enables quicker backflow of water to fields. This better water infiltration reduces flooding risks by storing high quantities of water in the soil and slowly releasing it to supply rivers. With DMCs, the soil is supportive, even under waterlogged conditions, so machinery has permanent access to fields without risk of compaction or accentuated deformation of the soil surface (reduction in production costs). Better infiltration helps to replenish the water table. The effects of DMC adoption on water management on a larger scale, such as landscape units and catchment basins, are still not fully clarified. The geographical range of crops can be changed through modification and improvement of the water ba ...
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CONTRIBUTION TO BIODIVERSITY CONSERVATION Featured
Untilled fields with permanent plant cover provide an excellent habitat for living soilborne organisms, while protecting the soil from various phenomena (erosion, etc.) and increasing the available quantity of organic matter—the basis of the food chain. This plant cover also provides physical protection for other species, which in turn attract insects, birds and other animals (however, this depends on the extent of crop protection treatments and their toxicity). Contrary to monocropping systems, genetic biodiversity is preserved and enhanced by diversifying crops, implementing rotations and using cover plants.DMCs promote the settling of shifting agriculture (cause of 27% deforestation in tropical areas every year), thus indirectly preserving tropical forests by reducing deforestation. Moreover, DMCs are the only inexpensive currently available techniques that enable natural control of plant pests, such as Striga (which attacks cereal crops on degraded soils in Africa, Madagascar and Asia), that destroy ...
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CARBON SEQUESTRATION AND REDUCTION IN THE GREENHOUSE EF... Featured
Storing carbon in the soil is an agricultural (enhanced physicochemical and biological soil properties) and environmental (reduction in atmospheric CO2) challenge. The increased atmospheric greenhouse gas (GHG) concentration contributes to global warming. It is now clearly established that agriculture is responsible for substantial GHG emissions and that this could be reduced by implementing cropping techniques like DMC. Agriculture can have a positive or negative impact on the greenhouse effect, i.e. as a GHG emitter in conventional agriculture and as a carbon sink. In DMC, the balance is markedly in favour of carbon sequestration. The use of direct seeding reduces fuel consumption (less mechanized work), thus reducing CO2 emissions from tractors. DMCs also promote carbon fixation in organic matter accumulated in the soil—this carbon is literally trapped. Hence, by implementing DMCs, 0.5 to over 3 t/ha/year of carbon can be fixed over a period of at least 10 years. Large-scale implementation of DMCs ca ...
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