Principles of Conservation Agriculture
Conservation agriculture is a set of tried and tested farming methods which when properly applied achieve highly productive, and sustainable yields, while first preventing, then reversing soil degradation and depletion of natural resources. It also provides the foundation of improved nutrition. It is rooted in the following principals and methods. When practised well, yields can match (sometimes exceed) yields from commercial agriculture.
Fertile soil comprises billions of microorganisms and bacteria (per square metre), and topsoil in particular comprises an entire ecosystem of its own, so vital to the fertility and sustainability of the land. The wholesale ploughing of land disturbs and exposes the billions of microorganisms and bacteria and causes considerable damage to the ecosystem. The ploughed land is then exposed to wind and water erosion. When heavy rains fall the run off of fertile soil into the river system cause great loss to the fertility of fields, followed by accelerated silting of rivers. The stopping of tillage will over time increase the water retention and nutrient holding capacity of the topsoil. Continued tillage leads to either lower soil fertility and yields, or the need to apply gradually increased amounts of fertilizer to maintain yield. This in turn has long term deleterious effects on the soil and gradual desertification sets in.
Planting Stations or Seed Basins
The alternative to tillage is to prepare the land by creating individual planting stations in the cropping rows at set intervals. There is a well-known and well-practiced method and tools for doing this. Once the holes are prepared each is filled with compost, and watered, in preparation of planting the designated seeds or seedlings. This is considered labour intensive by some as it can takes approximately 60 days of labour for each hectare. However our consortium partners Foundations for Farming state that this is no more labour intensive than ripping with ox driven ploughs after which the farmer needs to prepare holes anyway. The benefits of much higher yields and heathy crops far outweigh the effort and the costs.
Compost and Manure
The efficient use of live-stock manures combined with other green and brown material will create nutritious foliate for seed raising or direct infield sowing. It is designed to replace the need for fertilizer and replenish the fertility of the soils, and is thus an important element of conservation agriculture. The efficient and effective production of this compost in liquid form will be done in the bio-digester.
Weeds are toxic to agricultural production as they sap nutrients from the soil and compete with growing crops for soil nutrients, accelerate the spread of pests, and thus reduce yields dramatically. They must be eliminated, by hand and without resorting to herbicides. The weeds can be fed into the bio-digester or can be fed to livestock.
Overlaying the planted seeds/seedlings with a layer of vegetation (usually the previous crop residue) is vital to protecting the soils and seedlings from hard driving rain and minimises the run off of fertile soil into the river drainage system. Thereafter its role is effectively to retain the moisture within the soil and provide the endurance to withstand long periods of rain deficiency or even drought.
Rotations and Multicropping,
Crops (and livestock) that require differing nutrients can be selected and planted in an interspersed and symbiotic manner where the selection of crops is designed to provide both the household and the markets with balanced nutritional needs. The by-products of this interspersing is the incidence of pests is greatly reduced as large areas of monocropping which create pest magnets are avoided. The addition of fruit trees into the mix is an essential element of creating the food forest and is very effective in soil building. The symbiotic effect increases yield, diversity, and nutrition. Introduction of Soya beans, as well as daily production/ consumption of eggs are essential sources of daily protein.
Pests will always proliferate on any type of crop reducing yields dramatically. As the use of pesticides is considered deleterious to the environment and toxic to the food chain, a number of effective tried and tested method have been devised to deter pests, and minimise their impact.
Selective trees planted for particular purposes such as fodder yield for live-stock, providing fruits, or general reforestation, Â Â provide high nutrient return to the soil through leaf drop and seasonal pruning. Leguminous trees return nitrogen to the soil which increases long term fertility. These can and should be included in food forests as support species.
Results and increases in Yields
When Conservation Agriculture is diligently applied then maize yields go up from an average of a quarter tonne per hectare under conventional village agriculture, to five tonnes per hectare (and beyond) , a remarkable twentyfold increase in just two seasons. However the strong intention is to nevertheless diversify away from maize in order to improve household diet and nutrition, and to produce cash crops which fetch higher market prices.
Holistic observations on Deforestation and Environmental degradation
The START Program introduces wholesale use of biogas from livestock and rocket stoves for cooking. The resultant curtailment of cooking from firewood after the ban to chopping down of trees will have profound effects to the environment. An example is Zimbabwe which is currently losing 300,000 hectares of forest (or some 8,000,000 trees) annually used for domestic cooking and curing tobacco. The nexus between deforestation and drought has been irrefutably made. The decimation of forests and bushes for biomass results in the hydrological cycle being severely upset for reasons that are now well known, particularly the heavy reduction in transpiration into the atmosphere which aids rain cloud formation. So in simple terms, the use of biogas derived from livestock manure and the widespread deployment of rocket stoves to villagers will go a long way to preserve the environment and mitigate climate change. In fact, it is a recognized fact that the wholesale destruction of forests, which are very effective absorbers of carbon dioxide, in developing countries, is equivalent to spewing carbon dioxide into the atmosphere through industrial activity and power generation from fossil fuels in developed countries. As a minimum, the CO2 that is coming from the industrialized countries would be neutralized by the forests, so the preservation of these is an effective adaptation to climate change.