This is a dummy description. Key Features: Written by an international group of authors representing a cross-section of scientists, thought leaders, and policy-makers Includes chapters on the potential effects of climate change on forest soil carbon, microbial function, and the role of soils and biogeochemistry in the climate and earth system Explores historical development of land use ethics and stewardship. About the Author Thomas J. John M. Nelson 1. Norman 2. Thompson 3. Flader 4. Kees Stigter 5. Mackay 9. Sivakumar Organic material in soil includes microorganisms, animals and plant residues in different stages of decomposition that are intimately related to the minerals present in the soil.
The stock of organic material depends on the intensity of processes involving plant residual input to soil and decomposition. A number of biological, chemical and physical factors also protect organic material from the attack of microorganisms Feller et al. Most farmers do not know why soils have different colours and say that they are naturally the way they are, but some farmers say that dark soils are caused by the presence of organic material and nutrients. If pressed for details why the land is good or bad, farmers also associate the presence of organic material and earthworms.
Therefore, good land has lots of worms present in dark soil, particularly a type identified as big limp worms.
The dimensions of soil security - ScienceDirect
Farmers also note that certain little bugs are often found in humid soil and that the bugs fertilise the soil. Worms are absent in poor soils. The latter are located in hot land where there are numerous ant nests, particularly in red clay soils. From this we see that the presence of mesofauna is considered to be a sign of good land and fertile soil in local knowledge, and the presence of mesofauna dependents on soil types which retain moisture. Farmers use their experience and power of observation using all of their senses to characterise soil quality.
Good land has black humid soil rich in organic material, including plant residue, such as leaves, straw, roots and decomposing pods and fauna present such as the insects and worms cited above. From this we see that farmers have a clear notion of nutrient recycling used by agronomists to explain soil quality. The transformation of organic material and fresh biomass by worms, insects and micro fauna directly contributes to nutrient recycling from organic material in this biomass as well as from the liberation of nutrients from the soil minerals.
Through this transformation process organic material is fragmented into components which are grouped by particle size. Larger particles can serve as a short term labile nutrient reserve or can be stocked as a medium term reserve if organic material is protected inside soil aggregates. Earthworms transform organic material, help plants cycle nutrients, improve soil aggregation and porosity so that crops have access to adequate moisture. Higher biodiversity in soil acts as a biological control which maintains soil health and nutrient cycling.
University of Malta
Low biodiversity of organisms in soil indicates the presence of constraints for plant development and health. Tree species and remaining natural vegetation cover also contribute to soil biodiversity as well as to the development of deep root systems and soil porosity, adequate water infiltration and availability. Biomass production and organic material input are related to adequate soil fertility and biodiversity. The type and diversity of vegetation present and the aspect of plants may indicate soil and health constraints, such as low soil fertility, soil acidity and water availability restrictions.
Unprotected soil surface without the protection of vegetation and mulch is subject to high sunstroke, soil erosion, compaction and dryness. Farmers also consider the type of wild vegetation present before opening a field to be a good indicator of soil quality. Land with robust forest cover is appropriate for cropping and land with grass and thorn scrubs is not, reflecting the role of vegetation as an indicator of soil fertility.
They measure carbon accumulation and the presence of nitrogen and other plant nutrient cycling and then scale up to soil aggregation, moisture availability and organism activity soil life. Farmers see these processes in terms of the final visible organic materials present in the soil.
Straw, leaves and wild seed pods rot and fertilise the soil. These are absent in poor soils, which are not benefited by this process while soil science explains this in terms of depletion of chemical, physical and biological processes that support plant productivity. Soil structure and texture are important for water dynamics in the soil and ca n r echarge local and regional water resources.
The interaction of mineral particles and organic material promotes the formation and stabilization of soil aggregates as well as promotes the action of plant roots and soil organisms. The size and type of aggregates present are the building blocks of the soil porosity network that influences the expression of soil processes, such as water infiltration, storage and availability, gas exchange and aeration, root development, organism activity, among others.
For scientists high clay content indicates excessive moisture, root damage and anaerobic processes while farmers identify the same problems in heavy clay and red clay with soap stone present in bottomlands. Soil with too much sand is also considered to be poor by farmers because it does not retain moisture. They point out local examples, such as sandy patches on slopes, white grit on hill tops and river sand in bottomlands. For agricultural scientists texture is related to soil mineralogy which indicates soil acidity and nutrient availability capacity and necessary soil management corrective action, while local farmers just leave problematic areas in undemanding native pasture for animals to graze on.
Farmers associate colour to variation in soil texture according to the presence of more clay in better soil and more sand in poor soil but without referring to a matrix of mineral composition.
The role of soils and biogeochemistry in the climate and earth system
In addition to colour, farmers observe that when soils are shallow and slate is present on the upper most part of slopes only grass grows there. These areas are not cropped and are only used to pasture animals that transport bananas down slopes. Good soils are humid and dry soils are poor. Researchers perceive this relationship in terms of adequate moisture that permits good plant development and crop production while inadequate moisture damages plant nutrition and biochemical processes. This can be seen in farmer attitudes toward many bottom lands which they consider to be too moist and damp to be suitable for crops.
As most farmers have little bottomland they do not give the matter much thought. This utilitarian attitude is even stronger in how farmers rank indicators of soil quality. Indicators are important if they embrace a significant part of the landscape, such as the slope terrain type which is their principal area of production. This view expresses an integrated evaluation of soil quality with the interplay of criteria such as colour, humidity, organic material and texture. For farmers soil quality has a strong relation with the notion of natural stocks of soil as discussed above. Researchers also explain crop production using integrated explanations such as high productivity reflecting the optimal conditions of chemical, physical and biological properties of soil for the development of specific crops.
Low productivity is explained in terms of inadequate soil conditions for crop growth in terms of moisture, nutrients available, acidity, soil aeration, root depth, soil health, etc. All of these deal with soil stocks in the provision of environmental services for human use or for agriculture. Soil ecological functions identified are regulating hydrological and biogeochemical cycles that maintain ideal conditions of soil structure. Soil fertility is considered to be the natural base of agriculture which provides stability and support for plant growth.
Physical barriers to decomposition cause the occlusion of organic compounds by minerals present in clay and by the exclusion from specific soil pores of organisms that provoke decomposition. In addition, labile organic compositions, such as polysaccharides and proteins, which are subject to rapid decomposition, are protected when found inside soil aggregates which permits greater perenization of these substances in the soil.
Consequently, the high production of biomass in forests permits greater entry of organic material in the soil than in cultivated soil. A vegetation cover with a robust and healthy appearance therefore is an indicator of adequate soil fertility. When land is cultivated levels of organic material generally diminish because revolving and de-structuring the soil exposes organic materials present to the attack of microorganisms.
However, agronomists can recommend productive strategies using soil conservation techniques associated with permanent land cover and the management of organic material in no tillage systems and organic agriculture, all of which increase organic material in soil. This view attributes to soil a role in acting as a source and storage place or sink for carbon stocks, the amount of which depend on the relative rates of incorporation and decomposition of carbon by the organisms present in the soil. Soil with different layers of arboreal vegetation and crops also protects surface soil from the impact of rain water and erosion.
The depth and diversity of root systems also improves soil aggregation and porosity, which benefits water infiltration and accumulation in the soil. The difference between them is that while researchers are interested in evaluating soil potential for production, they are also interested in understanding the internal functioning of the indicators and how processes are caused.
Farmers are mainly interested in identifying land which is good for production as well as in farming methods that maintain the land productive. In this sense, farmers are practical empiricists while conventional agricultural scientists are rationalists who dissect landscapes, identify constituent parts and measure physical and chemical properties situated at multiple scales of analysis.
In the case presented here, the substitution of maize and manioc by bananas and regenerated forest on most of the slopes improved the environment quality. Farmers are aware of this process which is reflected on the way they perceive soil properties and functions. In the bottom lands human intervention caused the opposite. In the past soil was de-structured by drainage works and today by the use of conventional agricultural practices in commercial vegetable cropping based on the use of machinery and agrochemicals. The socio-economic viability of the agro-ecosystem is undermined by the economic need to obtain a dignified livelihood because the farmers do not know how to produce vegetables with an alternative farming system.
Consequently, developing good agriculture practice that is environmentally suitable would be crucial to cropping in an ecologically and socially sustainable way. The role of extension agents would be crucial for intermediating a technical transition toward organic and agroforestry methods that could benefit farmers cropping the slopes as well as the bottom lands.
In sum, farmers of the study area were shown to possess relevant human capital and capacities in the form of local knowledge but they also need to combine this with new knowledge from soil scientists and extension agents. Dialogue between scientific parameters and local parameters is possible and has the potential of uniting the natural capital of soils identified by agricultural scientists with the human capital of farmers who work them into integrated socio-ecological systems.
Dialogue promotes agronomic sustainability which is a crucial dimension in an agro-ecosystems approach because it mediates local and scientific knowledge at the interface of environmental quality and socio-economic viability. However, the lexicon used by soil scientists can often be in-intelligible to farmers and agricultural scientists confess that they have difficulty translating their findings to the farmers.
Scientific language is hermetic and many soil scientists remain cloistered in their research focussed solely on indicators of soil properties. Conclusions are inferred from laboratory analyses of samples collected in the field, often times by another person, so that a researcher may have no direct contact with the actual farmer whose agricultural practices are part of contemporary anthropogenic processes that have a strong influence on the results analysed in the laboratory. The results also may not even reach the farmer whose field was studied but when it does the message treats soil quality functions part of environmental quality out of touch with local human capital and capacities, so annulling social viability.
What is missing is appropriate farm extension, fundamental for agronomic sustainability interfacing the two dimensions. They recognise and are aware that agricultural scientists possess important knowledge beyond what they know, particularly concerning the chemical composition of their land and they would like to have their soil analysed and receive technical assistance on how to correct problems.
However, the farmers are relatively poor and do not have the means to pay for private soil analysis and diagnosis and depend on government farm extension. This important shift in the focus of rural extension was meant to promote farmer participation and to diminish dependency on top-down decision making. This strategy is fine for receiving community benefits like electricity and piped water, but technical assistance cannot be reduced to group organization and community development.
Some technical and farm management issues can be solved collectively but not all of them. Land varies from farm to farm and even internally from plot to plot.
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As a social group farmers can have common interests but this does not mean that land resources and soil quality are identical and in many cases there is a need for farm-level assistance. This is unfortunate because degradation of the Brazilian Atlantic Forest will only be reverted when socially viable rural systems also provide relevant environmental services, and for this to happen farmer and scientific knowledge must be harnessed together in order to build good agricultural practices that truly integrate socio-economic and ecological functions.