The principles of good soil management are universally applicable. The practices which embody those principles vary quite widely according to specific soil, climate and other environmental conditions. A soil management system that depends on large inputs of inorganic fertilizers may be sustainable when considered in isolation, but the sustainability of mineral and energy resources from which the fertilizers are made must also be taken into account. In addition, the environmental effects of the movement of chemicals out of the soil and into the groundwater, and of by-products released into the atmosphere, should also be considered. Particular attention should be paid to the effects of these chemicals on the plant and animal populations, and the biodiversity of those populations.
The biggest threats to the soil resources are the loss of soil organic matter, the lack of a thriving and diverse population of organisms, and the compaction of soil. As the agriculture has become more mechanized and many rotations have become shorter and more intense, the quality of many soils has declined over the last 4 to 5 decades. The soil is more vulnerable to degradation. Soils that are degraded are usually the result of soil erosion and the decline of organic matter levels. The lost soil carries nutrients with it so the topsoil becomes less fertile. Tillage of the soil begins to incorporate less fertile soil from below. As organic matter levels decline, the soil becomes less resistant to the erosion. The soil also becomes less resistant to the soil compaction.
The soil protection strategy from state macroscopic and long term perspectives is of great significance for sustainable use and protection of soil resources, improvement of soil environmental quality, and ensuring agricultural production and food safety. With the development of industrialization, urbanization, intensive agriculture and global change, the environmental status of soils has become more and more severe. Therefore, it is imperative to enhance strategic researches on the protection of soil resources and the environment. Aimed at major problems and demands in soil resources, soil fertility, soil ecology and soil environment, the strategic research on soil protection from macroscopic and long-term perspectives will have substantial realistic and far reaching historic value in sustainable use, protection of soil resources, improvement of soil quality, securing agricultural production, food safety, ecological safety, safety of human residence as well as in the establishment of a well off and eco-friendly society.
So let us be concerned about the soil, this basis of all life. Let us take care of our soil. Let us preserve our cultivated land. For our quality of life is directly dependent upon the quality and quantity of the soil. Let’s keep our feet on the ground. Statuses of Soil Resources:
The world soil resources and their statuses are; crop land 12.6%, grass land 13.0%, tree cover areas 27.7%, shrubs covered area 9.5%, herbaceous vegetation, aquatic or regularly flooded 1.3%, mangroves 0.1%, sparse vegetation 7.7%, bare soil 15.2%, snow and glaciers 9.7%, artificial surfaces 0.6%, and water bodies 2.6% . The effects of the increase in human population on the world, especially in terms of the decline in food security, indicates that soil has ecological limits and that these limits vary along with the variations within different ecosystems and the cultural relationships with the soil resources. There is an increasing disproportion in the production of food due to the difference in the rate of decline of soils and their functions and the rate of their regeneration. This situation requires an indepth reconsideration of human attitudes to natural resources in general, but to soil in particular.
The Function of Soil and Its Resources
Healthy soil performs numerous functions and ensures that planet earth remains habitable for humans. Soil is first and foremost the ground on which we walk. It gives the landscape its round and soft forms as well as a stable foundation for buildings, streets and tracks. The most evident link between the soil and us is the production of food, animal feed and wood. Soil is known for storing nutrients and providing them to plants, regulating climate, filtering water, assisting in the control of floods and conserving the natural and cultural history. The living organisms throughout the soil are the engines that render the soils diverse, keep irreplaceable functions running and are beneficial for the ecosystem.
No harvest without fertile soil
Fertile and intact soil is the central resource for sustainable agricultural production. To preserve soil’s natural fertility in the long term, agricultural use that suits the location and fosters the rich soil life is needed. Heavy machinery and overuse of mineral fertilizers, liquid manure and plant protection products damage the soil organisms and the loose structure of the soil habitat. This means that the soil must be used with consideration and sustainably. In crop land, too, healthy soil is the basic requirement for a sustainable harvest of crop. Furthermore, healthy soil ensures that it will perform all of its essential functions, such as flood protection and carbon storage.
Efficient recycling in the soil
Plants require a large number of nutrients for survival, including nitrogen, phosphorus, potassium, magnesium and calcium as well as trace elements such as zinc, molybdenum and boron. These are found as in dissolved form in the water within soil pores, where plants ultimately can absorb them. Thankfully an on-going supply is available. The most significant source of the nutrients is from the decomposition and transformation of dead plant material such as leaves and stems that fall to the ground and are decomposed by soil organisms. Soil organisms therefore provide plants with a continuous supply of nutrients, free of charge. Without soil organisms soil would not be able to make the nutrients made from decomposed plant material
available to living plants as food.
Soil protection is climate protection
Soil and climate are closely related. However, soil rarely plays a role in public awareness and in the discussion of climate change. Nevertheless there are enormous quantities of carbon stored within soil, which when in the form of carbon dioxide (CO2) is one of the main causes of climate change. Soil is the third largest repository for carbon, after the ocean and fossil fuels like coal, oil and natural gas. All types of soil together contain about twice as much of this element as the atmosphere and three times as much as land plants. Carbon continuously moves between plants, soils and the atmosphere. Plants adsorb atmospheric CO2 and, using energy from sunlight, create leaves, stems and roots. Carbon from dead plant materials is transferred to the soil. A part of this is released back into the atmosphere after being broken down by soil organisms and the rest is transferred into more stable form humus.
The soil provides clean drinking water
When you turn on the tap and get fresh, clean water, you have soil to thank. Most of drinking water is sourced from groundwater in the world. It is the soil that makes it the pure elixir of life. During seepage flow, soil filters suspended solids, pollutants and pathogens out of the water. It essentially is the filter between surface water and groundwater.
The soil protects against flooding
Water on the surface of the ground is stored in a network of hollow spaces known as pores. It does not simply seep down towards the groundwater; instead, thanks to the surface tension of the water, it is held in the soil pores until needed. The capacity of soil to store water depends on the proportion of the pores. Usually 30 to 60 per cent of the soil is made up of pores of differing sizes. In organic soils formed in raised bogs, this amount can be as high as 90 per cent. If the pores are too large, as in sandy soils, water travels rapidly deep into the soil, whereas soils with a high clay content store more water. The depth of the soil also determines its capacity to retain rainwater.
The archival record in the soil
Soil takes form over an extremely long time period; therefore it can be considered to have a good memory. Soil scientists have the ability and knowledge to read the different soil layers like a book gaining boundless information reflecting the environmental conditions that prevailed when the soil was first formed.
Conserving the basis of life
The soil beneath our feet is the perfect mixture of minerals, humus, water, air, animals, plants and fungi that interact in a variety of ways. The well being of our society is closely connected with this underground society as it fulfils numerous economic and ecological functions.
Establishment of sound principles for good soil management
Good soil management has always required that the soil be used in such a way that its productivity is maintained or preferably, enhanced. This requires that the chemical and physical condition of the soil does not become less suitable for plant growth than when cultivation commences.
Maintaining and improving soil productivity
If a soil is to sustain the production of crops, it must be provided the nutrient requirements of the crop, provided a physical medium in which the plant roots can grow adequately so that water and nutrients can be absorbed, provided a medium in which soil organisms are able to decompose organic materials, releasing nutrients to the plants, assist the transport of nutrients to plant roots, compete successfully with pathogens which might otherwise infect roots and damage the plants and form the soil organic compounds which will have a favorable effect on other soil properties.
Managing soil nutrients
A few soils contain sufficient nutrients to allow them to be mined for many years without significant loss of yield, but the majority of soils can only be exploited for a few years before their ability to supply nutrients falls to a low level. If yields are to be maintained, and the soils used to produce crops on a continuing basis, a method by which nitrogen, phosphorus, potassium and other nutrients can be replaced has to be found.
Managing soil physical conditions
Soils under natural vegetation normally support an active population of soil animals. These live on the roots and on litter from the vegetation, and they dig and burrow, keeping the soil loose and friable.
Managing soil organic matter and soil biological conditions
It is difficult to exaggerate the importance of soil organic matter to soil productivity, and particularly so for the poorer soils of the tropics. Its direct contributions to nitrogen, phosphorus and sulphur nutrition of crops, and its role in stabilizing soil aggregates and supporting the soil animals which create the pores through which air and water move, have already been mentioned. In addition, soil organic matter plays a major role in the retention of cationic nutrients by the dominant soils of the tropics which have clays composed of kaolinite, and iron and aluminium oxides-low activity clays, with only a weak ability to hold the nutrient cations.
Erosion is a natural process and is difficult to eliminate completely. However, on cultivated land there is a real risk of accelerated erosion if the natural vegetative cover of the soil is usually compatible with the cultivation of large areas by machinery. Trees used as windbreaks to control soil erosion by the wind are usually essential in drier areas of light textured soils, as are contour bunds and channels designed to drain away runoff water in areas subject to erosion by water. Other techniques such as tied ridge cultivation and alternate strip cropping can also be effective for erosion control.
Avoiding environmental damage
Soil management practices affect not only the site where the crop is being produced but also areas remote from the site. The off-site effects include those associated with the deposition of eroded soil materials, the pollution of water supplies due to inefficient use of fertilizers and pesticides, and the production of gases contributing to the greenhouse effect. These problems do not arise when good soil management practices are followed.
The practice of good soil management
The principles of good soil management are universally applicable. The practices which embody those principles vary quite widely according to specific soil, climate and other environmental conditions.
Sustainable systems in the humid tropics
Perennial crops, such as oil palm, rubber, cocoa, and bananas have been grown for many years throughout the humid tropics. The crops provide a cover for the soil and usually return sufficient residues to the soil to maintain a satisfactory organic matter level. Nutrient replenishment is necessary if the system is to sustain productivity. Where nitrogen fertilizers are used, acidity may need to be regulated by liming. Maintaining a leguminous cover under the canopy of the perennial crop can provide nitrogen to the crop and complement the protection against erosion afforded by the tree canopy. The greatest risk of erosion arises during the initial establishment phase, when it is normally necessary to use a cover crop to protect the soil until the canopy of the perennial closes.
Sustainable systems in the sub-humid tropics
In the wetter parts of the sub-humid tropics, plantation agriculture with perennials has sometimes been sustainable, but usually with coffee or tea, and at moderate elevations where the potential for erosion is not too great. Arable crop production has posed considerable problems for sustainable soil management. While the chemical condition of the soil is usually better than in the more humid areas, the do
minant soils are usually physically weak, and therefore readily eroded. Long-fallow shifting cultivation systems were sustainable, but broke down when demographic pressure forced a reduction in the length of the fallows, and an extension of the cropping periods. These changes led to deterioration of organic matter levels and structural condition, which in turn led to erosion and the associated problems. Agro-forestry offers the best route to a sustainable system, but requires that the trees in the system offer an economic return.
Sustainable systems in the semi-arid tropics
Uncertain rainfall and long dry seasons make sustainable crop production difficult in the semi-arid tropics. Pastoralism, rather than crop production, offers the greatest prospect of sustainability, but subject to the important provison that stocking rates are kept below the carrying capacity of the land. This ensures that the vegetation persists, and continues to provide the essential ground cover. In most parts of the semiarid semiarid tropics the demand for food has meant that stocking rates have often exceeded sustainable limits, and arable cropping has continued to invade traditional grazing areas. The cropping practices have been based on shifting cultivation systems in which fertility restoration depends on the regrowth of native grasses. The extent to which fertility is restored is often limited. This has lead to falling productivity, sometimes partly arrested by the introduction of fertilizers to supplement the animal manure used on the crops. In some instances, shorter duration crop varieties, e.g. sorghum, have helped to overcome water shortages by reducing the length of time that the crop is using water. The demand for nutrients, however, is not reduced. Legumes nearly always require an adequate level of soil phosphorus, and so fertilizer phosphorus has normally to be used together with a suitable legume.
Sustainable systems in the wetlands
The rice based farming systems of the wetlands are the example par excellence of a sustainable system. The factors which contribute to this are: i. nutrients are washed into rather than out of the soil; ii. water supplies are normally assured by irrigation and bounding of the fields to retain water; iii. erosion is not a problem as the bunds prevent run-off and the water held on the surface prevents soil displacement by raindrop impact; iv. acidity is not a problem as flooded soils will always approach the near neutrality of the flood water; v. nitrogen fixation in the flooded system is relatively high; phosphate availability in flooded soils is relatively high because iron is present in the ferrous rather than ferric state; and vi. weed problems are less in flooded than in dryland conditions.
The development of sustainable farming systems
Most production systems have evolved so that they are sustainable in terms of the environmental conditions prevailing at the time-including the level of demographic pressure. Given that demographic pressure has increased dramatically over the past century, and will continue to do so for the next half century, sustainability in relation to agriculture and soil management must be defined to include the need for increases in demand to be met.
Tactical thinking on soil protection
Soil problems and the urgency of soil protection
The following problems are facing for soil resources protection.
Loss of soil resources and its rapid deterioration
The world has boasted vast expanse of landscapes, complex natural conditions and plentiful soil resources. The soil resources can be characterized by diversified soil types, huge absolute quantity, and small per capita soil resources. Currently the soils have two major problems concerning soil resources: namely loss of soil resources and soil deterioration. A number of soil resource problems including water loss and soil erosion, soil fertility reduction, desertification, soil salinization, rocky desertification as well as soil acidification, which has posed serious threats to ecological safety.
Acceleration of regional soil pollution
Results of recent soil quality survey revealed obvious pedogeochemical abnormity or pollution at watershed or regional level. Cadmium, Lead and Mercury abnormality have been found in the river basin and coastal areas. Preliminary analysis showed that the pedogeochemical abnormalities at watershed level are combined results of high natural geochemical background and anthropogenic pollution. In some watershed with heavy metal abnormity or pollution, soil geochemical status deteriorates rapidly.
Lack of science & technology for soil protection
Although outstanding progress has been made concerning soil pollution survey, physical, chemical and biological remediation, gaps still exist between developing and developed countries where soil remediation have been commercialized. It is time to initiate studies on innovative remediation technologies and to develop technologies, equipments and management system for contaminated farmland, soil around mining area and soil on industrial sites.
Weak public awareness and incomplete legislations in soil protection
Public awareness of soil protection is weak with little consciousness and enthusiasm. Government officials in many countries do not have adequate knowledge of soil resources, soil quality and soil function and the social value of soils, therefore little was done to raise the awareness of the general public to protect the soil protection. Education concerning soil environment is also inadequate with no specialized authorities or organizations.
Macroscopic strategies of soil protection
The following points should be considered for soil protection
Guiding thoughts and strategic principles
Under the guidance of scientific development, a pedosphere research framework which incorporates soil water-air-biota-human and a soil management framework which incorporates prevention-control remediation-supervision should be established with the emphasis on dealing with soil problems at basin, regional levels. The goal is to secure national food safety, the environment, ecological safety and public health as well as construction of a well-off society. In the face of apparent or hidden problem of soil degradation and soil pollution at present or in the long run, scientific development should be implemented. The following relationships need to be considered: soil resource protection vs social economic development, maintaining soil fertility vs sustainable agriculture, soil ecology vs biodiversity, soil pollution control vs safe residential environment, wise utilization of soil vs global change, investment for soil protection from central and local governments. Soil utilization and soil protection, soil quantity and soil quality should be considered equally important. The importance of soil pollution prevention should be emphasized. Soils should be protected according to different regions and soil types.
Six strategic tasks
There are six strategic tasks to protection of soil.
Securing and promotion of agricultural production
National soil quantity and quality survey should be conducted periodically in a comprehensive and systematic way to understand the dynamic change of soil quantity and quality and prominent soil environmental problems. A national soil resources and quality information system should be established and soil environmental quality standard should be formulated on scientific basis. Great efforts should be made to strengthen environmental protection in rural areas including protecting soil in major agricultural areas, strictly control the use of chemical fertilizers, pesticides, sewage sludge and agricultural waste. By doing so, improvement of soil fertility and protection of soil environment can be achieved at the same time.
Protection of hum
an health and ecosystem
Effective measures should be taken to prevent pollutants from entering the soil. To prevent soil acidification, air borne deposition should be strictly controlled and the development of protected agricultural should be carefully controlled. Risk based approach should be used for assessment and management of soil environmental quality. To secure the safety of agricultural products and food, protect the safety of residential areas and human health, integrated measures need to be planned to remediate polluted urban and rural soils progressively.
Mitigation of degraded soil in ecologically fragile areas
To implement soil protection in ecologically fragile areas, it is important to strengthen control of regional soil erosion, sand storm source area and mitigation of degraded soil and control the trend of soil erosion, grassland degradation, desertification, salinization, and rock desertification.
Protection of soil in areas with important functions
It is important to protect soils at key ecological conservation areas and nature reserves such as water source zone, flood conditioning and storage area, windproof and dune-fixing area, water and soil conservation area, and habitat of important species so that soil environmental quality is good enough to protect the biota and water body.
Soil environmental research and development
An innovative soil research and development system should be established which integrates fundamental researches, environmental standards, and application of high technology. Long lasting soil scientific research and technological development should aim at soil problems at national or regional levels such as formation of soil obstacles, the rules of soil quality evolution, soil quality criteria and standards. Technologies and equipments are needed for soil monitoring, compressive control of soil erosion, grassland degradation, desertification, salinization, rock desertification, soil pollution control and remediation, prevention of secondary salinization.
Soil environmental management
Soil protection legislation, structure and mechanisms should be established to form a risk based national soil protection system. Soil protection laws, regulations, policies and standards should be enforced at national and local levels. A strict soil protection liability system, economic compensation and investment mechanism, economic and criminal penalty system and executive accountability system should be established. Soil protection supervision authorities as well as soil monitoring network should be established at national and local levels. A market oriented mechanisms should be sought for soil protection. Soil protection education should be strengthened to raise public awareness of soil protection.
The following strategies focuses should be considered.
Protection of basic farmland soils in different zones
Protection of basic farmland soil, control of dispersed source pollution and protection of rural ecosystem should be strengthened in major agricultural production. Comprehensive control and ecological conservation measures need to be taken in areas with serious soil erosion such as the loss plateau, arid zones, hilly areas. It is necessary to strengthen control of farmland soil degradation, ecological restoration and improvement of soil fertility.
Urban and rural soil pollution prevention and remediation
An action plan should be drawn up for soil pollution prevention and remediation in urban, peri-urban and rural areas, based on the principle of prevention first, integration of prevention with control. A staged plan should be made to dispose or clean up polluted soil at industrial sites, especially in economic booming areas, old industrial base, and around large mining areas. Comprehensive measures should be taken to deal with soil pollution around large lakes, river basins and large hydraulic projects.
Soil quantity and quality supervision
A functional division within the government should be responsible for soil quality supervision. A regional soil quantity and quality monitoring network and information share platform should be established. A risk assessment framework and emergency response plan should be established based on resource conditions. It is necessary to establish soil standard system, speed up soil pollution prevention and control legislation, launch soil protection advertisement campaign and education to raise public awareness of soil environmental protection.
The followings strategic countermeasures should be considered for the protection of soil resources.
Soil protection authorities should be established with clearly defined responsibilities among different governmental departments. Soil protection planning and action plan should be drawn. It is crucial to establish and improve soil protection legislation and enact practical rules for the implementation. The development of soil environmental protection NGOs and active participation of the general public in soil protection should be encouraged and promoted. It is necessary to establish and improve rules for the use of pesticides, fertilizers, sewage sludge and agricultural wastes, to implement rules for soil pollution prevention and remediation, to implement rules for economic and ecological compensation for soil remediation, to develop emergency treatment techniques for soil pollution and to establish a management pattern that integrates protection of soil, water and air quality and the use of soil resources.
National and international soil standard for different land use should be derived based on risk assessment. Local soil standard should also be encouraged. A soil protection standards system should be established. Ecotoxicity of soil pollutants should be studied. Soil background values and geochemical baselines should be derived. Methodologies for conducting soil ecological risk assessment, human health risk assessment and environmental risk assessment should be established. Rules for the management of polluted sites and technical specification of risk assessment should be drawn.
Soil protection research and technological development
It is necessary to strengthen national soil quantity and quality survey, research on the soil quality index and methods for assessing soil quantity and quality change and its impacts, and establish soil monitoring network and information system for protection and management of soil resources. An integrated treatment patterns that incorporates hydraulic engineering, biological engineering and agricultural technologies will be proposed for soil erosion, desertification control. To prevent soil salinization, soil irrigation and drainage techniques should be improved. It is necessary to strengthen research on soil pollution diagnosis, and risk assessment as well as soil monitoring equipments and remediation technologies. Deepen research on the impact of global change on soil processes, biodiversity and their ecological functions, establish soil biogeochemical models, and develop technologies for carbon fixation and emission reduction.
A great wealth of knowledge has been acquired about soil resources, their distribution and their management. There is now a sound understanding of the biophysical principles on which sustainable soil management must be based. The basis for changing this situation has been established in the knowledge and understanding of agricultural production systems available today. What is needed now is an evaluation of how the principles of sustainable soil management are being, or need to be, applied in areas where agricultural productivity is either static or declining. Sustainable soil development systems require the use of fertilizers and other inputs, including the
use of organic manures and the recycling of nutrients from residues. As long as demographic pressures continue to increase, the problems will become more difficult to resolve, and urgent action is required to arrest the spread of land degradation and to establish sustainable systems where non-sustainable farming methods are currently in use. Much work needs to be done to evaluate the sustainability of soil and land management systems for the foundation of sustainable development in different environments, and to develop policies and incentives to ensure that these systems are socially acceptable and economically attractive. The principal responsibility for action must be with national governments and agricultural administrations. They will need to be fully supported by international organizations and, of course, by the farming and scientific communities. Sustainability is not simply a matter of identifying effective biophysical solutions. The solutions must be economically viable and socially acceptable. It is therefore essential that the applied studies and adaptive research necessary to identify effective biophysical techniques will conducted in association with socio-economic studies, by which the voice of the farmer will heard.
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