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MAJOR LAND RESOURCE STRESSES IN RELATION TO
SUSTAINABLE AGRICULTURE IN ASIA
H. Eswaran, P.F. Reich, F.H. Beinroth, and E. Padmanabhan USDA Natural Resources Conservation Service, Washington DC, USA University of Puerto Rico, Mayaguez, Puerto Riuco, and Universiti Technologi Sumber, Kuching, Malaysia
ABSTRACT
Globally, there is enough high-quality land to support nearly double the current popula- tion. However, Asia already has an acute land shortage, and as a region it is already on the verge of a food deficit. Feeding the 4.2 billion people expected for the year 2025 cannot be achieved with available land resources. Under the low-input systems found in much of Asia, productivity will continue to decline as land degradation and other factors take their toll. Fur- ther, lack of political will, insufficient investment into modern agriculture, and a general indiffer- ence to sustainable land management, guarantee a food deficit and in some countries, contribute to poverty and famine. Local and regional food shortages are likely to continue to occur unless mechanisms for equitable food distribution, effective technical assistance and infusions of capital for infrastructure development are implemented throughout Asia.
INTRODUCTION
In the last two decades, a dramatic change has taken place in our thinking about research and development for agriculture in general, and utiliza- tion of the natural resources in particular. Even in the poorer third world countries, there is an increasing awareness of the need to maintain a healthy ecosys- tem and the quality of the environment. In many countries, especially in the affluent countries of the world, national priorities for environment manage- ment are in place. Donor countries that provide assistance to the developing world are requiring that this becomes an obligatory requirement for develop- mental assistance. The rationale for this approach is that the environment transcends national bound- aries, coupled to the valid argument that environ- ment and quality of life are linked. The concept of sustainable development was initiated by the Bruntlandt Commission (WCED 1987) and devel- oped further by Agenda 21 of the United Nations Conference for Environmental Development (UNCED 1993). Despite a political commitment to the con-
cepts of AGENDA 21 by practically all countries of the world, implementation is still elusive in many third world countries. Lack of funds is a major impediment, but in addition there is the daunting task of showing resource-poor farmers the complexity of the environment. Even the scientific community is grouping with the “holistic approach” which, is the most popular “buzz-word” today. There is thus an atmosphere of uncertainty as to which approach should be taken. Affluent countries have decided to reduce agricultural production, and research funding is given only to agricultural research with an environmental context. Unfortunately, this view is directly and indirectly (through assistance) imposed on third world countries, which must still face the challenge of increasing food and fiber production to satisfy the needs of a growing population. The issue in third world countries, as exem- plified by Asia (Eswaran et al. 1994), is “unsustain- able crop yields, unacceptably high rates of soil erosion, deforestation, loss of germplasm diversity, and bewildered farmers who do not know what to do next to eke out a reasonable standard of living…”.
Keywords: Asia, constraints, food deficit, land resources, soil map, soil stresses
This paper attempts to examine in this context the need for land resource assessment and monitoring. A major consideration is the diminish- ing budget that excludes many basic research activi- ties (Mermut and Eswaran 1997). At the same time, recent technology permits rapid information man- agement and delivery, and in a more client-friendly manner. Finally, an environmental orientation has different needs from the previous production orien- tation, and so requires a new agenda for land re- source assessment and monitoring.
Method of Assessment
There are many stresses experienced by a land resource system and its soils (Buol and Eswaran 1994). However, there are frequently one or two major stresses that prevent the use of the land for most agricultural purposes. Some of these stresses cannot be corrected, e.g. low temperatures unless heated glass-houses are used. Others may be cor- rected, e.g., irrigation for areas with moisture stress. Correcting the major stress may or may not ensure sustainable use of the soil. Other stresses may be present, or correcting one stress may result in creat- ing another stress. An example is irrigation in dry lands without adequate drainage. The result is salinity build-up within a short period of time, which reduces the quality of the land. Using a soil map of the world which also includes information on soil climate is the first step in making a broad assessment of the major land re- source stresses. On the map, each soil is assigned one major stress, if stresses occur. To do this, the stresses are listed in a priority ordering (Table 1) and each soil unit (polygon on the map) is tested to determine, if it meets any of the 24 (from number 2 to 25, in Table 1) identified stresses. If the soil fails to meet any of the 24 stress classes, then the polygon is indicated as having “Few Constraints” (class 1). To make the map easier to understand, multiple stresses are not depicted, though it is recognized that soils with multiple stresses may be the rule rather than the exception. Other stresses may be important locally. These can be represented on national or regional maps. Each of the 24 stresses listed in Table 1 requires a different level of financial investment to correct for agricultural use. The cost of correcting the stress is the main factor used to define classes on the list. The cost of correcting the stress varies with the country and the kind of stress. For sustainable development, an understanding of the kinds of stresses and the costs involved for correction and mainte-
nance is essential. The quality of the land shows great varia- tion between and within countries. In this study, the quality of the land in countries of Asia was also assessed and from this, an estimate of the current population supporting capacity of each country was estimated. Each country has land of differing capa- bilities, according to the quality of the soil and its performance under the prevailing climate. Until recently, databases that provide such information were not readily available. The FAO/UNESCO Soil Map of the World (FAO 1971-1981), provides for the first time a computer database of global soil resources (FAO 1991). The authors compiled a global climate database, using data from about 25, stations. Using a water-balance model, the soil moisture and temperature regimes were computed. Using GIS, the soil climate information was overlaid on the soil map. The combination of soil and climate information was used to empirically assign land quality classes, using the matrix shown in Table 2 (Wang et al. 1990). A country boundary overlay made it pos- sible to compute land quality classes for each coun- try. The error of such computation is estimated to be about 50 km 2. Population and arable land area data for 1995 and projections for 2025 were taken from FAO statistics. The terms and the characteristics of each of the nine classes are described in Table 3.
Land Resource Stresses in Asia
The first assessment of the major soil re- lated constraints to land use in Asia was made by Dent (1990). In this assessment Asia includes all countries from Afghanistan in the west to Japan and Korea in the east (Table 4). It includes China and Mongolia, but excludes the Central Asian Republics and the eastern part of Siberia. Indonesia, Papua New Guinea, and the Solomon Islands form the southern limit. Australia is excluded from this as- sessment. The scale of the database also prevents a good assessment of the Pacific Island nations. His assessment is based on a priority listing and multiple stresses are not considered. However, areas designated as “continuous moisture stress” may have soils with salinity problems and low water holding capacity. There are about 58,000 km 2 of land in Asia with long cold periods, which precludes use of the land for most agricultural purposes. These are mainly in Mongolia, northern China and in the high mountains of Pakistan and India. The deserts of Asia are the Thar desert of India and Pakistan, and the
Table 2. Matrix which defines land quality classes
Taklamakan desert of China extending into Mongolia. Water is limited unless irrigation is available. With good irrigation, as around Urumchi in China, the deserts are very productive. In the absence of appropriate drainage outlets, as in parts of Pakistan and India, there is rapid build-up of groundwater and salinity. Sustainable agricultural systems can be developed in deserts if good land management is practiced. Steep sloping land and shallow soils over- lying rock are major constraints to agriculture. Most countries of the region certain such lands, and if the climate is favorable, they are generally under forest. In the semi-arid and arid parts of the region, the steeper terrain and shallow soils are generally used for grazing small ruminants. The four land resource constraints listed in Table 4 – continuous moisture stress, continuous low temperatures, steep slopes, and shallow soils – are land use constraints that cannot be corrected easily by technology. It would be very difficult to have any form of sustainable agriculture on such land. Four other constraints are less severe. Soils with high shrink-swell potential are the Vertisols. India has the largest extent of Vertisols in the region. In a semi-arid environment as in India, the soils are hard when dry and sticky and plastic when wet. With traditional bullock-drawn plows, the soils cannot be tilled before or during the rainy season. Tilling is generally done at the end of the rainy season and the plants grow on the stored moisture, making them very susceptible to moisture stress. Yields are consequently low and production uncertain. In the semi-arid and arid parts of the region, there are expanses of saline and alkaline soils. How- ever, salinity induced by irrigation is also consuming large areas of land in the semi-arid regions. In addition to availability of moisture, salinity is a major problem of the semi-arid tropics. In the humid tropics, two major groups of problem soils are the acid soils and those with low fertility. Acid soils are dominant in the humid tropics, and are common in coastal plains. Many of
the “cat-clays” are being used for rice cultivation, with mixed success. Acidity in upland soils reduces crop production both directly and indirectly, due to its interactions with other soil components. In many of the acid soils of the humid tropics, exchangeable aluminum is the cause of acidity. Aluminum affects root elongation and has other physiological effects on most plants. In acid sulfate soils, the acidity is due to hydrogen. Acidity does not affect biomass pro- duction if the soil is flooded during crop growth. Only when there is insufficient water, particularly during the initial growing stage, is the plant suscep- tible to damage. The highly weathered and leached soils of the humid tropics – the Ultisols and Oxisols
- have fertility-related constraints in addition to being acid (Eswaran et al. 1997). Phosphorous, together with calcium and potassium, is generally unavailable. Any kind of agriculture on these soils requires ample application of these nutrients plus nitrogen. Some of the Oxisols and Andisols have a net positive charge, and these soils cannot hold the basic nutrients if organic matter is low. Sustainable management of these soils implies organic matter management and appropriate nutrient management. The other remaining major land resource stresses include poor internal drainage, which limits the soils to specific uses such as paddy cultivation. However, particularly if the soils occur on the coastal plains, acid sulfate conditions may prevail in the subsoil. This reduces the quality of the soils. High anion exchange capacity is a property of the volcanic ash soils and some of the Oxisols. They have a propensity to fix anions and make them unavailable to plants. The peat deposits of the region represent the last constraint. These soils are dominated by organic matter, which presents different kinds of problems for cultivation and sustainable agriculture (Padmanbhan and Eswaran 1998). Soils with few constraints are not the domi- nant soils in any country. These soils are generally considered to be prime agricultural land.
Table 3. Properties of the inherent land quality classes (Obtained by a combination of the performance and resilience attributes of soils in the context of their inherent stresses)
come reasons for conflict when limits of the resource is reached. Further, the increasing requirements of non-agricultural water use will inflate prices, result- ing in stringent irrigation policies that will be re- flected in efficiencies of production. Inadequate or inefficient irrigation continuously reduces the amount of land that can be used for food production. (World Bank/UNDP 1990). Another factor that prevents efficient use of land in many countries is the low purchasing power of the land users, the result of poverty (Swaminathan 1986). Appropriate inputs can double production. However, farmers may have no capital to invest in the land, or no incentive when they do not own the land. Sustainability and the efficient use of land can result only from the appropriate application of mod- ern knowledge. Rein-carnating past technologies is not a solution to the challenges of today; it is an excuse for a lack of national will.
Population Supporting Capacity of
Land
Land must also be used for purposes other than agriculture, such as forestry, recreation, and urban needs. The ideal partitioning of land for its multiple uses is based on social values and economic considerations. Table 4 is an idealized partitioning of land, based on its quality and its potential uses. There is always strong competition for land for multiple uses, and economic factors determine the final land use. In societies with strong social com- mitments, the economic forces are frequently re- quired to compromise. In many parts of the world, large amounts of Class I land are being converted to non-agricultural uses. Table 4 shows the amount of land used for grain crop production, while Table 5 shows the population supporting capacity based on this figure. The current population of Asia is already about 3.2 billion and is expected to grow to 4. billion by the year 2025. If we apply these estimates to the actual land area of each country in its various classes, it is clear that Asia as a whole will not be able to feed its population. Only a few countries such as Papua New Guinea, Myanmar, and Laos have land to spare. Others such as Malaysia and Indonesia, have enough land for grain crops but prefer to use it for cash crops such as rubber and oil-palm, and import food. Rich countries such as Taiwan, Singapore, and Japan rely on industry and services to earn money to pay for food. The remaining countries, which are not industrialized, will continue to exploit fragile land resources. Pakistan, India, Bangladesh, and China
will continue to irrigate large parts of their arid or semi-arid lands and increase the proportion of lands under agriculture, thereby endangering the environ- ment and permanently damaging biodiversity.
A NEW AGENDA
The attention given to soils from the point of view of research and development funds, does not match their significance. Governments seem to feel that much is already known about soils, and that generalizations made for one site are applicable everywhere. They also fail to recognize that agricul- ture is one of the major “stressors” of the environ- ment. The purpose of this Bulletin is to drive home the point that soils are a “non renewable resource”. Society has an obligation to protect them and their quality for future generations. To help convince others, we have to evalu- ate past paradigms that brought some of the coun- tries of the region to agricultural affluence. From here, we need to go onto current concerns, and the urgent need to develop new paradigms that will take us into the next millenium. We have to demonstrate clearly why some of the valid arguments of the past have little validity in the modern age of environmen- tal degradation.
Ecosystem Based Assistance
Ecosystem Based Assistance (EBA) is a strategic initiative to enhance the quality of the ecosystem. It integrates biophysical, socioeconomic, and political considerations into relevant land use and management options for decisions on sustain- able land use. It stems from the vision of a productive nation in harmony with a quality environment’. In this approach, not only the individual components of the system are given attention as in the past, but more importantly, the interactions between the components are also considered. EBA enables us to provide assistance that considers the space-time dimensions of technical intervention. To implement this strategic initiative, na- tional institutions should:
- Maintain a strong science base;
- Enhance the linkages between the inter- national institutions, national institutions, and land users to foster the collaborative spirit which must be the basis of all land management activities;
- Initiate appropriate structural changes
Table 5. Idealized population supporting capacity (persons/ha)
within national institutions to implement sound land use policy;
- Be proactive in information dissemina- tion, to ally support and cooperation from farmers.
- Make necessary changes to procedures to facilitate implementation.
Land Quality and Early Warning Indi-
cators of Land Degradation
The FAO/UNESCO/UNEP “Global Assess- ment of Soil Degradation” provides data to quantify the current magnitude of the soil degradation prob- lem, as does (Oldeman et al. 1991). UNEP and WRI provide further analyses of these, and of other as- pects of land degradation. Efforts to restore produc- tivity to degraded lands must be coupled with the ability to monitor all stresses before productivity is significantly impaired (Greenland et al. 1998). Causes of stressed systems are numerous. They include removal of nutrients, deve-lopment of acidity, salinization, alkalization, destruction of soil structure, accelerated wind and water erosion and loss of organic matter. In some regions of the world, a combination of these results in such degradation that the term “desertification” is popularly used. Finally, it must be appreciated that there is an important interaction between the causes of deg- radation. Erosion, for example, may be seen as the major problem where chemical degradation of the soil prevents establishment of vegetation and thus the inability of the soil to stabilize against erosion (Dumanski et al. 1992). In this example, lack of appropriate vegetation becomes an early warning indicator. Very few studies have been conducted on this linkage between factors. There is an urgent need to look into this.
Land Productivity and Land Use
Options
Sustainable land management (SLM) is the key to harmonizing the environmental concerns of society with the economic realities of producing adequate food and ensuring a minimal quality of life (Dumanski et al. 1992). SLM can only be realized if land users understand the impacts of land manage- ment options, so that they can optimize the benefits of their choice. Insufficient attention is given to this aspect of SLM. In addition to developing concepts and mechanisms of SLM, it is necessary to make a concerted effort to link SLM to the socio-economic realities of the farmer. A framework for sustainable land manage- ment (Dumanski et al. 1992) may emerge as one of the most powerful tools for the sustainable manage- ment of land. It will provide the scientific basis for evaluating the environmental impact of proposed land use changes. Research on land has traditionally been driven by agricultural imperatives. Although these are still important, the ecological concerns are in- creasing as a result of environmental problems (Szaro and Johnston 1996). The situation is made worse in developing countries by the lack of any kind of resource monitoring system. Knowledge of the resource base and the impact of different kinds of land use are the foundation of informed policy deci- sions (Tinker 1998). Agrotechnology transfer to developing countries has generally had mixed success (Eswaran et al. 1997). Germplasm transfer has been more successful, but land management technology has often been a failure. Part of the reason has been the inability to integrate scientific techniques with con- ventional farming practices. Acceptance is generally greater when farmers have participated in the tech- nology development. How to involve farmers in developing and implementing technology is a major challenge.
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