Part VII. Lessons learned and experiences, technology
measures and constraints in the implementation of
Integrated Nutrient Management (INM)

Lessons learned and experiences

Technical, policy measures

Constraints

• Soil fertility status severely declined due to intensive crop cultivation & imbalanced fer- tilization.

• Organic matter decomposition is high. Moreover, the addition of organic materials to soil through FYM, compost and organic residues has been reduced considerably because a major portion of these organic residues (cow dung & crop residue) is used up as fuel by the rural people.

• The increased intensity of cropping, especially changes in crop sequence with HYV, makes current management practices, including fertilizer use, less effective.

• More fertilizers are being used on lands with poorer soils or uncertain irrigation facilities.

• There is an imbalance in the supply of N, P and K with application of latter two nutrients often being too low.

• Deficiencies of secondary and micronutrients are prevalent.

• Production of a large amount of fertilizer (60% Urea & 100% mixed fertilizer), but not enough to meet the country's require­ ments with the increasing demand. Continuous demand is projected to increase in the next five years.

• The benefits of INM technology have been demonstrated and disseminated to the farmers through extension personnel.

• Research findings showed very encouraging effects of INM technology on the higher yield of many crops and cropping sequences of the country.

• More motivation and subsidy are required for the adoption of such technology by the farmers.

• Agricultural policy measures should be strengthened as such farmers may get proper support, encouragement and guidance.

• Farmers often have inadequate knowledge on use of fertilizers in balanced proportion. They also have insufficient funds.

• The linkage and interactions among researchers, extension services and NOG personnel are weak.

• Degradation of lands due to intensive cropping or over- exploitation by the enormous pressure of the ever-increasing population.

• Risk of water deficit at drought prone period is considered the most important deterrent to fertilizer use.

• During monsoon, water erosion is a serious threat on soil fertility and productivity.

Lessons learned and experiences

Technical, policy measures

Constraints

• Establishment, operation and maintennce of 3 run off and soil loss monitoring sites . Data collection, collation and assessment for SLM activities completed.

• Provision of technical assistance, training and capacity building activities and workshops re­ garding SFMC to 503 provincial technical staff, extension workers and private sectors.

• Development & strengthening of linkages to different sectors promote long sustainability of SFMC activities.

• Effective administration, man­ agement and information dis­ tribution systems allowed through: A balanced approach to the network management function, and country programme leadership; Effective distribution of information on SFMC/SLM several Agri-Notes, 5 annual technical reports, and workshop reports.

• The Soil and Plant Analysis Laboratory, a semi-autonomous agency under DAALI, initiated a QA programme to be used in the laboratory QC programme, and participation in the regional soil and plant sample exchange programme.

• SLM initiatives are being undertaken through a high quality research and develop­ ment activities in different agro-ecosystem target areas to demonstrate, extend and raise awareness of SFMC technologies in terms of sustainable land management.

• Capacity building activities to strengthen the capability of partners to demonstrate and extend relevant SLM techno­ logies to their farmer clients.

• Effective coordination and information support to strengthen and improve the existing col­ laborative network with regions having similar problems.

• The Soil & Plant analysis laboratory, provincial personnel and counterparts are col­ laborating with other agencies in conducting soil fertility and land management activities.

• The ability and willingness for further achieving SFMC/SLM needs time for development and guidance supporting a longer- term intervention.

• Effective activities in SLM require a dynamic approach from NAP considering the interactions of biophysical, social and economic factors affecting decision-making by farmers.

• Individual objective has to be consistent with and parallel to NAP’s objectives to encourage longer-term sustainability.

• SFMC staff, limited skills and knowledge on management, planning, monitoring and reporting.

• Not enough resources for TA to supervise and provide on-the-job training.

• Natural calamities that affect project implementation, i.e . floods, typhoons.

• Slow/Delayed releases of funds.

• Lack of clear procedural guidance.

• Land Management Office (LMO) and laboratory gave insufficient attention to: (1) trial design, (2) field and technical M&E activities. Quality man­ agement support to field operatives and farmers was neither enough nor provided properly.

Lessons learned and experiences

Technical, policy measures

Constraints

• According to a recent survey by the Chinese Ministry of Agriculture, about one-third of farmers over-apply N, while one-third use deficiency levels of N on their crops.

• A network of experiments was established in 1990 to test the effects of fertilizer and manure treatments on the productivity of a variety of cropping systems in eight highly diverse regions of the country and results showed that combined fertilizer and manure/straw inputs tended to produce greater benefits in crop yield and soil fertility than application of fertilizers alone.

• Since the 1980’s smallholders have converted to vegetable production on a large scale from subsistence level to marketable sales and vegetable production has developed very rapidly.

• With the support of the Chinese Ministry of Agriculture and the National Natural Science Foundation of China, a large scale project – development and implementation of rice nutrient resource management in co­ operation with IRRI – has been carried out since 2002 which features integrated nutrient management systems for 12 cropping systems at 58 sites across the country.

• Since 1998 the N-Expert System, a promising solution to optimize the supply of nitrogen in vegetable production, with different irrigation regimes has been modified for a rotation of amaranth (Amaranthus tricolor L.), spinach (Spinacia oleracea L.) and cauliflower (Brassica oleracea L.) on the north China Plain.

• The integrated nutrient man­ agement system for cotton involved the optimized nitrogen management technique based on the soil Nmin test and nitrogen nutrition diagnosis index system. Phosphorus and potassium fertilizers were recommended through constant monitoring.

• Low efficiency of agricultural technology extension services

• Limitation of small holdings

• Low level of education and insufficient trainings to improve agricultural knowledge of farmers

Lessons learned and experiences

Technical, policy measures

Constraints

• The small size of farms (960% -3 ha) in Fiji, results to intensive farming (monocropping) for high output, short-term production with minimal or no fallow period at all. These greatly contribute to land degradation through soil erosion and essential soil nutrients depletion.

• Burning of cane trash and forest fire is a widespread practice, repeated over the years, com­ bined with long or no fallow period, which resulted to serious fertility depletion and soil loss.

• Fiji’s Agricultural Landlord and Tenant Act (ALTA) and related legislations provide the legal mandate to enforce and improve appropriate land management practices. Relevant provisions cited are the maintenance of soil fertility, soil erosion control, planting along the slope, alley and agroforestry cropping . Fencing of cattle is encouraged by the government for sus­ tainable land management.

• In accordance with the UN Millennium Summit in 2000 on millennium Development goals, Fiji committed to ensure environment sustainability through the integration of the principles of sustainable development into the country’s policies and programmes.

• Insufficient funds for the Land Conservation Board to implement its mandates over land and water resources . Funding support has been made available for coastal dredging and drainage, not towards solving the causes responsible for downstream problems.

• Lack of expertise in agricultural extension, soil conservation, land use planning and environ­ mental planning, management and enforcement.

• Poor awareness and under­ standing on conservation and development.

• Lack of information at farm level on appropriate package of best practices.

• Poor understanding of laws pertaining to land, land use practices and soil conservation.

• Lack of clear guidelines on grazing management and soil erosion practice.

• Poor technology transfer for diversification, intensification and farming system.

Lessons learned and experiences

Technical, policy measures

Constraints

• In spite of continued growth of inputs, there has been no matching growth in agricultural production during 1990s, indicating a decrease in TEP in all major crops. Following are the causes of declining TEF:

 High nutrient turnover in soil-plant system coupled with low and imbalanced fertilizer use;

 Emerging deficiencies of micro and secondary nutrients (S, Zn, B, Fe, Mn, etc.);

 Soil degradation due to acidification, aluminum toxi-city, soil salinization and alkalization, soil erosion;

 Wide nutrient gap between nutrient demand and supply; and

 Consequent deterioration in soil physical, biological and chemical quality and low fertilizer use efficiency.

• Researches had led to:

 Development of INM prac­tices for major crops;

 Understanding the enhanced role of organic manures in increasing input use efficiency due to their favourable effect on physical, chemical and biological condition of the soil;

 Establishing the beneficial role of integrated use of organic manures in improving nutrient cycling in different production systems in various types of soils;

 Beneficial role of INM in improving soil chemical, physical and biological quality for sustainable crop pro­duction; and

 The work on INM has been compiled and published in the form of books/bulletins by several institutions.

• Long-term studies being carried out under All Indian Coordinated Research Project have indicated that it is possible to substitute a part of fertilizer N needs of kharif crop by FYM without any adverse effect on the total productivity of the system in major cropping systems such as rice-rice, rice-wheat, maize- wheat, sorghum-wheat, pearl millet-wheat, maize-wheat and rice-maize.

• There are INM strategies developed for different cropping systems all over the country.

• Recycling of crop residues and green manuring. Management of crop residues is through removal, burning or incorporation into soil.

• Studies on different types of biofertilizers available under intensive systems.

• Nutrient management practices have been developed, but in most of the cases, farmers are not applying fertilizers at recommended rates.

• There are several constraints to effectively utilize and popularize the use of biofertilizers, e.g., use of the biofertilizers is crop and location specific; low shelf life of the microorganisms; need for careful handling and storage; and, lack of suitable carrier material for restoration.

• Some research gaps: Mis­ matching of INM practices developed at research stations with the farmers’ resources and their practices; INM recommendations for different crops are not based on soil testing and nutrient release behaviour of the manures; Nutrient balance/flow analysis vis-à-vis soil fertility man­ agement practices with special reference to INM at farm level needs to be worked out; Nutrient release characteristics of farm residues in relation to their quality to develop decision support systems; Biofertilizers were not included as component of INM in many cases.

• Constraints in Use of Organics Complementary with Mineral Fertilizers: Convenience and advantages in use of fertilizers: Selective use of fertilizers and manures; Agro-ecological differences; Peri-urban/rural differences; Single multiple enterprises; Land tenancy; Lack of organic materials; Competitive use of organic resources; High cost of organic manures; High cost of organic manures; Transport; Pests, diseases and weeds.

Lessons learned and experiences

Technical, policy measures

Constraints

• Soil test data covering a 12-year period showed continuous decrease in soil organic matter content of arable lands in the country, while a nationwide soil investigation comparing 1997 and 1999 figures illustrated a reduction in the soil thickness of dry fields and a rise in soil loss amount particularly in sloping fields.

• Available nitrogen and pho­ sphorous content of cultivated lands have also decreased in recent years.

• Fertilizer application methods were validated and refined through the conduct of ex­ periments, namely, (1) Organic, mineral nutrient management in double cropping condition, and (2) Improvement of fertilization based on soil test data and fertilizer response in mono­ culture condition.

• Experiment results showed an increase in yield with less fertilizer inputs (30-50% decrease).

Lessons learned and experiences

Technical, policy measures

Constraints

• Farmers’ practice of planting crops without soil conservation measures caused high run off and soil loss. However, with the adoption of appropriate soil management technologies, the result have been effective (strip cropping, alley cropping, agro- forestry) in reducing run off, soil loss, maintaining soil fertility, increase crop yield and income. Application of fertilizer and lime increases soil pH and phosphorus content.

• Soil Organic Matter content decreases (from 3.71% to 1.78% in 7 year on farmers practice) due to removal of crop residues and soil loss through water erosion.

• Essential plant nutrient (P and K) declined over time due to intensive farming and unbalanced application of fertilizer.

• Other INM practices show negative net return during the implementation phase due to high cost of planting materials (fruit trees), plus the cost of establishing soil erosion control measures, but positive/high net return can be observed in the succeeding year.

• The Soil Survey and Land Classification Centre (SSLCC) in collaboration with National Agriculture and Forest Research Institute (NAFRI) & Northern Agriculture and Forestry Research Centre (NAFRec) conducted a long-term research on soil fertility using different technologies (model farms) to encourage farmers and decision- makers on the adoption of INM practices.

• A new government policy gives high priority to the protection of forest resources and to discontinue slash-and-burn activity. This policy in con­ junction with population growth, increasingly limits the area of land available to the individual upland family.

• INM technologies/strategies are being introduced through different model farms to assess economic returns and improve­ ment on land resources for the adoption of INM practices.

• The technology takes longer time and efforts for the farmers to adopt due to lack of training, limited knowledge and under­standing on the essence of nutrient management and its effect to environment.

Lessons learned and experiences

Technical, policy measures

Constraints

• Due to diverse crops of economic importance being grown in the country, the government emphasized the extension of cultivable land and cropping intensity to increase crop yield per acre. However, it neglected the soil and plant nutrient problem.

• In the past, the farmers have adopted three (3) kinds of traditional farming methods. However, the unskillful cropping systems and patterns had somehow degraded the soil condition, thereby depleting soil fertility that led to essential plant nutrient deficiency and soil nutrient imbalance.

• Recently, the government encouraged the implementation of high yield programmes wherein high yield varieties were used and large amount of chemical fertilizers particularly N was applied on rice. This resulted to a higher yield per acre.

• Most farmers rely on the organic and natural fertilizer like FYM, green manure, by-products of agro-based industry, crop residues and town wastes since these improve the soil’s nutrients, structure and fertility.

• Various kinds of biofertilizer which are good sources of nitrogen have been utilized for a long time by the farmers due to positive crop response.

• Land Use Division and Extension Division of MOAI cooperated in carrying out the Integrated Nutrient Management

Information and dissemination to the farmers on the use of scientific and modern agro-technique.

Planning of long-term and short-term systems that enhances soil fertility, prevent soil degradation and environ­mental deterioration.

Implementation of research and demonstration in soil problem areas.

Implementation of Nutrient Management and Soil Con­servation projects like the RTOP Projects International Rice Research Institute (IRRI), using Site Specific Nutrient Management (SSNM) techni­ques, Sustainable Control of Renewable Natural Resources in Sustainable Agriculture project.

• Establishment of three (3) state- owned Plants with a production capacity of 425,000 tonnes of Urea per annum. It was able to produce only an average of 46% of its capacity. Additional fertilizer requirements were imported to some extent by private fertilizer traders with help of Myanmar Agriculture Service (MAS) extension staffs.

• Effective microorganism (EM) has been introduced since 1993 by collaborative project with International Nature Farming Research Center (INFRC) of Japan. EM is very beneficial for crop production because of its better crop yield, better protection of pests and diseases, improvement of soil moisture, structure and texture, rapid decomposition of biomass.

• Inadequate human resource development particularly on the capabilities of implementers on the assessment of socio- economic and environmental benefits of traditional and improved farming/agronomic practices.

• Limited support to national and local policy-making process.

• Absence of international plat­ form for dissemination of technologies.

• Insufficiency of local and international projects co­ operated with FAO of the United Nations and advanced countries.

• Outstanding preference of farmers on the use of organic materials over chemical fertilizers due to high cost and poverty.

Lessons learned and experiences

Technical, policy measures

Constraints

• Crops remove a large quantity of all nutrients from the soil resulting to imbalance on crop nutrient. Additions such as the two principal fertilizers used in Pakistan, Urea and DAP, do not provide appreciable quantities of any nutrients other than N and P₂O₅. Urea is the most sought/ used due to its suitability to the country’s soil condition, availability and affordability.

• Farmyard Manure (FYM) is also being used and based on the number of animals, about 50% of animal droppings are collected and about 50% of which is used as fuel. Thus, nutrients recycled to crops are about 1/4^th of total. Green Manuring has also been adopted on the three cropping systems in Pakistan.

• A huge quantity of crop residues are also available but due to some economic compulsions such as need for animal fodder and fuel, the crop residues are partially recycled in the soil, or burned to clear field for next crop.

• Pakistan sugar industry is producing a considerable amount of filtercake and stillage every year, which is a rich source of organic matter, micro and macronutrients. However, a large portion of filtercake is sold to brick baking industry and the stillage is drained out which caused environmental pollution instead of essential plant nutrients for crop growth.

• Sewage sludge, city garbage, industrial wastewater and effluents are also good source of plant nutrients. However, these solid wastes are not being properly managed and recycled for different useful purposes including pre-treatment and composting for crop nutrition.

• Pakistan produces a large amount of fertilizer but not enough to meet its entire requirements, hence, high importation is done mostly by the private sector/ institution. Continuous import demand is forecasted to continue to grow in the next five (5) years.

• The Pakistan Agriculture Research Council (PARC), National Institute of Bio­ technology and Genetic Engineering (NIBGE) and Provincial Agricultural Research Institutes are carrying out work on biological fertilization. All these institutions are isolating strains of rhizospheric bacteria, which have potential for mobilizing atmospheric N, both on legumes and non-legumes.

• Technology has not been developed to suit different farms and farming systems. There is need for commitment at research extension and national level for bottom-up participatory approach and leadership. More allocation of resources is required to develop state-of-the- art technology.

• Amount of FYM available for use in the field is low and insufficient to meet the re� quirements of crops. Farmers lack proper knowledge about the preparation of FYM and composting. Most used as fuel. Alternate sources of energy are to be made available to farmers.

• Limitations in use of green manuring due to size of land holdings, high demand for fodder, lack of technical know- how on green manuring and organized research.

• Limitation in use of crop residues due to high financial benefits, shortage of fodder during winter, fuel energy and as raw materials for mud houses/ cattle sheds.

• Limitation in use of Bio- fertilizers due to application techniques and efficiency of strain, marketability packaging, shelf life and good quality.

Lessons learned and experiences

Technical, policy measures

Constraints

• Shifting cultivation is the basis of the traditional subsistence agriculture in PNG for food crop production and a natural way of restoring soil fertility.

• The use of large mounds associated with composting is the sweet potato cultivation technique used in the high altitude agro-ecological zones.

• Tethering of pigs in gardens is common practice in the highlands agro-ecological zone region. This process turns the soil over, remove weeds and improve soil fertility with their dung and urine.

• In the highlands agro-ecological zone, people construct barriers such as pegged logs, fences or hurdles and stonewall along the contour or below individual plants in order to prevent or reduce soil erosion.

• Most areas throughout the lowlands and highland agro- ecological zones in the country are using organic/natural fer­ tilizer in their gardens to increase soil fertility. This includes ash from fires, kitchen scraps, other plant wastes and animal manure.

• Already many emi-commercial farmers throughout the highlands agro-ecological zones in the country are using inorganic fertilizers on food crops that are sold.

• There is recycling of wastes to improve soil fertility and food production. Three or four of the plant nutrient management techniques commonly used are crop rotation, tilling soil and making drains, introducing new crops and use of animal manures and plant residues.

• There was restructuring of the National Department of Agriculture and Livestock. The mandated research body for the country, National Agricultural Research Institute (NARI) emerged in 1997.

• There was a review on con­ servation farming trials in composting and cropping, long-term soil exhaustion and cropping cycle trials, green manuring, improved fallow and alley cropping trials, agro- forestry and soil fertility research programme initiated in 1990.

• A programme aims to integrate animals in the current cropping system to improve and maintain soil fertility.

• An outreach and liaison com­ ponent was also established to disseminate released tech­ nologies and information to farmers.

• The indigenous knowledge and skills is well established in the subsistence farmers in PNG. People understand it as the best available method and they cannot easily accept and adopt new ideas.

• More research in developing technologies that are practical to farmers and more on cost benefit analysis of available plant nutrient application technique must be available to assist the farmers to make decision.

• Involving farmers in the research process so that farmers will be in a better position to make decision.

Lessons learned and experiences

Technical, policy measures

Constraints

• The country’s agricultural systems followed a very distinct policy-driven development characterized by increasing conflict caused by increasing population and inability to relate sustainable development of agriculture with urban and industrial development needs.

• The four decades of agricultural development in the Philippines is marked by mixed results of policy conflict, lack of continuity in programme implementation, and low public investments in targeted agricultural researches and technology development.

• An FAO-sponsored study showed that the incremental value of micronutrients, par- ticularly zinc for paddy rice, has been overlooked resulting to low yields in the entire decade of 1970-80, despite the marked investments on irrigation facili­ ties, high yielding varieties and a year-to-year dedicated national rice and corn production programme.

• Fast-tracked dissemination of information and knowledge of organic-based agriculture through establishment of nationwide network of large- scale technology demonstrations.

• Formal acceptance and imple­ mentation of Balanced Ferti­ lization Strategy (BFS) in 1997 through a Presidential Proclamation providing the legal and institutional basis for the adoption of a science-based organic farming which focused on the use of cost-efficient and location-specific and proper combinations of organic and inorganic fertilizers to sustain the increases in rice productivity.

• Reformulation of the BFS fertilizer recommendation leading to “Tipid Abono” or Optimally Reduced Fertilization Programme in 2004 to further reduce the fertilizer cost by increasing the portion of organic fertilizers at the rate of 70% organic fertilizers and 30% chemical fertilizers.

• Implementation of a nationwide programme funded by the Japanese government called “Agri-Kalikasan”, an organic- based agriculture develop­ ment programme which aims to ensure the long-term capacity of the natural resources base to sustain the economic, social and environmental services of the various agricultural lands of the country.

Lessons learned and experiences

Technology, policy measures

Constraints

• The productivity of major cereal crops, except maize and millet, and horticultural crops are far below compared with other countries due to land degradation caused by erosion, inadequate plant nutrient supply and poor quality of seeds.

• The various sources of plant nutrients in the Nepalese farming system have mainly depended on forest litters and livestock (farmyard manure) until the introduction of mineral/chemical fertilizer that gradually became the major source of nutrients. This has increased the demand vis-à-vis import rate of chemical fertilizer despite the limited purchasing capacity of the farmers

• Before the inception of the current government policy, Agriculture Perspective Plan (APP) was in place exclusively aimed to accelerate the agri­ culture economic growth. APP put emphasis on irrigation and use of chemical fertilizers in high production potential areas. This raised environmental effect on soil health.

• Deficiency of micronutrients especially zinc, boron and molybdenum is increasing at different ecological belts at varying intensity.

• Site-specific fertilizer recom­ mendation has been made for important crops but farmers deviate and use their own rate of fertilizer.

• The poultry industry is coming up as an attractive entrepreneur in the road access areas and farmers have discovered chicken dung as a new source of plant nutrients and are now used for maize and potato.

• Field research conducted on various cropping patterns indicated that integrated use of organic and inorganic sources of plant nutrients is the most sustainable nutrient management. The crop productivity has been found quite encouraging.

• The efficient use of inoculants in the farmers’ field increased the production of major summer and winter legumes crops such as soybean and lentil.

• Adoption of Rhizobium culture for different leguminous crops is on high demand. Since government agencies have not been able to meet the demand, private sectors are encouraged to do this job.

• Government lifting of the single door system of importing chemical fertilizers brought a free and healthy competition in the market. The government has put subsidy in transportation of the fertilizers and provided improved seeds to 26 very remote districts to support the food security.

• Application of cost-saving technology, the “Zero/minimum tillage Resource Conserving Technology (RCT)”, in rice- wheat combination to properly utilize the moisture had resulted to higher productivity.

• The SALT technology has been tested and found potential to reduce run off and soil loss and also provide fodder and biomass for various purposes

• Inclusion of Legumes in crop rotation due to its N-fixing property. Currently, Soil Science Division has identified effective strains of the most legume crops.

• Unavailability of appropriate technology, rain water erosion in the hills/mountains, nutrient mining, and increasing cropping intensities without judicious fertilization application have been the major technical pro­ blems. Small land holding, subsistence farming and poverty are social constraints.

• Weak adoption of green manuring despite its positive effects on crop production due to labour requirements, mechanization and other social factors

• Inaccessibility of hilly areas restricts the use of chemical fertilizers, hence, compost and farmyard manure are still the major sources of plant nutrients. The continuous production and proper management of compost or farmyard manure would be the priority in the hilly areas.

• Failure to record the knowledge and experience of women in soil fertility/plant nutrient man­ agement practices. It is well emphasized that their overall contribution in agriculture is very high particularly in compost preparation and application of the same in the field which is solely the work of women in Nepal

• Organic farming is one of the policies of the government under the competitive and commercialization agriculture. However, guidelines are not available for the production of organic produce.

• Slow or weak spread and adoption of technologies due to poor planning processes and setting priority. NARC recognizes that the first step would be to strengthen the planning processes.

Lessons learned and experiences

Technical, policy measures

Constraints

• Fertilizers necessary for the cultivation of food crops are imported, mostly Urea, Sulphate of Ammonia, Triplesuper- phosphate (TSP) and Muriate of Potash (MOP), either in straight form or as mixtures.

• The total quantity of fertilizer imported in 2002 was about 568 072 mt, and Urea is the fertilizer ingredient imported in the largest quantity accounting for just over 59%.

• The subsidy scheme is confined to Urea fertilizer only, resulting to a substantial increase in demand for Urea, and a reduc­ tion in use of P&K fertilizers.

• Production of SSP using local rock phosphate “Eppawala rock phosphate” has been done to counteract the price factor of P and K fertilizer. This will be an important step because phosphorus is the most limiting plant nutrient in majority of soils found in Sri Lanka. Besides, many food crops are very sensitive to P as they remove considerable amount of P during their growing period.

• The Ministry of Agriculture and the Department of Agriculture made a policy decision to pro­ mote Integrated Plant Nutrient System (IPNS) among farmers. This technology showed eco­ nomical benefits and soil fertility improvement in relation to many food crops grown in Sri Lanka.

• Decrease of organic matter, acidification, soil fertility depletion, soil erosion, iron toxicity in paddy fields, etc. have been identified as the main production constraints.

Lessons learned and experiences

Technical, policy measures

Constraints

• Yield of the main crops like rice, maize, and sugarcane somewhat increased, which were likely caused by the use of high yielding crop varieties or better irrigation/water management, rather than due to soil improve­ ment methods.

• Increasing yield, on the other hand, means more nutrients were removed from soil if the nutrient input rate remains the same.

• Compared to the total of 3,939,376 tonnes of imported chemical fertilizers in 2004, imbalance between nutrient losses by crop removal or other losses still overwhelm gaining by fertilizer application or other soil improvement.

• Conventional agricultural prac­ tices, such as burning of rice straw, accelerate the soil nutrient depletion and nutrient im­ balance, considering that the nutrients remaining in crop residues are not incorporated back into the soil.

• Thai national strategies are now moving towards improvement of agricultural resources such as “National Agenda on Organic Agriculture” strategy and al­ leviation of the drought pro­ blem with “Water Management Modernization” mega-project.

• The intensive nutrient man-agements for crop production such as site specific nutrient management or precision agri­ culture are also studied in some economic crops, for the integrated nutrient management in Thailand.

• The method uses decision support system based on fertilizer application experiments, soil and weather information, maize information, site-specific soil information including soil series, soil pH, N, P, K, simplified techniques and simplified soil test kits.

• Precision agriculture is another example in the integrated technologies for nutrient man­ agement in crop production, tested in sugarcane, which incorporates global positioning system (GPS), geographical information system (GIS), fertilizer application experiments, and variable fertilizer applicator system for precise fertilizer application.

Lessons learned and experiences

Technical, policy measures

Constraints

• The promotion of Integrated Plant Nutrition System (IPNS) for adoption by the farmers is a clear indication of addressing the factors that need to be addressed, particularly soil fertility.

• The Participatory Extension Approach (PEA) proved to be the most effective and productive method of advocating the adoption of IPNS based on several studies and researches.

• The PEA operates in a systematic manner involving the identi­ fication and active involvement of all stakeholders, conduct of networking activities, cross visits, technology demon­ strations, among others.

• The core farm villages established by the farmers themselves incorporate all aspects of PEA, and serve as nuclei for networking through farmer-to-farmer approach.

• As a result, more farmers become involved in the process of identifying solutions to their existing problems and formulating site-specific re­ commendations with the help and guidance of their respective extension workers.

• The presence of a decision support system greatly helped in the widespread adoption of the technology.

• The key concepts of PEA are empowerment of extension officers and farmers; parti­ cipatory manner; networking system, and monioring and assessment of the programme.

• Inappropriate soil organic matter management, unbalanced plant nutrient input and removal from soil, high cost of inputs, and drought in rainfed areas.

• Insufficient supply of legume seeds for green manure and lack of effective rhizobium strains for legume inoculation.

Lessons learned and experiences

Technical, policy measures

Constraints

• Shifting cultivation is being practiced for the indigenous species intended as food and cash crops, while green revolution technologies in­ volving mechanical tillage, use of fertilizer and pesticide on a monocrop base are being followed for the production of major crop for export.

• Export of squash which started in 1987 resulted to an enormous increase in fertilizer con­ sumption and a three-fold increase in the cropped area in the main island of Tongatapu.

• The Ministry of Agriculture issues recommended fertilization rates.

• The soil and plant analysis service provided by the Ministry of Agriculture costing about USD10.00 per sample is only being availed of by few squash companies.

• Technical researches such as on INM and disseminating information to farmers are among the responsibilities of the Research and Extension Division of the Ministry of Agriculture.

• Several key projects funded by the European Union and the Secretariat of South Pacific Commission are being im­ plemented in answer to the call from the UN summit on Sustainable Development in Johannesburg in September 2002.

• Several concerns such as scarcity of resources, large population, and even land tenure regulations are yet to be properly addressed.

Lessons learned and experiences

Technical, policy measures

Constraints

• Contributing to the increased yield were the widespread adoption and use of improved, high yielding varieties, better irrigation, plant protection, together with inputs of fertilizer.

• Use of crop residue or crop residue with suitable rate of chemical fertilizers seems to be more efficient compared to that of not using crop residues.

• Crop residue management is a subject of study and practice in Viet Nam especially for the sloping area and degraded soil (Acrisols).

• Crop rotation of four annual crops, spring rice, summer soybean, late summer rice and winter potato, respectively, was conducted on degraded soil in Bacgiang province (north Viet Nam).