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Resource management in rice systems nutrientsBook out of print
RESOURCE MANAGEMENT IN RICE SYSTEMS: NUTRIENTS A joint publication of IRRI and Kluwer Academic Publishers Edited by V. Balasubramanian, J.K. Ladha, and G.L. Denning Strategies for nutrient management in irrigated and rainfed lowland rice systems A. DOBERMANN1 and P. F. WHITE2 1 International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines 2 Cambodia-IRRI-Australia Project, P.O. Box 1, Phnom Penh, Cambodia Attaining maximum economical yield is the priority of irrigated rice farmers. Current fertilizer management practices in intensive, irrigated rice systems are, however, not tailored to the large between-field differences in indigenous nutrient supply and crop demand. Substantial improvements in nutrient use efficiency and economic performance will require a site-specific nutrient management (SSNM) approach. The major components of a field-specific, knowledge-based strategy are quantification of crop nutrient requirements based on nutrient interactions and economic yield target; measurement of potential N, P, and K supply; and monitoring of plant N status to optimize N nutrition. Recent research has provided many of the practical tools needed, but they need further refinement and have to be applied in an integrated manner. Because of often poor soils, high degree of spatial variability of soils, spatial and temporal variability of water availability, high risk of crop failure, and fewer resources for capital expenditure, rainfed lowland rice farmers give priority to reducing risk. Farmers' ability to invest in cost-intensive innovative technologies is limited. As a consequence, the range of technologies likely to be adopted by rainfed lowland farmers is restricted. Farmers' knowledge and experience become vital for the efficient management of nutrients in these environments. We discuss the nutrient management strategy that is being developed for Cambodia. Technologies are generated and tested through research at selected representative sites. Technologies are extrapolated and applied through a new agronomic soil classification and probabilistic modeling that integrates farmer's knowledge and experience with empirical data generated from the research sites. V. BALASUBRAMANIAN International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines Generally, agricultural research is conducted under the controlled conditions of research stations which, in many cases, do not represent farmers' circumstances. Thus, several technologies do not perform well in farmers' fields and so are not adopted by farmers. Many technical factors and management practices constrain the adoption of improved technologies including efficient N management techniques: (a) poor water control; (b) low plant population; (c) partial nutrient application; (d) insufficient weed control; (e) untimely sowing, transplanting, weeding, and/or harvesting; and (f) poor postharvest processing. Unless farmers improve many, if not all, of these conditions, they cannot reap the full benefits of modern rice varieties and related production technologies. In addition, soil-related constraints such as high spatial and temporal variability in nutrient status, nutrient imbalance, poor drainage, soil degradation (salinity, alkalinity, acidity), and subsoil compaction lessen the effectiveness of nutrient management techniques. Similarly, climatic factors such as variable and unpredictable rainfall, drought, flood, low radiation, and extremes in temperature affect crop growth and nutrient use in rice systems. Most of these factors are beyond farmers' control. Stress-tolerant rice varieties and improved management practices are being developed and evaluated on rice farms to tackle soil and climatic constraints, especially in rainfed lowland rice systems. Two of the management strategies rely on better N placement techniques and use of controlled-release fertilizers to improve nutrient use efficiency in rainfed lowlands. Some tools for site-specific N management in rice include the chlorophyll meter and the leaf color chart which are being evaluated on farmers' fields. Another strategy is integrated nutrient management to enhance crop nutrition and minimize fertilizer costs. Adequate farmer training is needed to receive, process, and effectively exploit improved rice varieties and related information, knowledge, and technologies. The role of legume fallows in intensified upland rice-based systems of West Africa M. BECKER and D. JOHNSON West Africa Rice Development Association (WARDA), BP 2551 Bouaké 01, Côte d'Ivoire Traditional upland rice-based cropping systems in West Africa rely on periods of fallow to restore soil fertility and prevent the buildup of insect pests and weeds. Demographic growth and increased demand for land are forcing many farmers to intensify their rice production systems. Declining fallow length and increasing number of crops before leaving the land to extended fallow significantly reduce yield. Promising cropping system options include the use of site-specific, weed-suppressing, multipurpose cover legumes as short-duration fallows. Poor adoption of legume technology and the near complete absence of research on fallow management in the extremely diverse upland rice-based systems of West Africa require a multiscale approach for generating and extrapolating fallow technology. Constraints to rice production and the yield gaps related to intensification were determined in 190 farmers' fields in three agroecological zones (farm-level). Nitrogen accumulation and weed suppression were evaluated in 54 legume accessions grown for 6 months during the dry season, under a range of hydrological and soil conditions (plot level). To increase benefits from improved fallow technology, the timing of legume establishment in relation to rice and the effect of removing, burning, mulching, or incorporating fallow residues before the rice crop on crop and weed growth were determined. Farmers' reaction to improved legume fallows was evaluated in group interviews. Best-bet technologies for given rice-based systems are being evaluated at the village level throughout the region in the framework of a regional research network (Rice Cropping Systems Task Force). Legume fallows appear to offer the potential to sustain rice yields under intensified cropping. Absolute effects varied as a function of site, legume species, and management practice. Weed control and multiple-use options are important determinants of potential legume technology adoption. Preferences for various legume phenotypes and management practices depend on farmers' resources and the production system. O. CHR. BØCKMAN1, M. LÆGREID1, and S. NYVOLD2 1 Norsk Hydro ASA, The Research Centre, N-3901 Porsgrunn, Norway 2 Norsk Hydro ASA, N-0240 Oslo, Norway The predicted increase in human population implies that agricultural yields must be sustainably increased and crops adequately supplied with plant nutrients. Raw materials for fertilizers and soil amendments differ in quality. The use of local resources should increase in importance, but global scarcities are not expected within the next generation. Because of variations in climate, soil fertility, and crop requirements, the need for nutrients varies. The need for external supplies is usually limited to a few elements: N, P, K and sometimes S, Mg, Zn, and B. However, variations in needs are so extensive that a single or a few formulations cannot adequately cover all the requirements and conditions. Quantifying local needs and fitting formulations to these is one of the challenges that must be addressed in nutrient management. A further challenge is the development of appropriate systems and physical product characteristics to suit special conditions, e.g., soils with a low cation exchange capacity, or areas with high rainfall intensity. Ways to increase the plant uptake of applied nutrients to minimize losses, and to maximize crop's ability to resist stresses such as drought and diseases through appropriate nutrition, must be found. However, chemical reactivity and economic considerations restrict the options available to the formulator. Production, packaging, transport and distribution costs, and farm-level realities also set practical limits to the range of formulations that can be supplied. Further, marketing and promotion must be tailored to the social and economic realities of farmers. A strategy for addressing all these issues implies a close cooperation among fertilizer producers, distributors, financial institutions, state and local authorities, plant breeders, soil and crop scientists, advisors, and finally -- the most important persons in food production --the farmers themselves. Although appropriate product formulation is important, the main strategic challenge is to integrate all the participants in food production into a harmonious working relationship which is profitable to all. Increasing the impact of public-sector agricultural engineering research, development, and transfer B. DOUTHWAITE International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines Public-sector agricultural engineering has a vital role in compensating for the externalities and market failures that cause the poor supply of agro-mechanical technologies to small-area rice farmers in Southeast Asia. A review of literature suggests that public-sector agricultural engineering is constrained in meeting farmers' needs because of the "top-down" and linear approach it adopts to the research, development, and transfer (RDT) of technology. This paper analyzes the RDT processes for three technologies which the public sector has been involved. For the three case studies, the RDT processes are clearly nonlinear, viz. iterative, participatory, and evolutionary. However, this is not usually reflected in the public sector planning of RDT, which is assumed linear. As a result, public-sector participation is inadequate or missing at critical intervention points. A rethink of the way the public sector carries out the RDT of agro-mechanical technology is needed, based on a good understanding of the processes of technology change in South East Asian ricefields. The paper shows that analysis and documentation of RDT process can contribute to this understanding. D. C. OLK1, K. G. CASSMAN2, G. SIMBAHAN1, P. C. STA. CRUZ1,3, S. ABDULRACHMAN4, R. NAGARAJAN5, PHAM SY TAN6, and S. SATAWATHANANONT7 1 International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines 2 Department of Agronomy; University of Nebraska, P.O. Box 830915, Lincoln, Nebraska, 68583-0915, USA 3 Philippine Rice Research Institute, Maligaya, Muñoz, Nueva Ecija, Philippines 4 Research Institute for Rice, Jl. Raya No. 9, Sukamandi 41256, Subang, West Java, Indonesia 5 Tamil Nadu Rice Research Institute, Aduthurai 612101, Tamil Nadu, India 6 Division of Agronomy, Cuu Long Delta Rice Research Institute, Omon, Can Tho, Vietnam 7 Pathum Thani Rice Research Center, Thanyaburi, Pathum Thani 12110, Thailand Although efficient use of N remains a critical constraint to productivity in irrigated lowland rice, a comprehensive database does not exist for the efficiency of on-farm management of N and other nutrients. In 1994, IRRI initiated its Mega Project on Reversing Trends of Declining Productivity in Intensive Irrigated Rice Systems in selected rice production domains of five tropical Asian nations to improve on-farm fertilizer-use efficiency and to monitor long-term productivity trends as related to fertilizers and other inputs. Data are reported here for the first crop cycle, the 1994-95 dry season. The indigenous soil N supply (INS) was estimated by aboveground crop N uptake and grain yield (GY) in plots without applied N established in farmers' fields under otherwise favorable growth conditions. The fertilizer N rate each farmer applied to his/her field surrounding these plots was recorded; GY was also measured in that area. In each domain, GY in unfertilized plots varied considerably among farms, as the range between maximum and minimum values within each domain was at least 2.8 t ha-1, thus of comparable magnitude to mean GY for these plots. Fertilizer N rates varied from 36-246 kg ha-1 across all domains, but their lack of relationship to INS contributed to relatively low fertilizer N efficiency and high variability in efficiency among farms. Mean agronomic efficiency (D GY/applied N rate) for each domain was only 6-15 kg grain kg-1 N, while values for individual farmers ranged from 0 to 59 kg grain kg-1 N. Initial data on P and K fertilizer management also suggest highly variable applications at suboptimal efficiency. These results indicate the potential for greater fertilizer efficiency from improved congruence between the indigenous soil supply and applied fertilizer, and emphasize the need for field-specific nutrient management. Although agronomic efficiency and partial factor productivity (GY/applied N rate) can each be used to describe the efficiency of fertilizer applications, a complete analysis of nutrient management should include both terms, grain yield, fertilizer rates, and native soil fertility. A. DIMYATI1 and A. SURYANA2 1 Assessment Institute for Agricultural Technology (AIAT), Lembang 2 Center for Agricultural and Socio-economic Research (CASER), Bogor, Indonesia There have been widespread complaints that agricultural research in Indonesia does not properly address farmers' problems and that technology transfer is slow because of weak linkage among research, extension, and users. To rectify this situation, farm trials and demonstrations involving researchers, extension workers, officials from agriculture-related offices, and farmers have been conducted. These efforts resulted in the creation of 17 Assessment Institutes for Agricultural Technology (AIAT) covering the 27 provinces in the country in April 1995. These institutes are tasked with doing research on location-specific agricultural technologies, gathering and channeling feedback from clients to researchers to improve agricultural research programs, and disseminating research results as extension material. AIAT's main strength is the integration of researchers and extension personnel under one umbrella at the provincial level. New mechanisms and institutional linkages for generating, evaluating, adapting, and applying location-specific agricultural technologies have been installed. A new paradigm adopting a participatory bottom-up planning approach is being implemented. A number of operational instruments such as implementing guidelines, innovative research methods, and protocols for enhancing users' participation in research activities should be continuously developed. The implications of the new approaches on various research management issues are discussed. A case of technology adaptation and promotion by AIAT through an assessment of a rice-based farming system with agribusiness orientation is described. G. L. DENNING and M. A. BELL International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines Publicly funded agricultural research institutions must increasingly generate impact and demonstrate accountability to a diversity of stakeholders. Drawing on experience at IRRI, the International Maize and Wheat Improvement Center (CIMMYT), and national agricultural research programs, the authors propose a "High impact strategy" framework, which is simplified in terms of 5 "Ps": roactivity, Purpose, Priorities, Partnerships, and People. With personnel and institutional commitment to the 5 "Ps", agricultural research can generate high impact, which is crucial to attracting and maintaining financial and political support to research. B. P. GOVIL and V. KUMAR Indian Farmers Fertilizer Cooperative Ltd. (IFFCO), 53-54, Nehru Place, New Delhi - 110 019, India Although fertilizers have played a pivotal role in increasing the productivity of rice in India, the utilization efficiency of applied plant nutrients has been a matter of concern. The Indian Farmers Fertilizer Cooperative Ltd. (IFFCO), the largest fertilizer cooperative in India, is helping farmers in identifying relevant fertilizer use technology and its field application. Field demonstrations have, by and large, proved to be the most successful activity, followed by village-level farmers' meetings, field days on demonstration plots, and crop seminars before the start of the season. Distribution of minikits containing critical inputs to small and marginal farmers in adopted villages has immensely helped farmers. IFFCO's lab-to-land program adopted in selected rice growing blocks of Uttar Pradesh has been successful. IFFCO's trials on urea supergranules (USG) have yielded useful information. The USG technology is on the threshold of adoption. Likewise, soil fertilizer trials, integrated plant nutrient system (IPNS) trials, maximum yield research trials, and biofertilizer demonstrations conducted under "on-farm" conditions have convinced a large group of farmers of the importance of soil testing and applying plant nutrients on the basis of the IPNS approach. J. A. ASHBY1, T. GRACIA2, M. DEL PILAR GUERRERO2, C. A. QUIROS2, J. I. ROA2, J. I. ROA2, J. A. BELTRAN2 1 IFPRI, Washington, DC, USA. 2 Hillsides Agro-ecosystem Program, IPRA Project, CIAT, Cali, Colombia Experimenting farmers are an important resource in on-farm testing, adaptation, and dissemination of new technologies, especially in resource-poor, highly heterogeneous areas . In Southern Colombia, farmers' research committees (Comites de Investigacion Agropecuaria Local or CIAL) were formed and used to mobilize local leadership among farmers to take responsibility for experimenting with technologies not known in their community. The CIALs were trained in participatory diagnosis and problem definition, planning and evaluation, and, ultimately, monitoring of adaptive technology testing and dissemination. It is possible to institutionalize this responsibility with farmers who often provide "hard-data" from farmer-managed adaptive research. Results show that current costs and coverage of CIAL approach compare favorably with some state or private sector systems, although the basis for comparison is very limited. A favorable cost structure is clearly related to the demonstrated effectiveness of paraprofessionals such as support-farmers, for scaling up and for achieving devolution. H. B. GURUNG, K.B. KADAYAT, R. P. SAH, and A. K. VAIDYA Lumle Agricultural Research Center (LARC), Pokhara, Nepal Rice research in Nepal started in 1951, although a systematic coordinated national research program was initiated only in 1972. Outreach research (OR) started in the mid-1950s when japonica varieties were evaluated in farmers' fields. A formal outreach OR program started with the inception of coordinated commodity programs in 1972 and a more systematic approach developed by the Integrated Cereals Project in 1977 when the Central Agronomy Division conducted on-farm research in six field research sites representing different agroecological environments. In 1985, a Central Farming Systems (FS) Division was established to conduct FS research, which was reorganized into Central FS and OR Division in 1990. This was dissolved in 1992 to form the Coordination and Special Projects Division which was again dissolved in 1994 to form a new Central OR Division. Until 1990, OR was largely designed, managed, and implemented centrally by a central division or a commodity program. Now, however, the Nepal Agricultural Research Council (NARC) conducts OR through its network of research stations in OR sites. Two major problems with OR in Nepal have been the lack of stability--i.e., the OR structure underwent several changes--and the lack of adequate OR policy guidelines and their implementation. Although a better OR structure is in place now, it still suffers from several deficiencies: use of conventional approaches to research, inadequate farmers' participation, and an almost nonexistent research-extension linkage. To be effective, structural reorganization, both in research and extension, must accommodate OR in the organogram as an important function to facilitate research-extension linkage, and it must include training and information functions at the regional station level to improve information flow and dissemination. It is essential that the research system effectively implement OR policy and operational guidelines, conduct interdisciplinary research programs, and enhance farmer participatory approaches to diagnosis and research. South-South cooperation: Indonesian apprenticeship program for African rice farmers A. S. MARTAAMIDJAJA1 and H. ANWARHAN2 1 Agency for Agricultural Education and Training (AAET), Ministry of Agriculture, Jakarta, Indonesia 2 Central Research Institute for Food Crops (CRIFC), Bogor, Indonesia The success of Indonesia in achieving rice self-sufficiency in 1984 motivated Indonesian farmers to share the fortune with their fellow African farmers who suffer from drought and food shortage. A fund amounting to an equivalent value of 100,150 tons of rice was raised and donated to needy farmers in several African countries. The donation was at first given in cash through the FAO and later on, beginning 1990, was allotted in the form of technical assistance comprising an apprenticeship program in Indonesia and expert assistance to African countries. The goal of the apprenticeship program is to help African countries increase food production, particularly rice, by improving farmers' capabilities in applying proper cultivation technologies and sound farm-business management. As an educational process, this program provides selected African participants with practical learning experience through interaction with Indonesian host-farmers who serve as facilitators of learning in rice farming activities. In addition, the participants are given practical knowledge and skills through a structured training to complement the farmer-to-farmer learning process. Since 1990, eleven groups comprising a total of 163 apprentice-farmers from 14 countries have participated in the program. Many of them have successfully applied in their own farms what they have learned from Indonesian farmers. In the future, more farmers from many African countries will be invited to join the program, either in Indonesia or in the outreach training facilities to be established by the program in Tanzania and The Gambia. Broad-based evaluation showed that most participants regard their experience in both technical and social aspects as meaningful and useful. They also expressed their willingness to apply the technologies they have learned as well as share the experience with fellow farmers. The importance of thorough assessment of training needs, careful selection of host-farmers and field facilitators, clear information on the objectives and nature of the program to both prospective participants and host-farmers, and intensive supervision are some lessons learned by the organizers from six years of experience. The Ministry of Agriculture of the Republic of Indonesia and the Indonesia Agricultural Society Foundation (YAMPI) as organizers of the apprenticeship program pay serious attention to the quality improvement and the continuity of the program for the benefit of African farmers and the enhancement of South-South Cooperation. M. HOSSAIN1 and MD. S. ALAM2 1 International Rice Research Institute, P.O. Box 933, Manila, Philippines. 2 Grameen Krishi Foundation, College Road, Alamnagar, Rangpur, Bangladesh. The Grameen Bank of Bangladesh has developed a target group-oriented financial institution to provide credit to land-poor households so that they could generate self-employment in economic activities of their choice. Initially, the Bank basically financed nonfarm rural enterprises. But with increases in income, the land-poor borrowers of the bank got access to land through the tenancy market and became involved in crop production activities and contributed to growth in foodgrain production. The Grameen Bank attempt to increase food production by establishing an independent Krishi (Agriculture) Foundation for developing an efficient irrigation management system to promote modern agriculture by providing inputs in kind and management advice, in exchange for a share of the harvest. More than 95% of Grameen Bank borrowers are women. Since the Bank has already mobilized these socially disadvantaged groups in village-level associations, it will be easier to extend natural resource management and mechanical technologies to conserve natural resources, add value to rice production, and reduce the drudgery of women. From-research-to-farmer practice: A case study in rice pest management K. L. HEONG International Rice Research Institute, (IRRI), DAPO Box 7777, Metro Manila, Philippines. In Asian rice farmers' pest management, knowledge gaps between what farmers need to know and what they actually know are the main constraints, and pesticide misuse is due primarily to these gaps. Over the last two decades, changes in pest management decisions and practices of about 300 million rice farmers in Asia are hardly evident. Knowledge gaps may be due to lack of research or lack of synthesis of research results. Even when research is well targeted, the results may not be adopted because of delivery problems. To facilitate adoption, research must distill research results further, developing them into forms that can facilitate communication. In addition, research will need to investigate factors constraining adoption and explore the utility of communication methods and systems. This paper discusses a case study illustrating the continuum, from research to practice, in leaffolder management. Large proportions of farmers' insecticide sprays are directed at rice leaffolder. Research has shown, however, that these sprays are unnecessary and are, in fact detrimental to ecological balance causing secondary brown planthopper problems. Farmers spray for leaffolder control primarily due to misperception. A simple rule-of-thumb, or "heuristic," was distilled from years of research by many scientists: "In the first first 40 days after sowing, leaffolder control is not necessary." When presented to farmers, the heuristic can be easily transformed into a research question, which can be tested. When farmers were invited to participate in experiments to test this heuristic, most found no yield difference between pesticide-treated and untreated plots, changed their attitudes toward leaffolders, and stopped spraying to kill them. In a pilot project in Vietnam, various media materials were used to encourage farmers to test the heuristic. The target audience was 20,000 farm families in Long An Province. An evaluation conducted 16 months after the project was initiated showed that farmers' insecticide application dropped from 3-4 to 1-2. Perceptions of leaffolder damage and the need to spray early for control also changed. Front-line demonstrations for evaluating and promoting new technologies in rice systems in India K. KRISHNAIAH Directorate of Rice Research (DRR), Rajendranagar, Hyderabad 500030, India Rainfed rice systems in eastern India are characterized by low yields, low adoption of high-yielding varieties (HYVs), and low fertilizer use. This paper illustrates the role of front-line demonstrations in identifying and popularizing viable and suitable modern rice technologies among farmers in rainfed lowland ecology, under the direct supervision of scientists. Front-line demonstrations, initiated in eastern India in 1990, were also intended to supplement ongoing special rice development programs in identifying location-specific HYVs and related production technologies based on simultaneous on-farm evaluation and popularization in the targeted area. A total of 337 compact block front-line demonstrations covering 2,346 ha were organized across eastern India during the past 5 yr (1990-95). As many as 80 rice cultivars, along with improved crop management practices, have been demonstrated/verified in farmers' fields. About 40 HYVs were found suitable for various rainfed systems. The demonstrations proved that the availability of suitable HYVs is not a limiting factor for the enhancement of productivity in this region. Rough-rice yields of these HYVs under improved management ranged from 4.5 to 5.0 t ha-1 in shallow water (0-30 cm inundation), 3.0-3.5 t ha-1 in semideep water (30-50 cm inundation), and 2.0 - 3.0 t ha-1 in upland rainfed rice systems, as against 1.0-1.5, 1.0-1.3 and 0.9-1.2 t ha-1 for traditional varieties and management in the 3 ecosystems. Thus, front-line demonstrations identified appropriate HYVs plus management packages that could outyield local varieties + traditional practices by nearly 1.5-2.0 t ha-1 (60-150%). These yield gains on an average produced an additional household income of US$ 114 ha-1. Toward sustaining the nitrogen fertility of lowland rice soils: issues and options K. KUNDU1 and J. K. LADHA2 1 Directorate of Rice Research, Rajendranagar, Hyderabad 500030, India; and 2 International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines Stagnant or declining yields observed under intensive rice cropping with high levels of inorganic N fertilizers have raised concerns about the sustainability of such a production system. Long-term fertilizer experiments in India and the Philippines recorded declining N availability to lowland rice over the years, regardless of the changes in total N content in the soils. Total N content was sustained in soils constantly flooded or saturated, but it declined in soils subjected to alternate drying and flooding cycles. Obviously, N fertility of lowland soils is determined not only by N content but also by its transformations and associated factors that govern its uptake by plants. Recent research has identified several factors responsible for declining N content in rice lowlands: nitrate accumulation in soils through a nonflooded dry phase followed by its loss on reflooding, negligible return of crop residues to soil, neglecting the use of organic manures and symbiotic N2-fixing systems, and heavy loss of applied fertilizer N. Continuous flooding and intense puddling drastically reduce permeability, allow accumulation of reducing substances in the rhizosphere, and retard mineralization and plant uptake of N in some soils. Further, shallow tillage practiced in intensively cropped lowlands often reduces plow layer thickness (to <15 cm) and nutrient availability from subsoil layers. In this paper, we discuss these issues and suggest options to help sustain the N fertility of lowland rice soils. S. K. MOHANTY1, U. SINGH2, V. BALASUBRAMANIAN3 and K. P. JHA1 1 Central Rice Research Institute, Cuttack - 753006, Orissa, India 2 International Fertilizer Development Center - International Rice Research Institute Collaborative Program, DAPO Box 7777, Metro Manila, Philippines 3 International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines The recovery of applied nitrogen by rice is low due to several loss processes operating in the ricefields. Split application of fertilizer suggested for increasing nitrogen-use efficiency is often not practical in rainfed lowland rice due to adverse soil-water situations. Hence, the entire required amount of N has to be applied in one single application when the water regime is favorable. A single broadcast application, however, increases N loss. Deep placement of urea supergranules (USG) has been proven to improve N fertilizer efficiency. The placement technology is best suited to conditions where the predominant N loss mechanism is ammonia volatilization rather than leaching or denitrification. Deep placement of USG thus has greater benefit over surface split application on soils with moderate to heavy texture, low permeability and percolation rate, and high cation exchange capacity and pH. Environments and management factors conducive to high ammonia volatilization potential would benefit most from deep-placement technology. Improved N recovery and efficiency of USG has been well-documented for lowland rice, but its market availability and methods to achieve placement pose problems. The technology has very limited adoption because USG is not commercially available or manufactured in most countries, and labor requirement is high with hand placement. Manual application creates more difficulties in handling the granules, besides taking 36-42 more hours per hectare, than 2 split broadcast applications of prilled urea. Applicators developed so far have not worked satisfactorily under standing water conditions and in direct-seeded rice conditions due to hardness of the soil. Hence, it is necessary to develop a suitable applicator to overcome these difficulties. Alternatively, for direct-seeded rice, N-fertilizers can be subsoil-banded near seedrows. The placement technology, if adopted by the farmers of the potential lowland areas in eastern India, is expected to give an additional production of 5.6 million tons of rice. E. PASANDARAN1, B. GULTOM2, J. S. ADININGSIH3, HAPSARI1, and S. ROCHAYATI3 1 Center for Agricultural Research Programming; 2 Center for Agricultural Machinery Development; 3 Center for Soil and Agroclimatic Research, Agency for Agricultural Research and Development, Jakarta, Indonesia Broadcasting of prilled urea not only is technically inefficient (recovery rate is only 30% of applied N); it also causes a substantial monetary loss to farmers and a high environmental cost to society. Urea tablet deep-placement technology has shown a 25% saving in N fertilizer rates, an average increase of 400 kg ha-1 in rice yield, and a benefit-cost ratio of 4-15 in various on-station and on-farm trials in Indonesia. The technology was introduced and promoted in Java island in 1992. Hand applicators and deep-placement machines were introduced to ease the application of urea tablets. Both consumption and area coverage of urea tablets increased substantially from 1992 to 1995. Farmers recognize the economic advantage of deep placement of urea tablets, but they think that it is less practical and more labor-intensive than broadcasting of prilled urea. There are also problems of storage, distribution, and handling of urea tablets, though these can be technically overcome. Appropriate dissemination strategies and government policy support on pricing, coordination of various fertilizer industries and distributors, and credit are vital for promoting the urea tablet technology further. Soil and crop management technologies for enhancing rice production under micronutrient constraints P. SAVITHRI, R. PERUMAL, and R. NAGARAJAN Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore, India Micronutrient deficiency is considered as one of the major causes of the declining productivity trends observed in rice-growing countries. The submergence created for rice cultivation influences electrochemical and biochemical reactions, and alters pH, pCO2, and the concentration of certain ions. This environment increases the availability of Fe and Mn with concomitant decrease in Zn and Cu. It is well known that Zn deficiency is predominant in lowland ecosystems. Sodic and upland soils, and calcareous coarse-textured soils with low organic matter content suffer from Fe deficiency, besides Zn and Cu deficiencies. Rice cultivars do not experience deficiency of B and Mo. The acid soils and the low-lying, poorly drained alluvial and colluvial soils are prone to Fe toxicity. Experiments in different agroecological zones all over India showed that Zn doses to correct Zn deficiency varied from 2.5 to 22 kg ha-1; 5.3 kg Zn ha-1 proved optimum and economical, with a maximum rice yield increase of 4.8 t ha-1. In the lowland ecosystem, amending the soil with the required amount of Zn before transplanting was effective and easy to adopt, compared with repeated foliar sprays of (0.5%) ZnSO4 or use of Zn-enriched seedlings through seed soaking in (2-4%) ZnSO4 solution, fertilizing the nursery with Zn, or seedling root dipping in 2% ZnO slurry. Hepta, as well as monohydrated ZnSO4, was better than other sources of Zn (ZnO, ZnCl2 and Zn frits). The Zn-blended diammonium phosphate (Zn-DAP), superphosphate, and nitrophosphates also proved effective. The Zn-enriched organic manures (FYM, greenleaf manure, and coir pith compost) were found advantageous for the direct and residual crops. Zinc fertilization with an optimal dose of 25 kg ZnSO4 ha-1 once a year yielded high economic return. A differential response of rice up to a maximum increase in yield of 4.8 t ha-1 was observed with the foliar spray (1-2% FeSO4 solution) or soil incorporation of Fe (50 kg FeSO4 ha-1) with bulky organic manure (12.5 t ha-1). The application of 12.5 kg CuSO4 ha-1 ameliorated Cu deficiency and significantly enhanced rice production. Management strategies such as liming and additional multinutrient supply (P, K, Mg, Zn, Cu and B), besides improving drainage, enhanced the rice productivity of soils prone to Fe toxicity by correcting the multinutrient deficiency syndrome. S. PANDEY International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines When semidwarf, fertilizer-responsive varieties became available in the late 1960s, a range of policy and institutional changes were introduced to exploit the potential of these varieties. As a result, adoption of both high-yielding varieties and chemical fertilizers increased rapidly, especially in irrigated areas. A review of how these policy and institutional changes have influenced adoption of chemical fertilizers is presented using a microeconomic model of technology adoption. It is argued that fine-tuning of these policy and institutional innovations will continue to be important in further increasing rice yields and farmers' incomes, especially in rainfed areas where fertilizer use is still very low. In the more intensive irrigated areas, where chemical fertilizer use is already high, a change in the paradigm from that of encouraging higher input use to achieving increased input-use efficiency is suggested. Based on a conceptual model of the likely evolution of the nature of rice production systems in Asia, a somewhat targeted approach to the design of technological, policy, and institutional interventions for improving farmers' nutrient management practices is recommended. On-farm adaptation of knowledge-intensive nitrogen management technologies for rice systems V. BALASUBRAMANIAN1, A. C. MORALES1, R.T. CRUZ2, and S. ABDULRACHMAN3 1 International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines; 2 Philippine Rice Research Institute (PhilRice), Maligaya, Muñoz, Philippines; 3 Research Institute for Rice, Sukamandi 41256, Subang, West Java, Indonesia. Efficient use of all inputs is vital to achieve and sustain high crop yields, maintain resource quality, and minimize environmental pollution. Fertilizer N is one of the major inputs in rice production. Blanket fertilizer recommendations do not take into account the high field-to-field variability and within-season dynamic changes in indigenous N supply. Since the plant growth reflects the total N supply from all sources, plant N status will be a good indicator of N availability to crops at any given time. The chlorophyll meter (SPAD) and leaf color chart (LCC) are simple, portable diagnostic tools that can measure the crop N status in situ in rice fields to determine the timing of N topdressing. Such decision aids are useful to vary N application rates to rice crops, based on crop demand and indigenous N supply. Although the chlorophyll meter cannot be owned by individual farmers due to its high cost, it is a practically useful tool for field researchers, extension specialists, and crop consultants who do not have access to well-equipped laboratories. On-farm, adaptive research is in progress in 3 countries to adapt the chlorophyll meter technique for transplanted and wet-seeded rice, local cultivar groups, and soil, crop, and environmental conditions. Initial results indicate that the SPAD threshold value of 35 is good for transplanted rice in dry season. The threshold has to be reduced to 32 for wet-seeded rice in dry season and for all rice during wet season with cloudy weather and low radiation. Thus, when calibrated with local cultivar groups and crop conditions, it can be used to accurately monitor crop N status and to advise farmers on N topdressing for rice. It can also be used effectively to verify the adequacy of existing N fertilizer recommendations to rice by the in situ monitoring of foliar N status of crops fertilized with current recommendations and to refine them to further improve N fertilization of rice. The LCC is not as accurate as the chlorophyll meter in determining the leaf N status in rice crops. However, LCC can be calibrated with the chlorophyll meter to fix the critical color shade for local rice cultivar groups and crop conditions. Farmers can, then, use the LCC to qualitatively assess foliar N status and adjust N topdressing to their rice crops. Initial feedback on the use of LCC from farmer cooperators in the Philippines is highly encouraging. Both methods are affected by factors such as varietal group, plant density, crop stress that causes leaf chlorosis, soil nutrient status, and climate; therefore, they have to be adapted to specific soil, climatic, and crop conditions. Adequate training is necessary for both extension agents and farmers to properly use the new tools for increasing the efficiency N fertilizer use on rice. Wider farmer adoption of the two diagnostic tools discussed in this paper will minimize over-fertilization of rice, increase profitability, and decrease fertilizer-related pollution of the environment. Ecosystem analysis-based methodology for technology extrapolation V. P. SINGH1, V. Q. MINH2, A.N. SINGH,3 and S. P. KAM1 1 International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines 2 Soil Science Department, University of Cantho, Cantho, Vietnam 3 Uttar Pradesh Remote Sensing Application Center, Lucknow, India Agroecosystems analysis and GIS are used to delineate target domains for extrapolation of a given technology. Biophysical, socioeconomic, and policy requirements of a chosen technology should match with similar conditions of potential target areas for the technology to be extrapolated successfully in such areas. Technology extrapolation requires the knowledge about the technology, the experimental site characteristics, and the characteristics of potential target areas. In agroecosystem analysis, biophysical conditions of test sites can be characterized in greater detail and in quantitative terms, while those of larger target areas can be assessed only in broader, qualitative terms. Both spatial and temporal variabilities become significant as we move up the scale in the characterization. GIS is used to combine data sets from different sources and to overlay maps to develop suitability classes of target areas for the chosen technology and to identify technology application domains. Ground truthing and detailed on-farm studies are necessary to validate the final results. A case study of double rice cropping technology is presented to illustrate the procedure in characterizing the technology utilization requirements (TURs), analysis of target area qualities (TAQs), and matching TURs with TAQs to delineate potential target areas. Resource management options for upland areas of Indonesia Z. ZAINI and A. M. FAGI Central Research Institute for Food Crops, Bogor, Indonesia The upland areas in Indonesia are highly diverse and fragile. Appropriate measures of land clearing, reclamation, and conservation are the essential first steps for developing intensive and sustainable upland farming systems. Because upland environments are fragile, nutrient management should be an integral part of upland conservation farming. Low-cost technology is the most preferable choice because most farmers in upland areas are relatively poor. Hedgerow planting or alley cropping has several advantages and limitations. Incorporation of green manure derived from trees planted along the contour lines improved both physical and chemical properties of acid upland soils, and thus increased productivity. A combination of green manure, lime, and inorganic fertilizer applications sustained soil fertility and crop productivity. On the other hand, trees along the contour lines compete with seasonal crops planted in alleys between rows of tree crops for sunshine, water, and nutrients. Selection of appropriate tree crops is therefore important. A holistic approach must be followed in designing household farming systems. Contributions of livestock and estate crops to farm income were significant in settlement areas. Resource mapping and resource flow within household units have to be considered in establishing sustainable household farming systems. |
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Strategies for nutrient management in irrigated and rainfed lowland rice systems The role of legume fallows in intensified upland rice-based systems of West Africa Increasing impact of public-sector agricultural engineering research, development and transfer South-South cooperation: Indonesian apprenticeship program for African rice farmers From research to farmer practice: a case study in rice pest management Front-line demonstrations for evaluating and promoting new technologies in rice systems in India Toward sustaining the nitrogen fertility of lowland rice soils: issues and options Soil and crop management technologies for enhancing rice production under micronutrient constraints On-farm adaptation of knowledge-intensive nitrogen management technolgies for rice systems Ecosystem analysis-based methodology for technology extrapolation |
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