999 resultados para Agriculture biologique


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A realistic alternative to traditional technology development and transfer has been utilized by the International Center for Living Aquatic Resources Management (ICLARM) to integrate pond fish culture into low-input farming systems in Malawi. Resource mapping was used to assess farm resources and constraints and introduce the concept of integrated resource management (IRM), the synergistic movement of resources between and among farm and household enterprises. Farmer-led IRM research projects are conducted on-farm and monitored by researchers through direct observation and on-station simulation of constraints and management practices. Technology-adoption rates by farmers involved in a pilot activity was 65% compared to 0% by farmers exposed only to top-down extension approaches. Within two years of adoption, every participating farmer had transferred the technology to an average of four other farmers without the involvement of the extension services.

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ICLARM introduced integrated aquaculture-agriculture (IAA) in Sakata, Malawi three years ago. Since that time, and without extension support, the number of farmers with ponds increased from 4 in 1993/94 to 12 in 1995/96. To learn why and how IAA is spreading, a study of impact and adoption was conducted in the 1995/96 production season. Interviews were conducted with farmers to discuss lAA and collect data on farm function through the use of bioresource flow diagrams. Motivations given by farmers as to why they adopted IAA were to improve household nutrition and income. Constraints to adoption identified by farmers were availability of labor and capital to purchase inputs

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This report is a contribution to an assessment of the current status of agriculture in Cambodia, focusing on the linkages between agriculture and water, mainly in the form of irrigation. It seeks to view current government policies on agriculture and irrigation in the context of experiences on the ground, as communicated through the many field studies that cover varied aspects of performance in the agriculture sector and irrigation schemes. In an effort to identify future research areas, this review examines the status quo, and connects or disconnects with stated policy through a broad lens to capture strengths and challenges across crop production, irrigation management and post-harvest contexts. It places irrigation under scrutiny in terms of its value as a major area of government expenditure in recent years, and asks whether it presents the best potential for future gains in productivity, when compared with the prospects offered by investments in other aspects of agriculture. The fieldwork and review of current literature that form the basis of this report were undertaken at the request of, and partly funded by, the Australian Centre for International Agricultural Research (ACIAR). It is also intended to contribute knowledge to the CGIAR Research Program on Aquatic Agricultural Systems (AAS) led by WorldFish, who co-funded the activities.

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The Census has been undertaken by the Department of Agriculture in conjunction with the Statistics Division of the Ministry of Planning and Community Development with technical assistance, in the form of experts and equipment, from the Food and Agriculture Organisation of the United Nations.

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In the present paper, sorption, persistence, and leaching behavior of three microcystin variants in Chinese agriculture soils were examined. Based on this study, the values of capacity factor and slope for three MCs variants in three soils ranged from 0.69 to 6.00, and 1.01 to 1.54, respectively. The adsorption of MCs in the soils decreased in the following order: RR > Dha(7) LR > LR. Furthermore, for each MC variant in the three soils, the adsorption rate in the soils decreased in the following order: soil A > soil C > soil B. The calculated half-time ranged between 7.9 and 17.8 days for MC-RR, 6.0-17.1 days for MC-LR, and 7.1-10.2 days for MC-Dha(7) LR. Results from leaching experiments demonstrated that recoveries of toxins in leachates ranged from 0-16.7% for RR, 73.2-88.9% for LR, and 8.9-73.1% for Dha 7 LR. The GUS value ranged from 1.48 to 2.06 for RR, 1.82-2.88 for LR, and 1.76-2.09 for Dha(7) LR. Results demonstrated the use of cyanobacterial collections as plant fertilizer is likely to be unsafe in soils. (c) 2006 Elsevier Ltd. All rights reserved.

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The contamination and distribution of polychlorinated dibeinizo-p-dioxins and dibenzofurans (PCDD/Fs) from two agricultural fields of a heavily polluted lake area in China (Ya-Er Lake) are presented. The vertical distribution pattern of total PCDD/Fs in soil cores reveals that the maximum concentration was in the layer of 20-30 cm. The concentrations in the top layer of soil at the two sites were similar (17.48 ng/kg at Site 1 and 18.10 ng/kg at Site 2), but the maximum concentration of Site 1 (120.8 ng/kg) was two times higher than that of Site 2 (64.39 ng/kg). The maximum concentration of PCDD/Fs in mud cores in rice fields (0-50 cm) at Sites 1 and 2 was in the layer of 0-10 cm. The maximum PCDD/F concentration in the top layer in mud at Site 1 (203.1 ng/kg) was higher than that at Site 2: (143.3 ng/kg). Significant correlations were found between the mind PCDD/Fs and the organic carbon content (R = 0.9743, P< 0,05 at Site 1; R = 0.9821, P< 0.05 at Site 2), the two variables being highly correlated (R = 0.9049, P< 0.05, at Site 1; R = 0.9916, P< 0.05 at Site 2). All correlation coefficients were significant at the 95% level. Concentrations were highly correlated with organic carbon, indicating that sorption to organic carbon was the dominant mechanism. Using principal component analysis, the homologue profiles of soil, mud, and plants (rice and radish) were compared. The PCDD/F patterns in plants were found not to be correlated to those in soil and mud. This suggests that atmospheric deposition may be the main source of PCDD/Fs in rice grain. However, mixed exposure involving uptake mechanisms and atmospheric deposition is considered main the source of PCDD/F pollution in radishes. (C) 2002 Elsevier Science (USA).

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