共查询到6条相似文献,搜索用时 0 毫秒
1.
《Soil Science and Plant Nutrition》2013,59(5):767-770
Sustainability of the local shifting cultivation practice in the mountainous region of Northern Laos was investigated. Due to low fertility of the soils derived from shale and its strongly weathered and acidic nature in the eastern side of the Nam Khan River watershed, shortening of the fallow period to produce enough amount of upland rice for the local population would not be sustainable any more. On the other hand, the eroded materials from limestone range were added to the soils in the western side of watershed which made the soil more fertile. Based on the calculated population capacity by Carneiro's equation, a system with 2- or 3-year fallow for 1-year cultivation can be the maximum to afford the current population. To make the shifting cultivation system more sustainable, introduction of fallow system with a tree species, paper mulberry (Broussonetia papyrifera) could be a good option to be proposed. 相似文献
2.
ZHOUYONG WANGSHANQIN DONGYUANHUA YANGLINZHANG 《土壤圈》2002,12(4):373-381
The design and applications of a land information system built upon ARC/INFO and ArcView are presented.The proposed system not only maintains all the advantages of the more conventional implemen-tations but also enhances them in the following ways:1)the application program interfaces(API)are used to transmit data and messages among different parts of the system;2)the integrated system can support studies on land evaluations and ecological analyses by efficient management of attribute and spatial data and 3)correspondingly,spatial records and attributive records are linked by the same identifiers(ID).A case study application in Zigui County of the Three Gorgas Area in China demonstrates that the system could employ land-use maps and land property data to predicate and analyze the land utilization changes in the past,present and future.The ecological environment analysis can be carried out with the data of land,economics and terrain map used,showing that the system can be widely applied,especially to survey land and environment resources in the countryside area. 相似文献
3.
H. I. Shuval 《Water, air, and soil pollution》2000,123(1-4):605-630
Are the conflicts over water resources between Syria, Lebanon and Israel who share the transboundary waters of the Jordan River Basin a major obstacle to the peace process? The Syrians and Lebanese have in the past claimed as their own all of the sources of the Jordan River which arise in their territory. International water law provides a strong legal basis to assure the water rights and continued use of water by a downstream riparian, such as Syria's use of the Euphrates which arises in Turkey and similarly, Israel's use of the Jordan River, based on prior use in an international river basin. This paper will evaluate the water security implications for Israel of a possible peace agreement with Syria and Lebanon which would involve Israel forgoing the continued use of those amounts of water from the Jordan River that were approved by the Israel Government under the so-called Johnston Plan of 1956 — 35 million m3/yr. for Lebanon from the Hasbani Springs and 42 mm3/yr. from the Banias Springs and Jordan River for Syria. The maximum replacement cost for that amount of water by desalination of seawater may be about $0.70/m3 or, some $56,000,000 per year. This is not a great amount of money as part of the price for peace. The paper also shows that Israel does not have to hold on to the entire area of the Golan Heights to assure its water security and that a 1–3 km water security zone along the Syrian side of the international border under joint and international inspection can be an effective water security measure to assure inspection, monitoring and control of all the sources of the Jordan River and Lake Kinneret vital to Israel's water security. The scare stories published by some groups in Israel, that Syria could, after a peace agreement is signed, covertly divert essentially all of Israel's water resources derived from the sources of the Jordan River or 30% of the country's water supply are highly unrealistic. Such major works could not go undetected and Syria and the world recognize that such an act would be viewed as a causus belli and as an act of war by Israel. In an era of peace, development of the shared water resources of the Jordan and continuous water systems in a program of regional cooperation can bring benefits to all of the partners on the Jordan River Basin. 相似文献
4.
《Communications in Soil Science and Plant Analysis》2012,43(2):163-176
Estimates of changes and possible causes of regional soil organic carbon (SOC) are critical for evaluation of potential responses of terrestrial biosphere to global changes. A total of 382 soil samples, collected in the 1980s from four counties in the Corn Belt of northeastern China, and of 1,514 samples collected in 2005 from the same area, were examined for SOC concentrations. Spatial and temporal SOC concentrations were evaluated after the 25-year interval using geostatistics and kriging interpolation method. Results indicated that the average topsoil SOC concentrations of the study area increased from 1.24% in the 1980s to 1.47% in 2005. Spatial distributions of SOC in the two separate evaluations showed greater SOC concentrations in the middle part of the study area and lower SOC concentrations in the remaining areas. From the 1980s to 2005, SOC concentrations in the central part increased, whereas those in the northeastern and southwestern parts decreased. The increasing trend of SOC concentrations might be attributed to the land-use and land cover changes, crop productivity increase, and agricultural management. 相似文献
5.
OBJECTIVES: To determine missed opportunities and problems relating to implementation of the Vitamin A Supplementation Programme in urban and rural regions of the Western Cape Province of South Africa.MethodA cross-sectional survey was conducted at primary health-care (PHC) clinics in Cape Metropole, an urban region, and West Coast Winelands, a rural region, of the Western Cape. A purposive sample of clinics where more than 30 children were seen per day was drawn from 10 of the 11 districts in the Cape Metropole region and the two districts of the West Coast Winelands region. The number of children selected from each district was weighted in terms of population size for the two regions. At each clinic visited, the first five to 10 children seen on a day, and meeting the inclusion criteria for vitamin A supplementation (VAS) based on the vitamin A provincial policy guidelines, were selected. These included children with low birth weight (LBW), growth faltering, underweight and severe undernutrition, recurrent diarrhoea and lower respiratory tract infection (LRTI), tuberculosis, measles, HIV/AIDS and eye signs of vitamin A deficiency. Clinic records were reviewed following consultation with the PHC nurse to identify if the child required vitamin A, exit interviews were conducted with mothers/caregivers, and Road to Health Charts (RTHCs) were reviewed. At the end of the study, PHC managers were interviewed to determine if problems could be identified with the Programme. RESULTS: Forty-three of 123 (35%) and 13 of 40 (33%) of the fixed PHC clinics in the Cape Metropole and West Coast Winelands regions were visited, and a total of 300 children (234 from Cape Metropole, 66 from West Coast Winelands) with a mean (standard deviation) age of 24.3 (16.3) months and who met the inclusion criteria for VAS were selected. Of the total sample of children, 198 (66%) had multiple (i.e. more than one) indication and 102 (34%) had a single indication for VAS. There were a total of 617 indications for VAS in the two regions; 238 (39%) for growth faltering, 119 (19%) for underweight, 98 (16%) for LBW, 70 (11%) for LRTI, 51 (8%) for diarrhoea, 21 (3%) for HIV/AIDS and 20 (3%) for tuberculosis. A total of 102 (34%) of the children in the two regions received vitamin A supplements (Cape Metropole 29%; West Coast Winelands 52%). A record was made on the RTHC of 79 (77%) of the children who received VAS (Cape Metropole 76%; West Coast Winelands 79%). Twenty-four per cent of the mothers knew why their child had been given vitamin A (Cape Metropole 29%; West Coast Winelands 12%). Eleven per cent of the mothers had previously heard about the Vitamin A Supplementation Programme (Cape Metropole 12%; West Coast Winelands 6%). More than 81% of PHC managers indicated that health staff had been trained to implement the Vitamin A Supplementation Programme. The main problems identified by health staff in the two regions were lack of vitamin A capsules, inadequate training and difficulties in implementing the Programme. CONCLUSIONS: Opportunities to administer vitamin A were underutilised in both regions. Recommendations such as improving mothers' awareness of the benefits of vitamin A and training of PHC nurses were made to the provincial Department of Health and are being implemented to improve the effectiveness of the Programme. 相似文献
6.
Promiscuous soybean lines have been bred on the basis that they would nodulate freely without artificial inoculation. However, our recent studies have demonstrated that the indigenous rhizobia are not able to meet their full nitrogen (N) requirement. Rhizobia inoculation might be necessary. We examined the competition for nodule formation among native Rhizobia spp. and two inoculated Bradyrhizobia strains (R25B indigenous strain and a mixture of R25B+IRj 2180A indigenous strain from soybean lines in the savanna of northern Nigeria), their effect on N fixation, and their contribution to the yield of four soybean cultivars, grown in the field in three different agroecological zones in the moist savanna of Nigeria. About 34% of nodules were formed by the mixture of introduced R25B+IRj 2180A, while R25B formed only about 24% of the nodules but did not influence biomass and grain yield production. The indigenous rhizobia strains that nodulated the soybean varieties fixed up to 70% of their accumulated total N, confirming the promiscuous nature of these soybean varieties. Even though these varieties fixed about 75 kg N ha -1; this was not enough to sustain their optimum grain yield, as earlier reported. However, the grain yield from inoculated soybean was not significantly higher than that from the uninoculated soybean, showing a degree of competitiveness among the introduced rhizobial strains and the native rhizobia population. 相似文献