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Всего публикаций в данном разделе: 47

Авторы:
все АБ ВГДЕЖЗИЙК Л МНОП Р С ТУ ФХЦЧШ ЩЭЮЯ
A B C D E F GH I J K L M N O P QR S T U V W X Y Z
 
Названия:
А БВ ГДЕЖЗИЙКЛМНОП Р СТУФХЦЧШЩЭЮЯ
A BC D E F G H I JKL M N O P Q R S T U V W XY Z
 

Опубликовано на портале: 24-12-2003
John Sumelius, Zoran Grgic, Milan Mesic, Ramona Franic
Durban, 2003
The aim of this paper is to identify optional ways of preventing NO3-levels from rising within Croatian farming systems, and the implications from the viewpoint of the manager. More specifically, the purpose is to

1) Determine whether Croatian farmers exceed profit maximising levels of N-fertiliser use in maize cultivation, and its possible influence on NO3-N-levels.

2) To estimate the marginal abatement cost (MAC), at the farm level, of reducing NO3-N leaching through the following instruments: a tax on optimal N-doses, a product tax and an N-fertiliser quota and a requirement for all instruments to correspond to the same abatement level.

Based on N-response experiment from feld trial for maize N-response curves were estimated. A sample of 20 family farms was used for calculating intensity, nutrient content in manure, and the prices paid for N and obtained for maize. Profit maximising doses from the field trials were compared with the use of nutrients on farms. An effluent production function was estimated based on experiments with NO3-N contents in lysimeter water for the same treatment levels as those in the N-response experiments. The results indicate that farmers use higher than optimal levels of N-fertilisers, if the manure is fully accounted for. In this case the estimated NO3-N/l level in groundwater is 162-192 % higher than the critical level stipulated by the Nitrate Directive. Neglecting the N-content in manure shows close to profit maximising nutrient levels . At this fertlising level the estimated NO3/l is approximately 62 mg NO3/l or clearly higher that the critical level stipulated by the nitrate directive (50 mg NO3/l). Through any of the three instruments a 76% NO3-leaching reduction could be obtained. It was concluded, however, that the quota has the lowest MAC (0.92 euro/mg NO3/l), followed by the N-fertiliser tax (3.65 euro/mg NO3/l), and the product tax comes in third place (9.32 euro/mg NO3/l). Management practices that may increase yield levels, and correspondingly NO3-leaching in the short and long run, were also identified. One way to achieve a quick improvement might be a system of cross compliance, stipulating a code of good agricultural practices.
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Опубликовано на портале: 28-11-2003
Maria Raquel Ventura-Lucas, Maria de Lurdes Ferro Godinho, Rui Sousa Fragoso
2002
Sustainable agriculture implies the exploitation of natural resources now, without compromising the natural resources stocks for the future generations. In the context of the paper, agricultural sustainability takes place at the interface between agriculture and the environment. The focus is on the interplay between farming systems and agrienvironmental policies. Agricultural policies have major impacts on soil and water quality and on bio-diversity. Support commodity price policies have lead to serious problems of water pollution; high levels of soil erosion; nitrate losses and lost of biodiversity. The semi decoupeted income support policies and the introduction of the agrienvironmental schemes under the 1992 CAP reform were the first attempts to correct the negative aspects of the production-orientated policies. For the first time farmers were regarded as countryside and landscape keepers and as environmental conservationists. Under the 2000 Agenda similar emphasis was given to the sustainability of agriculture. The objective of this paper is to evaluate the impact of the different agri-environmental policies on typical farming systems and consequently their effects on water pollution, soil erosion and bio-diversity/landscape. A bio-economic model, integrating a mathematical programming model and crop growth simulation model, is applied to estimated the changes in the levels of nitrogen leaching and soil erosion, and in the degree of bio-diversity under the current and proposed agricultural policy scenarios. The following farming systems are studied: dry land cereal farming systems (intensive and extensive), livestock and irrigated farming systems using conventional and conservation farming technologies. The results show The results show that the main changes on water pollution, soil erosion levels and biodiversity are mainly due to changes in price and arable compensatory payments. The agri-environmental measures are more important as farm income source than as a policy instrument to influence environmental parameters.
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