Assessment of the Finnish Agriculture 2000 Program: Effects on Nutrient Losses

A governmental committee has prepared a long-term programme (Agriculture 2000) concerning future agricultural policy in Finland. The purpose of this study was to assess the effects of these measures, mainly fallowing and reforestation, on nonpoint nutrient loads to watercourses. The work was mainly based on the use of a continuous simulation model, CREAMS. Using this model we estimated the relative effect of different management practices. Depending on the fallowing practice, the total amount of agricultural nonpoint nutrient load can increase by 15% or more, if fallowing is carried out by bare soil practices. If only green fallow is used, the nutrient load remains approximately at the level of normal cereal cultivation. It is recommended that fallowed fields not be located on permeable soils because of the risk of N leaching and not on steep slopes because of the high erosion and P losses. A reforestation programme planned in Finland could reduce the nutrient loads by 5-10%

Modelling of vegetative filter strips in catchment scale erosion control

The efficiency of vegetative filter strips to reduce erosion was assessed by simulation modelling in two catchments located in different parts of Finland. The areas of high erosion risk were identified by a Geographical Information System (GIS) combining digital spatial data of soil type, land use and field slopes. The efficiency of vegetative filter strips (VFS) was assessed by the ICECREAM model, a derivative of the CREAMS model which has been modified and adapted for Finnish conditions. The simulation runs were performed without the filter strips and with strips of 1 m, 3 m and 15 m width. Four soil types and two crops (spring barley, winter wheat) were studied. The model assessments for fields without VFS showed that the amount of erosion is clearly dominated by slope gradient. The soil texture had a greater impact on erosion than the crop. The impact of the VFS on erosion reduction was highly variable. These model results were scaled up by combining them to the digital spatial data. The simulated efficiency of the VFS in erosion control in the whole catchment varied from 50 to 89%. A GIS-based erosion risk map of the other study catchment and an identification carried out by manual study using topographical paper maps were evaluated and validated by ground truthing. Both methods were able to identify major erosion risk areas, i.e areas where VFS are particularly necessary. A combination of the GIS and the field method gives the best outcome.Tämän työn tarkoituksena oli kehittää käytännöllinen menetelmä herkästi erodoituvien peltoalueiden kartoittamiseksi, eli niiden alueiden, jotka ovat optimaalisia paikkoja suojakaistoille. Samalla arvioitiin myös suojakaistojen tehokkuutta eroosion torjunnassa. Tutkimusalueiksi valittiin kaksi valuma-aluetta eri puolilta Suomea. Helposti erodoituvat alueet arvioitiin paikkatietojärjestelmällä yhdistämällä tiedot maalajista, maan käytöstä ja pellon kaltevuudesta. Suojakaistojen tehokkuutta arvioitiin ICECREAM-mallilla, joka on Suomen oloihin sovellettu versio CREAMS-mallista. Mallinnus tehtiin ilman suojakaistoja sekä lisäämällä peltoon 1 m, 3 m ja 15 m leveät suojakaistat. Ilman suojakaistoja tehtyjen malliajojen perusteella eroosion määrä riippuu lähinnä pellon kaltevuudesta. Maalajilla on suurempi vaikutus eroosion määrään kuin kasvilla. Suojakaistojen tehokkuudet vaihtelivat suuresti eri tilanteissa. Malliajojen tulokset yhdistettiin paikkatietojärjestelmään ja tulokseksi saatiin, että valuma-aluetasolla suojakaistojen teho eroosion vähentämisessä ojiin rajautuvilta pelloilta oli 50-89 %. Paikkatietojärjestelmään perustuvaa suojakaistojen paikan arviointia verrattiin kenttätutkimukseen, joka oli tehty toisella valuma-alueella. Molemmilla menetelmillä löydettiin ne alueet, joilta eroosio on suurinta, mutta menetelmien yhdistelmällä päästiin parhaaseen lopputulokseen

Modelling of vegetative filter strips in catchment scale erosion control

The efficiency of vegetative filter strips to reduce erosion was assessed by simulation modelling in two catchments located in different parts of Finland. The areas of high erosion risk were identified by a Geographical Information System (GIS) combining digital spatial data of soil type, land use and field slopes. The efficiency of vegetative filter strips (VFS) was assessed by the ICECREAM model, a derivative of the CREAMS model which has been modified and adapted for Finnish conditions. The simulation runs were performed without the filter strips and with strips of 1 m, 3 m and 15 m width. Four soil types and two crops (spring barley, winter wheat) were studied. The model assessments for fields without VFS showed that the amount of erosion is clearly dominated by slope gradient. The soil texture had a greater impact on erosion than the crop. The impact of the VFS on erosion reduction was highly variable. These model results were scaled up by combining them to the digital spatial data. The simulated efficiency of the VFS in erosion control in the whole catchment varied from 50 to 89%. A GIS-based erosion risk map of the other study catchment and an identification carried out by manual study using topographical paper maps were evaluated and validated by ground truthing. Both methods were able to identify major erosion risk areas, i.e areas where VFS are particularly necessary. A combination of the GIS and the field method gives the best outcome

Regional variations in diffuse nitrogen losses from agriculture in the Nordic and Baltic regions

International audienceThis paper describes nitrogen losses from, and the characteristics of, 35 selected catchments (12 to 2000 ha) in the Nordic and Baltic countries. Average annual losses of N in 1994?1997 ranged from 5 to 75 kg ha-1, generally highest and characterised by significant within-country and interannual variations, in Norway and the lowest losses were observed in the Baltic countries. An important finding of the study is that the average nutrient losses varied greatly among the studied catchments. The main explanations for this variability were water runoff, fertiliser use (especially the amount of manure), soil type and erosion (including stream bank erosion). However, there were several exceptions, and it was difficult to find general relationships between the individual factors. For example, there was poor correlation between nitrogen losses and surpluses. Therefore, the results suggest that the observed variability in N losses cannot have been due solely to differences in farm management practices, although the studied catchments do include a wide range of nutrient application levels, animal densities and other relevant elements. There is considerable spatial variation in the physical properties (soil, climate, hydrology, and topography) and the agricultural management of the basins, and the interaction between and relative effects of these factors has an important impact on erosion and nutrient losses. In particular, hydrological processes may have a marked effect on N losses measured in the catchment stream water. The results indicate that significant differences in hydrological pathways (e.g. the relationship between fast- and slow-flow processes) lead to major regional differences in N inputs to surface waters and therefore also in the response to changes in field management practices. Agricultural practices such as crop rotation systems, nutrient inputs and soil conservation measures obviously play a significant role in the site-specific effects, although they cannot explain the large regional differences observed in this study. The interactions between agricultural practices and basic catchment characteristics, including hydrological processes, determine the final losses of nitrogen to surface waters, hence it is necessary to understand these interactions to manage diffuse losses of agricultural nutrients efficiently. Keywords: agriculture, catchments, diffuse sources, nitrogen, losses, Baltic, Nordi

Loss of plant species richness and habitat connectivity in grasslands associated with agricultural change in Finland

v2003o

Assessing the risk and magnitude of agricultural nonpoint source phosphorus pollution

Numerous site-specific studies have quantified the form and magnitude of P loss in agricultural runoff, but in order to meet the requirements of end-users who need to implement cost-effective control strategies, this research needs to be incorporated into generic models of nonpoint source pollutant loss from land. Such models need to be based on the expert knowledge and should be simple to use and easy to apply. End-users such as government agencies and water utilities are largely concerned with assessing the relative risk, or gaining rough estimates of the amounts, of agricultural nonpoint P pollution from different land use practices. Data-hungry process-based models, while elegant and all-encompassing, may not be suitable for the simple decision support frameworks. A number of risk assessment approaches aimed at predicting P loss from nonpoint sources are being developed in Europe, North America and Australia. There are many similarities in these independently-developed indices and models but also some important differences reflecting different strategic priorities for both research and land management needs. Similarly, more complex process-based models calculating P loads from land to water have been developed. These models are mostly used by research communities to get a more accurate and dynamic understanding of P loads and to develop sets of best management practices, which are often site-specific. This chapter critically reviews current risk assessment approaches for managing nonpoint P loss from agricultural land, and compares the criteria used to set risk-based targets. Examples of process-based models that can be used together with risk assessment approaches to ensure success in agricultural P management are also presented

Phytoplankton assemblages as a criterion in the ecological classification of lakes in Finland

Implementation of the Water Framework Directive requires the formulation of lake types and classification of the lakes within each type using biological quality elements. In this study phytoplankton was used to test the lake typology of 32 non-impacted lakes belonging to eight of the ten lake types described in the preliminary Finnish typology. Phytoplankton did not accurately define these types, as only five lake groups were clustered in the DCA ordination analysis. The ecological status was preliminarily established for 23 impacted lakes using total phytoplankton biomass and the number of taxa. Impacted oligo-humic lakes were tentatively classified to a lower ecological status than in the general water quality classification carried out in the 1990s. Even more variation was observed when assessing the ecological status of humic impacted lakes. The number of taxa, on the other hand, appeared to overestimate the ecological status of the lakes, obviously due to the preliminary boundary classes used in this study