The objective of this thesis is to explore opportunities to enhance the phosphorus use efficiencyof inorganic fertilizers in crop production, with techniques available today and in thefuture. Phosphorus is a finite resource of declining quality; therefore a phosphorus use efficiencyin crop production of only 15-30 % is unacceptable. The main reason for low efficiencyis the retention by Ca and Mg in calcareous soils and Fe and Al in non-calcareoussoils. Due to the low mobility of phosphorus, plant uptake is mainly dependent on root growthrather than diffusion. Therefore, measurements need to be taken that benefit contact betweenroot and fertilizer, before fertilizer phosphorus becomes unavailable to the plant.

Horse keeping is gaining an increasing interest in Sweden. During 2004 to 2010 the number of horses increased with 10 - 20 %, and was estimated to be 362 700 in 2010. Julmyra Horse Center (JHC), situated in Heby municipality, is a gated community for people sharing a large interest for horses and a vision of a sustainable horse management has been formulated. This study evaluates how the horse keeping of today at JHC, and how an expansion of the horse keeping may affect the risk of enhanced phosphorus load to the nearby lake system Vansjön ? Nordsjön.

This work is a part of the project ?Våtmarker i odlingslandskapet ? uppföljning av miljömålen? (Wetlands in arable land ? following-up of the environmental goals). The main objective with this project is to study nitrogen and phosphorus retention in a constructed wetland by using mass balance calculations. Continuous measurements of nutrients and water flow through the inlet and the outlet of the wetland are made. However, substantial amounts of nitrogen and phosphorus were assumed to reach the wetland with a drain-pipe transporting wastewater from nearby houses (10 persons).

Based on laboratory studies with lysimeters, the concentrations of dissolved reactive phosphorus(DRP) and particulate phosphorus, which is the main part of other P (OVRP), has been studied inpercolating water. The experiment was conducted through irrigation of small soil columnscontaining clay topsoil from an experimental field in Västergötland. Three rain simulations wereconsecutively performed. DRP concentrations in the percolating water ranged between 0.2 - 0.3mg·Lclearly related to the phosphorus concentration in the soil, measured in a soil extract ofammonium lactate (P-AL). Concentrations of OVRP were relatively low and ranged between0.12 and 0.16 mg·Lwas not proven and the experiment may reflect how a relatively slow percolation of water mayrelease DRP.

In connection with Henriksdals wastewater treatment plant (WWTP) a smaller plant is situated called Sjöstadsverket where new methods for wastewater treatment are tested and evaluated in different process lines. On one of the lines experiments with enhanced biological phosphorous removal (EBPR), have been carried out to evaluate if it is a good alternative to traditional chemical phosphorus removal. This thesis evaluates the results from the experiments conducted during fall 2005.The incoming water from Hammarby Sjöstad consists of only household wastewater, which gives a wastewater with high concentrations of nutrients and organic carbon. This is partly positive, because one of the limiting factors for effective biological phosphorus removal is the lack of easily biodegradable organic carbon. The high concentrations of ammonium and phosphorus demand a high reduction to achieve the requirements of outgoing concentration.To optimize the process experiments with different recirculations and different aeration techniques have been made.

Eutrophication is an environmental problem that affects more than ten percent of Swedish lakes. Excess nutrients increase the growth of algae, and cause major problems in the ecosystem through oxygen-free bottoms, fish kills, and at worst dead bottoms. Agriculture accounts for 44% of human emissions of phosphorus to lakes and rivers. Leaching occurs of particle bound phosphorus and of dissolved phosphate. The amount of phosphate in the soil solution that may be leached is partly due to the prevailing pH in the soil solution. The purpose of this study was to investigate how the relationship between phosphate solubility and pH was affected by liming.

The purpose of this essay is to find out if liming with Ca(OH2) and CaO can reduce leachingof phosphorus from agricultural land and the problem with eutrophication. This purpose alsoincludes getting knowledge about how to make the phosphorus retained in the soil and beaccessible for the plants. This essay is supposed to show if more research is needed in thissubject. There has not been much research about this subject and therefore the amount ofmaterial to study is limited in this literature review. The research reports that have beenstudied have similar results.

Environmental subsidies are used as incitements to farmers for development of sustainable land use. In 2014, applications for funding constructed wetlands were not available. This paper examines the environmental consequences of this lack of funding in one intensively cultivated region Skåne län, southern Sweden.A review of wetland applications between year 2007-2013 show that the average rate of applications has been 31 projects per year with a wetland size of 4,48 ± 1,61ha per project (mean±95% CI). Based on interviews, the result suggests that the lack of funding in one year leads to between 102 and 140 ha of constructed wetlands that is not built. This correspond to a total loss of increased nitrogen retention capacity between 6,0 and 91,7 tons/year and a loss of increased phosphorus retention capacity between 0,17and 2,1 tons/year in the drainage basins of Skåne.Further the interviews show that continuity of environmental regulations and funding is important for the farmers? interest in environmental measures.It is concluded that the total loss of increased retention capacity is small compared to the annual transport of nitrogen and phosphorus in the drainage basins.

Eutrophication was recognized in the early 1900's and results in severe algal blooms, increased biomass production and eventually leads to an altered ecosystem. In Mälardalen we find the most eutrophic lakes. Most of the applied phosphorus and nitrogen into seas and oceans comes from agriculture, and the nutrients losses are affected by local weather conditions and soil type. Guidelines for storage and distribution of manure were introduced in the 80s, and the rules were strengthened January 1, 2010. Localities and previous county administrations can whether there are special reasons, grant an exemption for manure application during winter-periods despite the current ban.In this essay I have examined how many exemptions of manure application that has been granted at the Sagån river, and what implications it has for the eutrophication of Lake Mälaren.

Hammarby Sjöstad is a new district of southern Stockholm built with focus on reduced environmental impact by recirculation of materials and sustainability. The environmental goals aim to cut the water consumption by half and a separate storm water treatment. Thus, the wastewater will be more concentrated and will originate from the households only. The Sjöstad project includes the idea of a local treatment plant for the household wastewater. To evaluate this possibility, Sjöstadsverket, an experimental treatment plant was constructed.

The Earths climate is changing at a higher rate, i.e between 1861 and 1994 the annual mean temperature in Scandinavia increased with 0,68º C and according to recent climate models the annual mean temperature is likely to rise with another 3º C during this century.A warmer climate in many ways is associated with changing conditions for lake ecosystems. An expected higher water temperature and a stronger summer stratification of the water column increases the risk of anoxic conditions at the lake bottom. Thus anoxic conditions are likely to cause a phosphate leakage from the sediment, i.e. a higher internal loading of phosphate.In this project, the extremely warm summer of 2002 has been used as an example for a possible scenario for a future climate. By comparing levels of phosphorus in the summer of 2002 with a ten-year median value, a phosphorus related sensitivity to climate change has been analyzed for 55 Swedish lakes.

Construction of wetlands in the agricultural landscape may reduce nitrogen and phosphorus transfer to streams, thereby reducing the eutrophication of lakes and seas. The agriculturalstream Lillån, a tributary to stream Sagån, ends up in Lake Mälaren and is transporting large amounts of these plant nutrients. The aim of this study was to estimate how hypothetical wetlands of different size and location may reduce nitrogen and phosphorus load from stream Lillån. Estimated nutrient retention in several small wetlands was compared to retention in a single large wetland based on existing data from the agricultural stream and from a nearby smaller stream. Retention in the stream was suggested to decrease along with the nutrient concentration in the water.

In Sweden more than 400 000 private households have not yet sufficient wastewater purification. These effluent is considered as an increasing problem and many onsite purification methods have been studied. In this investigation, the method of reactive bed filters have been tested by column and batch experiments. Five different kinds of filter materials with reactive surfaces have been studied concerning their capacity to absorb ammonium and phosphorus from wastewater. The materials that were examined are Filtra N, wollastonite Filtra P, blast furnace slag and Polonite®.

70 % of the lakes and waters in the water district of northern Baltic Sea do not reach the requirements for good ecological status. This is mostly due to eutrophication caused by a too high deliverance of nutrients from agricultural land or effluents. Losses of particulate phosphorus through water erosion contribute to a great extent to this eutrophication. In the action plan for the water district cover crops are mentioned as a measure for reducing losses of phosphorus from arable land. This paper reviews the possible effect of cover crops in the water district and discusses what crop that would be most suitable.

Eutrophication of the Baltic Sea is a serious problem. A major contributing factor is diffuse losses of phosphorus (P) from agricultural land in surrounding countries. In order to estimate P losses, environmental monitoring of small agriculture-dominated catchments is being carried out in most of these countries. Evaluation of the risk of P leaching to waters is usually based on chemical tests originally developed to quantify the amount of soil P available for plant production. The tests are performed in different ways in the different countries and a number of different extraction agents are in use.