In Kenya, many families subsist on agriculture and of the country's around 40 million residents 70% work in the agricultural sector. 50 % of the country's gross domestic production (GDP) comes from farming, and thus the country is largely dependent on income from this sector. Kenya's population has tripled in recent decades, which have led to that food availability is a growing problem. To ensure food security, it is important that the return from crops increases. The aim of this study is to evaluate what impact the use of Fertilizers and improved seeds has for farmer?s economic situation and income generation.

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.

Better, more efficient Fertilizers with great productivity and economic returns are needed, but it is important today to find Fertilizers that are also sustainable. It is also important to carefully monitor their impact on the environment, including potential side-effects. In this context, the microbial communities that carry out numerous essential functions contributing to a functional ecosystem are of particular interest. The present study is a complement to a pot experiment that investigated the potential of different waste products for use as Fertilizers and how they affect the microbial community. In the pot experiment, the clearest treatment change in microorganism community function was found in the fully fertilized treatment used as a positive control. The question was whether this was indirect, i.e.

In ambition to produce more and better harvests, artificial Fertilizers are used to produce a better growth of crops in the agriculture landscape. This contributes to leakage of nutrients. Our forests also exhibit a leakage of nutrients. Air pollution contributes to more nutrients. High precipitation with high water flows as a consequence seems currently to occur more frequently in the county of Halland.

Within agriculture it is important to optimize the use of nitrogen, not only from an economic point of view but also to minimize damage to the environment. This can sometimes be difficult, especially within organic farming. Organic farmers are using increasing amounts of waste products from the food industry to cover their nitrogen needs. These different organic Fertilizers release nitrogen at different rates and under specific soil conditions. Because of this, it would be beneficial to have a standardized method to measure the amount and rate of nitrogen mineralization from organic Fertilizers. This project contributes to this knowledge by investigating whether relatively simple and repeatable laboratory methods can be used to estimate the nitrogen fertilizer value of organic Fertilizers.

Plant nutrients are important for all life on earth and are also important as fertiliser infood production all over the world. Because of this, plant nutrients are of great valuebut they also bring problems. As an example, the loss of nitrogen and phosphorusfrom agriculture and urban society's sewage systems contributes to some of today?smajor problems in water environment. Another problem associated with plantnutrients is that finite recourses are used in the production of mineral Fertilizers.

Agricultural soils constitute the base in human food production and soil content of organic matter and plant nutrients together with soil microbial activity are all important parameters for high crop yield of good quality. These parameters are dependant on proper fertilization.Anaerobic digestion of organic wastes for biogas production generates a liquid residue called biogas residue (BR). It contains organic material and plant nutrients which makes ita potential fertilizer for arable cropping. However, it also contains heavy metals and toxic organic compounds and it is therefore in need of evaluation before usage.Microbial tests were performed aiming to evaluate the agronomic traits of four different BR and to find a viable procedure for evaluating slurry Fertilizers. Two experiments where soil respiration and soil potential denitrification activity (PDA) was measured at fertilizer addition were performed.

Phosphorus is essential to all plants and is taken up from the soil as the ion H2PO4 - (and to some extent HPO42-). Plant availability depends on, among other factors, the soil pH. In order to provide for plant available phosphorus, it is applied as mineral Fertilizers and farmyard manure. However, that causes phosphorus leaching from arable land to surrounding surface waters and lakes and contributes to the eutrofication. There are three types of soils in Sweden that are at higher risk of contributing to phosphorus leakage.

Climate changes today are mainly caused by anthropogenic activities and the increased emissions of greenhouse gases to the atmosphere and this has raised questions on how to reduce the usage of fossil fuels. Ethanol is a good alternative to conventional gas and has been used in Brazil since the 1970 ?s. In Sweden several newspapers has written about the poor working conditions on many farms thus making the Swedish company SEKAB design a certification for their ethanol to ensure that it can be considered to be a sustainable alternative.Furthermore WWF has developed a certification tool called Bonsucro in cooperation with Coca Cola, Ferrero group, BP and Shell. This is due to the fact that no global certification tool has been available up until now.

Green manuring is a way of creating an organic fertilizer by growing a crop that is mowed down. Besides the fertilizing effect this method has been shown to have a positive influ-ence on soil organic matter as well as weed flora, and green manure is an important me-thod of weed control in organic farming in parts of Sweden. However, the release of nu-trients from the green manure varies and can therefore be difficult to control. Risks for losses of nutrients are also present. Although the area of organic farmland is increasing in Sweden, the use of green manure is decreasing.This report contains a literature study which compiles research on the functions of green manure in a cropping system and also how the crop can be used if harvested, for example to produce biogas.

Green manuring is a way of creating an organic fertilizer by growing a crop that is mowed down. Besides the fertilizing effect this method has been shown to have a positive influ-ence on soil organic matter as well as weed flora, and green manure is an important me-thod of weed control in organic farming in parts of Sweden. However, the release of nu-trients from the green manure varies and can therefore be difficult to control. Risks for losses of nutrients are also present. Although the area of organic farmland is increasing in Sweden, the use of green manure is decreasing.This report contains a literature study which compiles research on the functions of green manure in a cropping system and also how the crop can be used if harvested, for example to produce biogas.

Sewage sludge contains plant nutrients and has earlier been utilised as fertilizer to cropland. Unfortunately not only plant nutrients but also heavy metals, pathogens and organic contaminants tend to accumulate in sludge. The suitability to use sewage sludge in agriculture has therefore been subject to several discussions over the years. The Swedish food industry does no longer accept sludge as fertiliser for Swedish producers. In 1999 the Swedish parliament accepted several objectives for environmental protection. In order to prevent environmental pollution and further exploitation of the earth crust, one of these objectives confirm that phosphorous from sewage shall be recirculated to arable land.

The Baltic Sea is threatened by eutrophication that largely is due to nutrient leaching from farmland within the catchment area. To solve this problem the surrounding countries cooperate within various configurations such as HELCOM and the EU-financed project Baltic Compass. Poor manure management in Russia has been discussed frequently the last couple of years. A literature review of different types of reports and legal acts is the core of this degree project which has been performed in connection to two ongoing research projects financed by EU (Baltic Compass) and SIDA. It is supplemented with interviews with Swedish agricultural consultants and travel reports from two occasions when I had the opportunity to discuss with Russians active within the agricultural sector. Different hypotheses were investigated and discussed. The environmental debate in Russia is quiet and there is a widespread approach that economic profit always trumps environmental concern ? a Soviet heritage that influence the Russian agriculture considerably. The Russian legal acts on stable manure management focus mainly on sanitary questions and only secondary on nutrient leaching.

Scandinavian Biogas is involved in the planning of a combined ethanol and biogas factory in Karlskoga, Sweden. Besides biogas and ethanol large amounts of digester residues will be produced, about 450 000 liquid tonnes residue (~7,3 % Dry Substance( DS)). The objective of this thesis was to investigate possible uses of the residue from the biogas production process ScandgasEthanol developed by Scandinavian Biogas, and to derive a methodological approach how to evaluate and compare handling systems. Three systems where proposed and compared in this thesis; spreading of the untreated residue as fertilizer (system 1), dewatering to a higher DS content to reduce transportation before spreading as fertilizer (system 2) and production of a solid fuel by dewatering and drying the residue (system 3). The general conditions for the proposed systems were investigated in terms of practical viability, economical aspects, environmental impact and energy inputs/outputs.

This thesis has been made on behalf of SCA Skog AB to assess the need of boron in Swedishforest fertilization. Boron has been added to Swedish forest Fertilizers since the beginning of the1980s. This makes the Fertilizers more expensive and therefore has the necessity of boron inSwedish forest fertilization been raised.The Swedish bedrock generally contains small amounts of boron. The boron in the bedrock istightly bound to the mineral tourmaline and mostly unavailable for plants. This leads to that thecontribution of boron to the soil from weathering is very low besides soils with marinesediments.