The researches were carried out from 2002-2007 in the upper reaches of the Šušvė River, a Nevėžis tributary, at the pig enterprise Limited company (LTD) 'Litpirma' breeding near the township of Šiaulėnai. LTD 'Litpirma' has been operating since 1978 and produces 25 thousand fattening pigs per year, along with an associated 56 thousand m3 organic fertilizers (liquid manure, slurry and solid manure), which are spread on surrounding agricultural fields. This article presents the impact of a large pig breeding company on the river water quality and quantifies the leaching of nitrogen, phosphorus and potassium (NPK). It is based on the water quality research data collected from an 11.6 km section of the Šušvė River, both upstream and downstream of Šiaulėnai, regarding the drainage water outflow from the fertilized fields and from Šiaulėnai domestic wastewater. Drainage water from 728 ha of fields that have been fertilized with organic fertilizers carry an average of 11.4 tons of nitrogen, 0.073 tons of phosphorus and 5.53 tons of potassium. Changes in NPK quantities carried by this section of the Šušvė were calculated as follows: total nitrogen increased by an average of 83 tons yrE–1 (58%), potassium by 51 tons yrE-1 (54%) and the smallest increase, for total phosphorus, by 1.2 tons yrE-1 (48%). All of these pollutants leached into the river during the cold season (to 60% total phosphorus and to 88% total nitrogen) when there was no vegetative growth. A wet year affects the quantities of leached NPK.

Technologies of keeping livestock and management of manure pig complexes holdings built in the country under the Soviet regime no longer satisfy modern veterinary and environmental requirements. Conditions for the modernisation of such complexes were created as from 2000, when agricultural aid programmes (funds) appeared in Lithuania. Information about old and newly implemented manure management technologies, fertilisation value of manure, and quality of the drainage runoff from manure-fertilised fields has been collected in six large livestock companies. Analysis of collected data revealed that new livestock keeping, feeding and manure management technologies are more cost-effective in using energy and mineral resources and conform to the animal welfare, environmental protection and hygiene requirements that are becoming more and more stringent. As the traditional manure management in economic terms is quite expensive and has a significant impact on the environmental quality, academic community is looking for new manure processing methods. The global development of manure management technologies focuses on the manure processing in biogas plants. Biogas generated from liquid manure and animal waste in such plants is an alternative source of energy.

The research was made in the Šušvė river basin fertilized with organic fertilizer in the vicinity of a pig complex 'Litpirma' Ltd (25.0 thousand fattening pigs per year), Šiaulėnai local administration, Radviliškis district, in 2001-2006. This article presents total nitrogen concentrations and its amounts leaching from the complex to the basin, in the field drainage water and the Šušvė River (at a distance of 11.6 km from the pig complex). In the investigated Šušvė section, biologically treated wastewater from Šiaulėnai Township and the areas fertilized with organic fertilizers comes into the river. In total, 11.8 t of nitrogen come into the river, of which 4% (0.49 t) come from the township's wastewater, and the rest major part (96% or 11.3 t) is the drainage water coming from fertilized agricultural fields. The dynamics of nitrogen concentrations both in the river and in the drainage outlet is of a seasonal nature: in winter (January – March) concentrations were higher, and in warm season (April – November) – lower. The Šušvė pollution by total nitrogen, both above and below the pig complex activities range, almost all the research period was exceeding the limit (2 mg lE-1). Due to the pig complex activities and intensive agriculture, the runoff of nitrogen pollutants increases from 14.9 to 29.3% in the Šušvė River. This proves that the processes of spontaneous purification are not intensive enough to neutralize completely the pollution from such size pig complex in this particular section of the river.

The research was conducted during the period of 2007-2011 in the fields fertilized by manure of pig breeding complex. According to the fertilization value of manure, the following total nitrogen levels reached the fields each year: 2007 – 169, 2008 – 167, 2009 - 168, 2010 - 168, 2011 – 168 kg haE-1. Ptotal reached the fertilized fields accordingly: 2007 – 9.4, 2008 – 18.9, 2009 – 12.0, 2010 – 10.8, 2011 – 13.5 kg haE-1. The aim of the research was to explore the impact of manure fertilized fields of a pig breeding complex on the water quality of streams. Streams, flowing through fields fertilized with manure, are usually polluted with nitrogen. The increase in Ntotal concentrations in streams’ water below fertilized fields was affected by precipitation (r = -0.31), fertilization rate (r = 0.41) as well as mineral nitrogen reserves in the soil (r = 0.20). Phosphorus concentrations in streams’ water were low and corresponded to a very good streams’ water ecological condition, except in times, when the water inflowing into the fertilized fields was already contaminated with this element. It was determined that an extremely high impact on streams’ water quality below fertilized fields comes from Ptotal concentration in streams’ water above fertilized fields (r = 0.91) as well as from the drainage water inflowing from fertilized fields into the streams (r = 0.71). Neither Ntotal, nor Ptotal pollution was observed in drainage water, because the highest concentrations during the research period were lower than the maximum allowable concentrations by 1.1 and 6.5 times respectively.

Biogas production from organic wastes is gaining popularity, especially in agriculture, which produces high quantities of organic wastes suitable for anaerobic digestion. Digestate is the valuable by-product of the biogas production that is considered as a valuable fertilizer. The objectives of the experiment conducted from 2012 to 2013 at the Estonian University of Life Sciences were to compare the impact of biogas digestate, undigested (raw) cattle slurry, and inorganic nitrogen fertilizer on grass yield and to assess the fertilizer value of digestate produced from different feedstock. Fertilizers were applied to the grassland rich in low grasses by broadcasting in quantities according to the nitrogen rate of 180 kg haE-1 in three split applications. The application rate of organic fertilizers was calculated based on NH4 -N content. Grassland yield was determined on four treatments: (i) control (no fertilizer was applied), (ii) mineral N-fertilizer (NH4 NO3), (iii) cattle slurry and (iv) cattle slurry digestate. Grass yield was measured three times during the growing period. Our research showed that digestate when applied based on its NH4 -N content is effective fertilizer in grassland. It could be used as a substitute for mineral-N fertilizer, but its efficiency is slightly lower when compared to cattle slurry, due to its lower application amount resulting in lower nutrient and organic matter amount applied to the grassland. Co-digestion of cattle slurry with solid manure, hay and silage does not decrease digestate fertilizer value in grassland, because the addition of other substrate increases digestate DM content.

The paper presents data on the water quality in drainage from manure-fertilized areas in a large livestock company (629 conditional livestock) from 2008 to 2012. The scheme of investigation consists of two field variants: manure fertilized and non-fertilized. Researches are carried out in drained areas, where the drainage water is drained away through outlets. The nitrogen rate 170 kg haE-1 is used annually to fertilize fields in spring. The aim of the research was to ascertain the impact of large livestock company fields fertilized annually with manure on the water quality in drainage. For the purpose of chemical investigations, water samples from drainage were taken once per month. Water analyses were carried out by the accredited Chemical Analytical Laboratory of the Water Management Engineering Institute of Aleksandras Stulginskis University according to specified methods. Investigation results have demonstrated that fields fertilized annually with manure raised the contents of Nmin and P2O5 in the soil by 1.5 and 2.2 times respectively in comparison to the non-fertilized ones. The increase in these contents was conditioned by the higher air temperature and the lower rainfall. The seasonality of Ntotal concentrations in drainage water was discovered: higher concentrations were identified in autumn and winter, lower concentrations – in spring and summer. Due to low dissolubility in the soil, low Ptotal concentrations were identified in drainage water. The highest concentrations were identified with the start of drainage operation.

The article provides the research data on the variation of organic matter in the Jaugila Stream, which flows through drained fields fertilized with organic fertilizers. The aim of the research was to determine the effect of manure application in drainage basin to the changes of organic matter concentration in the Jaugila Stream. Water samples for chemical analysis were taken once a month from the drainage water and the river. The samples from the river were taken upstream and downstream manure fertilized fields and the drainage water – from the outlets of the drainage system, which drains the fertilized area. Water analysis was performed by the Analytical Laboratory of Chemical Analysis of the ASU Water Research Institute. BOD7 was determined by titrimetric method. The research has shown that a greater impact on the increase of BOD7 concentrations in the Jaugila Stream was due to the stream water, saturated with the organic matter, flowing from the upstream areas, rather than the drainage water flowing into this stream from manure fertilized area. The assessment of BOD7 concentrations according to the water quality requirements for surface waters determined that in most cases the water of the Jaugila Stream, both in above and below fertilized areas, was in a very good or good ecological status. The impact of manure fertilized areas on the organic matter concentration in the stream was determined to be minimal, as the statistical analysis of the data has shown that the difference between BOD7 concentrations above and below fertilized areas is negligible.

Field trials were carried out on organic farming fields at the Research Institute of Agriculture of the Latvia University of Agriculture (LLU). The influence of harrowing (without harrowing, before emergence, at the stage of tillering, before emergence and at the stage of tillering) depending of pre-crop (red clover, winter rye for grain, bare fallow and green manure) and use of stable manure (60 t haE-1 or without) on the weediness and yield of spring barley 'Sencis' was tested during 2003-2004. In spring barley, 18 species of weeds were established at the stage of earing during 2003-2004. The most widespread of perennial weeds were Elytrigia repens (L.) Nevski and Sonchus arvense L. The dominant annual weeds were Chenopodium album L., Stellaria media L., Capsella bursa-pastoris L., Polygonum spp., and Matricaria inodorum L. The number of annual weeds at the stage of earing differed during the years 50-160 (in 2003) and 33-118 (in 2004) annual weeds per mE-2. The influence of harrowing on the number of annual weeds was different during the testing years. The influence of harrowing on the grain yield was negligible during 2003 and 2004.

The field experiment of IOSDV (set up in Tartu in 1989) with application of mineral nitrogen fertilizer in combination with different forms of organic fertilizer (manure, straw) during 2 years has led to changes in mineral nitrogen level depending on fertilization regime used. Crop rotation was the following: potato-spring-wheat-spring-barley. The weather conditions during the period of the study were rather different and it appeared that weather conditions are more important factors in determining mineral nitrogen content and crop yields than applying fertilizers.

The paper gives a brief overview and describes the main results of comparison research in grassland management of conventional and organic farms. The aim of this study was to assess yielding ability and biodiversity of leys depending on the nutritive status of soil. The investigation based on field experiments that were carried out in several regions of Estonia: Laeaene (West), Harju (North) and Voru (South-East) county in 2001. In the research on the productivity of grass-clover leys of the first harvest year was measured the DM yield and content, the botanical composition of the sward and the concentration of crude protein on grass. The soil pHKCL and content of organic matter were measured, also the content in soil of soluble plant nutrients P, K, Ca and Mg was estimated by AL- (ammonium acetate extraction) method. The soil profiles were described and soils were classified. The dominant soil types in farms of West-Estonia were Calcic Cambisols and in North-Estonian farms Calcic Gleysols, in South-East Haplic Podzols types prevailed.