The aim of the research was to study weed species occurrence and abundance in field bean (Vicia faba L.), maize (Zea mays L.), potato (Solanum tuberosum L.) fields and in perennial grasslands in Kurzeme region. Above mentioned crops and perennial grasslands were chosen for analysis as a part of seven-year-long weed survey performed in 14 conventional farms. Six constant fields per farm were monitored each year. The analysis of weed survey results showed that the main weeds in crop fields were annual dicotyledonous weeds, but perennial weeds were typical to perennial grasslands. Field horsetail (Equisetum arvense (L.)) had high occurrence and abundance in all studied crops in the 56 surveyed fields. The largest number of weed species was observed in field bean sowings, but the smallest – in maize sowings and perennial grasslands.

Precision livestock farming (PLF) can be defined as the management of livestock farming associated with continuous automated, real-time monitoring of animal health, welfare, and environmental impact on cows. The use of sensor technologies can be started in the beginning of cow’s life with feeding sensors in automatic feeding stations and can be extended through all cows’ life in different aspects. The main benefits that associate with PLF are far-reaching approach to animals, improved livestock welfare, increased profitability and improved product quality. The main areas beneficiary covered by sensor technologies are cow health, reproduction, nutrition, metabolic diseases, udder health and cow activity. The use of metabolic sensors results with early detection of ketosis, acidosis and other metabolic diseases, that leads to lowered treatment costs.

Oat (Avena sativa L.) grains are one of the most popular cereal grains for food production with a high nutritional value. The main objective for this research was to evaluate oat varieties recommended by grain processing companies as food oat in different countries. Tested grain indicators were thousand kernel weights, test weight, outcome of grain above 2 mm sieve, grains with two hulls and dehulling efficiency. The field trial and research in laboratory was carried out at the AREI Stende Research Centre in 2016. From 13 varieties that were tested in this research, the oat varieties ‘Peppi’, ‘Dal’, ‘Laima’, and ‘Matilda’ showed high usability as suitable for food processing. Varieties ‘OAC Woodstock’ and ‘Konkur’ also showed high adequacy; however, these varieties have high number of grains with double-hulls in yield.

Work summarizes the ash utilization opportunities. Five different ash and liquid manure mixture forms were researched and evaluated using the Technical (LLU) faculty-owned equipment. Master Thesis was carried out to create a new fertilizer production equipment, as well as to provide insights to farmers and foresters on efficiency of fertilizer formed from ash and liquid manure.

Bacterial diseases are economically important and widespread on stone fruits worldwide. The bacterial diseases of stone fruits have not been studied in Latvia, and the identification of causal agents has not been carried out previously. Thirty-seven farms were surveyed in 2008-2011 to detect and evaluate the occurrence of pathogenic Pseudomonas syringae on stone fruits in Latvia. During the surveys, the overall health condition of orchards was evaluated visually, and samples were collected from diseased trees. Bleeding cankers on trunks and branches, different stage of diebacks on branches, wilt of buds and flowers were the most often observed symptoms. Isolates with morphology characteristic to Pseudomonas were selected for species identification by LOPAT test. Pathogenic P. syringae were detected in samples from ten farms out of 37 surveyed. In six farms, pathogenic P. syringae isolates were determined on sweet cherries (Prunus avium), in two farms on sour cherries (Prunus cerasus) and in three farms on plums (Prunus domestica). Bacterial diseases of stone fruits caused by P. syringae are more spread in the central region of Latvia, where the stone fruits are widely grown. The low occurrence of pathogenic P. syringae reveals that severe symptoms observed on the stone fruits in orchards are also caused by other plant pathogens.

Buckwheat (Fagopyrum esculentum M.) is a very valuable nutrition product, however, from technological point of view, it is not widely used in the production of bread and other foods due to its low protein quality. Extrusion is one of the technological solutions that can be applied in the production of buckwheat products. Within the framework of the study, three raw buckwheat products were developed: with no additives, sweet with brown sugar and cinnamon, salted with salt and garlic. The aim of the study was to evaluate the sensory properties of the extruded raw buckwheat products. Sensory properties of the product (taste, colour, aroma, consistency) were evaluated by 53 evaluators using a 5–point hedonic scale and a total liking of the product using a 9–point hedonic liking scale. The results of the sensory evaluation showed that all three new products were rated within the range of ‘like moderately’ and ‘like very much’ (ranging from 7.24–7.57 points). No significant differences were observed between the obtained results (p is greater than 0.05); however, the salty buckwheat product with salt and garlic powder was rated higher.

The local honey bee population is suitable for the climatic conditions of Latvia; it characterizes with good wintering and economically used winter feed, high disease resistance, and ability to use late honey yield during wintering. Negative characteristics are aggressiveness and swarming. In Latvia, different varieties of bees were imported during the 20th century 30’s, and hybrids, which do not comply with A. mellifera mellifera, were developed because of uncontrolled crossings. Latvia University of Agriculture apiary is carrying out bees’ breeding material evaluation according to the morphometric analysis: the cubital index and discoidal deviation. Because of natural mating of queens and drones, up to 30% of offspring correspond to Latvian local honey bee, but using instrumental insemination – this proportion was 84–100%.

Nitrogen fertiliser use is important factor for increase of crop yield and its quality parameters. However, environmental consequences, especially leaching of mineral forms of nitrogen in post-harvest period, should be taken into account. One of the risk areas is usage of equal fertiliser norms for fields where some areas are covered by mineral, but some – with organic soils. Therefore, field experiment was carried out in such situation where mineral nitrogen content in soil was monitored during vegetation separately for three layers: 0 – 30, 30 – 60 and 60 – 90 cm. Nitrogen off-take by crops’ yield and balance were calculated. Pattern of mineral nitrogen content in both soils was similar – rapid increase after the use of fertiliser, than decrease during vegetation due to its consumption and then increase again after harvesting. Amount of soil nitrogen pool for organic soil was significantly higher if compared with mineral one. Finally, the non-used nitrogen in organic soil after harvesting was also high, that might cause environmental risk due to its leaching. Therefore, differentiation of nitrogen norms is necessary measure to apply for fields where mineral soils alternates with organic ones.

Technologies are evolving and the equipment working on sensors becomes more popular with every year, as they are faster, handier and more environmentally friendly. Portative spectrometer CL-710 CID Bio-Science allows analysing spectrum of 350–1000 nm and rapidly estimates vegetation properties. For crop farming in greenhouses, farmers more often choose to use LED (light emitting diodes). Red, blue LED and natural light was used to grow tomatoes’ plants in polycarbonate greenhouse of Latvia University of Agriculture. The aim of the study was to evaluate most appropriable indexes for characterisation of tomatoes’ growth in different illumination conditions. Results showed that the unique and the most appropriable indexes are FRI, NPCI, PSRI, WBI and G. Larger differences were observed at plants flowering stage.