Three treatments were tested with four replications at RCBD, namely cassava monoculture, corn twice under cassava intercropping, and corn with corn monoculture where the second corn was planted 5 days after harvested. Planting distance of cassava in monoculture was 100x100 cm, and in intercropping was 200x50 cm, by which corn was planted in 50x30 cm, 1 seed per hole. All plots received dairy cattle manure 5 t haE-1. Fertilizer applied for cassava was Urea 100 kg haE-1, Ponska 200 kg haE-1 and KCl 100 kg haE-1 split into two applications two weeks after cassava planting, then when first of corn was harvested. Corn fertilization was Ponska 150 kg haE-1 + Urea 100 kg haE-1 every 3 months and split into two applications: 1 week and 4 weeks after corn was planted. Cassava and twice corn fertilization was Urea 300 kg haE-1 + Phonska 400 kg haE-1 + KCl 100 kg haE-1. Results showed that cassava monoculture can be improved by inserting of twice corn in between rows. Under sole cropping cassava, the B/C ratio was the highest 1.61, however with incorporating twice of corn the B/C ratio was 1.58. Intercropping cassava and twice of corn resulted in the Land Equivalent Ratio 2.146. By intercropping cassava with corn twice at the end of dry season, there was an opportunity to find corn biomass for dairy cattle. Under intercropping, cassava was able to produce 21.5 t haE-1 of fresh roots, while first and second of corn produced fresh biomass of 34 t haE-1 and 28 t haE-1 respectively.

Reduced tillage is considered as one of the main tools to save biological diversity; however, it increases pressure of diseases, including wheat leaf blotches. The aim of present study was to clarify the impact of reduced soil tillage on the development of winter wheat leaf blotches in different schemes of crop rotation. The impact of different growing technologies on the severity of winter wheat disease was evaluated in a two-factorial experiment: A – soil tillage system, and B – different combinations of wheat pre-pre-crop and pre-crop (wheat, oilseed rape, barley and faba beans). Diseases were assessed every 10 days approximately and total impact of diseases was evaluated by calculating AUDPC (Area under Diseases Progress Curve). Tan spot, caused by Pyrenophora tritici-repentis was dominated disease over the long period, regardless of meteorological conditions. Development of Septoria leaf blotch was not influenced by neither crop rotation nor soil tillage. The level of tan spot was essentially higher after wheat, regardless of the pre-pre-crop. Reduced soil tillage promoted severity of tan spot. Ploughing mitigated effect of previous crops and differences in tan spot level were insignificant. Despite many positive effects of conservation tillage, increasing of fungicide treatment could be necessary, in conditions, when the tan spot is most devastating and widespread wheat disease.

Nitrogen management strategy in plant growth period based on chlorophyll content evaluation in plant can improve nitrogen usage efficiency and reduce environmental contamination. This study is aimed to determine the impact of different nitrogen and sulphur fertilizers rates on dynamics of chlorophyll content in winter wheat during vegetative growth and to determine the relationship between nitrogen and chlorophyll content and grain yield of winter wheat. Field trial involving a winter wheat (Triticum aestivum L.) variety ‘Kranich’ was conducted at the LUA Research and Study Farm Vecauce during a three-year period (2012-2015). The treatments were 0, 85, 153, 175+S21, 175 (in 2015), 187 N kg haE−1 and different nitrogen norms according to chlorophyll meter Yara N-tester (Konica Minolta Ltd.) data: 180, 150, 205 N kg haE−1 depending on the year. The results of the trial show that the maximum chlorophyll content in different plant parts was observed at the end of flowering stage. The chlorophyll content depended on the level of mineral fertilisation. The highest chlorophyll content in leaves, stems and ears was obtained by using additional sulphur in two trial years. Usage of chlorophyll meter Yara N-tester obtained the highest chlorophyll content in all analysed plant parts in one trial year. Chlorophyll content was significantly dependant on plant growth stage in stems in all trial years, in leaves in two trial years, and in ears in one year. Nitrogen fertilization significantly affected chlorophyll content in leaves and stems in one trial year. Close positive correlation was observed between grain yield and wheat plant chlorophyll content and average nitrogen concentration at the end of flowering stage in all three trial years.

Legume seed inoculation prior to sowing is a well-known practice in agriculture. Nitrogen fixation, due to the symbiotic relationship between legumes and rhizobia, improves the productivity of legumes. Rhizobia strain specificity can be observed very often, leading to differences in the total protein content. In this study two faba bean cultivars (‘Karmazyn’ and ‘Bartek’) and five pea cultivars (‘Retrija’, ‘Zaiga’, ‘Lāsma’, ‘Vitra’ and ‘Bartek’) were tested using various rhizobia strains. In addition, strain effectivity was observed in four different soil types. Overall, the protein content increase was observed after seed inoculation with Rhizobium sp. Rhizobia strain and plant cultivar interaction specification was observed. Plant cultivar appeared to have a decisive role in the formation of protein content when inoculated with Rhizobium sp. From these pilot experiments, it can be concluded that, when choosing Rhizobium sp. strains for legume inoculation, soil type also should be considered. Rhizobia has the potential to be used as a commercial preparation intended for increasing legume protein content, alongside with increased legume yield; however, different rhizobia strains should be mixed together to achieve the optimal result.

Climatic conditions for soybean cultivation in Latvia are challenging because of their variability. In addition, the sum of sunlight hours and the ratio of temperature and precipitation required to produce a quality crop are unpredictable. There is a risk that even early soybean varieties will not ripen due to weather conditions in a region. Studies show that soybean plants, including the green part of the crop, are well suited for animal nutrition prepared as hay or silage. The aim of this study was to evaluate the chemical composition of different soybean varieties harvested before ripening and assess them as hay or silage raw material. Weight, protein, fat, ash, fibre, acid detergent fibre (ADF) and neutral detergent fibre (NDF) of soybean varieties ‘Erica’, ‘Bolgar’ and ‘Viola’ green mass were determined at different stages of maturity. The results of the study showed a significant increase in protein (from 9.18% to 12.06%) and fat (from 1.18% to 4.40%) content of the dry matter variety ‘Bolgar’ from September to October. The protein content of the dry soya green mass was not affected by variety at the same developing stage but significantly changed among different stages of maturity. As the plant develops, the sucrose content in the green mass increases, the same as the total sugar content.

The article presents the results of studies of two samples of fenugreek: blue (Trigonella coerulea (Desr.) Ser.) and hay (Trigonella foenum graecum L.) on the set of economic, biological and biochemical parameters. The researched samples of fenugreek have a wide range of variability of indicators depending on the terms of sowing and weather conditions. More rapid development was shown by fenugreek species on the summer sowing dates (III decade of June) with a vegetation period of 36–37 days. To obtain a high yield of green mass of fenugreek plants, the early spring (II–III decade of April) and late spring (I decade of May) sowing terms were more suitable. The obtained green mass yield was: 5.7–6.9 t∙haE–1 – blue fenugreek, and 7.3–9.3 t∙haE–1 – hay fenugreek, with the content of the dry matter being 12.4–28.4%, the sum of sugars 2.5–5.0% and vitamin C – 38.0–51.8 mg∙(100 g)E−1. To obtain spices called “mushroom grass”, it is promising to use hay fenugreek with early spring (II–III decade of April) and late spring (I decade of May) terms of sowing, as a more developed vegetative mass is formed with the dry weight yield of plants 1.3–1.4 t∙haE–1. An increase in the amount of precipitation by 1 mm resulted in fluctuations of green mass yield from 15.0 to 77.3 kg∙haE–1 and dry mass yield from 0.693 to 25.9 kg∙haE–1.