We managed to create a self-developed sensor system, which is based on the simultaneous reflectance measurements at a 660 and 940 nm wavelength. The ratio of the reflectance refers to the concentration of the soil organic carbon (SOC). This instrument has a calibration range of 1.19 to 6.05 SOC%. The SOC content of twenty-six soil samples was measured by the self-developed system and a standard spectrophotometric method and we found that the SOC estimation in the self-developed system had a good approximation and the differences ranged from –27.72% ~ + 6.99%. We found a strong correlation between the data of the reference measurements (R² = 0.73) and the values indicated by our self-developed sensor system (Reference (SOX%) =1.4857 × E (SOC%) – 0.7393). This measurement system is easy to use and displays and records the data in real time. This allows one to map an agricultural production area based on the SOC concentration using its built-in GPS unit.

Micronutrients are as important as macronutrients for crops. Each micronutrient has its own function in plant growth. Zinc is important for membrane integrity and phytochrome activities. Copper is an essential micronutrient required for the growth of wheat. Manganese is required for enzyme activation, in electron transport, and in disease resistance. The pot experiment was set up in greenhouse on calcareous chernozem soil Debrecen-Látókép with a spring wheat. In certain development stages (according to BBCH growth scale of wheat), at the beginning of stem elongation (29–30), at the heading (51–59), at the flowering (61–69) stage three average plants were removed from all pots for analysis. Fresh and dry weight of the plant samples were measured. Plant leaves after drying were digested by HNO3-H2O2 methods and manganese, zinc and copper contents of plant were quantified by atomic absorption spectrophotometry. At the flowering stage, when the nutrient uptake of plants is the most intensive, the weight of wheat ranged between 0.94–1.57 g plant-1. In this development stage, the NS2 treatment produced the highest weight of wheat, and compared to this the NS3 treatment decreased that value already. The results show unfavourable effect of NS3 treatment. On the basis of microelement content of wheat and the weight of a plant, nutrient uptake by plant were calculated. At the beginning of growth the starter treatment had positive effect on Cu-uptake compared to the NS1 treatment, where the same dose of fertilizer was stirred into the soil. Wheat is very sensitive to copper deficiency, so copper dissolved by starter treatment could be favourable to the early development of wheat. At flowering stage the Zn-uptake of wheat became the highest and it was between 133.7–234.6 mg plant-1. The Mn-uptake of wheat plant was higher than the Cu- and Zn-uptake of wheat. This phenomenon can be explained by the fact that the untreated soil had higher Mn-content, than Cu- and Zn-content. To summarize the results, it can be stated, that the copper uptake of wheat was more affected by the different treatments in the stage of stem elongation, while Mn- and Zn-uptake of wheat were influenced primarily in the stage of heading and flowering.

The objective of this study was to investigate the effect of two sulphur forms (sulphate and tiosulphate) in combination with three different N:S ratios on the yield of spring wheat and total N- and S-content and uptake by the aboveground biomass on chernozem and sandy soil. In the greenhouse experiment, the effects of two sulphur forms were compared: sulphate (SO42-) and thiosulphate (S2O32-). The sulphate was applied as potassium-sulphate (K2SO4) and thiosulphate as ammonium-thiosulphate ((NH4)2S2O3). Increasing doses of both sulphur forms (24, 60, 120 kg S ha-1) were used with the same nitrogen dose (120 kg N ha-1) which caused three different N:S ratios background (1:0.2, 1:0.5, 1:1). Nitrogen was supplied in the form of monoammonium-phosphate (MAP), ammonium-nitrate and ammonium-thiosulphate. Plant samples were taken in three different development stages of spring wheat based on the BBCH scale: at the stage of BBCH 30–32 (stem elongation), BBCH 65–69 (flowering) and BBCH 89 (ripening). The total nitrogen and total sulphur content of plant at different development stages and also wheat grain were measured by Elementar Vario EL type CNS analyser. The nutrient uptake by plant and grain was calculated from the yield of spring wheat and the N and S content of plant.  The grain yield on chernozem soil ranged between 6.31 and 12.13 g/pot. All fertilised treatments significantly increased the grain yield compared to the control. The highest yield was obtained in the case of the application of 120 kg N ha-1 and 60 kg S ha-1in sulphate form. The grain yield on sandy soil varied from 2.53 to 6.62 g/pot. The fertilised treatments significantly enhanced the yield compared to the control. The highest yield was observed in the case of the application of 120 kg N ha-1 and 60 kg S ha-1 in thiosulphate form. On chernozem soil the increasing doses of sulphur (24, 60, 120 kg S ha-1) with the same N dose (120 kg N ha-1) increased the N-content of spring wheat at all development stages and in the grain. The treatments with different sulphur sources did not cause further changes in the N-content. On sandy soil in the most cases the N-content did not change significantly as a result of increasing sulphur doses. The treatments with sulphate form basically resulted higher nitrogen-content than treatments with thiosulphate form. The treatments with increasing sulphur doses resulted higher S-content on both of chernozem and sandy soil in the case of all development stage. Comparing the effect of the applied sulphur sources on the S-content it can be stated that at the stage of BBCH 30–31 and 65–69 the treatments with sulphate form resulted higher sulphur-content. At the stage of BBCH 89 there was no significant differences in S-content of grain as a result of different sulphur-sources.

Recently, plant-available sulphur (S) in the soil is decreasing due to the limited use of S containing fertilisers and the reduction of atmospheric S deposition. The aim of this work was to evaluate the S status in a long-term fertilisation experiment on a Chernozem in Hungary, with control and 2 NPK rate treatments, considering that after 27 years of superphosphate (SP) use, SP was replaced by monoammonium phosphate in 2010. Plant and soil sampling were performed in 2017 at three different development stages of winter wheat. To assess the S status, the S balance was estimated (for 34 years), KCl soluble soil sulphate, S as well as nitrogen (N) concentration and some amino acids in wheat grain were measured. N/S ratios, S and N uptake of wheat were calculated. The residual effect of SP could be measured only in terms of KCl soluble SO₄^2–-S in soil. According to the wheat grain S concentration (0.08–0.10%) and N/S ratio (14.9–22.0), wheat was S deficient, despite the positive S balance in the fertilised plots. In this experiment, where S fertiliser was applied with 84 kg S/ha dose in 1983–2010, followed by a 7-year period without S fertilisation, S supply is necessary for achieving adequate wheat quality.

The objective of this study was to evaluate the impact of long term NPK fertilization (considering that S containing superphosphate was supplied for 26 years of experiment, but since 9 years S has not used any longer) on sulphur- and nitrogen content and N/S ratio of winter wheat. The second objective of this work was to determine the changes of the amount of the different nitrogen and sulphur fraction in chernozem soil in a long term fertilization experiment. The third aim of the work was to determine if a relationship could be established between the studied parameters. Based on our results, it can be stated that the sulphur containing superphosphate supplied in the period of 1984-2010 has no longer significant effect on total sulphur content of plant in 2018. The NPK fertilization treatments had positive effect on total nitrogen content of winter wheat. In general, increasing NPK doses resulted in significantly higher nitrogen. The effect of irrigation applied in previous years has no statistically significant effect on the sulphur and nitrogen content of wheat. The wheat grain produced in our experiment, especially in fertilized treatments showed S deficiency. Analysing the changes of CaCl2 soluble nitrate-N and total N of the soil, it can be stated that the effect of increasing fertilizer doses clearly appears in these parameters, because the treatment with increasing fertilizer doses resulted higher CaCl2 soluble N forms compared to the control treatment in soil. These values increased until flowering stage of wheat and after that a slightly decrease was observed as a result of higher N uptake of plant. In overall, it can be stated, that the effect of superphosphate on measured sulphur fraction is prevailed. With increasing fertilizer doses higher sulphate content was detected in soil, but the sulphate content measured in different soil extractant is not enough for the wheat in this experiment area. Studying the correlation between the measured parameters of plant and soil, it can be concluded, that the relationships between nitrogen in the plant and in the soil is stable, and did not change during the growing season. The correlation between plant S and soil S varied in the measured periods and the r value was low in most cases. At the stage of flowering the highest r value was found between KCl-SO4 and plant S. In the stage of ripening the strongest correlation was detected between KH2PO4-SO4 and grain S content.