Jaroslav Hlušek

Nitrogen fertilization does not affect micronutrient uptake in grain maize (Zea mays L.)

Abstract Due to continuous single nitrogen fertilization, we hypothesized a built-up deficiency of micronutrients in crops that would limit plant growth and crop quality. In 2-year field experiments using urea-N fertilized grain maize (Zea mays L.), hybrid KWS 2376 at 0, 120 and 240 kg N ha−1 crop uptake of Zn, Mn, Cu and Fe was studied at DC 32, DC 61 and in the grain harvested. Micronutrient contents at DC 32 stage – 1st node (aboveground phytomass) and DC 61 – flowering (ear leaf) were all at levels indicative of adequate micronutrient supply to the crop. At both sampling occasions the Fe:Zn and Fe:Mn ratios were adequate implying that Fe did not inhibit the uptake of Zn and Mn. The application of nitrogen increased the Fe content at the 1st sampling in both years; in the second year the same was also the case for the Zn content. Nitrogen nutrition increased the contents of Mn and Fe at the 2nd sampling only in year 2; in the other treatments no changes were observed in the micronutrient contents. Micronutrient correlations in the grain were discovered between Zn and Mn contents and between Fe and Mn contents. In the second year the highest N-rate significantly increased the Fe and Zn content of the grain compared with the lower rates of nitrogen fertilization. Grain yields were not affected by the rate of nitrogen and ranged between 13.65 and 14.34 t ha−1 (1st year) and between 13.68 and 14.18 t ha−1 (2nd year). Nitrogen fertilization did not reduce the content of micronutrients in the plant or grain of maize. It is evident that the continuous single use of N fertilization so far has not resulted in a micronutrient deficiency of the plants limiting the nutrient density of the grain or reducing its quality.

Effect of combined nitrogen and sulphur fertilization on yield and qualitative parameters of Camelina sativa [L.] Crtz. (false flax)

Abstract Camelina (Camelina sativa (L.) Crtz., false flax) is described as a species requiring fewer inputs than other oilseed crops thus making it an interesting alternative in sustainable cropping systems. As information on the combined effects of nitrogen and sulphur on camelina yield and quality parameters is meagre, a pot fertilization experiment was carried out with nitrogen applied as NH4NO3 at three increasing rates equivalent to a range from 63 up to 127 kg ha−1. These treatments were combined with sulphur additions applied as (NH4)2SO4 to achieve a soil sulphate content of 25 or 45 mg kg−1, respectively (equivalent to 75 and 135 kg S ha−1). The medium and high nitrogen rates combined with the low sulphur fertilization level increased the number of branches per plant compared with the lowest nitrogen fertilization at the same sulphur rate. Camelina seed yield increased with increasing nitrogen doses at the same low sulphur level, whereas straw yield increased only at the highest rate of nitrogen. Thousand-seed mass increased at the highest nitrogen dose and with the low sulphur application rate. In addition, the increase in nitrogen fertilization reduced seed oil content from 39.8% to 37.1%. A highly negative correlation was observed between oil and protein content of seeds. Nitrogen fertilization increased total oil yield and total protein yield. Differences in crop parameters between the sulphur treatments were not significant statistically, although the higher sulphur treatment tended to increase seed yield as well as oil and protein content compared with the low sulphur treatment. Thus, the combined application of N and S as mineral fertilizers is only recommended when growing camelina on sulphur-deficient soils if the aim is to achieve both high oil and protein production.

Effect of foliar application of selenium on the content of se-lected amino acids in potato tubers (Solanum tuberosum L.).

Selenium (Se) is an important element associated with the enhancement of antioxidant activity in organisms. Po- tato is very suitable for fertilisation with Se (biofortification). The experiment was performed to examine the effect of foliar application of Se as sodium selenite (200 or 400 g Se/ha) at the tuberisation stage on a spectrum of amino acids in tubers of varieties. The trends of amino acids were consistent in both years of the study. Application of Se increased the relative content of total essential (EAA) and non-essential (NEAA) amino acids relative to the con- trols (Karin: EAA 16.81-21.73% and NEAA 14.18-18.63%; Ditta: EAA 4.71-13.00% and NEAA 5.78-6.49%). The increase in the content of phenylalanine (Phe) was particularly significant (up to 48.9%) when also the contents of aspartic acid (Asp), glutamic acid (Glu), threonine (Thr), and tyrosine (Tyr) increased significantly compared with the controls. The results of changes in the content of isoleucine (Ile), leucine (Leu), lysine (Lys), methionine (Met), valine (Val), alanine (Ala), arginine (Arg), proline (Pro), cysteine (Cys), glycine (Gly), histidine (His), and serine (Ser) were also discussed. The highest dose of selenium is shown as a stress factor. Its toxic effects resulted in a change of amino acid contents.

Response of "Jonagold" apple trees to Ca, K and Mg fertilization in an andisol in southern Chile

Abstract The effects of Ca, Mg and K fertilisation on the growth, yield, fruit quality and mineral concentration of the fruits and leaves of “Jonagold” apple trees that were grown in an Andisol in southern Chile were analysed. In general, the Andisols in this area contain low reservoirs of these elements; therefore, the roles of these elements as essential macroelements and their effects on plant growth, yield and fruit quality are key factors that should be considered in these soils in current and future apple orchards. The soil application of Ca, Mg and K (CaSO 4 , MgSO 4 and K 2 SO 4 ) did not significantly affect vegetative growth, fruit production or their quality parameters. Ca and Mg fertilisation did not affect the uptake at the present stage of development and production. The mineral concentration of K in the leaves was significantly increased in the plants that were treated with K alone (1.67% DW) or in combination with Ca and Mg (1.8% DW). The fertilisation did not result in the development of physiological disorders in the fruit. This study revealed no relationships between the apple nutrient status and the Ca, Mg and K saturation ratios in the soil. However, the medium to low exchangeable content of these elements in the soil may affect the yields and the quality of the fruit in the future due to the increased demand by the trees for those elements.

The effect of fertilisation with digestate on kohlrabi yields and quality

Three treatments were used in a two-year (2014–2015) vegetation pot experiment with kohlrabi of the cv. Moravia: (1) untreated control; (2) digestate; (3) digestate + phosphorus (P). The nitrogen (N) rate was the same in treatments 2–3. There were significant differences between years in all parameters. The weight of single kohlrabi bulbs in the unfertilised control was significantly lower in both years (33.1–46.9%) than in the digestate treatment (100%). Digestate supplemented with P (treatment 3) increased the bulb yield significantly by 11.0–14.3% compared with pure digestate (treatment 2). In both years the content of bulb nitrates (mg NO3 –/kg FM (fresh matter)) was significantly the lowest in the unfertilised control (135 and 163, respectively). After digestate applications the nitrates content (mg NO3 –/kg FM) increased significantly in both years, i.e. to 315–327 (2014) and to 486–509 (2015) compared to unfertilised control. In two years the content of ascorbic acid (mg/kg FM) did not differ among the three treatments (274–288 in 2014 and 311–329 in 2015). Digestates can be recommended for kohlrabi fertilisation prior to planting.

Fate of humic acids isolated from natural humic substances

Composition of humic acids (HA) is a function of plant-derived inputs, degradation processes regulated by microorganisms, organo-mineral interactions and age. Characterization of different origin humic substances is important for evaluation of their contribution to stabile and labile carbon pool in the environment. The relative abundance of chemical components in HA isolated from soils, compost, commercial lignohumates, alginite, acadiane and lignite was studied with aim to quantify content of important biomarkers such as amino acid, lipids and polyphenols. HA were considered as a heterogeneous complex and high concentration of peptides, polyphenols and lipids was determined in acadian-HA to compare with soil-HA. Compost-HA contained much more amino acids to compare with soil-HA samples. Alginite-HA and lignite-HA were similar in biomarkers content to soil-HA. Fourier transform infrared spectroscopy confirmed that chemical composition and functional groups content differs with the origin, humification degree and the age of studied samples. Soil-HA are typically composed of a variety of −OH, COOH−, C–O, C–H2, (aliphatic and aromatic) groups, quinines, lignin fragments, polysaccharide, monosaccharide and proteins fragments, which are linked together by −O−, −NH−, −H=, >C=O, metal ions and –S− groups. 13C NMR spectroscopy showed that aromatic carbon content was the highest in lignite-HA and soil-HA.

Effects of decreasing levels of n amendments on organic "granny smith" apple trees

The effect of decreasing levels of organic N-fertilization on fruit production, mineral composition and fruit quality was evaluated in organically cultivated “Granny Smith” apples trees. Treatments included the application of decreasing levels of N fertilization (100 kg N ha-1, 75 kg N ha-1, 50 kg N ha-1 and 0 kg N ha-1 ) applied as fossilized red guano (50% of the total amount of N) and blood meal (50% of the total amount of N) to twelve years old Granny Smith apple trees. Yield was not affected by the treatments (yield ranged from 0.28 to 0.4 kg cm-2 SCSA). Fruit mineral concentration and ratios were not affected by treatments. Fruits showed low Ca concentrations (2.8 to 3.3 mg Ca 100 g-1 FW), high levels of K (118.6 to 130.1 mg K 100 g-1 FW) and high values for K+Mg/Ca (> 12) and K/Ca (> 30) ratios. Mineral concentration on leaves was not affected by treatments (normal concentrations for macro and microelements). Bitter pit was only detected after 60 days of storage (100 kg N ha-1 tree, 1.1 in a scale 1-4). Besides orchard nitrogen management, fruit mineral ratios and Ca foliar applications should be considered for managing fruit production and quality in organic apples.

Changes in fertilisation and liming of soils of the Czech Republic for the past 20 years

Some basic soil fertility parameters have been monitored in the Czech Republic since 1961, at intervals of three to six years, as a part of the national agrochemical soil testing programme. This mandatory programme governs the wording of later regulations on fertilisers and covers in particular the determination of soil reaction and content of available nutrients (P, K, Mg and Ca). In specific cases (e.g. application of sewage sludge to soil, soil testing in organic farming, soil damage caused by flooding, etc.), soil physical and microbiological parameters are also measured. The results for the past 20 years (1989–2008) show a decreasing tendency in pH value and content of available nutrients in agricultural soils. The land parcel identification system (LPIS) is used for testing, and all sampling areas are fixed in the national mapping system (S-JTSK). All the results are available to farmers and government bodies.

Using foliar applications of magnesium and potassium to improve yields and some qualitative parameters of vine grapes (Vitis vinifera L.)

In a three-year field experiment (2011–2013) we assessed the effect of magnesium (MgSO 4 ) and potassium (K 2 SO 4 ) applied as foliar applications both separately (3.86 kg Mg/ha or 12.44 kg K/ha) and in combination (1.93 kg Mg/ha + 6.22 kg K/ha) on yields of grapes of cv. Zweigelt and some qualitative parameters of the grapes. The applications were repeated 4 times in stages BBCH 15–19; 55; 75 and 83. The experiment was carried out on soil well supplied with Mg and K in the subsoil layer. In terms of average 3-year results the grape yields were by 11.2% (MgSO 4 ), 13.9% (K 2 SO 4 ) and 6.6% (MgSO 4 + K 2 SO 4 ) significantly higher than the untreated control. The sugar content of grapes (sum of glucose and fructose) was lower (mostly insignificantly) by 0.5–4.3% in all the fertilized treatments than in the untreated control. Fertilization had no significant impact on the pH of must (juice) and ranged between 3.02 and 3.25. The content of titratable acids in the must ranged insignificantly between 8.73 and 10.86 g/L, and average values were the highest in the untreated control. On the basis of these results it is evident that separate applications of Mg and K have a positive effect, in particular in that they stimulate grape yields, and at the same time the effect of the year is significant.