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The impact of toxic elements (TEs) contaminating the root zone of Lupinus angustifolius L. on enzymatic activities, nitrification rate, and changes in the root system was evaluated. Lupine was cultivated in a pot experiment using two types of soil - control and contamination (with a high degree of arsenic (As), cadmium (Cd), lead (Pb), and zinc (Zn) contamination). After harvesting lupine biomass, enzyme activities (β-glucosidase, acid phosphatase, arylsulphatase, lipase, chitinase, cellobiohydrolase, alanine aminopeptidase, and leucine aminopeptidase) in soils were analysed. Enzyme activities decreased with TE soil contamination. According to our results, arylsulphatase was found to be the most sensitive soil enzyme to TEs. The nitrification rate is closely related to soil contamination and plant activity, as it stimulates microbial growth and multiplication through root exudates. The close correlations confirmed this relationship (r = 0.73-0.99). An increasing trend in TE contents in the roots was observed with soil contamination. Plant hormones are crucial in regulating root growth and development under stress conditions. The levels of determined phytohormones in our experiment (auxins, abscisic acid (ABA), salicylic acid (SA), and bioactive cytokinins (bCKs)) were lower in the contamination compared to the control. Correlations confirmed a significant negative relationship between the TE content in the roots and the contents of phytohormones (auxins: r = -0.96 to -0.97; ABA: r = -0.83 to -0.86; SA: r = -0.95 to -0.99, bCKs: r = -0.87 to -0.93). The ratios of these hormones (not their absolute values) appear to be the determining factor for regulating root development and protecting plants from oxidative stress.

In recent years, sulfur inputs into the soil have greatly diminished due to the significant decrease in SO2 emissions. Plant nutrients, like sulfur, can be released by the mineralisation of soil organic matter (SOM), which is a complicated mixture of substances (or fractions) like glomalin-related soil protein (GRSP) and fulvic acids (FA), humic acids (HA), humic substances (HS) and others. GRSP, FA, HA, and HS content, as well as the content of mineral and organic fractions of sulfur, was determined in different mineral and organic fertiliser treatments of the long-term field experiment. Using these results, the sulfur content in GRSP was calculated based on the soil's organic matter carbon and soil's organic bound sulfur (CSOM/SORG) ratio. Sulfur content in GRSP was 4.08-5.46 (easily extractable GRSP), 9.77-15.7 (difficultly extractable GRSP), and 13.9-21.1 (total GRSP) mg S/kg of soil. Overall, the application of the organic fertiliser caused an increase in S content bound to GRSP. A strong significant relationship was also observed between GRSP fractions and soil organic sulfur. A similar relationship was also observed for the HA and HS with organic sulfur.

The glomalin content is generally considered an indicator of the soil organic matter (SOM) quality. The content of easily extractable glomalin (EEG) and the total glomalin (TG) content was investigated across 71 different sites in the Czech Republic with arable soil and crop production (12 chernozems, 30 luvisols, 17 cambisols, and 12 fluvisols). The majority of the crops in the crop rotation were cereals (45.5%—mainly winter wheat, winter barley, and spring barley). The proportion of winter canola within the crop rotation was 15.9%. The contribution of other crops was substantially smaller (alfalfa, clover, potatoes, beet, silage maize, grain maize). The representation of crops in the crop rotation is standard for conventional farming in the Czech Republic. Based on the results of long-term field monitoring at 71 sites in different soil–climate conditions, we can state the following. The TG content was significantly correlated with the soil organic matter carbon content (CSOM), as well as another important indicator of SOM quality (humic and fulvic acid carbon content ratio—CHA/CFA). A significant and positive correlation was also determined for the TG and clay content (size < 0.002 mm), as well as particles smaller than 0.01 mm. The easily extractable glomalin content (EEG) did not differ based on the reference soil group (RSG). On the other hand, the total glomalin content (TG) was significantly higher in the chernozem RSG in comparison with other RSGs (luvisols, cambisols, fluvisols). There was no relationship between the pHCaCl2 and glomalin (EEG; TG). The same can be said about the relationship between glomalin (EEG; TG) and the bulk density and porosity. No link was established between the glomalin content (EEG; TG) and phosphorus plant-available content. There was no relationship between the amount of applied organic matter (carbon inputs) and the soil glomalin content (EEG; TG). This relationship was not influenced by the type of applied organic fertilizer. No significant relationship was found for either straw, manure, or compost. The data on the glomalin content are significantly influenced by the site (soil type and soil texture).

A continuous long-term field experiment with maize monoculture was conducted to evaluate the P availability and balance, DM yield, P uptake, and P sorption parameters in chernozem soil after 27 years. A total of 2 doses of nitrogen (120 and 240 kg ha−1) were applied as mineral nitrogen (N120 and N240) and sewage sludge (SS120 and SS240) and compared with unfertilized control (Con). The aboveground biomass (DM) yields significantly increased in the order of Con < SS120 < SS240 < N120 < N240 treatments and the maximum P uptake was recorded for both N240 and SS240 (25.1 kg P ha−1) according to the nutrient application gradient. The N120 and N240 treatments positively influenced the DM yield but negatively influenced the P balance (−648 and −678 kg P ha−1 27 years−1), gradually bringing a risk of P deficiency in the soil. On the other hand, applications of SS120 and SS240 positively influenced the P availability and pseudototal (PAR) content in the soil, which resulted in a buildup of legacy P or an increase in P saturation greater than the environmental threshold value. Aluminum was found to be a major controlling sorption factor for P in our chernozem soil.

Abstract Background Soil fertility is substantially influenced by soil organic matter quality and quantity. Much attention has also been given to glomalin content as one of the qualitative parameters of soil fertility. Glomalin content is considered an indicator of soil fertility due to its positive correlation with soil organic carbon. Aim This study aim to (i) determine the influence of different fertilization systems on maize yield and soil organic matter quality parameters, (ii) ensure that changes in total glomalin content (TG) and easily extractable glomalin (EEG) content are sensitive enough to reflect changes in the SOM quality resulting from long-term fertilization, and (iii) determine whether both forms of glomalin must be determined or if the easily extractable glomalin (EEG) content is sufficient, even for a fertile chernozem. Materials and methods Long-term field experiments with silage maize monocultures were used to study relationships under different rates of mineral nitrogen and sewage sludge fertilization. The trials comprised 5 treatments: (i) no fertilization control (Con), (ii) and (iii) two different calcium ammonium nitrate rates (N120 and N240 at doses of 120 and 240 kg N ha−1 year−1, respectively), and iv) and v) two different sewage sludge rates (S120 and S240 corresponding to mineral N doses). Topsoil (0–30 cm) analysis was performed 28 years after the onset of the experiment to determine soil organic carbon, the fractions of humic substances, potentially mineralizable carbon and dissolved organic carbon, the potential wettability index, soil aggregate stability, EEG, and total glomalin (TG). Results The control treatment, which did not include fertilization, showed significantly lower average yields (9.76 t DM ha−1 year−1) than the fertilization treatments (on average 12.3 DM ha−1 year−1). Significant differences in yields were not found between the fertilization treatments. A positive correlation between glomalin (EEG, TG) content and soil organic matter carbon content was observed. A periodic application of sewage sludge increased the content of glomalin. However, the highest quality of SOM was found in the control treatment (nonfertilized). This treatment had the highest values for the humic/fulvic acid ratio and the highest contents of humic acids and potentially mineralizable carbon. Furthermore, the Con treatment showed the highest soil aggregate stability and potential wettability index. Mineral N fertilization significantly reduced soil aggregate stability values. Conclusions The unfertilized control showed the highest SOM quality but the lowest yields. The data on glomalin content can be used to study soil organic matter quality. Because the EEG extraction method is easy to apply, uses lower quantities of chemicals and consumes less time, it presents a better option than TG extraction. The sensitivity of the methods for SOM quality determination decreases with increasing SOM content. Graphical Abstract

As with new technologies, plant nutrition has taken a big step forward in the last two decades. The main objective of this review is to briefly summarise the main pathways in modern plant nutrition and attract potential researchers and publishers to this area. First, this review highlights the importance of long-term field experiments, which provide us with valuable information about the effects of different applied strategies. The second part is dedicated to the new analytical technologies (tomography, spectrometry, and chromatography), intensively studied environments (rhizosphere, soil microbial communities, and enzymatic activity), nutrient relationship indexes, and the general importance of proper data evaluation. The third section is dedicated to the strategies of plant nutrition, i.e., (i) plant breeding, (ii) precision farming, (iii) fertiliser placement, (iv) biostimulants, (v) waste materials as a source of nutrients, and (vi) nanotechnologies. Finally, the increasing environmental risks related to plant nutrition, including biotic and abiotic stress, mainly the threat of soil salinity, are mentioned. In the 21st century, fertiliser application trends should be shifted to local application, precise farming, and nanotechnology; amended with ecofriendly organic fertilisers to ensure sustainable agricultural practices; and supported by new, highly effective crop varieties. To optimise agriculture, only the combination of the mentioned modern strategies supported by a proper analysis based on long-term observations seems to be a suitable pathway.

Soil organic matter (SOM) quantity and quality are important factors that significantly influence soil fertility. SOM quality indicators change throughout time. In this study, long—term field experiments (22–50 years in duration) on a Cambisol at four sites in the Czech Republic were selected. Seven crops were successively rotated in the sequence: clover, winter wheat, early potato, winter wheat, spring barley, potato, and spring barley with interseeded clover. Five treatments were investigated, including an unfertilized treatment, farmyard manure, and various combinations of farmyard manure and mineral fertilization. A total of 40 t ha−1 of farmyard manure was applied to the early potato and potato crops. Combining organic and mineral fertilizers increased soil organic matter quality and quantity over unfertilized or organic only treatment. The highest intensity of mineral fertilizers in our trials elevated the mean of carbon sequestration efficiency to 45.6% in comparison to pure manure treatment which reached only 22.9% efficiency. A strong correlation was established between the total glomalin content and soil organic matter carbon, fulvic acid, humic acid, carbon hot water extraction, potential wettability index (PWI), and aromaticity index. The PWI was also strongly correlated with these indicators. The E4/E6 ratio indicator was shown to be a much less sensitive method for reflecting the change in soil organic matter quality.

Long-term field experiments were conducted on luvisol at five sites in the Czech Republic (42–48-year duration). The average total organic carbon content in the soil varied between 9.0 and 14.0 g kg−1. In these trials, seven crops were rotated in the following order: clover, winter wheat, early potato, winter wheat, spring barley, potato, and spring barley with interseeded clover. Five treatments were studied: unfertilized treatment (Con), farmyard manure (F), and combinations of farmyard manure with three mineral fertilization levels (F+M1, F+M2, F+M3). Plant residues were not incorporated into the soil. An amount of 40 t ha−1 of farmyard manure fresh matter was applied twice during crop rotation. Intensive mineral fertilizer (F+M3) increased the average value of the carbon sequestration efficiency (CSE) by 12.9% and up to 26.3%. Combining organic and mineral fertilizers at moderate and higher intensities increased the soil organic matter quantity and quality compared to the unfertilized or manure treatment. Data on the glomalin content can be used to study the organic matter quality. We determined a strong correlation between the total glomalin content and the soil organic matter carbon, fulvic acid content, humic acid content, extractable carbon content, and dissolved organic carbon content, as well as the potential wettability index and aromaticity index.

Sulfur nutrition is a crucial part of proper crop growth. In this study, we investigated the influence of organic fertilizers in a long-term field experiment (23 years) with continuous maize monoculture. We focused on: (a) changes in the soil sulfur fraction pools, (b) the balance of total sulfur inputs and outputs, and (c) sulfur uptake by maize. The following treatments were selected: unfertilized control (Control), urea and ammonium nitrate (UAN), UAN and wheat straw (UAN + St), sewage sludge (SS), farmyard manure (FYM), and slurry (Slurry). Using sequential extraction, we determined water-soluble (SW—in water), adsorbed (Sads—in 0.032 mol L−1 NaH2PO4), and available (Sav = SW + Sads) sulfur content. Microwave-assisted digestion in an Aqua regia solution was used to measure the pseudo-total sulfur content (Spt). Organic-bound sulfur (Sorg) was calculated as a difference between Spt and Sav. We found that average biomass yields responded to a uniform 120 kg N ha−1 year−1 dose, rather than the dose of S in fertilizers, with an increase over the Control by 34–49%. The effect of an additional 33.5 kg N ha−1 year−1 on UAN + St treatment was not significant. Average sulfur uptake responded to increased yields (69-121% higher than Control), rather than the sulfur application, with the exception of SS, where the dose of sulfur was high enough to cause an additional uptake. In the topsoil, we discovered a significant decrease over time (from 1997 to 2019) in water-soluble (SW), adsorbed (Sads), available (Sav), and pseudo-total (Spt) fractions on all treatments to 29, 59, 37, and 82% of their initial values, respectively. For all treatments, the proportion of Sorg in Spt increased over time, which was caused by the decrease in mineral fractions (SW, Sads, Sav). The absolute content of Sorg decreased over time for all treatments except SS and FYM to about 85% of the initial value. Using the simple balancing method, we calculated that UAN + St, SS, FYM, and Slurry treatments annually lost 8.04, 66.1, 21.4, and 26.8 kg of S ha−1, respectively. This loss was attributed to the decrease in atmospheric depositions, as well as the release of sulfur from soil organic matter (for UAN + St and Slurry treatments) and a high proportion of easily mineralizable and inorganic sulfur from the SS treatment. Generally, the FYM fertilizer provided the highest potential for maintaining soil Spt status.

Experiments were used to determine the potassium release from the non-exchangeable K (Kne) forms that are involved in plant nutrition and which replenish the pool of available K. Long-term stationary field experiments with different fertilisation systems (organic: farmyard manure, sewage sludge, straw; mineral: NPK, N) were carried out to study the potassium balance and the K content changes in the topsoil (0-30 cm) and subsoil (30-60 cm). The trials were located at three sites with different soil-climatic conditions. The following crops were rotated within the trial: potatoes (maize) - winter wheat - spring barley. All three crops were grown each year over 21 years. Positive correlations between the contents of the available K in the topsoil and the potassium balance (K inputs - K outputs) were observed. There were no statistically significant differences among the treatments. Depending on the soil properties, the ratio of non-exchangeable K (Kne) was 12-37% of the values obtained via the aqua regia extraction. Depending on the site, the amount released from the Kne forms to the available K form was 46-69 kg K/ha/ year. The use of K from the farmyard manure varied from 7.4% up to 25%. Due to the low K content in the sewage sludge, the long-term fertilisation with sludge may only lead to the depletion of the available K in the soil, similar to the sole N mineral fertilisation.

Glomalin is one of the factors with an important role at forming and stabilising soil aggregates. Long-term stationary experiments were carried out to observe the influence of various fertilisation treatments on the content of glomalin in topsoil. The content of easily extractable glomalin (EEG) and total glomalin (TG) were determined. Moreover, glomalin was also determined by using the near-infrared reflectance spectroscopy (GNIRS). Both mineral and organic fertilisation significantly increased the content of glomalin compared to the unfertilised control. However, observed differences among individual fertilisation treatments were not significant. A significant correlation was determined between the content of EEG, TG, GNIRS, and the content of humic substances as well as humic acids. Both methods used (EEG, TG) can equally reflect soil organic matter quality. A significant correlation was also recorded between the GNIRS and extraction methods (EEG, TG).

The quality of soil organic matter plays a central role in soil structure, carbon sequestration and pollutant immobilization. The effect of 16–23 years of fertilization on the quality of soil organic matter was studied in field experiments at ten experimental sites in Central Europe. Soil samples were collected in 2016 after barley harvest. Six crops were rotated: pea–canola–winter wheat–spring barley–beet/potato–spring barley. Six treatments were studied: unfertilized control, mineral fertilization (NPK), farmyard manure, farmyard manure + NPK, straw incorporation, and straw incorporation + NPK. Although carbon input did not significantly correlate with any soil organic carbon fractions, the C/N ratio of applied organic fertilizers significantly correlated with the content of humic acid carbon (C-HA), the C-HA/C-FA ratio and humification index in soil. The combination of farmyard manure + NPK resulted in a higher humic acid carbon content in soil, humification rate, and humification index compared to the application of NPK, straw return, and the combination of straw return + NPK. Although straw return led to a lower E4/E6 (A400/A600, Q4/6) ratio compared to farmyard manure application, the C-HA/C-FA ratio was unchanged among these treatments. The application of farmyard manure with and without the addition of NPK led to higher values of carbon sequestration efficiency in soil compared to the straw return with and without the addition of NPK.

Different fertilisation systems cause changes in the content of mobile aluminium (Al) forms in the soil as a result of soil pH changes. Long-term stationary fertilisation experiments established in 1996 at 2 sites were evaluated. Experiments consisted of unfertilised control treatment and 6 other treatments, combining mineral fertilisation with the application of farmyard manure, sewage sludge and straw. To record the changes in mobile Al forms, we used 5 extraction procedures with agents: water, CaCl2, KCl, CaCl2/DTPA (CAT) and Mehlich 3 solutions. At treatment nitrogen (N) + straw, topsoil acidification was observed, resulting in the increased content of mobile Al. At treatments with mineral fertilisation (N, NPK), increased content of mobile forms of Al was recorded. Application of cattle manure and sewage sludge helped to stabilise the soil pH and reduce mobile Al forms. The close correlation between the methods determining the exchangeable Al (CaCl2 and KCl solutions) was observed; however, KCl extraction was more favourable in soils of low Al extractability, as the amount of extracted Al was 3-4 times higher. Positive correlations were determined between Al extracted by Mehlich 3 solution and the content of exchangeable Al. The less frequently used CAT method also turned out to be perspective for mobile Al determination. Furthermore, aluminium content determined in Mehlich 3 extract was compared with mobile phosphorus amounts in H2O, CAT and Mehlich 3, respectively. All three investigated phosphorus forms showed significantly negative correlations with Al.

The aim of this study is to describe the changes of bioavailable phosphorus content in soil in long-term 18 years field experiments with different fertilizing systems. The field experiments are located at three sites with different soil and climatic conditions in the Czech Republic (Červený Újezd, Humpolec and Prague-Suchdol). Same fertilizing systems and crop rotation (potatoes (maize) - winter wheat - spring barley) are realized at each site with following fertilizing treatments: (1) unfertilized treatment (control), (2) farmyard manure (FYM), (3) and (4) sewage sludge (SS 1 and SS 3), (5) mineral nitrogen (N), (6) mineral nitrogen with straw (N + straw) and (7) mineral nitrogen with phosphorus and potassium (NPK). The long-term fertilizing effect on available P content changes in soil was observed. Bioavailable phosphorus content in soil increased in treatments with organic fertilization after 18 year experiment at all sites. The treatments SS 3 had the highest increase at all sites. The highest bioavailable P content increase compared to control (258 mg/kg) was determined at site Červený Újezd. On the contrary, available phosphorus content decreased at treatments with mineral fertilization and control treatment among all sites. Bioavailable P content decrease in the treatment NPK was observed, although phosphorus was applied. The lowest differences in available P content among all fertilizing treatments were observed at the location Prague-Suchdol.

Balance of potassium (K) was observed in long-term stationary field experiments (21 years) at two sites with different soil and climatic conditions (Luvisol, Cambisol). The following crops were rotated within the trial: potatoes- winter wheat-spring barley. All three crops were grown each year. The trial comprised 6 treatments: (1) no fertilization; (2) farmyard manure; (3) half dose of farmyard manure + nitrogen (N) in mineral nitrogen fertilizers; (4) mineral nitrogen fertilizers; (5) NPK in mineral fertilizers; (6) straw of spring barley + N in mineral nitrogen fertilizers. The recovery rate of potassium from farmyard manure by crops was 24-26%, from mineral fertilizers it was 27-52%. Different fertilization intensities were manifested by significant differences in the content of exchangeable K in soil. Changes in non-exchangeable K (Kne) were recorded only at the Luvisol site (850 mg Kne/kg), but not at the Cambisol site (3000 mg Kne/kg). The maximum negative balance (-2376 kg K/ha/21 years) was recorded at the mineral nitrogen fertilization treatment.

The influence of different fertilizers (mineral/organic) on the quantity and quality of soil organic matter was monitored in long-term stationary experiments (27 years) with silage maize monoculture production on Luvisol. The main aim of this study was to investigate the relationship between easily extractable glomalin (EEG), total glomalin (TG), and parameters commonly used for the determination of soil organic matter quality, i.e., the content of humic acids (CHA), fulvic acids (CFA), and potential wettability index (PWI). A significant correlation was found between EEG content and CSOM content, humic acid content (CHA), humic acid/fulvic acid ratio (CHA/CFA), PWI, and index of aromaticity (IAR). Furthermore, the contents of EEG and TG correlated with soil organic carbon (CSOM). Periodical application of sewage sludge and cattle slurry increased the content of glomalin in soils. From the results, it is obvious that data about glomalin content can be used to study soil organic matter quality. A more sensitive method (a method that reacts more to changes in components of soil fertility) seems to be the determination of EEG rather than TG. The factors supporting use of EEG extraction in agronomic practice are mainly the substantially shorter time of analysis than TG, CHA, and CFA determination and lower chemical consumption. Furthermore, the PWI method is even suitable for studying soil organic matter quality. On the other hand, the humus quality ratio (E4/E6) does not provide relevant information about soil organic matter quality.

Soil carbon transformation was observed in long-term stationary field experiments (longer than 20 years) at two sites with different soil-climatic conditions (Luvisol, Chernozem). The following crops were rotated within the trial: row crops (potatoes or maize)-winter wheat-spring barley. All three crops were grown each year. Four different fertilization treatments were used: (a) no fertilizer (control); (b) sewage sludge (9.383 t dry matter/ha/3 years); (c) farmyard manure (15.818 t dry matter/ha/3 years); (d) mineral NPK fertilization (330 kg N, 90 kg P, 300 kg K/ha/3 years). At the Luvisol site, the control treatment showed a tendency to decrease organic carbon (Corg) in topsoil. At organic fertilization treatments the content of Corg increased: sewage sludge - +15.0% (Luvisol) and +21.8% (Chernozem), farmyard manure - +19.0% (Luvisol) and +15.9% (Chernozem). At the NPK fertilization, the increase was +4.8% (Luvisol) and +4.7% (Chernozem). The increased Corg content was also associated with an increase of microbial biomass carbon (Cmic) and extractable organic carbon (0.01 mol/L CaCl2 and hot water extraction). The ratio of Cmic in Corg was within the range 0.93-1.37%.

The status of macronutrients phosphorus (P), potassium (K), sulphur (S), calcium (Ca) and magnesium (Mg) was assessed 15 years after the establishment of a long-term crop rotation and soil tillage trial with mouldboard ploughing (MP), no-till (NT), deep conservation tillage (CTd) and shallow conservation tillage (CTs). The mobile proportions of macronutrients in an Austrian Chernozem soil were determined to a depth of 50 cm with the single reagent extractant acetic acid (AA) and Mehlich 3 (M3), which uses several reagents as extractants. AA revealed less P and K, but more Ca and Mg compared to M3. Both extractants could capture the distribution pattern of the nutrients in the soil profile, but M3 showed higher differences among the soil layers. In the first 5 cm in NT, the P concentration was higher than in MP, CTd and CTs. The concentration of K was higher in NT, CTd and CTs than in MP in the first 10 cm of the soil. Phosphorus and K concentrations did not differ between tillage treatments below these soil layers, and S, Ca and Mg were similar in all soil layers. As none of the analysed elements except for Ca were fertilized and no accumulation of S, Ca and Mg was observed in the upper soil layer, the higher concentrations are attributed to accumulation through crop residues and then less leaching of P and K. Crop rotation did not affect the distribution of the analysed macronutrients in the soil but affected the nutrient uptake by winter wheat mostly due to the yield differences of winter wheat in the two crop rotations.

Mehlich 3 is an extractant used worldwide for extracting bioavailable nutrients in soils; however, its extraction abilities for sulfur (S) are still not well described. The aim of this preliminary study was to compare the results of Mehlich 3 determined soil S fraction (SM3) with the results of sulfur fractionation, mainly focusing on bioavailable S (Sav - sum of water-extractable (Sw) and adsorbed (Sads) sulfur). Air dried soil samples from commonly used agricultural soils were chosen for the analyses. The following S fractions were determined: (i) Sw; (ii) Sads; (iii) Sav; (iv) 1 mol/L HCl extractable (SHCl); (v) estersulfate (Ses); (vi) organic (Sorg) and (vii) total (Stot). The median value of SM3 (18.3 mg/kg) was similar to Sav (17.9 mg/kg). From the correlation and regression analysis it is clear that SM3 results are in close relationship with Sav form. On the other hand, the relationships between SM3 and organic S (including SHCl) were very weak. Based on the obtained results it can be concluded that Mehlich 3 method has a good potential to determine bioavailable sulfur in commonly used agricultural soils. However, especially the plant response should be further studied to confirm this theory.

Relation between wheat (Triticum aestivum) nutritional status determined at the beginning of stem elongation and during anthesis, respectively, and available content of phosphorus (P-M3) and zinc (Zn-M3) determined by the Mehlich 3 extractant was studied. Both one-year pot experiment with spring wheat and two-year on-farm trials with winter wheat were run on various calcareous soils (pH values of 7.18-7.94, median 7.80, P-M3 1-289 ppm, median 54, and Zn-M3 2-14 ppm, median 4), in the Czech Republic (Central Europe). Phosphorus nutrition index (ratio of phosphorus concentration in shoot biomass to critical phosphorus concentration - Pc) was calculated using the Belanger et al.'s model: Pc = -0.677 + 0.221N - 0.00292N(2), where both phosphorus and nitrogen concentrations were expressed in g/kg shoot dry matter. Unlike phosphorus concentration in shoot biomass, phosphorus nutrition index significantly correlated with P-M3 content in soil. Optimal values of the phosphorus nutrition index were recorded if P-M3 was 51-68 ppm. Zinc concentration in shoot biomass more strongly correlated with P:Zn ratio (M3) in soil compared to Zn-M3 content in soil. P:Zn ratio in shoot biomass of 130:1 did not lead to phosphorus deficiency and corresponded to P:Zn (M3) ratio in soil of 9.3:1-14.3:1.

Sulfur nutrition is a critical part of proper crop growth and development. In our study, biomass yields (BY) and S uptake were investigated on long-term maize monoculture on haplic luvisol soil during the 23 years of this trial, as well as changes in water extractable (Sw), adsorbed (Sads), mineral (Sav), and pseudo-total S (St) fractions. Treatments used in this study are: (1) Control (Cont); (2) ammonium sulfate (AS); (3) urea and ammonium nitrate (UAN); (4) UAN + phosphorus and potassium (UAN + PK); (5) UAN + phosphorus, magnesium, sulfur (UAN + PMgS); and (6) Fallow. Recently, the Mehlich 3 method started to be used in the Czech Republic to determine content of plant available S. Using this method, it was found that the content of S extracted by Mehlich 3 (SM3) closely correlates to Sav in both topsoil and subsoil (r = 0.958 in 1997 and 0.990 in 2019, both at p < 0.001). We also found that, on average, during the entire experiment, all treatments had increased yields over Cont (135–147%) and increased S uptake (291, 192, 180, and 246% of Cont for AS, UAN, UAN + PK, and UAN + PMgS, respectively). Examining the changes from 1997 to 2019 in topsoil (0–30 cm depth), we discovered a decrease of S content in Sw, Sads, Sav, and St fractions on all treatments to an average of 34.6%, 65.8%, 42.2%, and 78.6% of their initial values. The exception was AS treatment, which doubled its initial content in mineral fractions and maintained the same levels of St, and which we attribute to the very high dose of S on this treatment (142 kg ha−1 year−1). Using the simple balance method, AS and UAN + PMgS treatments lost 142.2 and 95.3 kg S ha−1 year−1 to other sinks, except plant uptake, from the entire soil profile (0–60 cm) during 23 years of experiment. Other treatments also show significant losses with the exception of Fallow. Given these results, it is clear that content of sulfur in soil is generally decreasing and attention should be paid mainly towards minimizing of its losses.

Soil organic matter carbon (CSOM) compounds degradation was observed in long-term field experiments with silage maize monoculture. Over a period of 26 years, the content of carbon in topsoil decreased by 22% in control unfertilized plots compared to 25% and 26% in treatments fertilized annually with mineral nitrogen. With annual wheat straw application (together with mineral N), the content of CSOM decreased by 8%. Contrary to that, the annual application of farmyard manure resulted in a CSOM increase of 16%. The ratio of carbon produced by maize related to total topsoil CSOM content ranged between 8.1–11.8%. In plots with mineral N fertilization, this ratio was always higher than in the unfertilized control plots. With the weaker soil extraction agent (CaCl2), the ratio of carbon produced by maize was determined to be 17.9–20.7%. With stronger extraction agent (pyrophosphate) it was only 10.2–14.6%. This shows that maize produced mostly unstable carbon compounds. Mineral N application resulted in stronger mineralization of original and stable organic matter compared to the unfertilized control. However, the increase of maize-produced carbon content in fertilized plots did not compensate for the decrease of “old” organic matter. As a result, a tendency to decrease total CSOM content in plots with mineral N applied was observed.

The changes of soil pH in long-term 14-year field experiments with different fertilizing systems are described. The field experiments were located at four sites of the Czech Republic with different soil and climatic conditions (Červený Újezd, Hněvčeves, Lukavec, and Prague-Suchdol). At each site, the same fertilizing systems and crop rotation (potatoes - winter wheat - spring barley) were established. Six experimental treatments were applied to crop rotation: (1) unfertilized treatments (control); treatments with organic fertilization: (2) farmyard manure (FYM), (3) sewage sludge (SS); treatments with mineral fertilizers: (4) nitrogen (N), (5) nitrogen with straw application (N + straw), and (6) nitrogen with phosphorus and potassium (NPK). The long-term effect of fertilizers significantly depends on soil conditions. At the site Prague-Suchdol minimal differences in the soil pH were observed by all treatments. This is caused by the high buffering capacity of Chernozems against the soil acidification. At Červený Újezd (Haplic Luvisol), Hněvčeves (Haplic Luvisol), and Lukavec (Stagnic Cambisol) sites, soil pH decreased by all treatments. Only at Hněvčeves site the soil pH did not change with N treatment. The highest soil pH decrease in the treatment with NPK (ΔpH -0.89) and N + straw (ΔpH -0.70) was observed at Hněvčeves site. By the treatments FYM and SS the highest decrease was registered at Červený Újezd (ΔpH of about -0.30 and -0.63, respectively). The highest decrease in control treatment (ΔpH of about -0.63) was observed at Lukavec site. The results showed that to evaluate long-term soil pH changes a whole complex of factors must be examined.

In this paper, we are analyzing the yield and yield parameters of winter rape, fertilized using CULTAN system (Controlled Uptake Long Term Ammonium Nutrition) in comparison with top-dressing application of nitrogen fertilizers, which were studied on Haplic Luvisol over 5 years. No significant differences in seed yields between the two systems of fertilization were observed in 2008, 2009 and 2011. The effect of sulphur on a higher seed yield was proved in 2010 and 2012. The seed yield was higher by 11.4% in the treatments with sulphur amendment regardless of the system of fertilization in 2010. The seed yield was higher by 18.2 % in the CULTAN treatment with sulphur adittion in comparison to CULTAN treatment with no sulphur added in 2012. Nitrogen supply was ample in the first flowers open growth stage of winter rape in 2009, 2010 and 2012. The plant height was significantly lower after CULTAN method and as well as higher values of 1000 seed weight were recorded in comparison to top-dressing application in 2009. Nitrogen uptake by seed dry matter was the highest in the year 2009, which corresponds to the achieved seed yields this year.

Influence of CULTAN method (Controlled Uptake Long Term Ammonium Nutrition) on the iron and zinc uptake by winter wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.) was observed at four-year small-plot field experiments under conditions of the Czech Republic. No significant differences in iron and zinc concentration in grain of winter wheat as well as spring barley between conventional and CULTAN treatment were found. Neither increased supply of nitrogen fertilizer nor sulphur containing fertilizer resulted in significant differences in iron and zinc concentration in grain of winter wheat as well as spring barley at both nitrogen nutrition systems. No significant differences in sulphur concentration in aboveground biomass of winter wheat and spring barley between conventional and CULTAN treatment were recorded. Iron and zinc harvest index were not influenced by the CULTAN system. Because of no significant differences in iron and zinc concentration in grain of winter wheat as well as spring barley between conventional and CULTAN treatment, it can be assumed that nitrogen is taken up by CULTAN-treated plants in nitrate form.

Abstract Background Although fertilization and crop rotation practices are commonly used worldwide in agriculture to maximize crop yields, their long-term effect on the structures of soil microorganisms is still poorly understood. This study investigated the long-term impact of fertilization and crop rotation on soil microbial diversity and the microbial community structure in four different locations with three soil types. Since 1996, manure (MF; 330 kg N/ha), sewage sludge (SF; 330 and SF3x; 990 kg N/ha), and NPK (NPK; 330 kg N/ha) fertilizers were periodically applied to the soils classified as chernozem, luvisol and cambisol, which are among the most abundant or fertile soils used for agricultural purposes in the world. In these soils, potato (Solanum tuberosum L.), winter wheat (Triticum aestivum L.), and spring barley (Hordeum vulgare L.) were rotated every three years. Results Soil chemistry, which was significantly associated with location, fertilization, crop rotation, and the interaction of fertilization and location, was the dominant driver of soil microbial communities, both prokaryotic and fungal. A direct effect of long-term crop rotation and fertilization on the structure of their communities was confirmed, although there was no evidence of their influence on microbial diversity. Fungal and bacterial communities responded differently to fertilization treatments; prokaryotic communities were only significantly different from the control soil (CF) in soils treated with MF and SF3x, while fungal communities differed across all treatments. Indicator genera were identified for different treatments. These taxa were either specific for their decomposition activities or fungal plant pathogens. Sequential rotation of the three crops restricted the growth of several of the indicator plant pathogens. Conclusions Long-term fertilization and crop rotation significantly altered microbial community structure in the soil. While fertilization affected soil microorganisms mainly through changes in nutrient profile, crop rotations lead to the attraction and repulsion of specific plant pathogens. Such changes in soil microbial communities need to be considered when planning soil management.

The reuse of stabilized (under thermophilic conditions) sewage sludge and manure on agricultural soils is a common practice. The aim of this study was to evaluate the risks associated with their repeated applications on the spread of pathogenic bacteria and antibiotic resistance genes (ARGs) that encode resistance to tetracycline (tetA and tetW), sulphonamide (sul1 and sul2), erythromycin (ermB), vancomycin (vanA) and integron genetic element (intI1). The trial fields has been regularly fertilized every 3rd year since 1996 with manure (MF; 330 kg N/ha) and sewage sludge (SF; 330 kg N/ha and SF3; 990 kg N/ha). Unfertilized soil (CF) served as a control. Samples were collected at different time points: (i) right before fertilization (which was also 3 years after the last fertilization), (ii) 5 months after fertilization, and (iii) 11 months after fertilization. The relative abundance of amplicon sequence variants (ASVs) assigned to potentially pathogenic bacteria was low (0.3% and 0.25% in sludge and manure, respectively), and no association with the application of these fertilizers was found. On the other hand, our data indicate that an increased relative abundance of the ARGs sul1 and tetW was significantly associated with these fertilizer applications, and sul1 was increased in all treatments regardless of the time. It is suggested that sul1 should be monitored in organically fertilized soils to prevent its spread and possible further accumulation in crops.

Fertilization is a worldwide agricultural practice used in agronomy to increase crop yields. Fertilizer application influences overall soil characteristics, including soil microbial community composition and metabolic processes mediated by microbial enzymatic activity. Changes in the structure of microbial communities and their metabolic activity after long-term fertilization were studied in this research. We hypothesized that the different types of fertilization regimes affect nutrient levels in the soil which subsequently influence the metabolic processes and microbial diversity and community structure. Manure (MF; 330 kg N/ha), sewage sludge at two application doses (SF; 330 kg N/ha and SF3x; 990 kg N/ha) and chemical (NPK; N-P-K nutrients in concentrations of 330-90-300 kg/ha) fertilizers have been applied regularly to an experimental field since 1996. The microbial diversity increased in all soils amended with both organic (MF, SF, SF3x) and chemical (NPK) fertilizers. The shifts in microbial communities were observed, which were mainly caused by less abundant genera that were mostly associated with one or more fertilization treatment(s). Fertilization also influenced soil chemistry and the activity of β-xylosidase, β-N-acetylglucosaminidase (NAG), acid phosphatase and FDA-hydrolases. Specifically, all fertilization treatments were associated with a higher activity of β xylosidase and lower NAG activity. Only the NPK treatment was associated with a higher activity of acid phosphatase.