Effect of Zinc Foliar Fertilization Alone and Combined with Trehalose on Maize (Zea mays L.) Growth under the Drought.

Maize (Zea mays L.) is one of the most widely grown cereals in the world. Its cultivation is affected by abiotic stress caused by climate change, in particular, drought. Zinc (Zn) supplied by foliar nutrition can increase plant resistance to water stress by enhancing physiological and enzymatic antioxidant defence mechanisms. One of the possibilities to reduce the effect of drought on plant production is also the utilization of trehalose. In order to confirm the effect of the foliar application of selected forms of Zn (0.1% w/v solution)-zinc oxide micro- (ZnO) and nanoparticles (ZnONP), zinc sulphate (ZnSO4) and zinc chelate (ZnEDTA)-a pot experiment in controlled conditions was conducted in combination with trehalose (1% w/v solution) on selected growth parameters of maize exposed to the drought stress. A significant effect of coapplication of Zn and trehalose on chlorophyll content, chlorophyll fluorescence parameters, root electrical capacity, weight of maize aboveground biomass (AGB) and Zn content in AGB was found. At the same time, the hypothesis of a positive effect of carbohydrates on increasing the uptake of foliar-applied Zn was confirmed, especially for the ZnEDTA and ZnSO4. This paper presents the first empirical evidence of the trehalose addition to sprays for zinc foliar fertilization of maize proving to be an effective way of increasing the resistance of maize grown under drought stress conditions.

The combined effect of graphene oxide and elemental nano-sulfur on soil biological properties and lettuce plant biomass.

The impact of graphene oxide (GO) nanocarbon on soil properties is mixed, with both negative and positive effects. Although it decreases the viability of some microbes, there are few studies on how its single amendment to soil or in combination with nanosized sulfur benefits soil microorganisms and nutrient transformation. Therefore, an eight-week pot experiment was carried out under controlled conditions (growth chamber with artificial light) in soil seeded with lettuce (Lactuca sativa) and amended with GO or nano-sulfur on their own or their several combinations. The following variants were tested: (I) Control, (II) GO, (III) Low nano-S + GO, (IV) High nano-S + GO, (V) Low nano-S, (VI) High nano-S. Results revealed no significant differences in soil pH, dry plant aboveground, and root biomass among all five amended variants and the control group. The greatest positive effect on soil respiration was observed when GO was used alone, and this effect remained significant even when it was combined with high nano-S. Low nano-S plus a GO dose negatively affected some of the soil respiration types: NAG_SIR, Tre_SIR, Ala_SIR, and Arg_SIR. Single GO application was found to enhance arylsulfatase activity, while the combination of high nano-S and GO not only enhanced arylsulfatase but also urease and phosphatase activity in the soil. The elemental nano-S probably counteracted the GO-mediated effect on organic carbon oxidation. We partially proved the hypothesis that GO-enhanced nano-S oxidation increases phosphatase activity.

Time-dependent impact of co-matured manure with elemental sulfur and biochar on the soil agro-ecological properties and plant biomass.

Farmyard manure is the most common type of organic fertilizer, and its properties depend mainly on the type of livestock, bedding material and the conditions of fermentation. Co-maturing of manure with other amendments to modify its final properties has been seen as a win-win strategy recently. This study aimed to evaluate the differences in the effect of unenriched manure and manures co-matured with biochar, elemental sulfur or both amendments on the soil physico-chemical and biological properties, and plant (barley, maize) biomass production. For this purpose a pot experiment was carried out in a time-dependent way. Samples were taken from 12 week-lasting (test crop barley) and 24 week-lasting (test crop maize) pot cultivation carried out in a growth chamber. Co-matured manure with biochar showed the highest rate of maturation expressed as humic to fulvic acid ratio, its amendment to soil significantly increased the dry aboveground biomass weight in the half-time (12 weeks) of experiment. However, the effect vanished after 24 weeks. We received for this variant highest long-term (24 weeks) contents of total carbon and nitrogen in soil. Contrarily, co-matured manure with biochar and elemental sulfur led to short-term carbon sequestration (the highest total carbon in 12 weeks) due to presumed retardation of microbial-mediated transformation of nutrients. We conclude that the prolonged pot experiment with biochar or elemental sulfur enriched manure led to the increased recalcitrancy of soil organic matter and retardation of soil nutrient transformation to the plant-available form.

Effect of Natural Liquid Hydroabsorbents on Ammonia Emission from Liquid Nitrogen Fertilizers and Plant Growth of Maize (Zea Mays L.) under Drought Conditions.

The use of mineral nitrogen (N) fertilizers is associated with significant nitrogen loss through the volatilization. Ammonia (NH3) emissions are common from fertilizers with amide (NH2) and ammonium (NH4) nitrogen forms applied to the soil surface without incorporation. The objective of the laboratory and greenhouse pot experiments was to verify the hypothesis that liquid mineral fertilizers and fertilizer solutions containing N-NH2 and N-NH4 applied to the soil surface in combination with natural hydroabsorbents (NHAs) will reduce the volatilization of nitrogen. The effect of NHAs addition to urea ammonium nitrate (UAN) fertilizer and urea, ammonium nitrate (AN) and ammonium sulphate (AS) solutions was evaluated in a laboratory experiment. The effect of the two types of NHAs (acidic and neutral) was compared with the control (UAN) and its mixture with the commercially used urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT). The proportion of volatilized NH3 of the total N from the examined fertilizers applied to the soil surface was determined by the titration method. Subsequently, the effect of fertilization with UAN and its mixture with NHAs and NBPT on the growth of maize under the drought conditions was verified in a greenhouse pot experiment. While the addition of NBPT resulted in a reduction of NH3 emission for the fertilizers containing NH2 (UAN, urea solution), a decrease in volatilization after the addition of both acidic and neutral NHA was observed especially for UAN. A reduction in ammonia emission was also observed for AS after the addition of acidic NHA. The addition of both NHAs and NBPT to UAN increased the utilization of nitrogen from the applied fertilizer, which was reflected by an increase in chlorophyll content and increased CO2 assimilation by maize plants grown under the drought stress. UAN fertilizer combined with acidic NHA and NBPT significantly increased aboveground biomass production and root system capacity of maize. Significant increases in UAN nitrogen recovery were observed for all examined additives (UI and both types of NHAs). In addition to the known effects of hydroabsorbents, especially their influence on soil physical and biological properties and soil water retention, the effect of NHAs application in combination with UAN and AS solutions on the reduction of gaseous N loss, maize plant growth and fertilizer nitrogen recovery was found.

Effect of Digestate Modified with Amendments on Soil Health and Plant Biomass under Varying Experimental Durations.

A digestate with amendments provides plants with available nutrients and improves the microbiological properties of treated soil. Modification of a digestate through the addition of a biochar and sulphur source is less well-known. This pot experiment aimed at comparing the short- and long-time fertilization effects of a digestate enriched with biochar, with elemental sulphur, or with a combination of both on soil health and plant biomass. The experiment was carried out with maize, cultivated twice (1st-12th week = pre-cultivation; re-sowing after shoot harvest, 13th-24th = main cultivation) in soil amended with prepared digestate. The digestate used in pre-cultivation was incubated untreated (D) and was then treated with biochar (D + B), with elemental sulphur at a low (LS) and high (HS) dose, or with a combination of both (D + B + LS and D + B + HS). An additional unamended digestate (D) was added to each soil variant before the main cultivation. The application of digestate with a high dose of elemental sulphur and biochar mediated the most significant differences in the soil. The increase (compared to the unamended soil) was of short-term type (+11% and +6% increased total nitrogen and carbon after 12 weeks), then of long-term type (+54% and +30% increased sulphur and arylsulfatase activity after 24 weeks), and later emerged in the 13th to the 24th week of the experiment (+57% and +32% non-inhibited urease, increased N-acetyl-ß-D-glucosaminidase and phosphatase). No significant differences in the effect of the applied amendments on dry aboveground plant biomass were observed.

Slow-Release Nitrogen Fertilizers with Biodegradable Poly(3-hydroxybutyrate) Coating: Their Effect on the Growth of Maize and the Dynamics of N Release in Soil.

Fertilizers play an essential role in agriculture due to the rising food demand. However, high input fertilizer concentration and the non-controlled leaching of nutrients cause an unwanted increase in reactive, unassimilated nitrogen and induce environmental pollution. This paper investigates the preparation and properties of slow-release fertilizer with fully biodegradable poly(3-hydroxybutyrate) coating that releases nitrogen gradually and is not a pollutant for soil. Nitrogen fertilizer (calcium ammonium nitrate) was pelletized with selected filler materials (poly(3-hydroxybutyrate), struvite, dried biomass). Pellets were coated with a solution of poly(3-hydroxybutyrate) in dioxolane that formed a high-quality and thin polymer coating. Coated pellets were tested in aqueous and soil environments. Some coated pellets showed excellent resistance even after 76 days in water, where only 20% of the ammonium nitrate was released. Pot experiments in Mitscherlich vegetation vessels monitored the effect of the application of coated fertilizers on the development and growth of maize and the dynamics of N release in the soil. We found that the use of our coated fertilizers in maize nutrition is a suitable way to supply nutrients to plants concerning their needs and that the poly(3-hydroxybutyrate) that was used for the coating does not adversely affect the growth of maize plants.

Co-composting of cattle manure with biochar and elemental sulphur and its effects on manure quality, plant biomass and microbiological characteristics of post-harvest soil.

Improvement of manure by co-composting with other materials is beneficial to the quality of the amended soil. Therefore, the manure was supplied with either biochar, elemental sulphur or both prior to fermentation in 50 L barrels for a period of eight weeks. The manure products were subsequently analyzed and used as fertilizers in a short-term pot experiment with barley fodder (Hordeum vulgare L.). The experiment was carried out under controlled conditions in a growth chamber for 12 weeks. The sulphur-enriched manure showed the lowest manure pH and highest ammonium content. The co-fermentation of biochar and sulphur led to the highest sulphur content and an abundance of ammonium-oxidizing bacteria in manure. The biochar+sulphur-enriched manure led to the highest dry aboveground plant biomass in the amended soil, whose value was 98% higher compared to the unamended control, 38% higher compared to the variant with biochar-enriched manure and 23% higher compared to the manure-amended variant. Amendment of the sulphur-enriched manure types led to the highest enzyme activities and soil respirations (basal, substrate-induced). This innovative approach to improve the quality of organic fertilizers utilizes treated agricultural waste (biochar) and a biotechnological residual product (elementary sulphur from biogas desulphurization) and hence contributes to the circular economy.

Food and agricultural wastes-derived biochars in combination with mineral fertilizer as sustainable soil amendments to enhance soil microbiological activity, nutrient cycling and crop production.

The ever-increasing human population associated with high rate of waste generation may pose serious threats to soil ecosystem. Nevertheless, conversion of agricultural and food wastes to biochar has been shown as a beneficial approach in sustainable soil management. However, our understanding on how integration of biochar obtained from different wastes and mineral fertilizers impact soil microbiological indicators is limited. Therefore, in the present study the effects of agricultural (AB) and food waste derived (FWB) biochars with and without mineral fertilizer (MF) on crop growth and soil health indicators were compared in a pot experiment. In particular, the impacts of applied amendments on soil microbiological health indicators those related to microbial extracellular (C, N and P acquiring) enzymes, soil basal as well as different substrate induced respirations along with crop's agronomic performance were explored. The results showed that compared to the control, the amendment with AB combined with MF enhanced the crop growth as revealed by higher above and below ground biomass accumulation. Moreover, both the biochars (FWB and AB) modified soil chemical properties (pH and electric conductivity) in the presence or absence of MF as compared to control. However, with the sole application of MF was most influential strategy to improve soil basal and arginin-induced respiration as well as most of the soil extracellular enzymes, those related to C, N and P cycling. Use of FWB resulted in enhanced urease activity. This suggested the role of MF and FWB in nutrient cycling and plant nutrition. Thus, integration of biochar and mineral fertilizers is recommended as an efficient and climate smart package for sustainable soil management and crop production.

Effect of Lactic Fermentation and Cooking on Nutrient and Mineral Digestibility of Peas.

Peas are prospectively beneficial legumes in the human diet, and especially in a vegan and vegetarian diet, due to their high content of proteins and starch. Their frequent lack of appeal in human nutrition can be caused by their bloating effect and the content of some antinutritional compounds inhibiting the absorption of important nutrients. This study brings a comprehensive comparison of the nutrient content of pea flour after cooking and lactic fermentation before and after digestion in vitro. As a control sample, raw pea flour was used (sample 1). Raw pea flour was cooked for 10 min (sample 2) and 120 min (sample 3) at 100°C or it was fermented by Lactobacillus plantarum (sample 4) and cooked for 10 min at 100°C (sample 5). The samples were analyzed for protein and amino acids content, maltose, glucose, raffinose, total polyphenols, phytic acid, phytase, and mineral composition (P, Mg, Mn, Fe, Cu, Zn) before and after in vitro digestion. The results showed a significant (p < 0.05) increase in the protein digestibility of samples 3, 4 and 5. In the fermented samples were observed a higher concentration of Cys, Met, and Gln when compared to non-fermented samples. The fermentation of pea flour resulted in a significant (p < 0.05) decrease in glucose, maltose, and raffinose content. Cooking of pea flour for 10 and 120 min, but not fermenting, significantly (p < 0.05) decreased the polyphenols content. Cooking and fermentation together did not affect phytic acid concentration and phytase activity. Mg, Mn, Fe, Cu and, Zn concentration in pea flour was significantly (p < 0.05) decreased by cooking. On the other hand, fermentation significantly (p<0.05) improved the bioaccessibility of Mn and Fe. These findings suggest that lactic fermentation of pea flour is a promising culinary preparation that can improve the digestibility of peas.

Using Waste Sulfur from Biogas Production in Combination with Nitrogen Fertilization of Maize (Zea mays L.) by Foliar Application.

In Europe, mainly due to industrial desulfurization, the supply of soil sulfur (S), an essential nutrient for crops, has been declining. One of the currently promoted sources of renewable energy is biogas production, which produces S as a waste product. In order to confirm the effect of the foliar application of waste elemental S in combination with liquid urea ammonium nitrate (UAN) fertilizer, a vegetation experiment was conducted with maize as the main crop grown for biogas production. The following treatments were included in the experiment: 1. Control (no fertilization), 2. UAN, 3. UANS1 (N:S ratio, 2:1), 4. UANS2 (1:1), 5. UANS3 (1:2). The application of UAN increased the N content in the plant and significantly affected the chlorophyll content (N-tester value). Despite the lower increase in nitrogen (N) content and uptake by the plant due to the application of UANS, these combinations had a significant effect on the quantum yield of PSII. The application of UANS significantly increased the S content of the plant. The increase in the weight of plants found on the treatment fertilized with UANS can be explained by the synergistic relationship between N and S, which contributed to the increase in crop nitrogen use efficiency. This study suggests that the foliar application of waste elemental S in combination with UAN at a 1:1 ratio could be an effective way to optimize the nutritional status of maize while reducing mineral fertilizer consumption.

Oil-Based Polymer Coatings on CAN Fertilizer in Oilseed Rape (Brassica napus L.) Nutrition.

Fertilizer coating can increase the efficiency of N fertilizers and reduce their negative impact on the environment. This may be achieved by the utilization of biodegradable natural coating materials instead of polyurethane-based polymers. The aim of this study was to detect the effect of calcium ammonium nitrate (CAN) fertilizer coated with modified conventional polyurethane enhanced with vegetable oils on the yield and quality of Brassica napus L. compared to CAN fertilizer with a vegetable oil-based polymer and to assess the risks of nitrogen loss. Three types of treatments were tested for both coated fertilizers: divided application (CAN, coated CAN), a single application of coated CAN, and a single application of CAN with coated CAN (1:2). A single application of coated CAN with both types of coating in the growth stage of the 9th true leaf significantly increased the yield, the thousand seed weight, and oil production compared to the uncoated CAN. The potential of using coated CAN may be seen in a slow nitrogen release ensuring the nitrogen demand for rapeseed plants throughout vegetation and eliminating the risk of its loss. The increased potential of NH4+ volatilization and NO3- leaching were determined using the uncoated CAN fertilizer compared to the coated variants. Oil-based polymer coatings on CAN fertilizer can be considered as an adequate replacement for partially modified conventional polyurethane.

Response of Normal and Low-Phytate Genotypes of Pea (Pisum sativum L.) on Phosphorus Foliar Fertilization.

Phosphorus (P) is an important nutrient in plant nutrition. Its absorption by plants from the soil is influenced by many factors. Therefore, a foliar application of this nutrient could be utilized for the optimal nutrition state of plants. The premise of the study is that foliar application of phosphorus will increase the yield of normal-phytate (npa) cultivars (CDC Bronco a Cutlass) and low-phytate (lpa) lines (1-2347-144, 1-150-81) grown in soils with low phosphorus supply and affect seed quality depending on the ability of the pea to produce phytate. A graded application of phosphorus (H3PO4) in four doses: without P (P0), 27.3 mg P (P1), 54.5 mg P (P2), and 81.8 mg P/pot (P3) realized at the development stages of the 6th true leaf led to a significant increase of chlorophyll contents, and fluorescence parameters of chlorophyll expressing the CO2 assimilation velocity. The P fertilization increased the yield of seeds significantly, except the highest dose of phosphorus (P3) at which the yield of the npa cultivars was reduced. The line 1-2347-144 was the most sensible to the P application when the dose P3 increased the seed production by 42.1%. Only the lpa line 1-150-81 showed a decreased tendency in the phytate content at the stepped application of the P nutrition. Foliar application of phosphorus significantly increased ash material in seed, but did not tend to affect the protein and mineral content of seeds. Only the zinc content in seeds was significantly reduced by foliar application of P in npa and lpa pea genotypes. It is concluded from the present study that foliar phosphorus application could be an effective way to enhance the pea growth in P-deficient condition with a direct effect on seed yield and quality.

Effect of carbon-enriched digestate on the microbial soil activity.

OBJECTIVES: As a liquid organic fertilizer used in agriculture, digestate is rich in many nutrients (i.e. nitrogen, phosphorus, sulfur, calcium, potassium); their utilization may be however less efficient in soils poor in organic carbon (due to low carbon:nitrogen ratio). In order to solve the disadvantages, digestate enrichment with carbon-rich amendments biochar or humic acids (Humac) was tested. METHODS: Soil variants amended with enriched digestate: digestate + biochar, digestate + Humac, and digestate + combined biochar and humic acids-were compared to control with untreated digestate in their effect on total soil carbon and nitrogen, microbial biomass carbon, soil respiration and soil enzymatic activities in a pot experiment. Yield of the test crop lettuce was also determined for all variants. RESULTS: Soil respiration was the most significantly increased property, positively affected by digestate + Humac. Both digestate + biochar and digestate + Humac significantly increased microbial biomass carbon. Significant negative effect of digestate + biochar (compared to the control digestate) on particular enzyme activities was alleviated by the addition of humic acids. No significant differences among the tested variants were found in the above-ground and root plant biomass. CONCLUSIONS: The tested organic supplements improved the digestate effect on some determined soil properties. We deduced from the results (carbon:nitrogen ratio, microbial biomass and activity) that the assimilation of nutrients by plants increased; however, the most desired positive effect on the yield of crop biomass was not demonstrated. We assume that the digestate enrichment with organic amendments may be more beneficial in a long time-scaled trial.

Comparison of Biogenic Amines and Mycotoxins in Alfalfa and Red Clover Fodder Depending on Additives.

In the production of fermented feed, each crop can be contaminated with a variety of microorganisms that may produce natural pollutants. Biogenic amines, mycotoxins, and undesirable organic acids can decrease health feed safety. The aim of this study was to compare the counts of microorganisms, levels of biogenic amines, and the mycotoxins in forage legumes, and also to compare the occurrence of microorganisms and levels of mycotoxins in green fodder and subsequently produced silage and the influence of additives on the content of natural harmful substances in silage. The experimental plot was located in Troubsko and Vatín, in the Czech Republic. Two varieties of Medicago sativa and one variety of Trifolium pratense were compared. Green fodder and subsequently produced silage reaching up to 23% of dry matter were evaluated and prepared using a bio-enzymatic additive and a chemical additive. Green fodder of Medicago sativa was more contaminated by Enterococci than Trifolium pratense fodder. The obvious difference was determined by the quality of silage leachate. The silage prepared from Medicago sativa fodder was more contaminated with butyric acid. Fungi were present in higher counts in the anaerobic environment of green fodder and contaminated it with zearalenone and deoxynivalenol. Lower counts of fungi were found in silage, although the zearalenone content did not change. Lower content of deoxynivalenol was detected in silage, compared with green fodder. Silages treated with a chemical additive were found not to contain butyric acid. Lower ethanol content was determined, and the tendency to reduce the risk of biogenic amines occurrence was evident. The additives proved to have no influence on the content of mycotoxins.

Diffusive gradient in thin films technique for assessment of cadmium and copper bioaccessibility to radish (Raphanus sativus).

The aim of this study was to assess cadmium and copper uptake by radish (Raphanus sativus) and to test the capability of the diffusive gradient in thin films (DGT) technique to predict bioaccessibility of the metals for this plant. Radish plants were grown in pots filled with uncontaminated control and artificially contaminated soils differing in cadmium and copper contents. Metal concentrations in plants were compared with free ion metal concentrations in soil solution, and concentrations measured by DGT. Significant correlation was found between metal fluxes to plant and metal fluxes into DGT. Pearson correlation coefficient for cadmium was 0.994 and for copper 0.998. The obtained results showed that DGT offers the possibility of simple test procedure for soils and can be used as a physical surrogate for plant uptake.