Search

The presented set of data brings results of the experimental production of biogas and methane from silages of alternative substrates consisting of maize and three leguminous species with a potential to make the production of biogas more friendly to the environment because the cultivation of legumes is generally considered to be more environment friendly than the cultivation of maize: white sweet clover (Melilotus albus Medik.), fodder vetch (Vicia villosa Roth.) and white lupin (Lupinus albus L.). Obtained data allow to compare the composition of experimental substrates and their important parameters (VS, DM, NDF, ADF, CF, starch, cellulose, hemicellulose, CP, lipids and ADL) as well as the yield of biogas, methane and methane in biogas from silage produced as a monosubstrate from the biomass of maize shreddings on the one side with silages produced from the mixture of biomass from maize and diverse legumes on the other side. This set of data can contribute to awareness about possibilities for reducing environmental risks connected with the cultivation of maize in growers of energy crops and operators of biogas plants. The reason is that a considerable number of farmers do not use new technologies of growing biomass for the production of biogas as they cannot quantify the potential impact on biogas yield and hence on the profitability of biogas plant operation. The measured values demonstrate that silages made from the mixed culture were reaching at least the same production of biogas and its quality as the monocultural maize silage.

The presented research deals with the effect of plot size changes on the crop yield. Three plots were chosen in a company engaged in conventional agriculture, on which yields were monitored from 2019 using yield maps. In 2020, the plots (initial size > 30 ha) were divided into different parts sized < 30 ha. In 2021, these newly arisen parts of the plots were harvested. Changes in the yield of grown crops were analysed using yield maps acquired by the harvesting machines. Relative yields (%) and absolute yields (t/ha) were determined on all experimental land parts arising from the initial plots' division. The values were then compared with yields recorded before the division of individual plots using zonal statistics. Measured relative yield values clearly show (P < 0.05) that the division of plots resulted in the increased heterogeneity of crop yields. On the initial plots as well as on the newly arisen plots, the relative yield was divided into the following categories: < 70, 70-85, 85-95, 95-105, 105-115, 115-130 and > 130%, with the value of 100% representing average yield. The analysis of measured yield data showed that the division of plots into smaller parts resulted in an uneven yield distribution because if a divided plot was heterogeneous in terms of yield levels, a cumulation of "higher yield levels (> 100%)" could have occurred in one specific newly arisen plot at the expense of another one. Moreover, new marginal parts of lands came into being during the division of larger soil complexes, and hence zones with potentially reduced yields.

Chickpea (Cicer arietinum L.) is one of the most important legumes currently grown. It is an important source of proteins and nutrients, such as calcium, potassium and iron. As a result, precise crop management is necessary for maximizing its production. The presented study deals with the effect of soil heterogeneity caused by variable contents of macro- and micronutrients on the uptake of nutrients by chickpea. The values measured (contents of macro- and micronutrients in plant samples) indicate that soil heterogeneity is an important factor for the contents of nutrients and soil reactions, which strongly affect the growth of chickpea. We investigated the soil heterogeneity in a chickpea field. Two zones (A and B) with different stand development were found in the model plot. Zone A showed a healthy (green) growth, while Zone B exhibited a yellow-coloured growth, indicating deficits in nutrient uptake. The contents of selected nutrients (P, K, Ca, Mg, Fe, Cu, Zn and Mn) in the soil and in the plant biomass (i.e., stems, leaves, pods and seeds) were analyzed. In the zone with the yellow-coloured biomass, the results showed significantly (p < 0.05) reduced contents of N, P, K, Mg, Fe, Mn, Cu and Zn in the leaves; higher values of soil reaction (pH); and higher contents of calcium and calcium carbonate in the soil. The uptake of nutrients by the plants and their translocation were affected by the above-mentioned soil parameters and by their mutual interactions. Therefore, it is possible to state that soil heterogeneity (caused by variable contents of nutrients in soil) should be taken into account in the precise crop management of chickpeas.

Afforestation is important for the EU forest management strategy. Afforestation of abandoned and marginal arable land is a favourable non-agricultural land use option for climate change mitigation. It may prevent threats of drought or erosion e.g. by affecting the water balance in soil via increased structural stability. The structural stability control in afforested soil is related to i.a. organic matter content, nutrient content, soil reaction, planted tree species prosperity, and amelioration. A four-year field small-plot experiment on afforestation was carried out with Chernozem covered with deciduous (oak), coniferous (pine) or mixed planting, amended with 3 doses (no-application, 0.5 kg×m-2, and 1.5 kg×m-2) of alginite. In 2013 and 2016, soil reaction pHH2O, mean weight diameter (MWD), organic matter content (LOI) and total organic carbon (TOC) were determined and related to the soil structural stability to evaluate the soil precondition to sustain drought twice per vegetation period (spring and autumn). Afforestation significantly improved MWD compared to the field soil between 2013 and 2016 from 1.63 ± 0.04 mm to 1.85 ± 0.05 mm. Tree planting significantly neutralized the soil pHH2O, mixed planting appeared to improve LOI and TOC. Four-year afforestation led also to higher structural stability, less alkaline pH and deciduous tree-related increase in LOI, which may indicate better soil sustainability to drought.

Mycotoxins can pose a threat to biogas production as they can contaminate the feedstock used in biogas production, such as agricultural crops and other organic materials. This research study evaluated the contents of deoxynivalenol (DON), zearalenone (ZEA), fumonisin (FUM), and aflatoxin (AFL) mycotoxins in maize silage prior to it being processed in a biogas plant and in digestate produced at the end of the anaerobic digestion (AD) process. In the experiment, three samples of silage were collected from one silage warehouse: Variant 1 = low contamination, Variant 2 = medium contamination, and Variant 3 = heavy contamination, which were subjected to investigation. A significantly reduced biogas production was recorded that was proportional to the increasing contamination with molds, which was primarily due to the AD of silage caused by technologically erroneous silage treatment. The AD was connected with changes in silage composition expressed by the values of VS content, sugar content, lactic acid content, acetic acid content, and the ratio of lactic acid content to acetic acid content. The production of biogas and methane decreased with the increasing contents of NDF, ADF, CF, and lignin. The only exception was Variant 2, in which the content of ADF, CF, and lignin was lower (by 8–11%) than that in Variant 1, and only the content of NDF was higher (by 9%) than that in Variant 1. A secondary factor that also correlated with changes in the composition of the substrate was the development of undesirable organisms, which further contributed to its degradation and to the production of mycotoxins. It was also demonstrated in this study that during the AD process, the tested mycotoxins were degraded, and their content was reduced by 27–100%. Only the variant with low mold contamination showed a DON concentration increase of 27.8%.

The presented study deals with the use of legumes intercropped with maize for the production of biogas from silage. The main goal was to find out whether silages made from mixed cultures can be used in biogas production and how the use of such silages affects qualitative and quantitative parameters of the fermentation process compared with the pure maize silage. Variants prepared were pure cultures of maize, bean, lupin, and white sweet clover. In addition, mixed cultures were prepared of maize and individual legumes. Measured values showed that in terms of dry matter (DM) yield, mixed culture silages are almost of the same or even better quality than silage made from the maize monosubstrate. Compared with the maize monoculture silage, the presence of white lupine, white sweet clover, and broad bean in silages statistically significantly increased the content of DM, ash, and acid detergent fiber (by more than 5%). Bean and lupine in mixed silages with maize significantly increased the content of lipids (on average by more than 1.2%). Legumes in silages were significantly decreasing contents of neutral detergent fiber, crude protein, and starch. Production of biogas from silages of maize monosubstrates and mixed substrates of maize with white lupin, maize with white sweet clover, and maize with broad bean was directly proportional to the content of CAR and starch in these substrates. A perspective variant was the mixed substrate of maize and sweet clover from which biogas production was only 6% lower than that from conventional maize silage. The highest yield was recorded in the maize monosubstrate (0.923 m3/kgVS). Variants of mixed substrates had a yield ranging from 0.804 to 0.840 m3/kgVS.

Digestate prepared from anaerobic digestion can be used as a fertilizer, as it contains ample amounts of plant nutrients, mainly nitrogen, phosphorous, and potassium. In this regard, digestates produced from mixed intercropped cereal and legume biomass have the potential to enrich soil and plants with nutrients more efficiently than monoculture-based digestates. The objective of this study was to determine the impact of different types of digestates applied at a rate of 40 t·ha-1 of fresh matter on soil properties and crop yield in a pot experiment with lettuce (Lactuca sativa) as a test crop. Anaerobic digestion of silages was prepared from the following monocultures and mixed cultures: broad bean, maize, maize and broad bean, maize and white sweet clover, and white sweet clover. Anaerobic digestion was performed in an automatic custom-made system and applied to the soil. Results revealed that fresh and dry aboveground biomass as well as the amount of nitrogen in plants significantly increased in all digestate-amended variants in comparison to control. The highest content of soil total nitrogen (+11% compared to the control) and urease (+3% compared to control) were observed for maize digestate amendment. Broad bean digestate mediated the highest oxidizable carbon (+48%), basal respiration (+46%), and N-acetyl-β-D-glucosamine-, L-alanine-, and L-lysine-induced respiration (+22%, +35%, +22%) compared to control. Moreover, maize and broad bean digestate resulted in the highest values of N-acetyl-β-D-glucosaminidase and β -glucosidase (+35% and +39%), and maize and white sweet clover digestate revealed the highest value of arylsulfatase (+32%). The observed differences in results suggest different effects of applied digestates. We thus concluded that legume-containing digestates possibly stimulate microbial activity (as found in increased respiration rates), and might lead to increased nitrogen losses if the more quickly mineralized nitrogen is not taken up by the plants.

The presented research deals with the variable application of N fertilizers (VRA NF) in the stand of winter wheat and with possibilities for evaluating the effect of such application on grain yield. The effect of VRA NF was assessed in close cooperation between Spearhead Czech Ltd. and Mendel University in Brno within an operational experiment. In 2018 and 2019, three experimental plots were always chosen on which VRA NF was implemented by conventional technique according to application maps. Each application map included control strips with the uniform NF application. The application maps were prepared based on the spectral analysis of satellite images. The individual plots were divided into three zones: Zone 1 with the lowest yield potential, Zone 2 with the medium yield potential, Zone 3 with the highest yield potential. The highest dose of N was at all times applied in Zone 3, and conversely the lowest dose was applied in Zone 1. In 2018 and 2019, the experimental fields were harvested by harvester New Holland CX 8080 which was equipped with the technology for the monitoring of grain yields. The main goal of data processing was to remove error data at first and then to re-calibrate them using the information about the weight of harvested grain. The expected benefit, i.e. a yield increase by min. 3% was found only in 2018, when the benefit was about 5%. In the following year, the difference between the conventional application of N and VRA technologies was minimal. However, this condition was probably caused by drought which negatively affected all stands. In particular, measured values of grain yield do not indicate the negative effect of VRA NF on grain yield. This research further showed the applicability of yield data acquired by harvest technology; however, the elimination of error data is necessary as well as their re-calibration according to total yield ascertained by weighing the total production of grain from a specific plot.

In this paper, a possible use of white sweet clover (Melilotus albus Med.) for phytoremediation was assessed. The plants were grown on soils with naturally occurring concentrations of potentially toxic elements (PTEs). First, the content of PTEs was determined in plant biomass and in soil samples using: (a) Optical emission spectrometry with inductively coupled plasma to determine Sb, As, Cd, Cu, Ni, Pb, and Se, and (b) thermal decomposition, amalgamation, and atomic absorption spectrometry to determine Hg. The effectiveness of Melilotus albus Med. (M. albus) for phytoremediation was evaluated using the bioconcentration factor (BCF). The phytoextraction potential of M. albus was determined using bioaccumulation factor (BAC) and translocation factor (TF) values. The highest concentration of PTEs in roots was detected for zinc (10.56 mg/kg of dry weight, DW) and copper (5.128 mg/kg of DW). Similarly, the highest concentration in above-ground parts of the plant was detected for zinc and copper (12.638 and 4.0 mg/kg of DW, respectively). Although the values were relatively high, the effectiveness of the absorption of these PTEs by plant biomass from the soil was relatively very low. BAC and BCF were always lower than 1. On the other hand, the results suggested that M. albus effectively transports PTEs (only for Zn, Pb and Hg) from roots to shoots, because TF was always higher than 1. However, the accumulation of PTEs from soils with a natural abundance of PTEs was not excessive in comparison to conventional maize silage. Therefore, there is no potential risk of biomethane production in biogas plants when biomass from M. albus is used.

This work presents results from a field experiment which was focused on the impact of the drought period on microbial activities in rhizosphere and non-rhizosphere soil. To demonstrate the effect of drought, the pot experiment lasted from 2012 to 2015. Fifteen lysimeters (plastic containers) were prepared in our area of interest. These lysimeters were filled with the subsoil and topsoil from this area and divided into two groups. The first group consisted of two variants: V1 (control) and V2 (84 kg N/ha), which were not stressed by drought. The second group consisted of three variants, V3 (control), V4 (84 kg N/ha), and V5 (84 kg N/ha + 1.25 L lignohumate/ha), which were stressed by drought every year of the experiment for 30 days. Changes in the soil moisture content caused by drought significantly affect the growth of Deschampsia caespitosa L., the microbial activity, and the soil’s capacity to retain nutrients. The measured basal respiration and dehydrogenase activity values confirm the significant effect of drought on microbial activity. These values were demonstrably higher in the period before drought simulation by more than 60%. On the other hand, significant differences between microbial activities in the rhizosphere and non-rhizosphere soil were not found. We did not find a clear effect of drought on the formation of soil water repellency.

In order to evaluate influential mechanisms for photosynthetic processes on the yields of an intercropping system composed of maize (Zea mays), Lupinus sp. and Melilotus albus, three treatments were designed and conducted in southern Moravia (Czech Republic) in the form of agronomy trials. The treatments included sole maize (SM), maize with Lupinus sp. (ML) and maize with field melilot (MM). The photosynthetic processes of Zea mays were monitored using several chlorophyll fluorescence techniques on the three treatments for 20 days in the late summer season. An analysis of fast chlorophyll fluorescence transients (OJIP) showed that the capacity of photochemical photosynthetic reactions in photosystem II (FV/FM), as well as the photosynthetic electron transport rate (ET0/RC), declined in response to a four-day episode of extremely warm days with full sunshine. Similarly, the performance index (PI), an indicator of general plant vitality, declined. The episode activated protective mechanisms in photosystem II (PSII), which resulted in an increase of thermal dissipation. For the majority of Z. mays photosynthetic parameters, their values decreased for particular treatments in the following order: MM, ML, SM. The MM and ML intercropping systems had a positive effect on the primary photosynthetic parameters in Z. mays.

Research of new input raw materials for biogas plants is a very actual topic. There are only a very few studies dealing with the possibility of using silage prepared from the above-ground parts of the Jerusalem artichoke (Helianthus tuberosus L.) and maize (Zea mayse L.) for methane production. This study deals with the determination of methane production and methane content in biogas during the fermentation of maize silage with dissimilar additions of the biomass of the Jerusalem artichoke (JA). Except for the effect of the JA’s addition on the yield of methane, we also studied its potential influence on the inhibition of the process of anaerobic digestion and the bacterial and methanogenic archaeal composition of anaerobic digestate. There were five model silages prepared; two of them contained only maize or JAs, and the remaining three were mixtures of maize and JA silages (30%wt; 50%wt and 70%wt). The fermentation tests showed that the JA addition (from 30 to 70%wt) resulted in the production of biogas decreasing, on average, by 15%. Based on the performed metagenomic analysis, we cannot confirm an essential influence of JA biomass addition on the composition of the community of microorganisms during fermentation.

Experiments with lacy phacelia (Phacelia tanacetifolia Benth.) were carried out in the period 2017–2021, during which the effect of sowing date on the stand development was assessed (height, coverage, accomplishment of individual growth stages, and weed infestation). It was demonstrated that the sowing date affects the stand growth and development. In earlier sowing dates, plants developed slower than in later sowing dates but reached a greater average height (926 mm). The lowest height (802 mm) was exhibited by plants from May (sowing 3). The third sowing date also showed the worst stand canopy closure and at BBCH 31, the stand canopy closure in Sowing 1, 2, and 3 was 82.3%, 77.8%, and 67%, respectively. The third sowing date was also the highest weed infestation. The effect of sowing date on yield and yield parameters was also monitored (weight of a thousand of grains and germinative capacity). Based on the measured data, it can be concluded that the influence on the weight of thousands of grains was minimal and in germinative capacity. Significant differences were recorded only in first year in which the germinative capacity of plants from the later sowing dates was reduced.

Suitability of the vegetation indices of normalized difference vegetation index (NDVI), blue normalized difference vegetation index (BNDVI), and normalized difference yellowness index (NDYI) obtained by means of UAV at the flowering stage of oil seed rape for the prediction of seed yield and usability of these vegetation indices in the identification of anomalies in the condition of the flowering growth were verified based on the regression analysis. Correlation analysis was performed to find the degree of yield dependence on the values of NDVI, BNDVI, and NDYI indices, which revealed a strong, significant linear positive dependence of seed yield on BNDVI (R = 0.98) and NDYI (R = 0.95). The level of correlation between the NDVI index and the seed yield was weaker (R = 0.70) than the others. Regression analysis was performed for a closer determination of the functional dependence of NDVI, BNDVI, and NDYI indices and the yield of seeds. Coefficients of determination in the linear regression model of NDVI, BNDVI, and NDYI indices reached the following values: R2 = 0.48 (NDVI), R2 = 0.95 (BNDVI), and R2 = 0.90 (NDYI). Thus, it was shown that increased density of yellow flowers decreased the relationship between NDVI and crop yield. The NDVI index is not appropriate for assessing growth conditions and prediction of yields at the flowering stage of oil seed rape. High accuracy of yield prediction was achieved with the use of BNDVI and NDYI. The performed analysis of NDVI, BNDVI, and NDYI demonstrated that particularly the BNDVI and NDYI indices can be used to identify problems in the development of oil seed rape growth at the stage of flowering, for their precise localization, and hence to targeted and effective remedial measures in line with the principles of precision agriculture.

Low availability of native soil phosphorus (P) is a major constraint limiting sustainable crop production especially in alkaline calcareous soils. Application of organic manure in this regard has gained attention of the scientific community. Yet, the potential of fermented animal manure in improving P use efficiency and subsequent crop yield has not been assessed. This pot experiment was designed to study the performance of wheat under application of non-fermented and fermented animal manure in combination with 0, 45 or 90 kg·ha−1 phosphorus in the form of diammonium phosphate (DAP). Results show that non-fermented animal manure and split dose of phosphorus fertilizer improved plant quantitative attributes including plant growth, yield and nutrient uptake parameters. However, the placement of fermented animal manure combined with the full amount of P (90 kg·ha−1) fertilizer gave the mean highest value of fertile tillers per pot (12) and their grain yield (5.2 g). Moreover, plant physiological parameters were enhanced with fermented animal manure and the recommended rate of P fertilizer compared with the control. Likewise, the biochemical properties of wheat grain such as fat, fiber, ash and protein contents were increased by 1.24, 2.26, 1.47 and 11.2%, respectively, in plants receiving fermented animal manure and P fertilizer (90 kg·ha−1). Furthermore, co-application of fermented animal manure with P (90 kg·ha−1) into soil improved phosphorus uptake from 0.72 to 1.25 g·pot−1, phosphorus usage efficiency from 0.715 to 0.856 mg·pot−1, and soil phosphorus extent from 7.58 to 16.1% over controls. It is thus inferred that this new approach resulted in release of P from fermented manure that not only reduced fixation but also enhanced the growth, yield, physiology and nutrient uptake in wheat.

The ever-growing number of biogas plants also leads to an increasing demand for suitable, alternative plant substrates. A currently dominant plant substrate is maize silage. However, intensive cultivation of maize (Zea mays L.) as an energy crop in monocultures poses risk to the environment (soil erosion, depletion of soil nutrient supplies, increased concentration of pests—Ostrinia nubilalis). In this study, results of experimental methane production from silages of alternative substrates, such as fodder mallow (Malva verticillata var. crispa L.; FM), white sweet clover (Melilotus albus Medik.; WSC) and their mixture, are presented. Based on the dry matter yield of a mixed culture of mallow and sweet clover, the value of the land equivalent ratio parameter (LER) was set as 1.05. The obtained LER (>1) value shows that the cultivation of the two tested crops in the mixed culture is more beneficial than their monocultures. Methane production from all three silage variants was fully comparable with results of methane production from the maize silage. Anaerobic fermentation of the mixture of FM and WSC did not result in higher methane yield than the average result of monosubstrates.

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.

The objective of this study was to determine the biodegradability of bioplastic materials – sponge cloths – available on the European market. They are labeled as 100 % biodegradable but not certified as compostable. The test was carried out in real composting environment. The project duration was 12 weeks. The emphasis was put on discovering whether the sponge cloths are biodegradable or not. Based on the results, it can be concluded that sponge cloths have decomposed completely (sample C and sample D). Samples A have decomposed but exhibited slower degradation rate. Samples B exhibited the higher degradation rate. The main conclusion from this study is that biodegradation of bioplastics materials strongly depends on both, the environment where they are placed and the chemical nature of the material.

The effect of coating the seed of clover crops by water absorbing seed process (WASP) technology pelletization on its germination capacity was studied in conditions of diverse drought intensities simulated by different concentrations of polyethylenglycol (PEG) 8000 solution. Drought resistance was monitored in the seed of five fodder clover species: Anthyllis vulneraria L., Medicago lupulina L., Trifolium repens L., Melilotus albus Medik. and Onobrychis viciifolia Scop. In the seed of given plant species, germination capacity was determined along with the share of dead and hard seeds. Although the coating significantly (p < 0.05) affected the drought resistance of seeds, the germination capacity increased only in conditions of milder drought (simulation with PEG: 0.1–0.3 mol). With the increasing intensity of drought induced by higher PEG concentrations (0.4–0.7 mol) the number of germinable seeds demonstrably decreased and the number of dead seeds increased in the coated seed as compared with the uncoated seed. The coated seed can be appropriate for use in M. lupulina, M. albus and T. repens, while the uncoated seed can be used in A. vulneraria and O. viciifolia.

Meadows occupy more than 23 % of agricultural land in the Czech Republic and also represent the largest pool of carbon in soil organic matter. The organic material is an essential component of healthy soil. Decomposition of organic matter is a biological process, affected by high amount of N and P fertilizer applied in the second half of the twentieth century. This work presents the analysis of the effect of available nutrients nitrogen and phosphorus on the activity of cellulolytic microorganisms in permanent grassland of Sanguisorba-Festucetum comutatae association in the soil surface in the Protected Landscape Area of Žďárské Hills. Contents of available nutrients established by the Mehlich III method were measured ex situ. Data referring cellulose decomposition rates were obtained in situ using the standard mesh-bag method. In the field experiment, the highest loss of cellulose was recorded in variants with the addition of nutrients (PK, 90N + PK and 180N + PK) with result 90.38 % on average. The difference was statistically significant, compared with the control variant without added nutrients 27.87 % (P < 0.05). The added amount of nitrogen in the variant 90 kg of N + PK per ha had no significant effect on loss of cellulose compared to PK variant, as well as variant 180 kg of N + PK per ha. From the results obtained, it is evident that the highest decomposition of cellulose was observed at variant with added phosphorus, compared to variant with nitrogen. Moreover, the effect of different intensity of grassland utilization was found: the amount of decomposed cellulose was higher in two variants (control and 90N + PK) of two cut system in comparison with the same variant in three cut system.

Methods of growing plant biomass for the production of biogas in anaerobic digestion plants have a decisive influence on arable land and on the evaluation of biogas plant technologies from the environmental point of view. The main benefit of anaerobic digestion is the possibility to use various agricultural crops for energy production. Some of these plant species, e.g., legumes, are generally considered to be beneficial for arable soil quality, as compared with maize monocultures with frequently manifested soil degradation and adverse environmental impact on arable land. A possible change is offered by cultivation systems composed of two and more crops and defined as mixed cropping (MC) systems. The systems are characterized by a more efficient utilization of natural resources of the site as well as by a greater potential for arable soil protection. A question remains as to whether the MC system of growing maize and white sweetclover can be used for biogas yield. In the presented research study, a mixed cropping system was tested with maize (Zea mays L.) and white sweetclover (Melilotus albus MED.). The goal of our research was to determine an optimum ratio of maize and white sweetclover (s.c.) shreddings in silage for a biogas plant. For this purpose, model micro-silages of monocultures were prepared: maize (100%), white s.c. (100%), as well as variants with different weight shares of these two crops (maize:white s.c.; 3:7, 1:1, 7:3, 8:2, 8.5:1.5, 9:1). The silages were subjected to biomethanation tests, in order to determine the influence of the increased addition of white s.c. biomass on methane yield and methane concentration in biogas. The highest values of biogas yield were recorded in the maize monoculture and in the MC variant of maize and white s.c. at 9:1 (>0.26 m3/kgVS). The lowest methane yield values were recorded in the white s.c. monoculture (0.16 m3/kgVS). It was found out that the yield of methane decreased with an increasing share of white sweetclover in the maize silage, due to the increased content of poorly degradable organic substances and the presence of fermentation inhibitors (e.g., coumarin).

Currently, there is an increasing emphasis on the use of renewable sources. The Czech Republic is no exception. There has been an increase in the number of biogas plants and composting plants. The main purpose of these facilities is to process organic wastes of various origins in order to utilize the waste, both for energy production and as soil fertility enhancers. Last but not least, the biogas station produces digestate, which could be further utilized. The present work deals with the assessment of the effect of digestate (doses of 220; 150 and 80 kg N ha−1), mineral fertilizer (150 kg N ha−1), and compost application (150 kg N ha−1) on selected indicators of soil environment: (a) soil microbial activity (basal and substrate-induced respiration); (b) plant nutrient content (P, K, Ca, Mg); (c) leaching mineral N from the soil; and (d) production of plant biomass of model plant Lactuca sativa L. Furthermore, the work aims to assess the individual doses of digestate and to determine the optimal one. The above effects were studied within a pot experiment for 63 days in controlled conditions. There were significant differences in Nmin leaching, which was significantly the highest in the variant with the application of a mineral fertilizer and lowest in variants with the application of digestate (variant 150 and 80 kg N ha−1) and compost (150 kg N ha−1). In terms of soil microbial activity, a significant effect of digestate application (150 kg N ha−1) on basal respiration versus the mineral fertilizer application was found (difference > 20%). This dose of digestate also had the highest positive effect on substrate-induced respiration, proven against all other variants, except for the digestate application at 220 kg N ha−1. Particularly, as compared with the mere application of mineral fertilizer, the application of digestate dose at 150 kg N ha−1 had the best positive effect on plant biomass production (+20%). On the other hand, compost application most positively affected the increase in available contents of nutrients and thus long-term soil fertility. Therefore, the dose of 150 kg N ha−1 digestate may represent an interesting alternative to increase actual soil fertility and thus to partially replace conventional mineral nutrition.

The presented paper deals with the analysis of potential differences between organic waste compost (CBD), vermicompost (CVER) and mineral fertilizer (MF; 27% of N) applications affecting the quality of arable soil by influencing microbial activity therein. The selected types of compost represent alternatives to conventional organic fertilizers, which are, however, not available to Czech and Slovak farmers in sufficient amounts. Their mutual comparison and the comparison with organic fertilizers aim to provide farmers further information about their influence on arable land and thus to give them the possibility of deciding on the most suitable amendments. To demonstrate the effect of these amendments, six variants were prepared: one without the addition of fertilizers; two variants with the addition of 40 Mg/ha of CVER and CBD; one variant with the addition of double dosed CVER (80 Mg/ha), and the remaining two variants were fertilized only with MF (0.22 Mg/ha) and with the combination of CVER (0.20 Mg/ha) and MF (0.11 Mg/ha). Substrate induced respiration (SIR), basal respiration (BS), microbial carbon (Cmic) and enzymatic activities (hydrolysis of fluorescein diacetate—FDA, dehydrogenase activity—DHA, and phosphatase activity—PA) were used to evaluate the effect of CBD, CVER and MF application on the soil quality. Both organic and mineral amendments affected BS and SIR. The highest BS and SIR rates were found in variants with compost application (CVER and CBD). All variants treated with the mineral fertilizer showed the lowest level of enzyme activities; lower by about 30% in comparison with variants where CVER, CBD and the combination of MF and CVER were applied. We found insignificant differences between the individual types of compost. More importantly, we compared the situation at the beginning of the experiment and after its end. It was found that the application of mineral fertilizers automatically led to the deterioration of all enzymatic parameters, on average by more than 25%, as compared with the situation at the beginning of the experiment. However, when the mineral fertilizer dose was supplemented with organic amendments (CVER), this negative effect was eliminated or significantly reduced. Furthermore, both composts (CVER and CBD) positively affected plant biomass production, which reached a level of production enhanced by the MF. Results clearly showed that the application of both compost types could be used to improve soil quality in agriculture.

This work presents the analysis of the effect of grassland management on leaching of mineral nitrogen from rhizosphere and plant biomass production in area of our interest. The determined values show the influence of fertilization and species composition of permanent grassland on leaching of mineral nitrogen and biomass production. The values were determined during field and laboratory experiments. The highest availability of Nmin in the field experiment was detected in the variant N90+PK; the lowest availability of Nmin was recorded in the PK variant. The difference was statistically significant (P < 0.05). In the pot experiment, the highest loss of Nmin was recorded in the variant with N180+PK (16.88 mg.dm−3) with the difference being statistically significant as compared with the other variants (P < 0.05). Measured values of the availability of mineral nitrogen and plant biomass production indicate the importance of species composition at the establishment of new grassland. For example, species composition of permanent grassland has a great importance at the establishment of new grassland on erosion-affected soils in protection areas of drinking water. Because selected species of grasses can immobilize nitrogen in their bodies, thus preventing it’s leaching from the soil.

Studying green manure in several returning methods to enhance soil fertility and crop benefits is a strong foundation for cropland nutrient management. However, how different types of green manures and their variable doses affect the efficacy of applied manures, either buried or mulched, remain overlooked. The objective of this study was to optimize green manure management to enhance soil fertility and maize biomass using five types of green manures (white mustard, forest rye, fiddleneck, sufflower, and pea) in two different doses (low, 5 g per pot, and high, 10 g per pot), which were either buried or mulched before and after maize sowing. Results revealed that total carbon content increased due to green manure treatments, representing a 10% increase over control, particularly through buried w. mustard (10% increase before maize cultivation) and mulched safflower and pea (12% and 11% increase after maize cultivation over control). Dry maize aboveground biomass yields also improved across all variants, with buried mustard yielding 18.4 g·plant−1 (compared to 8.6 g·plant−1 in the control), mulched mustard yielding 16.4 g·plant−1, and buried pea yielding 17.8 g·plant−1. Green mulching generally acidified the soil (pH 5.71 compared to 6.21 in the control), except for buried fiddleneck (pH 6.39 after maize cultivation) at a high dose of manures. Carbon-mineralizing enzyme activities (dehydrogenase and β-glucosidase) were significantly increased by green manures, with buried fiddleneck showing a 22.6% and 20.6% increase over the control, and mulched fiddleneck showing a 24.5% and 22.4% increase under high doses. The study suggests that partially decomposed and mineralized mulched biomass may induce a negative priming effect on carbon-mineralizing enzymes due to a decrease in the C/N ratio of the soil. It emphasizes that the nutrient content and stoichiometry of green manures, alongside soil characteristics such as the C/N ratio, are critical factors for sustainable soil management and carbon sequestration. These findings underscore the need for careful selection and management of green manures to optimize soil health and carbon-storage outcomes.

Abstract Background Previous studies have suggested that the targeted application of biochars in agricultural soils may benefit soil health and crop production. Physico-chemical properties of soils after biochar addition have been explored, but less is known about how microbial parameters respond. Therefore, impact of biochar (NB), mineral fertilizer-activated biochar (AB), or mineral fertilizer (MF) application on selected chemical and microbial parameters of lettuce-planted soil was evaluated in a pot experiment. Results In comparison to the control, soil enzymes activities, related to carbon (C), nitrogen (N), and phosphorus (P) cycling, and their content in plant biomass, were significantly increased by the addition of mineral fertilizer with or without biochar (MF, NB + MF). Conversely, microbial respiration (basal and substrate induced) was highly responsive to the activated biochar amendment (AB) as compared to other treatments. N, P, and potassium (K) concentrations in soil pore water were stabilized by the mineral fertilizer-activated biochar, indicating reduced leaching and the likelihood of increased longevity of these nutrients in soils. Enhanced carbon acquisition and mitigated nitrogen acquisition in soil of the most experimental treatments were coupled with higher crop (lettuce) biomass. Conclusions Our study demonstrates that the application of biochar both with and without mineral fertilizer has the potential to enhance microbial activity and fertility in the tested agricultural soil, but that leaching of fertilizer-borne nutrients may be mitigated by the activation process. Graphical Abstract

Abstract 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.

Abstract Background Sewage sludge (SS) has been considered a potent source of soil nutrients. However, its direct application to agricultural soils have been discouraged owing to its toxic nature. Therefore, conversion and modification of SS to decrease its toxicity has resulted in advanced methods. Co-pyrolysis of SS with other amendments is an ideal treatment resulting in an environmentally safe and nutrient rich final products with additional properties to sequester carbon. In the present study, a novel biochar was produced through the microwave pyrolysis of SS mixed with zeolite and sawdust. The pyrolysis product was thus characterized for elemental composition, polycyclic aromatic hydrocarbons, via Fourier Transform Infrared Spectroscopy (FTIR), and for its effects on soil microbial characteristics, soil health and plant biomass after soil application. Results Results revealed that, the SS modification resulted in stable product with higher nutrients which further depend on the type and ratio of feedstock used. Its application to soil significantly improved soil chemical and microbiological properties and altered lettuce biomass. Conclusions We concluded that sawdust feedstock promoted nutrient availability in the resulting biochar and induced higher activity of nutrient mineralizing enzymes, whereas zeolite slowed down the release of nutrients from soil and putatively immobilized enzymes. This joint effect of sewage sludge biochar, sawdust and zeolite benefited the plant acquisition of nutrients in comparison with the microbial nutrient uptake. We thus conclude that microwave pyrolyzed SS could be used as a soil enhancer. Graphical Abstract

Abstract Background Elemental sulfur (S0) is a cost-efficient fertilizer and the least rapidly utilizable source of S for soil microorganisms and plants. Its bacterial-mediated oxidation to sulfates is dependent on particle size. Finely formulated (micronized, nanosized) S0 exerts enhanced oxidation rate and benefit due to nutrient availability and crop nutrition efficiency. Graphene oxide (GO) affects soil properties both negatively and positively. A pot experiment was carried out with lettuce using soil supplemented with S0 in different composition, applied alone or in combination with GO. The following variants were tested: control, GO, micro-S0, micro-S0 + GO, nano-S0, nano-S0 + GO. Results Nanosized S0 improved most of enzyme activities (dehydrogenase, arylsulfatase, N-acetyl-β-d-glucosaminidase, β-glucosidase, phosphatase). However, respirations induced by d-glucose, protocatechuic acid, l-arginine were decreased. GO mitigated negative to neutral effect of micro-S0 in the soil pH, dehydrogenase and urease activity. Furthermore, micro-S0 positively affected basal respiration and respirations induced by d-trehalose and N-acetyl-β-d-glucosamine. Nano-S0 + GO improved plant biomass yield and enzyme activities. However, nano-S0 + GO significantly decreased all substate-induced respirations. Conclusions The benefit of soil treatment with nano-/micro-sized S0 and its combination with GO on soil biological parameters was partially demonstrated. Graphical Abstract

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.

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.

Abstract Background Soil carbon-rich organic amendments (biochar, humic substances) may improve the quality and fertility of arable soil. Their co-application can additively enhance the beneficial effect on soil. Hypothetically, the pre-treatment of biochar, by aging via soaking in a solution of commercially available humic substances, could result in synergism, which may exceed the benefit from simple co-application of both amendments to the soil. Therefore, the aim of this study was to investigate the impact of biochar, humic substances, the combination of both, and the impact of biochar aged by humic substances solution on soil microbial activities and plant growth in a short-term pot experiment with lettuce. Results The aging of biochar decreased the C:N ratio as compared to non-activated biochar. The co-application of biochar and humic substances into the soil resulted in the highest microbial biomass carbon and respiration activity. The majority of enzyme activities (β-glucosidase, arylsulfatase, N-acetyl-β-d-glucosaminidase, phosphatase) were the highest in humic substances-amended soil. The application of humic substances and biochar with humic substances seemed to stimulate microbial growth and activity followed by the competition of microflora for nutrients with plants, whereas the aged biochar behaved differently. The plants treated by aged biochar achieved the highest values of dry aboveground and root biomass of all variants. However, the assumed rapid uptake of nutrients by plants resulted in lower nutrient availability for microflora, and a decline in microbial viability. Conclusions Based on this study, the positive effect of co-applied humic substances and biochar on soil fertility, quality, and health can be concluded. The usability of biochar aging by humic solution requires further study. Graphic abstract

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.

Endophytic bacteria improve the growth, physiology, and metabolite profile of plants. They are known as potential biocontrol agents of soil-borne diseases. This study evaluated the effects of endophytic bacterial strains on growth, vase life, biochemical attributes, and antioxidant and nematicidal activities of French marigold (Tagetes patula). French marigold seeds were sole and consortium inoculated with three promising endophytic bacterial strains, Burkholderia phytofirmans (PsJN), Enterobacter sp. (MN17), and Bacillus sp. (MN54). The vase life of French marigold was promoted by 66.6% in the individual application of PsJN and 100% in plants treated with consortium compared to the uninoculated control. The shoot and root fresh weights were also increased by 65.9 and 68.7%, with the combined application of all three strains. The total phenolics, flavonoid, and protein contents were higher in consortium treatment with an increase of up to 38.0, 55.9, and 65.9%, respectively, compared to the uninoculated control. Furthermore, combined application of endophytic bacterial strains promoted DPPH radical scavenging, mortality of plant-parasitic nematodes, and ferric reducing antioxidant power activities with increase of up to 278.0, 103.8, and 178.0%, respectively, compared to uninoculated control. An increase in antioxidant activities of ascorbate peroxidase (APX), catalase (CAT), glutathione peroxidase (GPX), and superoxide dismutase (SOD) were observed up to 77.3, 86.0, 91.6, and 102.9%, respectively by combined application of endophytic bacterial strains. So, given the economic importance of floriculture crops, endophytic bacterial isolates studied here have shown a great potential for improving the productivity of cultivated ornamental French marigold.

Abstract Background Organic mulches are widely used in crop production systems. Due to their benefits in improving soil fertility, retention of soil moisture and weed control. Field experiments were conducted during wheat growing seasons of 2018–2019 and 2019–2020 to evaluate the effects of Jatropha leaves mulch on the growth of wheat varieties ‘Wadan-17’ (rainfed) and ‘Pirsabaq-2013’ (irrigated) under well irrigated and water stress conditions (non-irrigated maintaining 40% soil field capacity). Jatropha mulch was applied to the soil surface at 0, 1, 3 and 5 Mg ha−1 before sowing grains in the field. Under conditions of water stress, Jatropha mulch significantly maintained the soil moisture content necessary for normal plant growth. Results We noted a decrease in plant height, shoot and root fresh/dry weight, leaf area, leaf relative water content (LRWC), chlorophyll, and carotenoid content due to water stress. However, water stress caused an increase in leaf and root phenolics content, leaf soluble sugars and electrolytes leakage. We observed that Jatropha mulch maintained LRWC, plant height, shoot and root fresh/dry weight, leaf area and chlorophyll content under water stress. Moreover, water stress adverse effects on leaf soluble sugar content and electrolyte leakage were reversed to normal by Jatropha mulch. Conclusion Therefore, it may be concluded that Jatropha leaves mulch will minimize water stress adverse effects on wheat by maintaining soil moisture and plant water status.

The unprecedented rise in the human population has increased pressure on agriculture production. To enhance the production of crops, farmers mainly rely on the use of chemical fertilizers and pesticides, which have, undoubtedly, increased the production rate but at the cost of losing sustainability of the environment in the form of genetic erosion of indigenous varieties of crops and loss of fertile land. Therefore, farming practices need to upgrade toward the use of biological agents to maintain the sustainability of agriculture and the environment. In this context, using microbial inoculants and amino acids may present a more effective, safer, economical, and sustainable alternative means of realizing higher productivity of crops. Therefore, field experiments were performed on chickpea for two succeeding years using Rhizobium and L-methionine (at three levels, i.e., 5, 10, and 15 mg L–1) separately and in combinations. The results show that the application of Rhizobium and all the three levels of L-methionine increased the growth and yield of chickpea. There was a higher response to a lower dose of L-methionine, i.e., 5 mg L–1. It has been found that maximum grain yield (39.96 and 34.5% in the first and second years, respectively) of chickpea was obtained with the combined use of Rhizobium and L-methionine (5 mg L–1). This treatment was also the most effective in enhancing nodule number (91.6 and 58.19%), leghemoglobin (161.1 and 131.3%), and protein content (45.2 and 45%) of plants in both years. Likewise, photosynthetic pigments and seed chemical composition were significantly improved by Rhizobium inoculation. However, these effects were prominent when Rhizobium inoculation was accompanied by L-methionine. In conclusion, utilizing the potential of combined use of L-methionine and microbial inoculant could be a better approach for developing sustainable agriculture production.

In several studies, the discriminating factor in land use of arable soil is tilling, along with its depth and intensity. Reduced and no-till technologies are held to be beneficial for soil health. Strip-till reduces soil disruption and enables the application of liquid fertilizer directly in rows at different levels. The objective of the research reported here was to evaluate the effects of digestate application on the biochemical and microbiological properties of soil at various soil depths. Three doses of digestate (0, 20, and 40 m3∙ha−1) applied at three different soil depths (0–10, 10–15, and 15–20 cm) were tested in two seasons (2020 and 2021) of semi-operational field trials with maize cultivated according to strip-till practice. In 2020, a lower (20 m3∙ha−1) dose of digestate caused the most significant improvement in β-glucosidase, urease, and basal and L-alanine-induced respiration in topsoil (0–10 cm) and in oxidizable carbon in mid-soil (10–15 cm). In 2021, the most significant positive effect on arylsulfatase, N-acetyl-β-D-glucosaminidase, urease, and all types of respiration were caused by higher (40 m3∙ha−1) digestate dose in mid-soil (10–15 cm). The benefits of the strip-till amended digestate in 2020, as revealed by respiration indicators, strongly decreased with soil depth. Finally, the markedly positive impacts of the digestate applied via the strip-till agromanagement technique were similar for three different depths of soil in 2021, verifying its benefits.

The conversion of bio-wastes to useful products such as biochar provide a suitable option not only to minimize the mass of wastes, but also to use the biochar as soil amendment. In the present study, food waste biochar (FWB) and agricultural waste derived biochar (AB), either alone or in combination (FWB + AB), were tested for their effects on soil microbiological characteristics (soil enzymes, soil basal as well as substrate-induced respiration), plant growth and photosynthetic parameters. Four treatments were tested: control, FWB, AB and FWB + AB. The results indicated that the application of AB significantly enhanced the plant above ground and below ground fresh and dry biomass as compared to other amendments and control (+41 to +205% compared to control). The application of FWB enhanced the quantum yield of photosystem II (QY-max, +4% compared to control) and normalized difference vegetation index (NDVI, +13% compared to control). Moreover, the FWB application improved the soil dehydrogenase (DHA) activity (+24% compared to control). Furthermore, the soil basal respiration was found to be increased under AB application (+46% compared to control) and the substrate-induced respirations were relatively decreased, depicting negative effects of applied biochars on substrate-induced respirations. Thus, we concluded that the differential responses of observed crop and soil attributes might be related to the biochar specific effects on soil properties.

Continuous use of chemical fertilizers has deteriorated soil health and crop productivity. Replenishing soil nutrients and microbial activity with eco-friendly soil amendments such as biochar and manure is therefore necessary to sustain soil health for crop production. However, studies are limited regarding the evaluation of biochar and poultry manure effects on soil health, attributed mainly to microbial extracellular enzymes and respiration. Therefore, the present study was designed to investigate the effects of poultry manure and biochar on soil physico-chemical and microbiological properties and lettuce biomass accumulation in a pot experiment. The pots were amended with poultry manure either alone and or in combination with low (10%) and high (20%) rates of biochar. The treatments included were; (i) control, (ii) manure alone (M), (iii) manure plus 10% biochar (M + B10, and (iv) manure plus 20% biochar (M + B20). Results revealed that soil extracellular enzymes related to C, N, and P mineralization, soil basal (BR), and substrate induced respirations (SIR) were significantly affected by applied manure and manure–biochar. However, there were large differences observed for applied amendments regarding various soil and crop parameters. Specifically, the manure combined with a high rate of biochar (M + B20) enhanced total carbon (TC) content, dehydrogenase activity (DHA), BR, and all SIRs except Arginine-IR. On the other hand, manure combined with a low rate of biochar (M + B10) resulted in enhanced lettuce aboveground dry biomass (AGB-dry). The manure treatment alone (M), however, proved to be the most influential treatment in improving soil enzymes (β-glucosidase, N-acetyl-β-d-glucosaminidase and phosphatase) involved in C, N, and P mineralization compared to the other treatments and control. Thus, it was concluded that the sole application of M and M + B20 improved both fertility and soil health, which therefore could be a promising direction for the future to enhance soil quality and crop productivity.

Rice (Oryza sativa L.) feeds to two-third of the global population by serving as staple food. It is the main export commodity of several countries; thus, contributes towards foreign exchange earnings. Unfortunately, average global rice yield is far below than its genetic potential. Low nitrogen (N) use efficiency (NUE) is among the major reasons for low average yield. Current study evaluated the impact of nitrogen fertilizer application methods (conventional and deep placement) on growth, yield-related traits, chlorophyll contents, photosynthesis rate, agronomic N-use efficiency (ANUE), partial factors productivity of applied N (PFP) and economic returns of two different transplanted rice varieties (Basmati-515 and Super-Basmati). Fertilizer application methods significantly affected allometry, yield-related traits, chlorophyll contents, photosynthesis rate, ANUE, PFP and economic returns. Deep placement of N-fertilizer (DPNF) observed better allometric traits, high chlorophyll contents, photosynthesis rate, ANUE, PFP, yield attributes and economic returns compared to conventional application of N-fertilizer (CANF). Similarly, Basmati-515 had better allometric and yield-related traits, chlorophyll contents, photosynthesis rate, ANUE, PFP and economic returns than Super-Basmati. Regarding interactions among N-fertilizer application methods and rice varieties, Basmati-515 with DPNF resulted in higher chlorophyll contents, photosynthesis rate, ANUE, PFP, allometric and yield related traits and economic returns than CANF. The lowest values of these traits were observed for Super-Basmati with no application of N-fertilizer. Both varieties had better yield and economic returns with DPNF compared to CANF. It is concluded that DPNF improved yield, ANUE and economic returns; therefore, should be opted to improve productivity of transplanted fine rice. Nonetheless, lower nitrogen doses need to be tested for DPNF to infer whether it could lower N use in rice crop.

ObjectivesAs 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.MethodsSoil 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.ResultsSoil 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.ConclusionsThe 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.

The effective use of digestate as exogenous organic matter to enhance soil carbon sequestration depends on the balance between labile and recalcitrant organic carbon, which is influenced by the type of feedstock, the fermentation process, and the fraction (liquid, solid) of the fermented product used. In this work, in order to change the ratio of labile to stable carbon in the resulting fertiliser, the digestate was mixed with organic carbon-rich supplements: biochar and Humac (a humic acid-rich substance). The pot experiment was carried out under controlled conditions with maize (Zea mays L.) in soil amended with the digestate (D), which was incubated with Humac (H), biochar (B), or a combination of both (D + B + H) before the application. Digestate enriched with Humac showed improved short-term nutrient (carbon, phosphorus, nitrogen) transformation, as indicated by soil enzyme activity and the highest maize biomass production of. Total carbon content, C:N ratio, short-term respiration activity, and nitrification were most enhanced by digestate enriched with either biochar or combined biochar + Humac). Long-term nitrogen mineralization was mostly enhanced by digestate + Humac, as indicated by amino-acid-induced respiration and urease activity. Short-term positive effects of digestate + biochar (eventually + Humac) on catabolism were proven, whereas their long-term effects on nutrient mineralization were negative (i.e., biochar-mediated immobilization, sequestration), which should be the focus of further research in future.