Soil Microbiological Properties Research Articles

Use of zeolite to neutralise nickel in a soil environment

Nickel is a heavy metal which is a stable soil pollutant which is difficult to remediate. An attempt to reduce its impact on the environment can be made by changing its solubility. The right level of hydrogen ions and the content of mineral and organic colloids are crucial in this regard. Therefore, methods to neutralise heavy metals in soil are sought. There are no reports in the literature on the possibility of using minerals in the detoxication of a soil environment contaminated with metals. It is important to fill the gap in research on the effect of zeolites on the microbiological, biochemical and physicochemical properties of soils under pressure from heavy metals. Therefore, a pot experiment was conducted on two soils which examined the effect of various levels of contamination of soil with nickel on the activity of soil enzymes, physical and chemical properties and growth and development of plants. An alleviating effect of zeolite Bio.Zeo.S.01 on the negative impact of nickel on the soil and a plant (oats) was examined. The enzyme activity and the oat yield were found to be significantly and negatively affected by an excess of nickel in the soil, regardless of the soil type. The metal was accumulated more in the oat roots than in the above-ground parts. An addition of zeolite decreased the level of accumulation of nickel in oats grown only on sandy-silty loam. Zeolite Bio.Zeo.S.01 used in the study only slightly alleviated the negative effect of nickel on the biochemical properties of soil. Therefore, its usability in the remediation of soil contaminated with nickel is small.

Influence of rice (Oryza sativa) habit groups and moisture conservation practices on soil physical and microbial properties in rice + lathyrus relay cropping system under rice fallows in Eastern Plateau of India

The study involving bio-physical aspects of popular rice (Oryza sativa L.) + lathyrus relay system for conserving natural resources and deriving the best benefits out of them was carried out in a vertisols at Indira Gandhi Krishi Vishwa Vidyalaya, Raipur (India) during 2011-14. The study location comes under tropical sub humid climate that receives an annual precipitation of 1582 mm. Two rice habit groups (a tall local rice Masuri maturing at 140 days visà -vis a dwarf HYV of rice Swarna with 110 days duration) were combined with two moisture conservation practices (retaining rice stubble height up to 15 cm versus 30 cm) for growing two contrasting varieties of lathyrus (early high biomass accumulating Ratan vis-à -vis medium high biomass Prateek). The study showed that soil moisture depletion pattern was relatively lower in case of residue retention at a higher cutting height, i.e. 30 cm in comparison to 15 cm with better and higher crop cover in the former. At later stages of lathyrus, faster moisture depletion was observed in case of lathyrus Ratan over that in Prateek. Yet, maximum soil moisture depletion was recorded under Prateekespecially under long rice habit group since it stayed for long as compared to ‘Ratan’. Similarly, bulk density (BD) was increased slightly with both time and soil compaction as a result of tillage or soil traffic. Soil strength indicated higher order variation (0.13 to 0.19) which could explain relatively higher sensitivity of soil strength to relay cropping situation in comparison to BD. However, marginal changes did occur in respect of soil porosity (47- 50%), pH (6.6 to 7.2) and EC (0.12 to 0.14 dS/m) at 15 cm profile depth. Moreover, as a result of slow depletion of soil moisture storage (SMS) following stubble retained at 30 cm height, soil organic carbon (SOC) status was greatly enhanced under it. Similar small increments in respect of soil fertility attributes such as soil available N (193.4 to 210.4 kg/ha), soil-P (10.3 to 12.2 kg/ha), soil-K (465.4 to 475.4 kg/ha), Cu (2.2 to 2.5 mg/kg), Fe (6.9-7.6 mg/kg), Zn (0.69-0.84 mg/kg) and Mn (6.2-6.9 mg/kg) after the harvest of rice were observed with diverse treatment combinations. Similarly, soil microbiological properties such as Rhizobium, dehydrogenase activity, crop growth and nodulationdid affect following treatment imposition. Besides these, weed dynamics and the resultant yield attributes and grain yield were favoured especially in those treatments where soil moisture is conserved (higher SMS) and availability of it was extended over a period of time. Therefore, the study carried out in a lentil relayed with diverse rice habits showed that efficient management of soil and land resources was crucial for realizing higher output through adequate soil cover with better soil health.

Analysis of microbiological and physiochemical properties of top soil from municipal dumpsites in Benin City

The effect of disposing municipal waste on soil was evaluated by analyzing the microbiological and enzyme activity of soil samples at three different locations, from five municipal waste dumpsites and compared with soil samples from a farmland which serves as the control. Soil microbial load, physicochemical parameters and enzyme activities were determined using standard procedure. The highest heterotrophic bacterial count (1.02 ± 0.4 × 10 7 cfu/g) was recorded from New Benin market Dumpsite (sampling point A) while the least (3.25 ± 0.4 ×10 4 cfu/g) was from the control (sampling point C). The result obtained showed that there was significant difference (p> 0.05) in the Heterotrophic bacteria and fungi count between the control and the soil samples from the various locations of the dumpsites. The bacteria identified were Acinetobacter species, Micrococcus luetus , Pseudomonas aeruginosa , Serratia species, Bacillus subtilis , Klebsiella species, Staphylococcus aureus , Arthrobacter species, Escherichia coli and Streptococcus feacalis , while fungi identified were Aspergillus niger , Trichoderma species, Penicillium species, Fusarium species, Mucor species, Saccharomyces species, Rhizopus species. Pseudomonas aeruginosa was the most prevalent bacterial isolate (20.3 %) while Streptococcus feacalis was the least isolate (3.1 %). Aspergillus niger was the most prevalent fungi isolate and Fusarium species the least isolated fungi. The enzymatic profile revealed that Oba market and Satana market had the highest Dehydrogenase and Urease activities with the values of 23.70 ± 16.32 mg/g/6h and 97.90 ± 14.93 mg/g/24h respectively. The physicochemical parameter measured in this study showed that the soil samples were acidic (5.60 ± 0.17 – 6.23 ± 0.35) and sandy (72.20 ± 4.11 - 90.60 ± 0.00 %). Trace amount of zinc (0.10 ± 0.00 – 1.53 ± 1.02 mg/kg), lead (< 0.01 – 1.23 ± 0.17 mg/kg) and copper (0.01 ± 0.00 – 0.80 ± 0.10 mg/kg) was observed in both the control soil and the test samples. The result showed that although municipal waste dump is an unsustainable practice, it has a positive impact on the quality of the soil samples examined. Keywords: Microbiological, Enzymatic, Municipal Waste Dumpsites, Soil, Benin City

The sensitivity of soil enzymes, microorganisms and spring wheat to soil contamination with carfentrazone-ethyl

ABSTRACTHerbicides pose a significant threat to the natural environment, in particular in soils that are most exposed to plant protection agents. Prolonged herbicide use leads to changes in soil metabolism and decreases soil productive potential. In this study, the influence of carfentrazone-ethyl (CE) on the microbiological and biochemical properties of soil and the yield of Triticum aestivum L. was evaluated. Carfentrazone-ethyl was applied to sandy loam (pHKCl – 7.0) in doses of 0.000, 0.264, 5.280, 10.56, 21.18, 42.24, 84.48 and 168.96 µg kg−1 DM soil. Soil samples were subjected to microbiological and biochemical analyses on experimental days 30 and 60. Carfentrazone-ethyl disrupted the biological equilibrium in soil by decreasing the abundance and biodiversity of soil-dwelling microorganisms, the activity of soil enzymes, the values of the biochemical activity indicator and spring wheat yields. Carfentrazone-ethyl had the most adverse effects when applied in doses many fold higher than those recommended by the manufacturer. The toxic effects of CE were also determined by its soil retention time. Soil treated with CE was characterized by higher counts of oligotrophic bacteria, organotrophic bacteria, bacteria of the genus Azotobacter, actinomycetes and fungi on day 60, and spore-forming oligotrophic bacteria on day 30. The activity of dehydrogenases, urease, alkaline phosphatase and β-glucosidase was higher on day 30 than on day 60.

Biological attributes of soil cultivated with corn intercropped with Urochloa brizantha in different plant arrangements with and without herbicide application

Cultural techniques such as spatial distribution of plants and initial control of the growth rate of forage by applying herbicide sub-doses should be adopted for economic sustainability of intercropping between corn and forage. However, disturbances in the system can affect mycorrhizal colonization, metabolic quotient, microbial respiration, and the number and diversity of arbuscular mycorrhizal fungi (AMF). The objective of this study was to evaluate the effect of nicosulfuron spraying and the seeding density of Urochloa brizantha on soil microbiological attributes. The treatments were arranged in a 2×4 factorial design in randomized blocks. The first factor was nicosulfuron doses (0 and 1/5 of the recommended), and the second factor was the forage seeding densities (0, 2, 4 and 6kg of seeds per hectare). Soil samples were collected 60days after the emergence of corn plants. The respiratory rate, carbon associated with microbial biomass, metabolic quotient, diversity and number of mycorrhizal fungi spores and mycorrhizal colonization were determined in the soil samples. The seeding density of U. brizantha interfered with microbial respiration, metabolic quotient, mycorrhizal colonization and the population of AMFs. A planting density of 8kgha−1 associated with the application of nicosulfuron resulted in a lower metabolic quotient. The increase in forage seeding density linearly reduced corn yield when sub-doses of nicosulfuron were not applied. Management of the spatial distribution of plants and control of initial forage growth by spraying nicosulfuron provide economic and environmental sustainability to the production system.

Quality of Organic Vegetables Grown in Two Certified Sites on the Outskirts of Bucharest Municipality

Abstract Soil fertility properties, irrigation water quality, mineral nutrition, and some vegetables mineral composition were studied in the frame of a project regarding yield quality monitoring in certified organic vegetable farms, in two farms placed on the outskirts of Bucharest Municipality which provide products for the town’s organic market. Chemical analysis of the soil samples collected from the two farms reflects a good fertility, close to the natural one of this region soils, with well-balanced organic matter, total nitrogen, accessible phosphorus and potassium contents. The nitrates contents concord with the plants nutrition demands and don’t present the risk to accumulate in vegetables or to leach into the groundwater. Slightly increased microelements, both total and soluble forms, occur. Soil microbiological properties are favorable for vegetable plants growth. A good biodiversity is noticed. There are differences between soil properties in open field and greenhouses, induced both by the type and degree of mechanical works and materials applied for fertilization and plant protection. Good conditions are generally created for plants mineral nutrition. Mineral nutrition status of the vegetables grown in organic conditions, assessed by the leaves mineral composition, doesn’t differ from the one of the vegetables grown in conventional conditions. The vegetables (fresh material) harvested from the two studied farms have good, even high, concentrations of mineral elements important for the yield nutritional quality. The excessive microelements quantities noticed in soil don’t transfer in the yield, so the latter quality and nutritional properties are not altered.

Functional Diversity of Fungal Communities in Soil Contaminated with Diesel Oil.

The widespread use and consumption of crude oil draws the public’s attention to the fate of petroleum hydrocarbons in the environment, as they can permeate the soil environment in an uncontrollable manner. Contamination of soils with petroleum products, including diesel oil (DO), can cause changes in the microbiological soil properties. The effect of diesel oil on the functional diversity of fungi was tested in a model experiment during 270 days. Fungi were isolated from soil and identified. The functional diversity of fungal communities was also determined. Fungi were identified with the MALDI-TOF method, while the functional diversity was determined using FF-plates made by Biolog®, with 95 carbon sources. Moreover, the diesel oil degradation dynamics was assessed. The research showed that soil contaminated with diesel oil is characterized by a higher activity of oxireductases and a higher number of fungi than soil not exposed to the pressure of this product. The DO pollution has an adverse effect on the diversity of fungal community. This is proved by significantly lower values of the Average Well-Color Development, substrates Richness (R) and Shannon–Weaver (H) indices at day 270 after contamination. The consequences of DO affecting soil not submitted to remediation are persistent. After 270 days, only 64% of four-ringed, 28% of five-ringed, 21% of 2–3-ringed and 16% of six-ringed PAHs underwent degradation. The lasting effect of DO on communities of fungi led to a decrease in their functional diversity. The assessment of the response of fungi to DO pollution made on the basis of the development of colonies on Petri dishes [Colony Development (CD) and Eco-physiological Diversity (EP) indices] is consistent with the analysis based on the FF MicroPlate system by Biolog®. Thus, a combination of the FF MicroPlate system by Biolog® with the simultaneous calculation of CD and EP indices alongside the concurrent determination of the content of PAHs and activity of oxireductases provides an opportunity to achieve relatively complete characterization of the consequences of a long-term impact of diesel oil on soil fungi.

BENEFICIAL ROLE OF BIOFERTILIZATION ON YIELD RELATED CHARACTERISTICS OF TWO APPLE CULTIVARS AND SOIL MICROORGANISMS UNDER ORCHARD CONDITIONS

Intensive development of agriculture and increasing utilization of synthetic nitrogen fertilizers significantly contributes to a series of undesirable effects and results in excessive environmental pollution. Approximately half of all nitrogen applied to boost agricultural production escapes its intended use and is lost to the environment. Over the past years, fruit growing practice has been focused on a new concept, which relies primarily on the application of microbial inoculants i.e. biofertilizers. In line with the concept, we conducted comparative study of the effect of bio- and chemical fertilizer applications on yield-related characteristics of „Granny Smith‟ and „Cadel‟ apple cultivars and microbiological properties of the soil. The yield-related characteristics of the tested plants were evaluated for generative potential parameters i.e flowering intensity, fruit set intensity, final fruit set intensity and yield (kg tree-1; t ha-1).The microbiological properties of soil were monitored by determining the total microbial count, numbers of soil fungi, actinomycetes, oligonitrophilic bacteria and Azotobacter. The analysis of the results points to the fact that the efficient apple nutrition management should ensure both enhanced and sustainable production. This approach seems to contain a certain potential as an appropriate technique in commercial apple production, which may improve yield-attributing characteristics and soil fertility. Keywords: bacterial fertilizer, (Malus domestica Borkh), soil biological properties, generative potential

Effects of cotton stalk, maize stalk and almond bark on some soil microbial activities

AbstractWith the increase of agricultural production, residues of crop are the main source of organic matter in the soil and they are alternatives to inorganic fertilizers. For this purpose, effects of organic residues (cotton stalk, maize stalk, almond bark) commonly grown in Turkey were investigated for some soil microbial activity in clay soil. In this study, incubation experiment was set up. Five doses (0%, 2%, 4%, 6% and 8%) of organic residues (maize stalks, cotton stalks or almond bark) were applied to soil. Soil microbiological properties of soil samples such as CO2respiration, dehydrogenase and urease activity were determined. According to the results obtained, maize stalk, cotton stalks and almond bark applications increased some soil microbiological activities, such as CO2respiration, dehydrogenase and urease activities according to control soil. Maize stalk in comparison to other residues affects better on the biological properties of the soil. It is determined that enhancing effects of the added organic residues (maize stalk, cotton stalk, almond bark) into the soil were changed according to the type of organic residues, dosage and application terms.

The Role of Compost in Stabilizing the Microbiological and Biochemical Properties of Zinc-Stressed Soil

The progressive development of civilization and intensive industrialization has contributed to the global pollution of the natural environment by heavy metals, especially the soil. Degraded soils generally contain less organic matter, and thus, their homeostasis is more often disturbed, which in turn manifests in changes in biological and physicochemical properties of the soil. Therefore, new possibilities and solutions for possible neutralization of these contaminations are sought, inter alia, through reclamation of degraded land. At present, the use of additives supporting the reclamation process that exhibit heavy metal-sorbing properties is becoming increasingly important in soil recovery. Research was conducted to determine the role of compost in stabilizing the microbial and biochemical balance of the soil due to the significant problem of heavy metal-contaminated areas. The study was conducted on loamy sand, to which zinc was applied at the following doses: 0, 250, 500, 750, 1000, and 1250 mg Zn2+ kg−1 DM of soil. Compost was introduced to the appropriate objects calculated on the basis of organic carbon content in the amount of 0, 10, and 20 g Corg kg−1 DM of soil. The study was conducted over a period of 20 weeks, maintaining soil moisture at 50% capillary water capacity. Zinc significantly modified soil microbiome status. The abundance of microorganisms and their biological diversity and the enzymatic activity of the soil were affected. The negative effects of contaminating zinc doses were alleviated by the introduction of compost into the soil. Organic fertilization led to microbial growth intensification and increased biochemical activity of the soil already 2 weeks after compost application. These effects persisted throughout the experiment. Therefore, it can be stated that the use of compost is an appropriate method for restoring normal functions of soil ecosystems contaminated with zinc.

Chemical and microbiological soil properties in organic and conventional management systems of Coffea arabica L.

ABSTRACTThe goal of this study was to evaluate the effect of organic (OS) and conventional (CS) farming of Arabica coffee on chemical and microbiological soil properties and to identify which attributes correlate and/or contribute to distinguishing these two management systems. We collected soil samples on a 100 × 100 m2 grid in both, the OS and CS, in winter and summer and submitted chemical and microbiological properties to univariate and multivariate analyses (canonical discriminant analysis – CDA – and redundancy analysis – RDA). The best indicators to discriminate OS and CS were chemical and microbiological properties, as the elements calcium (Ca) and boron (B), besides microbial biomass carbon (MBC), metabolic quotient (qCO2), acid phosphatase (ACP), and alkaline phosphatase (ALP). The RDA showed that, regardless of the season, MBC and ACP correlated with nitrogen (N), sulfur (S) and organic matter (OM), whereas basal respiration (C-CO2) and ACP correlated with qCO2 and with magnesium (Mg), calcium (Ca), phosphorus (P), potassium (K) and pH.

Effect of different agricultural management practices on soil biological parameters including glomalin fraction

The aim of the study was to determine the glycoproteins content (total glomalin (TG), easily extractable glomalin (EEG) and soil proteins related to glomalin (GRSP)) in soil under long-term monoculture of maize. Soil microbiological and biochemical properties, including microbial biomass and enzymatic activity were also assessed. The presence of total, easily-extractable glomalin and soil proteins related to glomalin was dependent on both the growth phase of the plant and tillage system. The highest content of glomalin was detected in the soils under maize in direct sowing and reduced tillage. The glomalin content was correlated with soil biological activity. The linear regression was observed between TG and GRSP content, but no linear relationship was found between GRSP and C&lt;sub&gt;org&lt;/sub&gt;. The principal component analysis showed the strong correlations between the parameters of soil quality and biodiversity indicators. Selected indicators of soil microbial parameters explained 52.27% biological variability in soils.

Soil carbon and nitrogen dynamics as affected by land use change and successive nitrogen fertilization of sugarcane

Abstract The land use change (LUC) and application of N fertilizers have potential to affect soil C and N dynamics and long–term C and N stocks. We aimed to evaluate the effects of the LUC from native vegetation (seasonal semideciduous forest) to sugarcane (Saccharum spp.) cultivation under successive annual N fertilizer applications on chemical and microbiological attributes of sugarcane–cropped soils. Two field trials were performed during three (Site 1) or four years (Site 2) in southeastern Brazil. Soil sampling was carried out in the following N treatments applied to the crop: control (N–unfertilized plots), organomineral fertilizer (100 kg ha−1 yr−1 N), and synthetic fertilizer (100 and 200 kg ha−1 yr−1 N). Soil samples from native vegetation located near each site were also taken, to serve as reference for studying LUC. For Site 1, successive application of N fertilizers on sugarcane managed under green cane trash blanketing system maintained the C and N dynamics and stocks in soil to conditions similar to those found before LUC. At Site 2, however, modifications in soil attributes caused by LUC were more impacting than the N fertilization management. Compared to synthetic N fertilizers, successive application of organomineral fertilizer did not improve the soil microbiological attributes as well as organic C and total N stocks. Lastly, successive high N input (200 kg ha−1 yr−1, via synthetic fertilizer) promoted accumulation of mineral N deep in the soil profile, thus increasing potential losses through NO3− leaching.

The Influence of Silicon Oxide Nanoparticles on Morphometric Parameters of Monocotyledons and Dicotyledons in Soil and Climatic Conditions of Western Siberia, as well as on Microbiological Soil Properties

Using a field small-plot experiment, the influence of pre-sowing seed treatment of monocotyledons and dicotyledons, namely hulless oat (Avena sativa L.) and lucerne (Medicago sativa L. subsp. varia (Martyn) Arcang.), with suspensions of silicon oxide (SiO2) nanoparticles in different concentrations on morphometric parameters and microbial cenosis of their rhizosphere was studied. It has been found that spraying of seeds with 3 × 10−5 and 3 × 10−4% suspensions of SiO2 nanoparticles accelerates the growth, and development of oat and lucerne increases the content of photosynthetic pigments in leaves and contributes to 30–40% decrease in height of an oat straw and size reduction of internodes, while increasing the specific weight of a plant by 26–38%. These findings demonstrate a higher lodging resistance of plants. In general, the monocotyledonous crop Avena sativa L. has a stronger physiological response to seed treatment with a suspension of nanoparticles than the dicotyledonous crop Medicago sativa L. The pre-sowing seed treatment of oat and lucerne induced changes in the microbial community of their rhizospheres: on the one hand, it increased proportions of nitrifying and phosphate mobilizing bacteria, as well as cellulose-decomposing actinomycetes; on the other hand, it reduced population density of microscopic fungi, while increasing a taxonomic diversity of soil fungi. In general, these findings demonstrate the improved environmental situation in rhizospheres of plants and reduced risk of root rot.

Microbial Carbon Substrate Utilization Differences among High- and Average-Yield Soybean Areas

Since soybean (Glycine max L. (Merr.)) yields greater than 6719 kg ha−1 have only recently and infrequently been achieved, little is known about the soil microbiological environment related to high-yield soybean production. Soil microbiological properties are often overlooked when assessing agronomic practices for optimal production. Therefore, a greater understanding is needed regarding how soil biological properties may differ between high- and average-yielding areas within fields. The objectives of this study were to (i) evaluate the effects of region on soil microbial carbon substrate utilization differences between high- (HY) and average-yield (AY) areas and (ii) assess the effect of yield area on selected microbiological property differences. Replicate soil samples were collected from the 0–10 cm depth from yield-contest-entered fields in close proximity that had both a HY and an AY area. Samples were collected immediately prior to or just after soybean harvest in 2014 and 2015 from each of seven geographic regions within Arkansas. Averaged across yield area, community-level carbon substrate utilization and Shannon’s and Simpson’s functional diversity and evenness were greater (p &lt; 0.05) in Region 7 than all other regions. Averaged across regions, Shannon’s functional diversity and evenness were greater (p &lt; 0.05) in HY than in AY areas. Principal component analysis demonstrated that a greater variety of carbon substrates were used in HY than AY areas. These results may help producers understand the soil microbiological environment in their own fields that contribute to or hinder achieving high-yielding soybeans; however, additional parameters may need to be assessed for a more comprehensive understanding of the soil environment that is associated with high-yielding soybean.

Altered humin compositions under organic and inorganic fertilization on an intensively cultivated sandy loam soil

Humin is the most recalcitrant fraction of soil organic matter (SOM). However, little is known about quantitative structural information on humin and the roles of soil mircoorganisms involved in the humin formation. We applied advanced solid-state 13C nuclear magnetic resonance (NMR) spectroscopy to provide deep insights into humin structural changes in response to long-term balanced fertilization on a Calcaric Fluvisol in the North China plain. The relationships between humin structure and microbiological properties such as microbial biomass, microbial quotient (qmic) and metabolic quotient (qCO2) were also studied. The humins had a considerable (35–44%) proportion of aromatic C being nonprotonated and the vast majority of O-alkyl and anomeric C being protonated. Alkyl (24–27% of all C), aromatic C (17–28%) and O-alkyl (13–20%) predominated in humins. Long-term fertilization promoted the aliphatic nature of humins, causing increases in O-alkyl, anomeric and NCH functional groups and decreases in aromatic C and aromatic CO groups. All these changes were more prominent for treatments of organic fertilizer (OF) and combined mineral NPK fertilizer with OF (NPKOF) relative to the Control and NPK treatments. Fertilization also decreased the alkyl/O-alkyl ratio, aromaticity and hydrophobic characteristics of humins, suggesting a more decomposed and humified state of humin in the Control soil. Moreover, the soil microbiological properties had strong correlations with functional groups of humins. Particularly, microbial biomass C was a relatively sensitive indicator, having positive correlations with oxygen-containing functional groups, i.e., COO/NCO and protonated O-alkyl C, and negative correlations with nonprotonated aromatic C. The qmic and qCO2 were also significantly positively correlated with NCH and aromatic CO, respectively. Our results deepen our understanding of how long-term fertilization impacts the structure of humin, and highlight a linkage between microbiological properties and recalcitrant fraction of SOM besides labile fraction.

Soil Tillage as a Factor of Soil Conservation

The work describes the question of the soil treatment system influence on agro-physical and microbiological properties of gray forest soils, and yield of barley in Western Siberia. Research works were carried out in 2013-2014 in Yaya region of the Kemerovo region. Tillage affects soil structure. The water stability in zero tillage conditions was poor (15.7%). Soil density corresponding to the optimum rate for barley is formed by the zonal processing system, while at the zero tillage soil remains solid. The best indicators of phosphataze, catalysis and amylase activity are formed with minimum processing system. In the experiment the highest yield of barley was obtained with minimum tillage - 12.1 c/ha.

THE EFFECT OF NITROGEN ON THE MICROBIOLOGICAL AND BIOCHEMICAL PROPERTIES OF ZINC-CONTAMINATED SOIL

The aim of these studies was to determine the influence of excessive zinc doses on the microbiological and enzymatic properties of soil. Also, an evaluation of the possibility to stimulate remediation processes by nitrogen fertilisation of the soil was attempted. Zinc was applied to loamy sand in the amounts of 0, 250, 500, 750, 1000, 1250 mg Zn2+ kg–1 DM soil, while nitrogen in the form of urea in doses of 0, 250, 500 mg N kg–1 DM soil. Soil samples were incubated at a temperature of 25 °C, maintaining a constant humidity equal to 50% of the maximum water capacity. In the 2nd and 20th week of the experiment, the following factors were determined: activity of dehydrogenases and catalase, and number of organotrophic bacteria, copiotrophic bacteria, oligotrophic bacteria, actinomycetes, and fungi. Zinc inhibited the enzymatic activity of the soil, while causing a slight increase in populations of microorganisms. Only fungi reacted unequivocally positively to contamination of the soil with zinc, therefore demonstrating changes in the biodiversity of microorganisms. Nitrogen fertilisation of the soil resulted in stabilization of the environment contaminated with zinc by stimulation of growth of microorganisms resistant to the influence of this metal.

Effects on soil quality of biochar and straw amendment in conjunction with chemical fertilizers

The objective of this study was to evaluate the effects on chemical and microbiological properties of paddy soil of short-term biochar, straw, and chemical fertilizers compared with chemical fertilization alone. Five soil fertilization treatments were evaluated: regular chemical fertilizers (RF), straw+regular chemical fertilizers (SRF), straw biochar+regular chemical fertilizers (SCRF), bamboo biochar (BC)+regular chemical fertilizers (BCRF), and straw biochar+70% regular chemical fertilizers (SC+70%RF). Their effects were investigated after approximately 1.5 years. The soil pH and cation exchange capacity (CEC) were significantly higher in biochar-treated soils. The soil phosphorous (P) and potassium (K) contents increased with biochar application. The soil Colwell P content was significantly increased with the addition of straw biochar in the treatments of SCRF and SC+70%RF. The oxygen (0):carbon (C) ratio doubled in BC picked from the soil. This indicated that BC underwent a significant oxidation process in the soil. The denaturing gradient gel electrophoresis (DGGE) fingerprints of microbial communities differed among the treatments. Soils with added biochar had higher Shannon diversity and species richness indices than soils without biochars. The results suggest that biochar can improve soil fertility.

Changes in the microbiological and biochemical properties of soil contaminated with zinc

Changes in the microbiological and biochemical properties of soil contaminated with zinc