Soil Catalase Activity Research Articles

Effects of a one-time application of bentonite on soil enzymes in a semi-arid region

Soil enzymes play a key role in many soil processes that affect soil health and which may be adversely affected under a changing climate. We investigated the short- and long-term effects of bentonite amendments on soil catalase, invertase, urease, and alkaline phosphatase activity in a field experiment in a semi-arid region in northern China. Treatments included six rates of bentonite amendments (0, 6, 12, 18, 24, and 30 Mg ha−1) applied only once in 2011. Addition of bentonite had a significant (P < 0.01) effect on the activity of each enzyme at different layers and days after millet sowing. Observed increases in catalase, invertase, urease, and alkaline phosphatase activities were up to 42%, 46%, 58%, and 50%, respectively, and they were approximately linear with increasing bentonite rate up to 24 Mg ha−1over the 5 yr experimental period. Averaged over 5 yr, the 24 Mg ha−1rate of bentonite amendment led to the largest effect on soil enzyme activity in all soil layers at five growth stages over the growing season. The observed increased enzyme activity suggests that bentonite can help maintain and improve soil health to support plant growth and contribute to sustainable agriculture production in a semi-arid environment.

The Successional Trend of Soil Microbial Characteristics after Reclamation Amended with Arsenic Sandstone in the Mu Us Sandy Land, China

Soil microorganisms have played an important role in the formation and evolution of soil ecosystem. Based on sand-binding by arsenic sandstone in Mu Us Sandy Land, to evaluate the effects of land reclamation on soil microbial characteristics, we researched on soil enzyme activities, soil microbial biomass and soil basal respiration rate in different reclamation years. The result showed sandy land reclamation through arsenic sandstone has a positive role in changing the soil texture, accumulation of soil nutrients. Soil catalase activity, dehydrogenase activity, urease activity, alkaline phosphatase activity, invertase activity and arylsulphatase activity increased with the year of reclamation, and significant difference between the different years of reclamation. Soil microbial biomass carbon, soil basal respiration rate and microbial quotient became higher with the increase of the reclamation time, metabolic quotient reduced, that showed sandy land reclamation by blending arsenic sandstone, accelerate succession of the soil ecosystem from low to high range. The results indicate soil enzymes and soil microorganisms play an important role in instructing and predicting the sand soil quality, which provide reference for reasonable sand management measures in Mu Us Sandy Land.

Physiological responses of Suaeda glauca and Arabidopsis thaliana in phytoremediation of heavy metals

The over discharge of mine tailing cause consequent heavy metal pollution. Phytoremediation as one of the most viable and efficient method for this problem has aroused much attention. In this research, the growth and physiological responses of Suaeda glauca and Arabidopsis thaliana plants were investigated, and the soil conditions (pH and enzyme activity) were evaluated further under varied levels of cadmium (Cd), lead (Pb) and manganese (Mn). The results showed that heavy metals could inhibit the growth of plants. The fresh weight and photosynthetic pigments contents of Suaeda and Arabidopsis decreased with the increased concentration of Cd, Pb and Mn. As a monitoring plant, growth status of Arabidopsis showed good dose-effect when treated by heavy metals. S. glauca showed better tolerance capacity for Cd, Pb and Mn, when compared with Arabidopsis. Moreover, the physical and chemical properties of soil were significantly improved after phytoremediation. The soil catalase activity decreased with increased concentration of metal treatments, which showed similar regularity with microbial community. Changes of microbial community could not only indicate the soil environment but also suggest that S. glauca plants had better influences on the soil microbial environment. The introduction of plants resulted in a 0.5–0.8 units change in soil pH compared with the initial pH level. The present study provided the potential of S. glauca plants for phytoremediation in contaminated soil. Microbial community of Suaeda and Arabidopsis were evaluated and showed different regularity because of the rhizosphere effect. Soil microorganisms played an important role in the process of bioremediation. Meantime the main problems about physical and chemical properties of mine tailings were improved. It could be of great significance to the large-scale resource utilization and economical remediation of mine tailings.

The impact of copper on catalase activity and antioxidant properties of soil under amaranth cultivation

The impact of copper on catalase activity and antioxidant properties of soil under amaranth cultivation

Effects of plant neighborhood on arbuscular mycorrhizal fungal attributes in afforested zones

Arbuscular mycorrhizal (AM) fungi are an important determinant of plant performance, and conversely their community composition greatly depends on host plants and their neighbors. Understanding how the interaction of host plants and their neighbors affects AM fungal communities in afforested zones is of primary interest in forest ecology. We sampled roots and rhizosphere soils in monocultures and mixtures of black locust (Robinia pseudoacacia) and oriental arborvitae (Platycladus orientalis) to define AM fungal colonization level, spore density and communities using 454 sequencing. Neighboring oriental arborvitae only affected AM fungal community in black locust rhizosphere. For oriental arborvitae, however, growing in a mixture with black locust changed AM fungal colonization, sporulation and communities in the roots and rhizosphere. In particular, neighboring black locust modified the rhizosphere- and root-inhabiting AM fungal pool through improving soil NO3-N and water contents and reducing soil catalase activity, and the modification in the root AM fungal resource, especially the Glomus and Rhizophagus genera, further affected AM fungal colonization and sporulation under oriental arborvitae. All the results presented here suggest that both hosts and neighbors can largely affect AM fungal attributes mainly through changing soil nutrient levels and enzyme activity, whereas the reciprocal effects are not always symmetric.

In Situ Earthworm Breeding to Improve Soil Aggregation, Chemical Properties, and Enzyme Activity in Papayas

The long-term use of mineral fertilizers has decreased the soil fertility in papaya (Carica papaya L.) orchards in South China. In situ earthworm breeding is a new sustainable practice for improving soil fertility. A field experiment was conducted to compare the effects of four treatments consisting of the control (C), chemical fertilizer (F), compost (O), and in situ earthworm breeding (E) on soil physico-chemical properties and soil enzyme activity in a papaya orchard. The results showed that soil chemical properties, such as pH, soil organic matter (SOM), total nitrogen (TN), available nitrogen (AN), and total phosphorus (TP) were significantly improved with the E treatment but declined with the F treatment. On 31 October 2008, the SOM and TN with the O and E treatments were increased by 26.3% and 15.1%, respectively, and by 32.5% and 20.6% compared with the F treatment. Furthermore, the O and E treatments significantly increased the activity of soil urease and sucrase. Over the whole growing season, soil urease activity was 34.4%~40.4% and 51.1%~58.7% higher with the O and E treatments, respectively, than that with the C treatment. Additionally, the activity of soil sucrase with the E treatment was always the greatest of the four treatments, whereas the F treatment decreased soil catalase activity. On 11 June 2008 and 3 July 2008, the activity of soil catalase with the F treatment was decreased by 19.4% and 32.0% compared with C. Soil bulk density with the four treatments was in the order of O ≤ E < F < C. The O- and E-treated soil bulk density was significantly lower than that of the F-treated soil. Soil porosity was in the order of C < F < E < O. Soil porosity with the O and E treatments was 6.0% and 4.7% higher, respectively, than that with the F treatment. Meanwhile, the chemical fertilizer applications significantly influenced the mean weight diameter (MWD) of the aggregate and proportion of different size aggregate fractions. The E treatment significantly increased the MWD, but the F treatment decreased it. The MWD with the E treatment was 14.5% higher than that with the F treatment. The proportion of >2 mm size aggregates in the O and E treatments was vastly improved. In conclusion, in situ earthworm breeding in orchards performed better than traditional compost and chemical fertilizer in improving soil aggregation, chemical properties, and enzyme activity. This is a new, organic fertilizer application for improving soil structure, chemical properties, and soil enzymes due to the activities of the earthworms and the production of vermicomposting.

Effects of Byproduct Amendment on Enzyme Activities and Physicochemical Properties of Acidic Orchard Soil from Jiaodong Peninsula of China

ABSTRACTApplication of byproduct amendment containing silicon, calcium, magnesium, and potassium has been shown to improve acidic soil quality in Jiaodong Peninsula of China. In this study, we explored the influences of amendment supplemented with and without urea on the physicochemical properties as well as microbial activities of acidic soil from Jiaodong over a 120-day period. With the amendment, the electronic conductivity and pH of soils changed. The amendment treatment significantly reduced inorganic nitrogen content and increased microbial biomass nitrogen content during the whole incubation period. The microbial biomass, activities of phenol oxidase and dehydrogenase were increased by the addition of amendments, while the soil respiration, catalase and urease activity were declined. Our results indicated that application of byproduct amendment could improve the chemical and biological properties of the acidic orchard soils from Jiaodong over a short time period of investigation.

Influence of Radioactive Contamination of the Sr-90 Terrestrial Ecosystems on the Enzymatic Activity of the Soil

One of the most promising methods of soil diagnostics is the determination of the parameters of enzymatic activity. Changes in urease, invertase, dehydrogenase and catalase activity of soil subjected to radioactive contamination with radionuclide Sr-90 have been studied. When the specific activity of Sr-90 in the soil varies in the range from the control value to more than 1.5 kBq / kg, the stability of invertase, urease and dehydrogenase is established. At the same time, the catalase activity of the soil is a sensitive indicator to radioactive contamination, which is described by a reliable model with a threshold value, after which the oppression of the indicator is observed.

Repeated treatments of ciprofloxacin and kresoxim-methyl alter their dissipation rates, biological function and increase antibiotic resistance in manured soil

The dissipation of ciprofloxacin (CIP, 1.0 and 10.0mg/kg) and kresoxim-methyl (KM, 1.0 and 2.0mg/kg) in manure-amended soil, the variations in soil enzyme activities and microbial functional diversities, and CIP-induced bacterial community tolerances were studied using a chromatographic analysis, enzyme colorimetric and titration analyses, and the BIOLOG EcoPlate method. Three successive treatments of individual and combined samples of CIP and KM at low and high concentrations were performed at 60d intervals. The dissipation half-life of CIP increased, but that of KM decreased in manured soil with treatment frequency; furthermore, the combined treatment altered the dissipation rates of CIP and KM. A stronger inhibitory effect on the activities of soil neutral phosphatase and urease was observed in the individual KM treatment than in the individual CIP treatment. A similar inhibitory trend was also found in soil neutral phosphatase activity in the combined treatment at high concentration compared to that at low concentration, but the activity of soil catalase was enhanced in the early stages of the KM or CIP treatments. Meanwhile, the inhibitory trend on the overall activity and functional diversity of soil microorganisms was observed in the individual KM or CIP treatment, and the combined treatment exerted a greater suppression effect than that in the individual treatment. Bacterial community resistance to CIP increased significantly with increasing treatment frequency and concentration, and furthermore antibiotic resistance developed faster in the combined treatment than in the individual treatment. It was concluded that the repeated treatments of CIP and KM could alter their dissipation rates and soil enzyme activities, suppress microbial functional diversity, and increase bacterial community resistance to CIP in manured soil.

Changes in oxidoreductases activity in anthropogenic salty soils

To study the effects of anthropogenic salinity-sodicity on dehydrogenase (DHA) and catalase (CAT) activity in soil, samples were collected from the Ciech Soda Polska S.A. Plant in Inowroclaw. The soils closest to the plant were assayed to determine pH, electrical conductivity(EC1:5), and enzymes activity. The soil resistance (RS) and resilience (RL) indices were computed. The soil was sampled in July and October 2015 from the plant area not covered by the recultivation treatments (locations no 1, 2, 3, 4) and the locations where the agrotechnical soil recultivation was performed (5, 6). The successive soil sampling locations (7, 8) were located in the vicinity of the plant, while the control (point 9) – beyond the impact of the plant. Soil was sampled from the depth of 0–20 cm and 20–40 cm. To compare the activity of the oxydoreductases sampled from various locations, indices were calculated to facilitate estimation of both soil processes degradation and recultivation. It has been observed that the highest value of pHKCl and electrical conductivity increased the CAT and inhibited the DH activity. RS values for the dehydrogenase activity closed to 0 for the soil from stands in the vicinity of the plant, meaning the effect of saline on soil not only in places of stored post-soda sludge, but also in the area near the Ciech Soda Polska S.A. The highest value of soil catalase RL in location no 5, 0–20 cm deep, from recultivation area suggests a correct recultivation.

Response of soil microbial communities to red mud-based stabilizer remediation of cadmium-contaminated farmland.

In this work, a field test was conducted to investigate the effects of heavy metal stabilizer addition on brown rice and microbial variables in a cadmium (Cd)-contaminated farmland from April to October in 2016. Compared with the control, red mud-based stabilizer (RMDL) effectively reduced the concentration of Cd in brown rice (with the removal rate of 48.14% in early rice, 20.24 and 47.62% in late rice). The results showed that adding 0.3kgm-2 RDML in early rice soil or soil for both early and late rice increased the microbial biomass carbon (MBC), the number of culturable heterotrophic bacteria and fungi, and the catalase activity in soil at different stages of paddy rice growth. Furthermore, there was no notable difference in the diversity of the bacterial species, community composition, and relative abundance at phylum (or class) or operational taxonomic unit (OTU) levels between the control and treatment (RMDL addition) groups. In a word, RMDL could be highly recommended as an effective remediation stabilizer for Cd-contaminated farmland, since its continuous application in paddy soil cultivating two seasons rice soil could effectively decrease the Cd content in brown rice and had no negative impact on soil microorganisms.

Effects of elevated ozone concentrations on enzyme activities and organic acids content in wheat rhizospheric soil.

The elevated concentration of tropospheric ozone (O3) is an important global climate change driver, with adverse impacts on soil ecological environment and crop growth. In this study, a pot experiment was carried out in an open top chamber (OTC), to investigate the effects of elevated ozone concentration on soil enzyme activities (catalase, polyphenol oxidase, dehydrogenase and invertase), organic acids contents (oxalic acid, citric acid and malic acid) at different growth stages (tillering, jointing, heading and ripening stages) of wheat, and combined with the rhizospheric soil physicochemical properties and plant root characteristics to analyze the underlying reasons. The results showed that, elevated ozone concentration increased soil catalase, polyphenol oxidase, dehydrogenase and invertase activities at wheat ripening period to different degrees, with the effects on the activities of catalase and polyphenol oxidase being statistically significant. At the heading stage, activities of dehydrogenase and invertase were significantly increased by up to 76.7%. At the ripening stage, elevated ozone concentration significantly increased the content of citric acid and malic acid and redox potential (Eh) in rhizospheric soil, but reduced soil pH, electrical conductivity, total carbon and nitrogen. For root characteristics, elevated ozone concentrations significantly reduced the wheat root biomass, total root length and root surface area but increased the average root diameter.

Exploring patterns of Camellia seed cake application in relation to plant growth, soil nematodes and microbial biomass

ABSTRACT The suppression of plant-parasitic nematodes is crucial for maintaining the worldwide development of the banana industry. In this study, different application patterns of Camellia seed cake previously reported to suppress root-knot nematode were conducted to manage pests and promote banana seedling growth. The results demonstrated seven days delay before transplanting was necessary after Camellia seed cake application. The dose 5 g/kg soil resulted in best plant growth promotion performance, which increased banana seedling height, stem diameter, shoot, and root fresh weight by upto 29%, 27%, 47%, and 21%, respectively. Plastic film mulching was beneficial when high amount (2%) of Camellia seed cake was added. The application of Camellia seed cake increased nutrient potassium amounts; the abundance of soil free-living nematodes, especially bacterivores; and the abundance of soil microbes and the soil catalase activity, while reduced plant-parasitic nematodes amounts. Further correlation analysis between the soil nematodes and microbial abundance showed that plant-parasite numbers had significant negative correlations with the bacterial biomass and a portion of the fungal biomass; bacterivores had significant positive correlations with the bacterial biomass; and omnivores had significant correlations with the bacterial biomass and fungal biomass. A fundamental challenge of root-knot nematode control is to sustain ecological services without losing biodiversity. This study provided an environmentally friendly strategy based on Camellia seed cake to regulate the soil health and quality.

Effects of heavy metal Cd pollution on microbial activities in soil.

Heavy metal contamination of soil occurs when heavy metals are introduced to soil through human activities, leading to the gradual deterioration of the ecology and environment. Microorganism activity reflects the intensity of various biochemical reactions in soil, and changes in it reflect the level of heavy metal pollution affecting the soil. The effects were studied of heavy metal Cd on the microbial activity of soil at different concentrations by investigating the respiratory intensity, urease activity, and catalase activity in forest soil and garden soil. The results showed that the respiratory intensity, urease and catalase activities in the garden soil were all higher than in the forest soil. Cd has obvious inhibitory effects on microbial activities. The three parameters exhibited a downward trend with increasing concentrations of Cd. Catalase activity increased when the mass concentration of Cd reached 1.0mg/kg, indicating that low concentrations of Cd can promote the activity of some microorganisms. Respiratory intensity and urease activity also increased when the concentration reached 10.0mg/kg, showing that respiratory intensity and urease activity have strong response mechanisms to adverse conditions. The effective state of Cd in soil, as well as inhibition of microbial activity, decreased with incubation time.

Study on the Improvement Effects of the Petroleum Hydrocarbon Contaminated Loess by Common Agricultural Wastes

Four agricultural wastes ( walnut shell, corn cob, soybean straw and wheat straw) were selected as the soil conditioners to treat the petroleum hydrocarbon contaminated loess in this study ,according to its difficulty to be treated quickly and completely once, the principal component function model was set up to confirm the optimal conditioner for soil improvement on the basis of data processing of principal component analysis(PCA) through 120 days’ indoor decomposition and analysis and SPSS software to analyze the dynamic changes of various soil properties and their relationships with oil content, The results were shown as following: Firstly, the petroleum ether was selected as the extraction agent to detect the content of petroleum hydrocarbon in loess soil by gravimetric method, it could found that there was a much more obvious linear relation between the actual values and the measured ones than other methods and its linear formula was (Y=0.63814+1.39684*X (R2=0.99416) by which the calculated accuracy rate of oil content was up to above 94% with the deviation value of 3.27% relative to the standard value, which indicated this detection method had a better reproducibility by using petroleum ether to extract the oil content of the petroleum hydrocarbon in loess soil. Secondly, compared with blank control group, adding walnut shell, corn cob, soybean straw and wheat straw could decrease the oil content inordinately by13.59%, 17.85%, 27.38% 15.21%, separately and lowered pH values (0.35,0.56,0.46,0.45) promoted soil respiration(66.32%, 216.94%, 1874.17%, 159.71%) and facilitate alkaline phosphatase activity(64.21%, 81.47%, 140.25%, 147.69% )respectively. Thirdly, with the decreasing oil content in the soil, he pH value and the urease activity decreased, oppositely, the soil respiration and the alkaline phosphatase activity increased by adding walnut shell, soybean straw and wheat straw to the soil simultaneously. The invertase activity which strengthened by adding corn cob, soybean straw and wheat straw to the soil, however, lowered in the walnut shell-added soil. The catalase activity increased in the soil added soybean straw and decreased in the soil added walnut shell, corn cob, and wheat straw oppositely. Meanwhile, adding corn cob, soybean straw and wheat straw simultaneously to the soil could promote invertase activity (8.89%, 117.06%, 3.08%) the result was soil catalase activity (1.77%, 40.72%, 1.10%) respectively; adding walnut shell merely to the soil can inhibit invertase activity (-9.44%) and soil catalase activity (-3.03%). Finally , the comparison expression of the aggregative principal component function model Y=0.61712Y1+0.18307Y2+0.15805Y3 was got by the SPSS software and through which the result we got was: soybean straw (Y=2.762)>corn cob (Y=0.360)>wheat straw (Y=-0.048)>walnut shell(Y=-1.175)> blank group (Y=-1.897), and the principal component analysis (PCA) showed that all of these four) agricultural wastes all had certain degree of soil improvement effect, in which the soybean straw and corn cob could much more significantly promote the improvement effect of the petroleum hydrocarbon contaminated loess soil. Presently, the domestic and foreign research direction for the petroleum contaminated soil remediation technologies mostly focused on the degradation of petroleum hydrocarbon removal, but for how to improve the biological and chemical properties of the oil contaminated soil has little attention, especially to improve the soil properties using agricultural waste of natural organic matter to improve the oil pollution of hydrocarbon contaminated soil was very rare now [1]. The common agricultural wastes had the advantages of low cost, fixed stability, no two pollution and other advantages, it is not only rich in C, N, P and other nutrients, but also have good affinity to soil enzyme and soil microorganisms, and in humic process can also release of dissolved organic matter into the soil, and the most of which was the common metabolic substrate of microbial degradation, which can be of persistent organic pollutants in soil (PAHs) have strong biological The ability to degrade so that both the purpose of the degradation of petroleum hydrocarbons in the soil can be improved, and the nature of the petroleum hydrocarbon contaminated soil can be improved by it [2]. Because of its large specific surface area, fine particles and poor permeability, the Loess in Northwest China makes its adsorption and retention ability of petroleum hydrocarbon pollutants very strong. When a large amount of petroleum hydrocarbons enter the loess, it will permeate rapidly to a certain depth, which not only changes the soil composition, but also gradually changes the ecology of the Loess surface and kills the microorganisms in the Loess [3]. Therefore, once the loess is polluted, it will be more difficult to control [4]. This study takes walnut shell, corncob, soybean straw, wheat straw four common agricultural wastes as conditioner; study the biochemical effects of different bulking agents on petroleum hydrocarbon contaminated loess soil and the improvement effect, so as to determine the characteristics of the four conditioners to provide a theoretical basis for its application in the Soil remediation field.

Dynamics of soil microbial biomass and enzyme activities along a chronosequence of desertified land revegetation

Large-scale sand control and afforestation in the Mu Us Sandy land of China have greatly improved soil nutrients and physicochemical properties; however, little is known about their effects on soil biological properties. This study aimed to investigate the changes in soil microbial biomass and enzyme activities and their relationships with soil physicochemical properties during sand land rehabilitation. Soil samples were collected from the shrub and arbor plantations with an age sequence of 20, 30, and 51 years in Yulin at depths of 0–10cm and 10–20cm and with semi-fixed sand land selected as a control (0-year-old site). The soil physicochemical and biological properties in the 0–10cm soil layer were significantly (P<0.001) higher than in the 10–20cm soil layer for all stand lands. The soil microbial biomass (e.g., microbial carbon and nitrogen) in the 0–10cm and 10–20cm layers greatly increased, by 1.58–5.59 times and 2.27–6.07 times, respectively, during the revegetation of shrub and arbor from 20 to 30 years on the control land. During the same period, the activities of soil catalase, urease, alkaline phosphatase and invertase also greatly increased, by 1.27–2.18, 0.59–1.23, 0.48–3.66 and 0.57–2.72 times in shrub land, respectively, whereas they increased by 1.51–2.73, 0.46–2.09, 0.97–2.79 and 2.00–6.65 times in arbor land, respectively, compared with the control land. However, during the 30–51 years of revegetation on the control land, the soil microbial biomass and all enzyme activities remained relatively stable or slightly increased in the arbor land, whereas they were reduced in the shrub land. The soil organic carbon (SOC), dissolved organic carbon (DOC), total nitrogen (TN) and available nitrogen (AN) contents also greatly increased after revegetation in the control land. Principal component analysis (PCA) also confirmed that most of the chemical and biological properties were influenced by the afforestation and showed coordinated variation between the analyzed parameters. Moreover, redundancy analysis (RDA) showed that the soil microbial biomass and enzyme activities were correlated with the changes of SOC, DOC and TN, whereas they were negatively correlated with the bulk density, pH and total potassium. Therefore, we concluded that revegetation by the establishment of both shrub and arbor plantations significantly improved soil biological properties. Moreover, SOC, DOC and TN were regarded as the key factors in the enhancement of soil biological activity during desertified land revegetation in the Mu Us Sandy land of China.

Effect of forest fire on changes in the content of total and available forms of selected heavy metals and catalase activity in soil

Abstract The aim of the paper was to assess the effect of forest fire on the content of total and available forms of zinc, copper, lead, nickel and cadmium, as well as the activity of catalase in soil. The study was performed directly (2012) and a year after the fire (2013). The fire had a significant effect on the content of those heavy metals in surface horizons, however, it did not result in their rapid growth. The concentrations of total forms of metals did not exceed the norms provided for in Regulation of the Polish Minister of the Environment. The soil samples analysed can be considered unpolluted with those metals. The availability coefficients calculated showed an unfavourable higher availability of lead and cadmium over zinc and copper. The statistical analysis showed a significant effect of fire on the activity of catalase. Resistance of soil (RS) for catalase demonstrated lower values in the year 2012 as compared with 2013 (except for B soil). The calculated values of time index (TI) pointed to the activation of the enzyme a year after the fire. The Ward clustering method facilitated determining similarities between the sites in two research years (2012 and 2013) with the selected soil parameters. With the PCA method a negative effect of fire was identified.

Microbial remediation of a pentachloronitrobenzene-contaminated soil under Panax notoginseng: A field experiment

Pentachloronitrobenzene (PCNB) is an organochlorine fungicide that is mainly used in the prevention and control of diseases in crop seedlings. Microbial removal is used as a promising method for in-situ removal of many organic pesticides and pesticide residues. A short-term field experiment (1 year) was conducted to explore the potential role of a PCNB-degrading bacterial isolate, Cupriavidus sp. YNS-85, in the remediation of a PCNB-contaminated soil on which Panax notoginseng was grown. The following three treatments were used: i) control soil amended with wheat bran but without YNS-85, ii) soil with 0.15 kg m-2 of solid bacterial inoculum (A), and iii) soil with 0.30 kg m-2 of solid bacterial inoculum (B). The removal of soil PCNB during the microbial remediation was monitored using gas chromatography. Soil catalase and fluorescein diacetate (FDA) esterase activities were determined using spectrophotometry. In addition, cultivable bacteria, fungi, and actinomycetes were counted by plating serial dilutions, and the microbial biodiversity of the soil was analyzed using BIOLOG. After 1 year of in-situ remediation, the soil PCNB concentrations decreased significantly by 50.3% and 74.2% in treatments A and B, respectively, when compared with the uninoculated control. The soil catalase activity decreased in the presence of the bacterial isolate, the FDA esterase activity decreased in treatment A, but increased in treatment B. No significant changes in plant biomass, diversity of the soil microbial community, or physicochemical properties of the soil were observed between the control and inoculated groups (P < 0.05). The results indicate that Cupriavidus sp. YNS-85 is a potential candidate for the remediation of PCNB-contaminated soils under P. notoginseng.

Impacts of chemical fertilizer reduction and organic amendments supplementation on soil nutrient, enzyme activity and heavy metal content

AbstractExcessive use of agro-chemicals (such as mineral fertilizers) poses potential risks to soil quality. Application of organic amendments and reduction of inorganic fertilizer are economically feasible and environmentally sound approaches to develop sustainable agriculture. This study investigated and evaluated the effects of mineral fertilizer reduction and partial substitution of organic amendment on soil fertility and heavy metal content in a 10-season continually planted vegetable field during 2009–2012. The experiment included four treatments: 100% chemical fertilizer (CF100), 80% chemical fertilizer (CF80), 60% chemical fertilizer and 20% organic fertilizer (CF60+OM20), and 40% chemical fertilizer and 40% organic fertilizer (CF40+OM40). Soil nutrients, enzyme activity and heavy metal content were determined. The results showed that single chemical fertilizer reduction (CF80) had no significant effect on soil organic matter content, soil catalase activity and soil heavy metal content, but slightly reduced soil available N, P, K, and soil urease activity, and significantly reduced soil acid phosphatase activity. Compared with CF100, 40 or 60% reduction of chemical fertilizer supplemented with organic fertilizer (CF60+OM20, CF40+OM40) significantly increased soil organic matter, soil catalase activity and urease activity especially in last several seasons, but reduced soil available P, K, and soil acid phosphatase activity. In addition, continuous application of organic fertilizer resulted in higher accumulation of Zn, Cd, and Cr in soil in the late stage of experiment, which may induce adverse effects on soil health and food safety.

The research on effect of purple soil enzyme activities by biogas slurry recirculation at large-scale farms

Soil enzyme plays an important role in converting soil nutrient, improving soil fertility and enhancing agricultural products quality. In this paper, the effect of purple soil enzyme activities was investigated by different biogas slurry (BS) recirculation load and period at large-scale farm in southwest China. The results indicated that the value of soil enzyme activities all increased by different BS recirculation load and period comparing to control check group. Its value was at high level by low BS recirculation load and long BS recirculation period. Soil urease and invertase activity reached highest value by T4 (7 m3·hm-2) and T8d (8 d), respectively. The value of soil catalase activity was highest by T1 (40 m3·hm-2) and T10d (10 d). In addition, soil phosphatase activity got peak value by T4 (7 m3·hm-2) and T4d (4 d). The effect of purple soil enzyme activities by BS recirculation at large-scale farms was explored to provide the theoretical basis for utilizing biogas slurry rationally.