МИКРОБНЫЕ ПУЛЫ ПОЧВ ЗАБАЙКАЛЬЯ: СТРУКТУРА МИКРОБИОЦЕНОЗА, ФЕРМЕНТАТИВНАЯ АКТИВНОСТЬ, РАЗЛОЖЕНИЕ ЦЕЛЛЮЛОЗЫ

Assessing the effects of air-drying and rewetting pre-treatment on soil microbial biomass, basal respiration, metabolic quotient and soluble carbon under Mediterranean conditions

The aim of this study was to evaluate microbial biomass and total organic carbon and nitrogen of an irrigated Quartzarenic Neosol cultivated with two cowpea cultivars in Bom Jesus, Piauí, Brazil. The experiment was conducted in a randomized experimental block design in split plots. The plots consist of two cowpea cultivars (Aracê and Tumucumaque) and the subplots were composed of five different irrigation regimes (L1 = 108.2; L2 = 214.7; L3 = 287.9; L4 = 426.1, and L5 = 527.7 mm). Soil samples were collected at a depth of 0-0.20 m in order to evaluate basal soil respiration, microbial biomass carbon, metabolic quotient, microbial quotient, content, and storage of soil carbon and nitrogen. Basal soil respiration, microbial biomass carbon, microbial metabolic quotient, and microbial quotient are influenced by the interaction between cowpea cultivars and irrigation. The cultivar Aracê showed greater stimulus to the microbial community, while the irrigation regimes with 214.7 and 287.9 mm (60 and 90% of ETo, respectively) provided the best moisture conditions for microbial activities.

Rhododendrons spp. brushland (DJ), Salix cupularis brushland (GL), Dasiphoru fruticosa brushland (JL), Polygonum viviparum grassland (ZY), Grass steppe (HC), Swamp grassland (ZZ) and Kobresia grassland (SC), which designate seven different alpine grassland types in the Eastern Qilian Mountains of Qinghai-Tibetan Plateau of Western China, were selected for soil carbon investigation (including microbial biomass carbon with Fumigation Extraction Method, soil organic matter and K2SO4-extractable carbon). The results show that the soil organic matter varies from 82.3 to 207.2 g·kg-1 and is influenced by vegetation type. K2SO4-extractable carbon and microbial biomass carbon (MBC) range from 23.61 to 138.81 mg·kg-1 and from 156.19 to 1 182.84 mg·kg-1 respectively. Contribution of K2SO4-extractable carbon to soil organic matter and MBC varies from 0.03% to 0.06% and from 9.97% to 18.46% respectively. Under brushland, the value of K2SO4-extractable carbon under GL is lower than that under DJ. Under grassland, however, that value under HC is lower than under ZY, ZZ and SC. MBC contribution to soil organic matter ranges from 0.19% ( under HC) to 0.48% (under JL), and the value for upper layer is greater than that for the lower layer, except under ZY and ZZ. MBC, which is higher in the upper layer than in the lower layer, has significant positive correlations (at P 0.05 or P 0.01) with soil organic matter, total nitrogen and available phosphorus under the seven vegetation types. Furthermore, MBC has significant positive correlations with K2SO4-extractable carbon for brushland (at P 0.05) and for grassland (P 0.01). MBC also has significant positive correlations (P 0.01) with microbial biomass nitrogen and microbial biomass phosphorus under DJ, GL, JL, ZY, HC, ZZ and SC. MBC content and its contribution to soil organic matter are commonly different among sampling sites and soil layers. Furthermore, MBC is influenced by soil organic matter, K2SO4-extractable carbon, total nitrogen and available phosphorus.

Decades of ecological restoration on the Loess Plateau has achieved significant on-site benefits to reduce soil erosion and improve soil quality, with remarkable off-site effects of reducing sediment delivery to Yellow River. However, regional forest community succession is still far from being adequately developed. The Ziwuling forest region and its highly developed forest community, as an advanced eco-zone, can lend practical experience to other regions on the Loess Plateau and help to identify the most suitable tree species for a better regional restoration in the future. With the aim to systematically understand the potential effects of typical local tree species to soil properties, three typical and well-established artificial forests in the Ziwuling region, Robinia pseudoacacia, Pinus tabuliformis and Platycladus orientalis were investigated in this study, with the climax community Quercus wutaishanica as a reference. All the four forest type had comparable stand age (25 years). Soil samples from 0-20 cm layers were collected from those four plantations. The soil microbial biomass (carbon and nitrogen), soil enzyme (invertase, urease and alkaline phosphatase) activities and their correlations were measured and analyzed. The results showed that: 1) soil invertase activity ranged from 16.94 to 64.49 mg·g-1·24 h-1, the soil urease activity from 0.15 to 0.26 mg·g-1·24 h-1, and the alkaline phosphatase activity from 0.65 to 1.23 mg·g-1·24 h-1. The activities of those three enzymes were significantly higher in the P. orientalis soil that in the R. pseudoacacia and P. tabuliformis soils. The geometric average values in the P. orientalis soil were even greater than that in the Q. wutaishanica soil. 2) The soil microbial biomass carbon and nitrogen varied from 247.37 to 529.84 mg·kg-1 and 41.48 to 77.91 mg·kg-1, respectively. Both of them were significantly greater in the P. orientalis soil than that in the R. pseudoacacia and P. tabu-liformis soils. Even though the soil microbial biomass carbon in the P. orientalis soil remained lower than that in the Q. wutaishanica soil, its soil microbial biomass nitrogen was greater than in the Q. wutaishanica soil. 3) The dissolved organic carbon and nitrogen in the P. tabuliformis soil were much greater than that in other species, even greater than their own soil microbial biomass carbon and nitrogen. Such a result indicated that dissolved organic matter might play a more important role in providing plant available nutrients than microbial biomass in the P. tabuliformis soil. 4) The microbial biomass carbon and nitrogen were significantly positively correlated with the total organic carbon and the total nitrogen, particularly for the R. pseudoacacia and P. tabuliformis soils. There were significantly positive relationships between the soil invertase activity, urease activity and alkaline phosphatase activity, and their soil organic carbon, total nitrogen and total phosphorus contents. 5) Based on the results of principal component analysis, we concluded that the artificial forests types had obvious effects on soil microbial carbon and nitrogen, soil organic carbon, total nitrogen, the ratio of carbon to phosphorus, the ratio of nitrogen to phosphorus and urease activity. Overall, our findings suggested that P. orientalis is better than R. pseudoacacia and P. tabuliformis in term of improving soil properties in the south forest zone on the Chinese Loess Plateau.

Peat moss-based potting mix was amended with either of two composted swine wastes, CSW1 and CSW2, at rates from 4 to 20% (vol/vol) to evaluate suppression of pre-emergence damping-off of impatiens (Impatiens balsamina) caused by Rhizoctonia solani (anastomosis group-4). A cucumber bioassay was used prior to each impatiens experiment to monitor maturity of compost as the compost aged in a curing pile by evaluating disease suppression toward both Pythium ultimum and R. solani. At 16, 24, 32, and 37 weeks after composting, plug trays filled with compost-amended potting mix were seeded with impatiens and infested with R. solani to determine suppression of damping-off. Pre-emergence damping-off was lower for impatiens grown in potting mix amended with 20% CSW1 than in CSW2-amended and nonamended mixes. To identify relationships between disease suppression and microbial parameters, samples of mixes were collected to determine microbial activity, biomass carbon and nitrogen, functional diversity, and population density. Higher rates of microbial activity were observed with increasing rates of CSW1 amendment than with CSW2 amendments. Microbial biomass carbon and nitrogen also were higher in CSW1-amended mixes than in CSW2-amended potting mixes 1 day prior to seeding and 5 weeks after seeding. Principal component analysis of Biolog-GN2 profiles showed different functional diversities between CSW1- and CSW2-amended mixes. Furthermore, mixes amended with CSW1 had higher colony forming units of fungi, endospore-forming bacteria, and oligotrophic bacteria. Our results suggest that enhanced microbial activity, functional and population diversity of stable compost-amended mix were associated with suppressiveness to Rhizoctonia damping-off in impatiens.

Soil amendments, such as compost and biochar are known to affect soil properties, soil microbial activity, and plant growth. These organic amendments have the ability to increase soil fertility, carbon sequestration, and crop productivity. However, there is limited information available on the integrated application of biochar and compost on microbial and enzymatic activity, nutrients availability and plant growth in arid soil. The present study was designed to quantify the effect of biochar along with compost on soil microbial biomass (carbon, nitrogen, phosphorus), enzyme (urease, alkaline phosphatase, dehydrogenase) activity, nutrients (N, P, K) availability in soil, and plant growth. The treatments comprise a control, biochar at 20 g kg−1 soil, compost at 20 g kg−1 soil, biochar + compost at (10 g kg−1 soil + 10 g kg−1 soil), biochar + compost at (15 g kg−1 soil + 5 g kg−1 soil), and biochar + compost at (5 g kg−1 soil + 15 g kg−1 soil). Tomato was grown as a test plant in the pot experiment. The results revealed that biochar and compost alone or in combinations proved statistically significant for Soil pH. Application of biochar at 20 g kg−1 soil proved useful and increased (130%) microbial biomass carbon (MBC) as compared with control. Compost at 20 g kg−1 soil increased alkaline phosphatase (143%), urease activity (10%) and plant nitrogen (33%) over control. However, microbial biomass nitrogen (MBN), and dehydrogenase activity increased by 62, and 100% respectively in the treatment receiving biochar and compost at 10 + 10 g kg−1 soil compared to that in the control. Plant phosphorus and potassium contents were 34 and 70% higher in the treatment receiving biochar and compost at 5 + 15 g kg−1 soil than in the control. However, for plant parameters (plant height, plant fresh weight, and plant dry weight), the combination of biochar and compost at 15 + 5 g kg−1 soil was superior to other treatments.

Biochars are adsorptive solids potentially of benefit to soil microbes by providing improved nutrient retention, a carbon substrate and contaminant adsorption. A 28-day incubation experiment gauged the interactive effects of biochar application and contaminants on the microbial biomass and respiration of a sandy loam soil. Soil was amended with 250 mg/kg phenol or p-nitrophenol (two toxic but nevertheless biodegradable organic contaminants) or 50 mg/kg cadmium or copper. Biochar application generally caused increased microbial respiration and biomass relative to non-amended controls. Of the heavy metal-amended soils, Cu effected significant reductions in microbial biomass carbon and basal respiration, which were improved with concurrent biochar amendment. The biochar’s functional groups are likely to have mitigated the metals’ negative effects via complexation and sorption, while the soil’s proportion of negative pH-dependent sites was increased by the pH rise induced by biochar application, allowing more cationic retention. Organic contaminant-spiked soils had higher microbial biomass-specific respiration without biochar amendment, indicating that surviving microbes utilised the compounds and necromass as substrates. Paranitrophenol proved to be particularly toxic without biochar application, causing marked reductions in the microbial quotient and biomass carbon. Remarkably, concurrent biochar and pNP application led to hugely increased microbial biomass carbon and nitrogen, significantly higher than those in contaminant-free replicates. It is likely this arose from biochar sorbing the contaminant and allowing its microbial utilisation as a carbon and nitrogen source, stimulating growth. Biochar application is a highly promising strategy for reducing the soil microbial toxicity of heavy metals and aromatic organic contaminants, particularly p-nitrophenol.

In sodic soils, excessive amounts of salts have an adverse effect on soil biological activity and stability of soil organic matter. The study analyzes the role of silvopastoral systems to improve soil organic matter and microbial activity with a view for effective management of soil fertility. The silvopastoral systems for the present study (located at Saraswati Reserved Forest, Kurukshetra; 29°4′ to 30°15′ N and 75°15′ to 77°16prime; E) are characterized by tree species of Acacia nilotica, Dalbergia sissoo and Prosopis juliflora along with grass species of Desmostachya bipinnata and Sporobolus marginatus. Soil microbial biomass carbon was measured using the fumigation extraction technique and nitrogen mineralization rates using aerobic incubation method. The microbial biomass carbon in the soils of D. bipinnata and S. marginatus treatments were low. In silvopastoral systems, microbial biomass carbon increased due to increase in the carbon content in the soil – plant system. A significant relationship was found between microbial biomass carbon and plant biomass carbon (r = 0.83) as well as the flux of carbon in net primary productivity (r = 0.92). Nitrogen mineralization rates were found greater in silvopastoral systems compared to 'grass-only' system. Soil organic matter was linearly related to microbial biomass carbon, soil N and nitrogen mineralization rates (r = 0.95 to 0.98, p < 0.01). On the basis of improvement in soil organic matter, enlarged soil microbial biomass pool and greater soil N availability in the tree + grass systems, agroforestry could be adopted for improving the fertility of highly sodic soil.

Biomass conditioner made from agricultural and animal husbandry waste for resource disposal could be used to improve desertified soil, which is one of the effective ways of ecological management on desertified grasslands in northwest Sichuan. To clarify the effects of different raw material conditioners on alpine desertified grassland in northwest Sichuan, we analyzed the effects of three conditioners on soil nutrients and microbial community characteristics. With no conditioner as the control (CK), three different biomass conditioners were set up with an application rate of 12 t·hm-2, including mushroom dregs (JZ), straw (JG) and biochar (SWT). The results showed that all biomass conditioners could significantly increase soil available nutrients and active organic carbon by 23.0%-521.6%. Among the three conditioners, JG had the best effect, with an improvement range for soil nutrient and organic carbon of 65.1%-521.6%. Because biomass conditioner was only applied in the first year, soil available nutrients and active organic carbon in the second year decreased by 4.5%-92.3% compared with that of the first year, while soil organic carbon and microbial biomass carbon content of the second year increased by 5.6%-458.0%. The biomass conditioners changed the relative abundance of the dominant bacteria in the microbial community. JG significantly affected bacterial flora, while JG and JZ affected fungal flora. Compared with CK, JG significantly reduced the diversity of soil bacteria and fungi. The Shannon index was decreased by 2.9% and 31.8%, while the Simpson index was increased by 175.0% and 320.9%, respectively. Results of the redundancy analysis showed that the contents of soil available nutrients and active organic carbon were important factors affecting microbial community composition. The contents of soil nitrate and microbial biomass carbon had greater impacts on bacterial community composition, explaining 65.9% of community variations. The contents of soil available potassium and microbial biomass carbon had a greater impact on fungal community composition, explaining 83.2% of community variation. According to the comprehensive comparison, straw conditioner could significantly increase soil available nutrients and active organic carbon, and benefit the growth of beneficial bacteria and fungi, which could be used as a promotion measure to improve soil quality of alpine desertified grassland in northwest Sichuan.

Surface soil samples (0∼20cm) were collected from a Calamagrostis angustifolia freshwater marsh in the Sanjiang Plain from May to September and soil active organic carbon including microbial biomass carbon (MBC), easily oxidizable carbon (EOC), dissolved organic carbon (DOC) were analyzed aiming to reveal their seasonal dynamics characterisitics and their correlationships with activities of soil invertase, amylase and cellulase. The results indicated that MBC, EOC and DOC varied significantly with season and their variation coefficients were 42.1%, 16.6%, 7.7% respectively. MBC increased slowly from may to June and then decreased to minimum in July, then increased rapidly and occurred maximum in September. EOC and DOC had similar dynamic rules, they decreased from May to July, then they increased rapidly, and the content of EOC and DOC in July were minimum and that in September were maximum. And the seasonal dynamics of the ratios of MBC, EOC and DOC to SOC were similar to MBC, EOC and DOC. Soil invertase, amylase and cellulase are key enzymes involved soil carbon cycle. The activities of invertase and cellulase were similar to MBC with seasonal variation. The seasonal change of amylase activity was different from the other two enzyme activities, which firstly decreased rapidly from May to July, and then increased gradually and maximum value of amylase activity was in September. Correlation analysis suggested that soil organic carbon fractions had significant response to the activities of soil invertase, amylase and cellulase with the variation of season. Invertase activity was significantly positively related to SOC, MBC, EOC and DOC (p&#60;0.05), amylase activity was significantly positive correlation with EOC and DOC (p&#60;0.05), and cellulase activity was significantly positive correlation with SOC and MBC (p&#60;0.05).

Ant nesting can modify soil physicochemical conditions in the tropical forest, exerting a crucial effect on spatiotemporal variation in soil microbial biomass carbon and quotient. In this study, the chloroform fumigation method was used to measure the spatiotemporal dynamics of microbial biomass carbon and quotient in ant nests and the reference soils in Syzygium oblatum community of tropical Xishuangbanna. The results were as following: 1) Microbial biomass carbon and quotient were significantly higher in ant nests (1.95 g·kg-1, 6.8%) than in the reference soils (1.76 g·kg-1, 5.1%). The microbial biomass carbon in ant nests and the reference soils showed a signifi-cantly unimodal temporal variation, whereas the temporal dynamics of microbial biomass quotient presented a distribution pattern of "V" type. 2) The microbial biomass carbon and quotient showed significant vertical changes in ant nests and the reference soils. The microbial biomass carbon decreased, and microbial biomass quotient increased significantly along the soil layers. The vertical variations in microbial biomass carbon and quotient were more significant in ant nests than in refe-rence soils. 3) Ant nesting significantly changed the spatiotemporal distributions of soil water and temperature in ant nests, which in turn affected spatiotemporal dynamics of soil microbial biomass carbon and quotient. Soil water content could explain 66%-83% and 54%-69% of the variation of soil microbial biomass carbon and quotient, respectively. Soil temperature could explain 71%-86% and 67%-76% of the variation of soil microbial biomass carbon and quotient in ant nests and the reference soils, respectively. 4) Changes in soil physicochemical properties induced by ant nesting had significant effect on the soil microbial biomass carbon and quotient. There were positive correlations of soil microbial biomass carbon to soil organic carbon, soil temperature, total nitrogen and soil water content, and to bulk density, nitrate nitrogen and hydrolyzed nitrogen; whereas a negative correlation of them was observed with soil pH. Soil pH was positively and other soil physicochemical properties were negatively correlated with microbial biomass quotient. Total organic carbon, total nitrogen and soil temperature had greater contribution to microbial biomass carbon, while total organic carbon and total nitrogen had the least negative effect on microbial biomass quotient. Therefore, ant nesting could modify microhabitats (e.g., soil water and soil temperature) and soil physicochemical properties (e.g., total organic carbon and total nitrogen), thereby regulating the spatiotemporal variation in soil microbial biomass carbon and quotient in tropical forests.

Effect of repeated drying–rewetting cycles on microbial biomass carbon in soils with different climatic histories

Responses of microbial biomass carbon and nitrogen to experimental warming: A meta-analysis

PDF HTML阅读 XML下载 导出引用 引用提醒 黄土丘陵区植被类型对土壤微生物量碳氮磷的影响 DOI: 10.5846/stxb201304160723 作者: 作者单位: 西北农林科技大学,西北农林科技大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(41101254, 41171226);西北农林科技大学基本科研费(QN2011020) Effects of vegetation types on soil microbial biomass C, N, P on the Loess Hilly Area Author: Affiliation: Northwest A,Northwest A Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:选择黄土丘陵区延河流域4种典型植被类型下的土壤为研究对象,测定了土壤微生物量碳、氮、磷和相关基本理化性质。结果表明,在此流域的典型天然草地、人工灌木林、人工乔木林和农地中土壤微生物量碳(MBC)的含量范围分别为315.15-400.89、246.56-321.25、267.76-347.05和118.96-245.14 mg/kg,土壤微生物量氮(MBN)的含量范围分别为35.87-47.63、27.63-42.89、24.66-36.20和15.64-22.56 mg/kg,土壤微生物量磷(MBP)的含量范围分别为14.14-22.96、12.89-19.75、11.54-14.40和7.23-11.59 mg/kg;土壤微生物量总体呈现出天然草地最高、人工乔、灌木林次之,且均显著高于农地的趋势,表明退耕还林还草对土壤微生物生物量有明显的促进作用。不同植被类型下,土壤微生物量碳氮比和碳磷比的变化范围分别为7.49-10.87和16.27-24.11,土壤微生物量碳、氮、磷占土壤有机碳(SOC)、全氮(TN)、全磷(TP)百分比的范围分别为2.70%-4.85%、2.56%-4.45%、2.08%-5.34%。其中天然草地、人工灌木林和农地土壤的微生物量碳氮比、碳磷比均显著小于人工乔木林(P < 0.05); MBC/SOC在不同植被类型下的差异不显著,MBN/TN和MBP/TP均呈现出天然草地>人工灌木林>人工乔木林和农地的趋势,且差异显著(P < 0.05)。微生物量碳、氮、磷与土壤有机碳、全氮和土壤含水率呈现极显著或显著相关性,与土壤pH值呈现出不同程度的负相关性,表明植被类型对这些与土壤微生物量紧密相关的理化性质也有显著影响。 Abstract:The Loess Plateau is an important site for many ecological restoration studies in China. Different vegetation types change the soil environment to different extents, influencing the biogeochemical cycles of materials such as soil microbial biomass carbon, nitrogen and phosphorus. Determining the relationship between soil physicochemical properties and soil microbial biomass under different vegetation types can provide useful information for vegetation restoration in the Loess Plateau. Soil profiles under four typical vegetation types (natural grassland, artificial shrub land, artificial timber forest and crop land) were collected in the Yanhe River catchment in a hilly area of the Loess Plateau. The Yanhe River catchment (36°23'-37°17' N, 108°45'-110°28' E) is situated in the north of the Shaanxi Province. It belongs to the continental monsoon climate. The basic soil physicochemical properties and microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP) were measured. The results indicated that the MBC of natural grassland, artificial shrub land, artificial timber forest and crop land ranged from 315.15-400.89, 246.56-321.25, 267.76-347.05 and 118.96-245.14 mg/kg, respectively and the MBN ranged from 35.87-47.63, 27.63-42.89, 24.66-36.20 and 15.64-22.56 mg/kg, respectively and the MBP ranged from 14.14-22.96, 12.89-19.75, 11.54-14.40 and 7.23-11.59 mg/kg, respectively. Natural grassland showed the highest soil microbial biomass, followed by artificial timber forest, artificial shrub land and crop land, indicating that returning crop land to forests or grassland had a significant promoting impact on the soil microbial biomass. Under the different types of vegetation, the MBC/MBN ranged from 7.49 to 10.87, and the MBC/MBP ranged from 16.27 to 24.11. The ratio of MBC/soil organic C was 2.70%-4.85%, the ratio of MBN/total N was 2.56%-4.45% and the ratio of MBP/total P was 2.08%-5.34%. The MBC/MBN and MBC/MBP of natural grassland, artificial timber forests and crop land were all significantly less than the artificial shrub land (P < 0.05), but the MBC/soil organic C showed no significant differences between vegetation types. The MBN/total N and MBP/total P of natural grasslands were significantly more than the artificial shrub land, followed by the artificial timber forest and the crop land (P < 0.05). The soil microbial biomass correlated or significantly correlated with soil organic C, total N and soil moisture, but negatively correlated with the soil pH. This showed that the vegetation types had a significant impact on the physical and chemical properties of soil that are closely associated with the soil microbial biomass. 参考文献 相似文献 引证文献

Knowledge of the dynamics of microbial biomass and water-soluble organic carbon (WSOC) are important in understanding microbial cycling of nutrients, especially where external inputs of nutrients are low. We investigated the effect of preceding legumes-soybean (Glycine max), cowpea (Vigna unguiculata L.), Centrosema pascuorum, and a natural fallow on soil microbial biomass carbon (SMBC) and nitrogen (SMBN) and WSOC and their relationship with soil pH, soil organic carbon (SOC) and total N in the second season of maize cropping. The SMBC and its proportion in SOC and WSOC were significantly (P