Soil Microbial Biomass Phosphorus Research Articles

模拟不同春季降雨量下典型草原土壤微生物磷周转特征

模拟不同春季降雨量下典型草原土壤微生物磷周转特征

Response of soil microbial biomass and microbial entropy to desertification in desert grassland

Using an approach of spatial sequence instead of temporal succession, we investigated the variation and driving factors of soil microbial biomass and microbial entropy in desert grasslands across four different desertification stages (grassland, fixed dune, semi-fixed dune and mobile dune) in Yanchi County, Ningxia, China. The results showed that soil microbial biomass carbon, nitrogen and phosphorus reduced by 46.1%, 80.8% and 30.0% from grassland to mobile dunes, respectively. The soil microbial entropy (qMBC, qMBN, and qMBP) decreased but soil-microbial stoichiometry imbalance (C:Nimb, C:Pimb and N:Pimb) generally increased with the development of desertification. There were significantly positive relationship between soil microbial biomass nitrogen and C:Nimb, soil microbial biomass phosphorus and C:Pimb, while negative relationship between soil microbial biomass nitrogen and N:Pimb. The RDA result showed that soil ecological stoichiometry (C:N, C:P) had the strongest negative effect on soil microbial entropy carbon (qMBC). Soil microbial biomass and microbial entropy were significantly affected by desertification in desert grassland.

间伐和凋落物处理对华北落叶松人工林土壤磷形态的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 间伐和凋落物处理对华北落叶松人工林土壤磷形态的影响 DOI: 10.5846/stxb201809061907 作者: 作者单位: 北京林业大学林学院,北京林业大学林学院,北京林业大学林学院,北京林业大学林学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划（2016YFD0600205）；国家自然科学基金项目（N31700372） Effects of thinning and litter manipulation on soil phosphorus dynamicsin a Larixprincipis-rupprechtii plantation Author: Affiliation: Forestry College of Beijing Forestry University,Forestry College of Beijing Forestry University,Forestry College of Beijing Forestry University,Forestry College of Beijing Forestry University Fund Project: National Key Research and Development Program of China (2016YFD0600205) 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:土壤磷在维持生态系统功能稳定性中发挥重要作用，研究间伐和凋落物处理下的土壤磷组分特征及转化机理，对森林生态系统磷素管理和可持续发展具有重要意义。采用Tiessen改良的Hedley分级方法，探究了不同间伐强度（未间伐、轻度间伐、中度间伐、重度间伐）和凋落物处理（对照、加倍、去凋、切根去凋）下土壤磷形态的变化特征及其驱动因子。结果显示：随着间伐强度的增大，土壤活性磷（Resin-Pi、NaHCO3-Pi和NaHCO3-Po）、土壤微生物量磷和酸性磷酸酶活性呈先增加后降低的趋势，且在中度间伐最高。凋落物加倍（DL）显著增加了土壤活性磷（Resin-Pi、NaHCO3-Pi和NaHCO3-Po）、土壤微生物量磷和酸性磷酸酶活性。稳定态磷（HCl-Pi、浓HCl-Pi和浓HCl-Po）、残留态磷（Residual-P）不受间伐和凋落物处理的影响。冗余分析（RDA）显示，土壤微生物量磷、酸性磷酸酶活性和土壤有机碳是引起华北落叶松人工林表层土壤磷组分变化的重要因子。研究表明，适度的间伐和增加凋落物能够显著提高华北落叶松人工林表层土壤磷素的活化能力。本研究为华北落叶松人工林的可持续经营提供依据。 Abstract:Soil phosphorus (P) plays an important role in maintaining the stability of ecosystem functions. Understanding the effects of forest management practices (e.g., thinning) on soil phosphorus fractions is important for soil phosphorus management for sustainable development in forest ecosystems. In this paper, a modified Hedley phosphorus fractionation method was used to sequentially extract soil samples and investigate the characteristics of soil phosphorus fractions with different thinning intensities (control, T0; Low thinning, T15; Moderate thinning,T35; Heavy thinning,T50)and litter manipulation (control, CK; exclusion litter, NL; addition litter, DL; exclusion litter and roots, NRL) in a Larixprincipis-rupprechtii plantation and addressed its determining factors. The results showed that soil labile phosphorus(Resin-Pi, NaHCO3-Pi and NaHCO3-Po), soil microbial biomass phosphorus, and acid phosphatase activity increased first and then decreased with the increase of thinning intensity, and the maximum appeared in T35.DL treatment significantly increased soil labile phosphorus (Resin-Pi, NaHCO3-Pi and NaHCO3-Po), soil microbial biomass phosphorus, and acid phosphatase activity. No-labile phosphorus (HCl-Pi, concentrated HCl-Pi and concentrated HCl-Po) and residual phosphorus (Residual-P) were not affected by thinning or litter treatments. The redundancy analysis (RDA) indicated that the changes in phosphorus fractions were mainly driven by soil microbial biomass phosphorus, acid phosphatase activity, andsoil organic carbon in the surface soil of the Larixprincipis-rupprechtii plantation. The results suggested that moderate thinning and increased litter could significantly improve the activation of phosphorus in the surface soil of the Larixprincipis-rupprechtii plantation. 参考文献 相似文献 引证文献

Soil organic matter and its active pools as affected by legume/cereal cropping systems under some agronomic practices in the derived savannah zone of Nigeria

Introduction of grain legumes facilitates farmers’ acceptance in adopting legume cropping system. This study evaluated effect of four cropping systems on soil organic carbon (SOC), total vesicular arbuscular mycorrhiza (VAM) spore count, soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN) and soil microbial biomass phosphorus (SMBP) within two locations (Nsukka and Moniya) of the derived savannah zone of Nigeria. The experiment was set up in a 4 x 2 x 2 factorial in randomized complete block design (RCBD), represent- ing 4 cropping systems, 2 fertilizer application rates (0 and 60 kg N ha-1) and 2 residue management methods (incorporated and not-incorporated). This set-up was replicated three times and the experiment was repeated the following year (2008 and 2009). At the end of the experiment, soil samples for laboratory analy- ses were collected from 0 – 20 cm soil depth using auger. The result showed that SOC was not significantly (p≤0.05) affected by all factors and their interaction at both locations. In Nsukka, cropping systems and their interaction with residue management significantly (p≤0.05) affected SMBP and total VAM spore count. Continuous maize had the highest total VAM spore count (280), which was sta- tistically the same with cowpea/maize rotation (277). Soybean/maize cropping system had the least value (259). Velvet bean/maize cropping system had the highest SMBP (0.0007 mg g-1). In Moniya, SMBC, SMBN and SMBP were sig- nificantly (p≤0.05) affected by the cropping systems with velvet bean/maize plots having highest values (0.053, 0.006, 0.0007 mg g-1). Residue incorporation and fertilizer application (60 kg ha-1) significantly (p≤0.05) increased SMBC and SMBN at Moniya. Interaction between cropping systems and residue manage- ments at this location also significantly affected SMBC, SMBP and SMBC. In this study, SMBP distinguished the effect of the factors on soil quality better than the other measured parameters. Velvet bean-based cropping system improved soil microbial properties better than other cropping systems.

Effects of snowfall depth on soil physical–chemical properties and soil microbial biomass in moss–dominated crusts in the Gurbantunggut Desert, Northern China

Winter snowfall is an important source of moisture that may influence the growth and development of biological soil crusts (BSCs) in temperate desert regions of China. Yet there is still limited empirical knowledge about the effect of snowfall on BSCs. In this study, moss crusts from the Gurbantunggut Desert were exposed to five snow depths to evaluate how snowfall affected the physical–chemical properties (pH; electric conductivity, EC; soil organic carbon, SOC; total nitrogen, TN; available nitrogen, AN; available phosphorus, AP; available potassium, AK) and microbial biomass (soil microbial biomass carbon, SMBC; soil microbial biomass nitrogen, SMBN; soil microbial biomass phosphorus, SMBP) of soil in the BSCs, before (in October 2016: representing three consecutive years of snow manipulation) and after winter (in April 2017). Results showed that the soil water content increased significantly as snowfall depth increased (p < 0.05) in October 2016 and April 2017. Most of the soil physical–chemical features (EC, SOC, TN, AN, AP, and AK) and microbial biomass (SMBC and SMBN) showed an increase with an increase of snowfall depth after three consecutive years of snow manipulation. Moreover, for most experimental treatments, after a winter of melting snow (in April 2017) most of the soil properties were significantly higher (p < 0.05) than found in October 2016. Together, these results showed that the dynamics of soil nutrients and microbial biomass in moss BSCs were affected by snowfall depth in Gurbantunggut Desert. Different snowfall depths can have different effects on the dynamics of soil nutrients and microbial biomass of moss crusts, an impact that may alter the future growth and development of BSCs. Thus, we suggest that the potential influence of snowfall depth on soil nutrients and microbial biomass dynamics in BSCs require consideration when discussing the effects of moisture on ecological functions of BSCs in arid and semi–arid regions.

Plant biomass management impacts on short-term soil phosphorus dynamics in a temperate grassland

The objective of this study was to quantify the combined effects of long-term plant biomass retention/removal and environmental conditions on soil microbial biomass phosphorus (P), bioavailable P, and acid phosphomonoesterase activity. Topsoil samples (0–2.5 and 2.5–5 cm) were collected from replicate field-based plots that had been maintained under contrasting plant biomass retention and removal regime for 21 years. Samples were collected on 14 occasions over a 17-month period and assessed for microbial P, bioavailable P, and phosphomonoesterase activity. All P measurements were consistently and significantly higher under plant biomass retention compared with biomass removal. Temporal variations in microbial P and phosphomonoesterase activity were evident in top soil (0–2.5 cm) and were driven by environmental conditions, mainly soil moisture, rainfall, and potential evapotranspiration, while bioavailable P had no temporal variation. Detailed analysis of microbial P data for the top 2.5-cm soil depth revealed that annual P flux through this pool was two times greater under biomass retention (10.3 kg P ha−1 year−1) compared with plant biomass removal (5.0 kg P ha−1 year−1). Similar and consistent trends were observed in soil from 2.5- to 5-cm sampling depth; however, differences were not significant. The findings of this study confirm the importance of the microbial biomass in determining the bioavailability of P in temperate grassland systems.

Multiple gradient effects on spatial distribution of island soil microbial biomass

Soil microbial biomass (SMB) rapidly responds to the environment and can function as an important indicator for monitoring archipelago ecological vulnerability. An archipelago is featured by distinct and unique gradients between and within islands. The multiple gradient effects on the island ecosystem are worth exploring. We established a multiple gradient system comprising natural, human, and ecological gradients in island and site scales. The natural gradients consist of island area, shape, and distance to mainland in island scale, and terrain and distance to shoreline in site scale; the human gradients include population and exploitation in island scale, and distance to hardened ground in site scale; and the ecological gradients are composed of community type, biomass, biodiversity, and soil physical-chemical properties in site scale. SMB, including SMB carbon (SMBC), SMB nitrogen (SMBN), and SMB phosphorus (SMBP), was used to verify the multiple gradient effects on the island ecosystem, and the northern Miaodao Archipelago in North China was selected as the study area. Results revealed that SMB exhibited distinct spatial heterogeneities. SMBC was sensitive to the natural and human gradients in both scales; SMBN was influenced by parts of natural, human, and ecological gradients in both scales; and SMBP did not show regular changes along the gradients in island scale, yet responded sensitively to the ecological gradients in site scale. The multiple gradient system is unique and fundamental in the spatial heterogeneities of the island ecosystem, and fully revealing the multiple gradient effects is essential for reasonable island conservation and exploitation.

Rice husk biochar impacts soil phosphorous availability, phosphatase activities and bacterial community characteristics in three different soil types

To assess the effects of rice husk biochar (400°C, 0.5h) on the conversion of soil phosphorus in different soil types in China, a nine week microcosm incubation experiment was performed using acid red soil, organic brown soil, and saline soil, which were amended with 0, 10, 20 and 40t/hm2 biochar. Soil physico-chemical properties, microbial biomass, phosphatase activities, phosphate solubilizing bacteria, and bacterial community characteristics were investigated. The results showed that rice husk biochar significantly modulated the pH of the three studied soils by 0.1–0.2 units and increased the soil gravimetric water content by 0.3–1.4% over that of the controls. The addition of biochar significantly enhanced the Olsen-P and microbial biomass carbon in all studied soils, and this was partly dependent on the rate of biochar application. The levels of soil microbial biomass phosphorus and phosphatase activities were most significantly increased with 20t/hm2 biochar treatment. These results showed that treatment with rice husk biochar could provide more suitable growth conditions for soil bacteria and significantly enhance soil phosphorus availability and related enzymes. Furthermore, bacterial communities were investigated in all three soils using Illumina MiSeq pyrosequencing to generate tentative taxonomic assignments, which differed statistically over time. The results of a heat map with principal component analyses suggested that the biochar tended to shape the structure of bacterial communities in degraded soils such as acid red soil and saline soil. The most significant variation could be observed in the acid red soil. Biochar increased the relative abundance and distribution of Thiobacillus, Pseudomonas, and Flavobacterium in soils by varying degrees; all three are reported to be genera of phosphate solubilizing bacteria. In conclusion, biochar had a positive effect on phosphate solubilizing bacteria and contributed to increasing phosphorous availability.

Long-Term Effect of Fertilizers and Amendments on Different Fractions of Organic Matter in an Acid Alfisol

ABSTRACTThe effect of fertilizers and amendments on organic matter dynamics in an acid Alfisol was studied in a long-term field experiment initiated during 1972 at experimental farm of Department of Soil Science, CSK HPKV, Palampur (India). Continuous application of chemical fertilizers either alone or in combination with farmyard manure (FYM) or lime for 42 years significantly influenced water-soluble organic carbon (WS-OC), water-soluble carbohydrate (WS-CHO), soil microbial biomass carbon, soil microbial biomass nitrogen, soil microbial biomass phosphorus, soil microbial biomass sulfur, humic acid (HA), and fulvic acid (FA). Continuous cropping without fertilization resulted in depletion to the order of 17, 21, 24, 23, 22, 26, 12, and 18% in WS-OC, WS-CHO, microbial biomass carbon, microbial biomass nitrogen, microbial biomass phosphorus, microbial biomass sulfur, HA, and FA, respectively. Different fractions of soil organic matter were found to be positively and significantly correlated with grain and straw/stover yield of wheat and maize crops.

石羊河下游退耕地土壤微生物变化及土壤酶活性

PDF HTML阅读 XML下载 导出引用 引用提醒 石羊河下游退耕地土壤微生物变化及土壤酶活性 DOI: 10.5846/stxb201412282593 作者: 作者单位: 甘肃农业大学 草业学院,甘肃农业大学 草业学院,甘肃省荒漠化与风沙灾害防治国家重点实验室培育基地,甘肃省荒漠化与风沙灾害防治国家重点实验室培育基地,甘肃省荒漠化与风沙灾害防治国家重点实验室培育基地,甘肃省荒漠化与风沙灾害防治国家重点实验室培育基地,甘肃省荒漠化与风沙灾害防治国家重点实验室培育基地 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（41161049，31360584，31160264） Soil microbial and soil enzyme activity in a discontinued farmland by the Lower Shiyang River Author: Affiliation: Gansu Desert Control Research Institute,Pratacultural College of Gansu Agricultural University,,,,, 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:采用时空替代法，对石羊河下游不同年限（1，2，3，4，5，8，15，24、31 a）退耕地土壤微生物（细菌、真菌和放线菌）数量、生物量（碳、氮和磷）及土壤酶（过氧化氢酶、蔗糖酶、脲酶和磷酸酶）活性变化及三者的相关性进行了测定和分析。结果表明，在退耕1-31 a的9个样地样方中土壤三大类微生物数量以细菌最高，放线菌次之，真菌最低。总体来看，三大土壤微生物数量的加权平均值最大值均在退耕后的前8 a。土壤微生物生物量碳在退耕初期随着退耕年限的增加而减小，退耕4 a后逐渐增大，退耕24 a期间达到了加权平均值的最大，最后趋于稳定；土壤微生物生物量氮在退耕初期随着退耕年限的增加而增加，退耕4 a加权平均值的最大值出现，随后逐渐减小的趋势，并且不同退耕年限土壤微生物生物量氮差异显著；土壤微生物生物量磷在退耕初期随着退耕年限的增加而增加，退耕8 a前后加权平均值达到最大值，随后逐渐减小，最终趋于稳定。土壤酶活性总趋势随着退耕地自然演替时间的增加呈波动式下降。不同土壤层次（0-10 cm，10-20 cm，20-30 cm及30-40 cm），土壤微生物数量、生物量及土壤酶活性随土层深度显著降低，并且表层土壤微生物生物量及土壤酶活性占有较大比例。土壤微生物及土壤酶活性的变化是一个极其缓慢的互动过程，存在着互相回馈的响应，特别是真菌与放线菌、微生物量氮及蔗糖酶，放线菌与过氧化氢酶、蔗糖酶，微生物量碳与磷酸酶，微生物量氮与脲酶，微生物量磷与蔗糖酶均存在极显著的相关性。总体来看在退耕年限4-5 a前，有利于土壤发育，退耕后期土壤肥力呈下降的趋势。 Abstract:To better understand the changes in soil conditions after agriculture use ceases, we measured and analyzed the changes in three components-soil microbial quantity, soil microbial biomass, and soil enzyme activity-in sample sites where farming had been discontinued for different periods (1, 2, 3, 4, 5, 8, 15, 24 and 31 years), in the lower Shiyang River area. By using the data, the correlations between the three components were also studied in 2012. The three components, respectively, contained 1) bacteria, fungi, and actinomycetes; 2) microbial biomass carbon, microbial biomass nitrogen, and microbial biomass phosphorus; and 3) catalase, sucrase, urease, and phosphatase. Synchronic space investigation was adopted instead of diachronic temporal investigation. Results showed that bacteria were the most abundant of the three soil microorganisms in the nine soil samples taken 31 years after farming ceased, followed by actinomycetes and fungi. Overall, the maximum weighted average of the three soil microbial quantities all occurred in the first 8 years after farming ceased. The quantity of soil microbial biomass carbon initially decreased with increasing time since farming ceased. It gradually increased starting in the 4th year and reached the peak in the 24th year, after which it became stable. The soil microbial biomass nitrogen appeared to increase with time. After the maximum weighted average in the 4th year, there was a steady reduction with large significant differences in soil microbial biomass nitrogen among soil sites of various ages. The weighted average soil microbial biomass phosphorus increased at the same pace as nitrogen at the beginning of the soil restoration period. The biomass phosphorus level climaxed at the 8th year, after which it tended to decline gradually before finally stabilizing. The general trend of soil enzyme activity decreased, but with fluctuations, with increasing soil succession age. Moreover, soil microbial quantity, soil microbial biomass, and soil enzyme activity declined dramatically in all restoration ages with soil depth from 0 to 10 cm, 10 to 20 cm, and 20-30 to 30-40 cm. In addition, the surface soil microbial biomass and soil enzyme activity were the largest among the four soil levels. The changes in soil microbial quantity, soil microbial biomass, and soil enzyme activity were extremely slow. In addition, an interactive process and a feedback response between the three components was observed. Highly significant correlations were found, especially between fungi and actinomycetes, microbial biomass nitrogen and sucrase, actinomycetes and catalase and sucrase, microbial biomass carbon and phosphatase, microbial biomass nitrogen and urease, and microbial biomass phosphorus and sucrose. To summarize, we noted an improvement in the soil conditions in the initial 4-5 years after ceasing agricultural practice, followed by a declining trend in soil fertility. 参考文献 相似文献 引证文献

峡谷型喀斯特不同生态系统的土壤微生物数量及生物量特征

Determining the relationship between soil microbial populations and soil microbial biomass in ecosystems can provide useful information for vegetation restoration in the canyon Karst region. Therefore,based on a combination of field investigation and laboratory analysis,we analyzed soil microbial populations and soil microbial biomass at different soildepths as well as their fractal relationships under six typical ecosystems,i. e.,paddy field,dry land,grassland,Shrubbery,plantation forest,and secondary forest,in the canyon Karst region in southwest China. Three plots with size of20 m × 20 m were constructed in each ecosystem type,and five soil samples were collected at four corners and the middle in each plot and then mixed as one sample. The dilution plate method and the chloroform fumigation extraction method were used to determine soil microbial populations and soil microbial biomass.,respectively. The results showed that soil microbial populations and composition varied under different ecosystems in the canyon karst region. Soil microbial populations were largest in the secondary forest,followed by the plantation forest,while least in the dry land,indicating that the project of returning crop land to forests or grassland have a significant impact on increasing the soil microbial populations. Microbial composition in the six ecosystems performed in the order of bacteria actinomycetes fungi. The bacteria number was 26. 66×105—71.64×105cfu /g with the highest proportion of 87. 00% —95. 50% of total soil microbial number; followed by actinomycetes,whose number and proportion were 1. 45 × 105—3. 78×105cfu /g and 4. 21% —12.39%,respectively. However,the fungi quantity was 0. 07×105—0.23×105cfu /g,and the proportion was less than 1%,just only 0. 24% —0. 61%. Under different ecosystem types,soil microbial biomass carbon( MBC),soil microbial biomass nitrogen( MBN),and soil microbial biomass phosphorus( MBP) were diverse,but all of them appeared to be a trend of MBC MBN MBP. Soil MBC and MBN was highest in the secondary forest,while MBP was highest in the plantation forest,in comparison with that MBC was lowest in the dry land,MBN and MBP were lowest in the grass. The ratios of MBC /SOC,MBN /TN and MBP /TP ranged from 0. 44% —0. 97%,2. 13% —3. 13%, and 1. 46% —2. 13%,respectively,with no significant differences among the six ecosystems. The value of MBC /MBN ranged from 3. 06 to 6. 54,which in the secondary forest was significantly higher than that in other ecosystems; however,no significant differences existed among the rest ecosystems. A good fractal relationship existed between soil microbial populations and soil microbial biomass at a highly significant level( P0. 01). Moreover,both soil microbial populations and soil microbial biomass in the six ecosystems decreased as an increase in soil depth. As a result,exploring soil microbial activities could provide the basis for improving the soil fertility of lime soil and boosting vegetation restoration in karst regions.

Microbial biomass P dynamics and sequential P fractionation in high and low P fixing Kenyan soils

We tested how the incorporation of farmyard manure (FYM) and inorganic phosphorus (P), KH2PO4 fertilizer changed soil microbial biomass phosphorus (biomass Po and inorganic and organic P fractions) in high and low P fixing Kenyan soils. Four soil treatments were compared during 32 weeks of laboratory incubation: (i) Nil; (ii) FYM (10 g kg−1); (iii) KH2PO4 (2.5 g kg−1) (P); and (iv) FYM (10 g kg−1) + KH2PO4 (2.5 g P kg−1). Biomass P was determined by fumigation-extraction followed by resin extraction, and P availability determined using a modified Hedley P fractionation method. The addition of FYM + KH2PO4 only increased biomass P in the high P fixing soil. From a maximum of about 22.5 μg P g−1 soil (week 1), biomass P declined to 4.8 (week 2), increased steadily to week 16 (15.2), and then decreased to 9.7 μg P g−1 soil (week 32). Biomass P in the low P fixing soil, with higher fertility, resin P and organic matter concentrations did not show any significant change. The P fractions that changed the most relative to the control, were the resin, Po–HCO3 and P–OH (week 1 and 16). This difference was enhanced in the high P fixing soil but resin P was the same in that soil at week 16, and the reduction in Po–OH in the FYM + KH2PO4 treatment (162.4 μg P g−1) compared to the control (242.2 μg P g−1) was more pronounced. This indicates an enhancement of microbial activity in the high P fixing soil.

The Effect on Soil Microbial Biomass and Soil Nutrient of Interplanted in Chestnut Forest

By analyzing the different crop interplanting test in chestnut forests, the results show that soil nitrate nitrogen, ammonium nitrogen and available phosphorus fell in October when intercropped plants, this may be related to the growth of chestnut trees absorb nutrients and microorganisms in the soil. The results of this study show that interplanting different plants had an impact on soil microbial biomass carbon and microbial biomass phosphorus. Microbial biomass carbon turnover rate in the order: ryegrass&gt; clean tillage&gt; natural grass&gt; Alfalfa&gt; flat Agropyron&gt; soybean; turnover rates of soil microbial biomass phosphorus in the order: clean tillage&gt; Alfalfa&gt; ryegrass natural grass&gt; soy&gt; flat crested wheatgrass.

Seasonal variation of microbial biomass, activity, and community structure in soil under different tillage and phosphorus management practices

No-tillage systems contribute to physical, chemical and biological changes in the soil. The effects of different tillage practices and phosphorus (P) fertilization on soil microbial biomass, activity, and community structure were studied during the maize growing season in a maize–soybean rotation established for 18 years in eastern Canada. Soil samples were collected at two depths (0–10 and 10–20 cm) under mouldboard plow (MP) and no-till (NT) management and fertilized with 0, 17.5, and 35 kg P ha−1. Results show that the duration of the growing season had a greater effect on soil microbiota properties than soil tillage or P fertilization at both soil depths. Seasonal fluctuations in soil microbial biomass carbon (SMB-C) and nitrogen (SMB-N), in dehydrogenase and alkaline phosphomonoesterase activities, and in total phospholipids fatty acid (PLFA) level, were greater under NT than MP management. The PLFA biomarkers separated treatments primarily by sampling date and secondly by tillage management, but were not significantly affected by P fertilization. The abundance of arbuscular mycorrhizal fungi (AMF; C16:1ω5) and fungi (C18:2ω6,9) was lower under NT than MP at the 10–20-cm soil depth in July. Phosphorus fertilization increased soil microbial biomass phosphorus (SMB-P) and Mehlich-3 extractable P, but had a limited impact on the other soil properties. In conclusion, soil environmental factors and tillage had a greater effect on microorganisms (biomass and activity) and community structure than P fertilization.

Re-evaluation of phosphorus availability for plant in Andosol : Is soil microbial biomass phosphorus an indicator?

Re-evaluation of phosphorus availability for plant in Andosol : Is soil microbial biomass phosphorus an indicator?

Soil microbial biomass phosphorus as an indicator of phosphorus availability in a Gleyic Andosol

The relationship between plant phosphorus (P) uptake and soil microbial biomass phosphorus (biomass P) or available phosphorus (Truog P) was estimated in a Gleyic Andosol in Sapporo, Hokkaido, in a 4-year field trial (2004–2007). Every year, the soil was treated in duplicate (each plot 36 m2) or triplicate (each plot 24 m2) with chemical fertilizer, cow manure compost or sewage sludge compost, and then kidney beans (Phaseolus vulgaris) were planted. Pooled data of the shoot content of P at harvest over the 4 years was significantly correlated with biomass P determined 1 month after the application of fertilizer (P < 0.01). A multivariate analysis revealed that the grain yield was significantly positively correlated with the shoot content of P (P < 0.01) and significantly negatively correlated with the shoot content of calcium (P < 0.05), but not correlated with the shoot content of either nitrogen or potassium. These results suggest that P is the most limiting element to affect the productivity of kidney bean plants in this trial and that biomass P is an important P source that explains the differences in P availability among soil amendments. Biomass P is a better indicator of P availability for kidney beans grown in Gleyic Andosols compared with Truog P, which is widely used in Japan.

Improvement of chloroform fumigation-extraction method for measuring soil microbial biomass phosphorus in Andosols

Improvement of chloroform fumigation-extraction method for measuring soil microbial biomass phosphorus in Andosols

A microplate assay to measure soil microbial biomass phosphorus

Quantification of phosphorus (P) concentrations in microbial biomass is required to better understand how P immobilization and turnover in soils are controlled by environmental and anthropogenic factors. Soil microbial biomass P (MBP) is generally extracted using the chloroform fumigation-direct extraction procedure and then analysed for P using the ammonium molybdate-ascorbic acid method on a flow injection analysis (FIA) system. Our objective was to determine whether a microscale malachite green method on a microplate system would provide as accurate MBP analysis as the ascorbic acid method on an FIA system. Twelve soils were collected from agricultural fields in southwestern Quebec, fumigated with chloroform and extracted with 0.5 M NaHCO3 (pH 8.5). The dissolved inorganic phosphorus (DIP) concentration in fumigated soils was not affected by the method of analysis, and results from the two systems of analysis were significantly correlated (r =0.998, P <0.05). The MBP concentrations in these agricultural soils were between 0.36 and 60.05 μg P g−1, consistent with other published values. Our results indicate that MBP can be assessed equally well with the malachite green method using a microplate system as with the ascorbic acid method on an FIA system. The microplate system is rapid and requires smaller volumes of samples and reagents than the FIA system, thus reducing the quantity of waste produced. We conclude that the microscale malachite green method could be applied to measure the MBP concentration in a wide range of soils with good sensitivity, reproducibility and accuracy.

Determination of soil microbial biomass phosphorus in acid red soils from southern China

A CHCl3 fumigation and 0.03 M NH4F- 0.025 M HCl extraction procedure was used to measure microbial biomass P (Pmic) in 11 acid red soils (pH <6.0) from southern China and the results compared to those obtained by the commonly-used CHCl3 fumigation and 0.5 M NaHCO3 extraction method. Extraction with NH4F- HCl was found to be more effective and accurate than NaHCO3 extraction for detecting the increase of P from microbial biomass P following chloroform fumigation due to its higher efficiency in extracting both native labile phosphate and added phosphate ( 32 P) in the soils. This was confirmed by the recovery of 32 P from in situ 32 P- labeled soil microbial biomass following fumigation and extraction by the NH4F-HCl solution. Soil microbial biomass P, measured by the NH4F-HCl extraction meth- od, was more comparable with soil microbial biomass C (with a more narrow C:P ratio range of 4.3 to 22.3 and a mean of 15.6 in the microbial biomass), than that obtained by NaHCO3 solution (with a mean C:P ratio of 30.7 and a wide range of 14.9 to 48.9). Kp, the fraction of soil microbial biomass P extracted after CHCl3 fumigation, by the NH4F-HCl solution was 0.34. The amount of micro- bial biomass P determined (using Kp =0.34) was 3-400% (mean 131%) higher than that obtained by the NaHCO3 extraction (using Kp =0.40) for the 11 red soils studied. The results suggest that the CHCl3 fumigation and NH4F- HCl extraction method is more reliable for measuring microbial biomass P than the NaHCO3 extraction method in acid red soils.

Measurement of soil microbial biomass phosphorus by an anion exchange membrane method

A method to measure soil microbial biomass phosphorus (biomass P) in granitic soils and andosols of high P retention capacity is described. Strips of anion exchange membrane (AEM) were shaken with suspensions of soil in (1) distilled water, (2) a mixture of distilled water and alcohol free chloroform (CHCl 3) liquid, and (3) a standard inorganic P solution (2.5 mg KH 2PO 4P1 −1), to estimate the recovery of CHCl 3-released P. After shaking, the AEM strips were rinsed with distilled water to remove the soils from the AEM strips. Phosphorus adsorbed by the AEM strips was then eluted by 0.5 m HCl, and determined colorimetrically. The amount of CHCl 3-released P was calculated from the difference between the amount of inorganic P adsorbed by AEM in unfumigated and fumigated soils. The high P retention capacity of soils, and the dark color of the extracts solution due to humic substances did not interfere with the measurement of P by this method. Biomass P was calculated from: biomass P = Ep Kp × 100 R , where Ep = (inorganic P released by CHCl 3 and extracted by distilled water) minus (inorganic P released from unfumigated soil), Kp = Biomass P released by CHCl 3 and extracted as inorganic P by distilled water (Kp = 0.40 at 25°C), R = percentage recovery (82.0–91.2%) of added P. Compared to the original CHCl 3-fumigation extraction (FE)-method, the AEM-method is simpler, more accurate, and more flexible, allowing assay of biomass P in soils of high P retention capacity, e.g. andosols. The use of AEM allows quick and efficient adsorption of P in the soil suspensions, and is analytically very convenient.