A novel semi-dominant allele of the transmembrane NAC transcription factor ZmNTL2 reduces the size of multiple maize organs

Maize plant architecture influences planting density and,in turn,grain yield.Most of the plant architecture-related traits can be described as organ size.We describe a miniature maize mutant,Tiny plant 4(Tip4),which exhibits reduced size of multiple organs and exhibits a semi-dominant monofactorial inheritance characteristic.Positional cloning confirmed that a 4-bp deletion in the NAC TF with transmembrane motif 1-Like(NTL)gene ZmNTL2,denoted as ZmNTL2^(Δ),confers the Tip4 mutation.qRT-PCR showed that ZmNTL2 was expressed in all tested tissues.ZmNTL2 functions as a transcriptional activator and is located in both the nucleus and biomembranes.The mutation does not affect the mRNA abundance of ZmNTL2 locus,but it does result in the loss of transmembrane domain and confines the ZmNTL2^(Δ)protein to the nucleus.Knocking out ZmNTL2 has no effect on maize organ size development,indicating that the 4-bp deletion might be a gain-of-function mutation in organ size regulation.Combining transcriptome sequencing with cytokinin and auxin content determination suggests that the decreased organ size may be possibly mediated by changes in hormone homeostasis.

Effects of tree size and organ age on variations in carbon,nitrogen,and phosphorus stoichiometry in Pinus koraiensis

Carbon(C),nitrogen(N),and phosphorus(P)are of fundamental importance for growth and nutrient dynamics within plant organs and deserve more attention at regional to global scales.However,our knowledge of how these nutrients vary with tree size,organ age,or root order at the individual level remains limited.We determined C,N,and P contents and their stoichiometric ratios(i.e.,nutrient traits)in needles,branches,and fine roots at different organ ages(0-3-year-old needles and branches)and root orders(1st-4th order roots)from 64 Pinus koraiensis of varying size(Diameter at breast height ranged from 0.3 to 100 cm)in northeast China.Soil factors were also measured.The results show that nutrient traits were regulated by tree size,organ age,or root order rather than soil factors.At a whole-plant level,nutrient traits decreased in needles and fine roots but increased in branches with tree size.At the organ level,age or root order had a negative effect on C,N,and P and a positive effect on stoichiometric ratios.Our results demonstrate that nutrient variations are closely related to organ-specific functions and ecophysiological processes at an individual level.It is suggested that the nutrient acquisition strategy by younger trees and organ fractions with higher nutrient content is for survival.Conversely,nutrient storage strategy in older trees and organ fractions are mainly for steady growth.Our results clarified the nutrient utilization strategies during tree and organ ontogeny and suggest that tree size and organ age or root order should be simultaneously considered to understand the complexities of nutrient variations.

Pelleting and particle size reduction of corn increase net energy and digestibility of fiber,protein,and fat in corn-soybean meal diets fed to group-housed pigs

Background Reduction of the particle size of corn increases energy digestibility and concentrations of digestible and metabolizable energy.Pelleting may also reduce particle size of grain,but it is not known if there are interactions between particle size reduction and pelleting.The objective of this experiment was to test the hypothesis that particle size reduction and pelleting,separately or in combination,increase N balance,apparent total tract digestibility(ATTD)of fiber and fat,and net energy(NE)in corn-soybean meal diets fed to group-housed pigs.Methods Six corn-soybean meal-based diets were used in a 3×2 factorial design with 3 particle sizes of corn(i.e.,700,500,or 300μm)and 2 diet forms(i.e.,meal or pelleted).Pigs were allowed ad libitum access to feed and water.Twenty-four castrated male pigs(initial weight:29.52 kg;standard diviation:1.40)were allotted to the 6 diets using a 6×6 Latin square design with 6 calorimeter chambers(i.e.,4 pigs/chamber)and 6 periods.Oxygen consumption and CO_(2)and CH_(4)productions were measured during fed and fasting states and fecal and urine samples were collected.Results Regardless of particle size of corn,the ATTD of gross energy(GE),N,and acid-hydrolyzed ether extract(AEE),and the concentration of NE were greater(P<0.05)in pelleted diets than in meal diets.Regardless of diet form,the ATTD of GE,N,and AEE,and the concentration of NE were increased(linear;P<0.05)by reducing the particle size of corn,but the increase was greater in meal diets than in pelleted diets(interaction;P<0.05).Conclusions Both pelleting and reduction of corn particle size increased nutrient digestibility and NE,but increases were greater in meal diets than in pelleted diets.

Unveiling Organic Electrode Materials in Aqueous Zinc-Ion Batteries:From Structural Design to Electrochemical Performance

Aqueous zinc-ion batteries(AZIBs)are one of the most compelling alternatives of lithium-ion batteries due to their inherent safety and economics viability.In response to the growing demand for green and sustainable energy storage solutions,organic electrodes with the scalability from inexpensive starting materials and potential for biodegradation after use have become a prominent choice for AZIBs.Despite gratifying progresses of organic molecules with electrochemical performance in AZIBs,the research is still in infancy and hampered by certain issues due to the underlying complex electrochemistry.Strategies for designing organic electrode materials for AZIBs with high specific capacity and long cycling life are discussed in detail in this review.Specifically,we put emphasis on the unique electrochemistry of different redox-active structures to provide in-depth understanding of their working mechanisms.In addition,we highlight the importance of molecular size/dimension regarding their profound impact on electrochemical performances.Finally,challenges and perspectives are discussed from the developing point of view for future AZIBs.We hope to provide a valuable evaluation on organic electrode materials for AZIBs in our context and give inspiration for the rational design of high-performance AZIBs.

Gastrointestinal tolerability of organic infant formula compared to traditional infant formula: A systematic review

BACKGROUND Infants'nutrition significantly influences their growth,development,and overall well-being.With the increasing demand for organic infant formula driven by the perception of health benefits and growing awareness of natural feeding options,it is crucial to conduct a comparative analysis of the gastrointestinal tolerability between organic and traditional infant formulas.AIM To provide a concise and precise analysis of the gastrointestinal tolerability of organic infant formula compared to traditional infant formula.Due to limited direct comparisons,the review synthesizes available literature on each formula type,presenting insights into their potential effects on infants'digestive health.METHODS An extensive literature search was conducted,compiling studies on organic and traditional infant formulas,their compositions,and reported effects on gastrointestinal tolerability.We searched academic databases such as PubMed and Google Scholar and specialized nutrition,paediatrics,and infant health journals using relevant keywords till October 1,2023.RESULTS Although specific comparative studies are scarce and formula heterogeneity is a significant limitation,this systematic review provides an in-depth understanding of organic infant formulas'composition and potential benefits.While scientific evidence directly comparing gastrointestinal tolerability is limited,organic formulas strive to use carefully selected organic ingredients to imitate breast milk composition.Potential benefits include improved lipid profiles,higher methionine content,and decreased antibiotic-resistant bacteria levels.Understanding the gastrointestinal tolerability of organic and traditional infant formulas is crucial for parents and healthcare providers to make informed decisions.CONCLUSION Despite limitations in direct comparisons,this systematic review provides insights into the composition and potential benefits of organic infant formulas.It emphasizes the need for further research to elucidate their gastrointestinal effects comprehensively.

Organic carbon stratification and size distribution of three typical paddy soils from Taihu Lake region,China

Developing realistic soil carbon （C） sequestration strategies for China＇s sustainable agriculture relies on accurate estimates of the amount, retention and turnover rates of C stored in paddy soils. Available C estimates to date are predominantly for the tilled and flood-irrigated surface topsoil （ca. 30 cm）. Such estimates cannot be used to extrapolate to soil depths of 100 cm since soil organic carbon （SOC） generally shows a sharp decrease with depth. In this research, composite soil samples were collected at several depths to 100 cm from three representative paddy soils in the Taihu Lake region, China. Soil organic carbon distribution in the profiles and in aggregate-size fractions was determined. Results showed that while SOC decreased exponentially with depth to 100 cm, a substantial proportion of the total SOC （30%-40%） is stored below the 30 cm depth. In the carbon-enriched paddy topsoils, SOC was found to accumulate preferentially in the 2-0.25 and 0.25-0.02 mm aggregate size fractions. δ^13C analysis of the coarse micro-aggregate fraction showed that the high degree of C stratification in the paddy topsoil was in agreement with the occurrence of lighter δ^1313C in the upper 30 cm depth. These results suggest that SOC stratification within profiles varies with different pedogenetical types of paddy soils with regards to clay and iron oxyhydrates distributions. Sand-sized fractions of aggregates in paddy soil systems may play a very important role in carbon sequestration and turnover, dissimilar to other studied agricultural systems.

Effects of free iron oxyhydrates and soil organic matter on copper sorption-desorption behavior by size fractions of aggregates from two paddy soils

Effects of free iron oxyhydrates （Fed） and soil organic matter （SOM） on copper （Cu^2＋） sorption-desorption behavior by size fractions of aggregates from two typical paddy soils （Ferric-Accumulic Stagnic Anthrosol （Soil H） and Gleyic Stagnic Anthrosol （Soil W）） were investigated with and without treatments of dithionite-citrate-bicarbonate and of H2O2. The size fractions of aggregates were obtained from the undisturbed bulk topsoil using a low energy ultrasonic dispersion procedure. Experiments of equilibrium sorption and subsequent desorption were conducted at soil water ratio of 1：20, 25℃. For Soil H, Cu^2＋ sorption capacity of the DCB-treated size fractions was decreased by 5.9% for fine sand fraction, by 40.4% for coarse sand fraction, in comparison to 2.9% for the bnlk sample. However, Cu^2＋ sorption capacities of the H2O2-treated fractions were decreased by over 80% for the coarse sand fraction and by 15% for the clay-sized fraction in comparison to 88% for bulk soil. For Soil W, Cu^2＋ sorption capacity of the DCB-treated size fraction was decreased by 30% for the coarse sand fraction and by over 75% for silt sand fraction in comparison to 44.5% for the bulk sample. Cu^2＋ sorption capacities of the H2O2-treated fractions were decreased by only 2.0% for the coarse sand fraction and by 15% for the fine sand fraction in comparison to by 3.4% for bulk soil. However, Cu^2＋ desorption rates were increased much in H2O2-treated samples by over 80% except the clay-sized fraction （only 9.5%） for Soil H. While removal of SOM with H2O2 tendend to increase the desorption rate, DCB- and H2O2-treatments caused decrease in Cu^2＋ retention capacity of size fractions, Particularly, there hardly remained Cu^2＋ retention capacity by size fractions from Soil H after H2O2 treatment except for clay-sized fraction. These findings supported again the dominance of the coarse sand fraction in sorption of metals and the preference of absorbed metals bound to SOM in differently stabilized status among the size fractions. Thus, enrichment and turnover of SOM in paddy soils may have great effects on metal retention and chemical mobility in paddy soils.

Effects of different levels of compost application on amounts and distribution of organic nitrogen forms in soil particle size fractions subjected mainly to double cropping

Effects of different levels of compost application on the amounts and percentage distribution of organic N forms in whole soils and particle size fractions were investigated. Soil samples were collected from three plots: (a) F, only chemical fertilizers;(b) F+LC, chemical fertilizers plus low level of compost;(c) F+HC, chemical fertilizers plus high level of compost. Each soil sample was divided into five fractions: coarse sand-sized aggregate (CSA), medium sand-sized aggregate (MSA), fine sand-sized aggregate (FSA), silt-sized aggregate (SIA) and clay-sized aggregate (CLA) fractions. The sand fractions were subdivided into decayed plants (DP) and mineral particles (MP). The amounts of total N and different organic N forms in the whole soils as well as size fractions generally increased with increasing the amount of compost. In the whole soils, percentage distribution of non-hydrolysable-N and amino sugar-N increased by compost application while the distribution values of the hydrolysable ammonium- N and unidentified-N decreased. The application did not affect the distribution degree of amino acid-N. In the size fractions, the distribution values of most organic N forms increased in the CSA-DP, MSA-DP and FSA-DP fractions by compost application. In the CLA fractions, the amounts and percentage distribution of organic N forms were the highest, although the application caused decreases in their distribution values. These findings indicate that the CLA fraction merit close attention as an important reservoir of various organic N.

Grain size composition and transport of sedimentary organic carbon in the Changjiang River(Yangtze River) Estuary and Hangzhou Bay and their adjacent waters

Surface sediments from the Changjiang River （Yangtze River） Estuary, Hangzhou Bay, and their adjacent waters were analyzed for their grain size distribution, organic carbon （OC） concentration, and stable carbon isotope composition （δ13C）. Based on this analysis, about 36 surface sediment samples were selected from various environments and separated into sand （〉0.250 ram, 0.125-0.250 ram, 0.063-0.125 mm） and silt （0.025-0.063 mm） fractions by wet-sieving fractionation methods, and further into silt- （0.004-0.025 mm） and clay-sized （〈0.004 mm） fractions by centrifugal fractionation. Sediments of six grain size categories were analyzed for their OC and 613C contents to explore the grain size composition and transport paths of sedimentary OC in the study area. From fine to coarse fractions, the OC content was 1.18%, 0.51%, 0.46%, 0.42%, 0.99%, and 0.48%, respectively, while the δ13C was -21.64‰, -22.03‰, -22.52‰, -22.46‰, -22.36‰, and -22.28%0, respectively. In each size category, the OC contribution was 42.96%, 26.06%, 9.82%, 5.75%, 7.09%, and 8.33%, respectively. The OC content in clay and fine silt fractions （〈0.025 ram） was about 69.02%. High OC concentrations were mainly found in offshore modern sediments in the northeast of the Changjiang River Estuary, in modern sediments in the lower estuary of the Changjiang River and Hangzhou Bay, and in Cyclonic Eddy modern sediments to the southwest of the Cheju Island. Integrating the distribution of terrestrial OC content of each grain size category with the δ13C of the bulk sediment indicated that the terrestrial organic material in the Changjiang River Estuary was transported seaward and dispersed to the Cyclonic Eddy modern sediments to the southwest of the Cheju Island via two pathways： one was a result of the Changjiang River Diluted Water （CDW） northeastward extending branch driven by the North Jiangsu Coastal Current and the Yellow Sea Coastal Current, while the other one was the result of the CDW southward extending branch driven by the Taiwan Warm Current.

Tailor-Made Mesh for Pelvic Organ Prolapses: Correlation between Patient’s Height and Mesh Size

Tension-free vaginal mesh (TVM) surgery is a common and minimally invasive procedure for pelvic organ prolapses. Since commercial kits are not readily available in Japan, we have planned tailor-made mesh by information of each patient before every TVM surgery. The aim of this report is to inform methods to design mesh for individual patients with pelvic organ prolapses. We also investigated the correlations among mesh size and height, weight, and body mass index (BMI). Before the operation, we obtained a KUB (abdominal X-ray). Three factors were measured from this X-ray: the first was the distance between the bilateral ischial spine, the second was the distance between the obturator foramen, and the third was the length of the arcus tendineus fascia pelvis (ATFP). These three factors always should be considered for designing of mesh. The correlations among the bilateral ischial spine distance, obturator foramen distance, ATFP length, height, weight, and BMI were assessed using the Pearson correlation coefficient. Although these three factors described above are necessary to design a mesh for individual patients, the bilateral ischial spine and obturator foramen distance correlated with the height of the patient. On the other hand, since the length of ATFP differs in each patient and is not correlated with height, we should consider this length when we design the mesh. Well-designed, tailor-made mesh will probably fit each pelvic organ prolapsed patient very well.

Effects of Dihydromyricetin Extracted from Ampelopsis grossedentata on Visceral Organ Indexes and Intestinal Digestive Enzyme Activities of Chickens

To provide a reference basis for reasonable development and utilization of Ampelopsis grossedentata resource and its application in production,we added 0.025%,0.05% and 0.1% dihydromyricetin（DMY）extracted from A.grossedentata into the basal diets of Yaoshan chickens,and studied the effects of DMY on visceral organ indexes and digestive enzyme activities of 40-day-old healthy Yaoshan chickens.Supplementation of DMY in basal diets influenced visceral organ weight,organ index,length and digestive enzyme activity of small intestine of chickens.Among them,0.05% DMY was the most appropriate volume for supplementation.Compared with control group（without DMY）,0.05% DMY reduced lung weight and index（P〉0.05）,significantly reduced liver weight（P〈0.05）,extremely reduced stomach weight and stomach index（P〈0.01）,increased activity of amylase in small intestine（P〉0.05）,significantly increased length of small intestine and activity of protease（P〈0.05）.Supplementation of 0.05% DMY reduced the visceral organ weight and organ index,enhanced digestion and absorption ability of gastrointestinal tract,thereby improving feed utilization rate and promoting the growth of chickens.

Chemical composition and size distribution of secondary organic aerosol formed from the photooxidation of isoprene

Photooxidation of isoprene leads to the formation of secondary organic aerosol （SOA）. In this study, the chemical composition of SOA formed from OH-initiated photooxidation of isoprene has been investigated with gas chromatography/mass spectrometry （GC/MS） and a home-made aerosol time-of-fiight mass spectrometer. Sampling particles generated in a home-made smog chamber. The size distribution of SOA particles was detected by a TSI 3321 aerodynamic particle size spectrometer in real time. Results showed that SOA created by isoprene photooxidation was predominantly in the form of fine particles, which have diameters less than 2.5 μm. The obtained mass spectra of individual particles show that products of the OH-initiated oxidation of isoprene contain methyl vinyl ketone, methacrolein, formaldehyde, and some other hydroxycarbonyls. The possible reaction mechanisms leading to these products were also discussed.

The Dynamics of Organic Matter in Soil Size and Density Fractions Traced by Stable Carbon Isotopes

On the basis of different photosynthetic pathways, there is an obvious difference in {δ+{13}C} values between C-3 plants and C-4 plants. In terms of this characteristic, we analyzed the {δ+{13}C} values in different size and density fractions from two profile-soil samples either in farmland and forestlands near the Maolan Karst virgin forest, Southwest China, where there were developed C-3 plants previously and now are C-4 plants. Results showed that the δ+{13}C values of different size fractions in forestland soil are δ+{13}C-{coarse sand}<δ+{13}C-{fine sand}<δ+{13}C-{coarse silt}<δ+{13}C-{clay}<{δ+{13}C-{fine silt}}, and the δ+{13}C values of different size fractions in farmland soil are δ+{13}C-{coarse sand}>{δ+{13}C-{fine sand}}>δ+{13}C-{coarse silt}>δ+{13}C-{clay}>δ+{13}C-{fine silt}, indicating that soil organic matter is fresh in coarse sand and oldest in fine silt. The δ+{13}C values of different density fractions in forestland soil are δ+{13}C-{light}<δ+{13}C-{heavy}, and the {δ+{13}C} values of different density fractions in farmland soil are {δ+{13}C-{light}}>{δ+{13}C-{heavy}}, indicating that the soil organic matter is fresh in light fractions and old in heavy fractions .

Sand Grain Size and Organic Matter Concentration in the Intertidal Zones on the Southwest Coast of Taiwan

From April 2013 to April 2014, the average pH and water temperature of the Taisi oyster cultivation area (TS, Yunlin County, Taiwan) were 8.05 (7.35 - 8.45) and 24.7˚C (13.7˚C - 32.8˚C) (N = 8226) The average organic matter (OM) concentration at sites TS-A and TS-B were 6.9% ± 1.3% and 6.9% ± 1.2%, and the weight of drift sand was 40.3 ± 19.1 g/d/m2 and 28.5 ± 34.3 g/d/m2 (N = 27). Considerable sand drifting typically occurs during the southwest monsoon season in summer. The average OM concentration at five dunes from Zhuoshui estuary to Zengwun estuary was 23.9 ± 4.5 g/kg. The percentage of sand grain weight of 0.15 - 0.25 mm and 0.25 - 0.60 mm was 82.5% ± 14.2% and 10.5% ± 12.0%. In the spring and autumn of 2015, the average OM concentration at the eight intertidal zones from Hanbao to Cigu was 49.8 ± 34.1 g/kg (N = 177), and the OM concentrations at Huwei estuary and Hanbao and Fangyuan intertidal zones were relatively high. The OM concentration (95.3 ± 75.7 g/kg) of the low tide zone of Huwei estuary was the highest among all tidal zones. The OM concentration during spring (59.4 ± 41.7 g/kg, N = 95) was higher than that in autumn (39.1 ± 17.8 g/kg, N = 84). For sand grain size ranges 0.15 - 0.25 and 0.063 - 0.15 mm, the weight ratio of intertidal sediment was 39.4% ± 26.9% and 27.6% ± 20.1%, respectively. The broad and flat intertidal zone was marked by fine sand and long intertidal zone;the weight ratio of SGSs < 0.25 mm exceeded 65%, and the OM concentration was between 20 and 30 g/kg. Coastal habitat diversity creates differences in biological communities, especially among crabs and benthic organisms. A greater understanding of coastal environments can aid in the management of coastal wetlands.

Molecular Weight Distribution of Dissolved Organic Matter in Lake Hongfeng Determined by High Performance Size Exclusion Chromatography (HPSEC) With On-Line UV-Vis Absorbance and Fluorescence Detection

The molecular weight distribution (MWD) of dissolved organic matter (DOM) in lake waters from Lake Hongfeng was examined using high performance size exclusion chromatography (HPSEC) with UV-vis absorbance and fluorescence detection. The elution curves obtained by absorbance and fluorescence techniques expressed similar patterns, with the exception of diminishing of large fraction and the peaks behind several seconds in fluorescence chromatograms. According to its molecular weight (MW), DOM in water samples is divided into several fractions: large ({>3.5} kDa); medium-large ({3.5}-{2.0} kDa); medium ({2.0}-{1.0} kDa) and small ({<1.0} kDa). The average molecular weight was calculated using the elution curve detected by UV-vis absorbance and fluorescence detection techniques. The results showed that the weight-average molecular weight (Mw) and number-average molecular weight (Mn) calculated by UV-vis absorbance techniques range from 1750 to 2050 Dalton and from 1450 to 1850 Dalton, respectively. And the Mw and Mn obtained by fluorescence detection are lower by 50 to 400 Dalton. As a reference, the molecular weight of Fluka humic acid (FHA) is larger than that of water samples by about 200 Dalton. The average molecular weight of DOM for water samples collected in March and July was compared. The results revealed that the molecular weight is lower for water samples obtained in July than that obtained in March, indicating the ambient environment has an influence on the molecular weight, including photo-degradation and biological activity.

Effect of Organic and Chemical Fertilizer Application on Growth, Yield, and Quality of Small-Sized Tomatoes

Tomatoes in Japan are generally cultivated under management systems that use chemical fertilizers and synthetic chemical pesticides. However, the continuous use of these fertilizers and pesticides damages the soil environment and reduces the number of soil microorganisms. Organic farming has a relatively low environmental impact compared to conventional farming techniques, but typically has lower and more unstable yields. In this study, we investigated the effect of organic and chemical fertilizer application on growth, yield, and quality of small-sized (cherry) tomatoes. Cherry tomatoes were cultivated using organic and chemical organic fertilizers. Average weight and lateral diameter were significantly higher under organic fertilizer than under chemical fertilizer. In addition, shoot dry weight was significantly higher under organic fertilizer than chemical fertilizer. Lycopene content was significantly higher under organic fertilizer than chemical fertilizer. The total carbon (TC), total phosphorus (TP), total potassium (TK), available phosphoric (SP) and exchangeable potassium (SK) contents, C/N ratio, and pH were significantly higher under organic fertilizer than chemical fertilizer. Bacterial biomass, nitrite (NO? 2-N) oxidation activity, nitrification (N) circulation activity, and phosphoric (P) circulation were higher under organic fertilizer than chemical fertilizer. From these results, the study indicates that appropriate controls such as TC, total nitrogen (TN), and C/N ratio of organic fertilizer increased microbial biomass and enhanced nutrient circulation such as N circulation activity and P circulation activity. These results can be used to improve current organic farming practices and promote soil conservation.

HRM Practices Necessary to Be Applied Differently According to Organization Size

This paper offers evidence and data to support the idea that HRM practices should be utilized and theorized in a different way in relation to organization size. Other HRM practices which may not be influenced by firm growth will be discussed as well.

微波消解-电感耦合等离子体质谱法同时测定有机肥料中9种有毒有害元素的含量

提出了微波消解-电感耦合等离子体质谱法(ICP-MS)同时测定有机肥料中As、Cd、Co、Cr、Ni、Pb、Sb、Tl、V等9种有毒有害元素含量的方法。取0.10 g有机肥料样品于聚四氟乙烯微波消解罐中,以2.5 mL盐酸、7.5 mL硝酸和2.0 mL氢氟酸为混合酸进行微波消解。消解结束后,于140℃赶酸,然后加入1.0 mL 50%(体积分数)硝酸溶液,再用水定容至50 mL,摇匀,过滤,取滤液待测,在线加入混合内标溶液。结果表明:9种元素标准曲线的线性范围均为2~100μg·L^(-1),方法检出限(3s)为0.59~66.75μg·kg^(-1);按照标准加入法对典型有机肥料样品进行回收试验,9种元素测定值的相对标准偏差(n=7)为2.0%~3.5%,回收率为81.5%~112%。

微波消解-电感耦合等离子体质谱法测定有机肥中镉、砷、汞、铅、铬含量

采用电感耦合等离子体质谱法(ICP-MS)测定,比较湿法消解30 min,湿法消解至近干和微波消解等不同前处理方法对有机肥料中镉、砷、汞、铅、铬元素的提取效果,建立了一种基于ICP-MS测定有机肥料多种重金属元素含量的方法。结果表明:湿法消解至近干和微波消解法对有机肥多元素成分分析标准物质(RMH-F001)中5项重金属含量的测试结果均满足标准要求,方法定量值、标准值偏差分别低于6.3%、5.7%;硝酸/过氧化氢体系-微波消解处理下,样品结果稳定性最佳,相对标准偏差为0.8%~6.8%,相对偏差为1.1%~9.0%,相对相差为2.2%~18.0%,加标回收率为99.4%~102.9%。硝酸/过氧化氢体系-微波消解-ICP-MS法可作为有机肥中5项重金属统一化测定的常规方法。

接种蚯蚓对有机茶园土壤结构及有机碳库的影响

为探讨接种蚯蚓对有机茶园土壤团聚体、孔隙分布及有机碳库的影响,设置375条/m^(2),250条/m^(2),125条/m^(2)三种蚯蚓投放密度,将威廉腔环蚓接种于信阳有机茶园土壤中。结果表明:接种蚯蚓能显著提升>2mm大团聚体的比例而降低<0.25mm粒径的微团聚体的比例;提高水稳性小团聚体(0.25mm≤d≤2mm)比例,但对水稳性大团聚体d>2mm的影响不显著;高密度蚯蚓处理平均重量直径(MWD),平均几何直径(NWD)以及分型维数(D),团聚体破坏率(PAD)显著高于其他密度处理及对照(CK)。接种蚯蚓使得结构性孔隙(土壤颗粒间和团聚体间孔隙)所占比重增加,其中以团聚体间孔隙增加最为显著,其次为颗粒间孔隙,对由粘粒及矿物层间形成的毛管孔隙分布无显著影响;随着接种密度的增加,颗粒间孔隙度变化不显著而团聚体间孔隙度的相对值和绝对值均显著增加。添加蚯蚓能显著增加土壤活性有机库总量。接种密度的增加对活性有机碳库总量影响不大,但对土壤呼吸速率提升较多,故从温室气体排放角度考虑低接种密度更合适。可见,有机茶园中少量接种蚯蚓即能达到改良土壤结构的效果,并能缓解由于采茶造成的土壤压实问题。