Carbon stocks and sequestration potentials of agricultural soils in the federal state of Baden‐Württemberg,SW Germany

Soil organic carbon (SOC) inventories are important tools for studying the effects of land‐use and climate change and evaluating climate‐change policies. A detailed inventory of SOC in the agricultural soils of the federal state of Baden‐Württemberg was therefore prepared based on the highest‐resolution geo‐referenced soil, land‐use, and climate data (BÜK200 inventory). In order to estimate the quality of different approaches, C inventories of the region were also prepared based on data from the National Inventory Report (UBA, 2003) and by applying the IPCC (1997) method to the two data sets. Finally, the BÜK200 inventory was used to estimate potentials of no‐tillage agriculture (NT) and peatland restoration to contribute to C sequestration and greenhouse‐gas (GHG)‐emission mitigation since both measures are discussed in this context. Scenario assumptions were change to NT on 40% of the cropland and restoration of 50% of cultivated peatlands within 20 years. On average, grasslands contained 9.5 kg C m^–2 to 0.3 m depth as compared to only 6.0 kg C m^–2 under cropland, indicating strong land‐use effects. The SOC content depended strongly on waterlogging and elevation, thus reflecting reduced C mineralization under aquic moisture regimes and low temperatures. Comparison of the BÜK200 inventory with the approach used for UBA (2003) showed high inconsistencies due to map resolution and SOC contents, whereas the IPCC method led to fairly good agreements. Results on the simulated effects of NT and peatland restoration suggested that 5%–14% of total agricultural GHG emissions could be abated with NT whereas peat restoration appeared to have a minor mitigation potential (0.2%–2.7%) because the total area of cultivated organic soils was too small to have larger impact.     

Impact of intensive agricultural management on carbon and nitrogen dynamics in the humid tropics

ABSTRACT

The concern about global climate change continues to increase research interest regarding carbon and nitrogen dynamics in the soil. This is based on their role in maintaining soil fertility, which can instead be a source of greenhouse gas emissions if not managed properly, while threatening food security. Humid tropical conditions enable intensive agricultural cultivation with various cropping systems to fulfill the demand for agriculture products. Such climate accelerates the soil organic matter decomposition rate so that it strongly influences soil carbon and nitrogen dynamics. However, inappropriate implementation of intensive agricultural systems that does not consider the balance between carbon and nitrogen input and output, negatively affects soil fertility, mainly decreasing soil organic carbon and total soil nitrogen, changing the composition of carbon and nitrogen owing to the loss of soil organic matter through erosion and leaching, thus, causing soil degradation. Mitigation strategies can be performed by using organic matter and crop residue, crop rotation and improvement of crop pattern, soil tillage and fertilization, cover crops and mulch. Sustainable land management for maintenance of soil organic carbon and total soil nitrogen dynamics should be locally and globally developed and adopted for a more sustainable agricultural system. Recovery of soil capacity to accumulate carbon is a strategic step to reduce the impact of climate change. Hence, an intensive study on efficient soil organic carbon management is required to improve food production and mitigation of climate change to attain sustainable development goals in 2030.     

Long‐term no‐tillage effects on particulate and mineral‐associated soil organic matter under rainfed Mediterranean conditions

Soil organic carbon (SOC) plays an essential role in the sustainability of natural and agricultural systems. The identification of sensitive SOC fractions can be crucial for an understanding of SOC dynamics and stabilization. The objective of this study was to assess the effect of long‐term no‐tillage (NT) on SOC content and its distribution between particulate organic matter (POM) and mineral‐associated organic matter (Min) fractions in five different cereal production areas of Aragon (north‐east Spain). The study was conducted under on‐farm conditions where pairs of adjacent fields under NT and conventional tillage (CT) were compared. An undisturbed soil nearby under native vegetation (NAT) was included. The results indicate that SOC was significantly affected by tillage in the first 5 cm with the greatest concentrations found in NT (1.5–43% more than in CT). Below 40 cm, SOC under NT decreased (20–40%) to values similar or less than those under CT. However, the stratification ratio (SR) never reached the threshold value of 2. The POM‐C fraction, disproportionate to its small contribution to total SOC (10–30%), was greatly affected by soil management. The pronounced stratification in this fraction (SR>2 in NT) and its usefulness for differentiating the study sites in terms of response to NT make POM‐C a good indicator of changes in soil management under the study conditions. Results from this on‐farm study indicate that NT can be recommended as an alternative strategy to increase organic carbon at the soil surface in the cereal production areas of Aragon and in other analogous areas.     

A comparison of peat properties in intact,afforested and restored raised and blanket bogs

Recognition of peatlands as a key natural store of terrestrial carbon has led to new initiatives to protect and restore them. Some afforested bogs are being clear-felled and restored (forest-to-bog restoration) to recover pre-afforestation ecosystem function. However, little is known about differences in the peat properties between intact, afforested and restored bogs. A stratified random sampling procedure was used to take 122 peat cores from three separate microforms associated with intact (hollows; hummocks; lawns), afforested and restored bogs (furrows; original surface; ridges) at two raised and two blanket bog locations in Scotland. Common physical and chemical peat properties at eight depths were measured in the laboratory. Differences in bulk density, moisture and carbon content between the afforested (mean = 0.103 g cm⁻³, 87.8% and 50.9%, respectively), intact (mean = 0.091 g cm⁻³, 90.3% and 51.3%, respectively) and restored bogs (mean = 0.095 g cm⁻³, 89.7% and 51.1%, respectively) were small despite their statistical significance. The pH was significantly lower in the afforested (mean = 4.26) and restored bogs (mean = 4.29) than the intact bogs (mean = 4.39), whereas electrical conductivity was significantly higher (mean: afforested = 34.2, restored = 38.0, intact = 25.3 μS cm⁻¹). While significant differences were found between treatments, effect sizes were mainly small, and greater differences in pH, electrical conductivity, specific yield and hydraulic conductivity existed between the different intact bogs. Therefore, interactions between geographic location and land management need to be considered when interpreting the impacts of land-use change on peatland properties and functioning.     

Ethno-Practices and Adaptation Strategies for the Mitigation of Climate Change by Arable Crop Farmers in Osun State: Implications for Extension Policy Formulation in Nigeria

The study investigated methods used by arable crop farmers to mitigate climate change in Osun State, Nigeria. Data were collected with the aid of a structured interview schedule from 120 arable crop farmers selected from 24 communities. Age (b = ?.392; p < .05), household size (b = .190; p < .049), income (b = .182; p < .057), sources of information (b = .161; p < .105), and farm size (b = .258; p < .004) were significant with adaptation strategies. Strategies regularly employed included use of different planting dates (88.6%), multiple cropping (73%), and cover cropping (55%). The study concluded that arable crop farmers use sustainable methods to ameliorate climate change to the advantage of their production.     

Inactivation of Escherichia coli in soil by solarization

Abstract

Contamination of agricultural soil by fecal pathogenic bacteria poses a potential risk of infection to humans. For the biosafety control of field soil, soil solarization in an upland field was examined to determine the efficiency of solarization on the inactivation of Escherichia coli inoculated into soil as a model microorganism for human pathogenic bacteria. Soil solarization, carried out by sprinkling water and covering the soil surface with thin plastic sheets, greatly increased the soil temperature. The daily average temperature of the solarized soil was 4–10°C higher than that of the non-solarized soil and fluctuated between 31 and 38°C. The daily highest temperature reached more than 40°C for 8 days in total in the solarized soil during the second and third weeks of the experiment. Escherichia coli in the solarized soil became undetectable (< 0.08 c.f.u. g^?1 dry soil) within 4 weeks as a result, whereas E. coli survived for more than 6 weeks in the non-solarized soil. Soil solarization, however, had little influence on the total direct count and total viable count of bacteria in the soil. These results indicate that soil solarization would be useful for the biosafety control of soil contaminated by human pathogens via immature compost or animal feces.     

Inactivation of Escherichia coli in soil by solarization

Contamination of agricultural soil by fecal pathogenic bacteria poses a potential risk of infection to humans. For the biosafety control of field soil, soil solarization in an upland field was examined to determine the efficiency of solarization on the inactivation of Escherichia coli inoculated into soil as a model microorganism for human pathogenic bacteria. Soil solarization, carried out by sprinkling water and covering the soil surface with thin plastic sheets, greatly increased the soil temperature. The daily average temperature of the solarized soil was 4–10°C higher than that of the non-solarized soil and fluctuated between 31 and 38°C. The daily highest temperature reached more than 40°C for 8 days in total in the solarized soil during the second and third weeks of the experiment. Escherichia coli in the solarized soil became undetectable (< 0.08 c.f.u. g⁻¹ dry soil) within 4 weeks as a result, whereas E. coli survived for more than 6 weeks in the non-solarized soil. Soil solarization, however, had little influence on the total direct count and total viable count of bacteria in the soil. These results indicate that soil solarization would be useful for the biosafety control of soil contaminated by human pathogens via immature compost or animal feces.     

Diversity–Productivity Trade‐off During Converting Cropland to Perennial Grassland in the Semi‐arid Areas of China

The trade‐off between plant community structure and function is an important issue during grassland restoration. It is essential to assess changes of structure and function after converting farmland to grassland. Three restoration stages (5, 15, and 30 years) were studied to determine the optimum time when the trade‐off between diversity and productivity occurs. The results showed that the vegetation coverage, height, and productivity significantly increased, but the species richness, diversity, and density significantly decreased along the restoration time. Grassland community presented a succession from small individuals and high density to larger individuals and lower density. The community changed from being dominated by grass and forb functional groups to being dominated only by the grass functional group. The dominant grass functional group plays a decisive role on community structure and function (productivity, diversity, and density) during grassland succession. Our results suggest that community structure and function were mainly driven by the dominant grass functional group during the long‐term succession. Grassland should be utilized to suppress the leading role of the dominant functional groups in the 20th year for keeping the trade‐off of diversity and productivity. We suggest that the restoration grassland should be considered to use appropriately in the 20th year. Our study could provide a key guidance for maintaining the community structure and function trade‐off for cropland‐converted grassland management in the semi‐arid areas. Copyright © 2016 John Wiley & Sons, Ltd.     

pfl-act基因在大肠杆菌中的高效表达及其纯化

丙酮酸甲酸裂解酶是肠道细菌在厌氧代谢中十分关键的酶,丙酮酸甲酸裂解酶激活因子(pyruvateform ate lyase activator,PFL-A)在功能上具有重要的作用。为进一步研究PFL-A的激活机理,以大肠杆菌K-12的基因组为模板,通过G enB ank上公布的序列设计引物,扩增出目的基因,克隆到pM D 18-T载体,经测序,所扩增出的基因与p f l-act基因具有99%的同源性。将p f l-act连接到高效表达载体pET-22b( )中,经异丙基硫代-β-D-半乳糖苷(IPTG)诱导,结果发现,p f l-act以包涵体形式表达。改变诱导剂、诱导剂量或培养温度,对包涵体的形成均没有明显的影响。     

Fate of Escherichia coli and Escherichia coli O157 in soils and drainage water following cattle slurry application at 3 sites in southern Scotland

Abstract. Slurry from farm animals may contaminate water supplies, rivers and bathing waters with faecal coliforms, such as Escherichia coli . Where animals harbour the O157 strain the hazard to human health is particularly high, but both the hazard level, and the low incidence and sporadic nature of the excretion of E. coli O157 make it difficult to study this strain under field conditions. The survival of total E. coli and of E. coli O157 were compared in the laboratory for two soils under controlled temperature and moisture. E. coli O157 die-off rate was the same as or quicker than for total E. coli . This result meant that field experiments studying the fate of total E. coli should give a satisfactory evaluation of the risk of water contamination by the O157 strain. In four field experiments at three sites, slurry containing total E. coli numbers of 2.2 × 10⁴ to 5.7 × 10⁵ colony forming units per mL (c.f.u. mL^–1) was applied to drained field plots. Field die-off was faster than expected from laboratory experiments, especially in one experiment where two weeks dry weather followed application. In all but this experiment, the first drain flow events after slurry application led to very high E. coli concentrations in the drains (10³ to 10⁴ c.f.u. mL^–1). E. coli O157 was present in the slurry used for two of the experiments (33 c.f.u. per 100 mL in each case). However the proportion of E.coli O157 was very low (about 1 in 10⁵) and it was not detected in the drainage water. After the first week E. coli drainage water numbers decreased rapidly but they were 1–10 c.f.u. mL^–1 for much of the sampling period after slurry application (1–3 months).     

Soil loss and run‐off characteristics under different soil amendments and cropping systems in the semi‐deciduous forest zone of Ghana

Soil erosion is a major constraint to crop production on smallholder arable lands in Sub‐Saharan Africa (SSA). Although different agronomic and mechanical measures have been proposed to minimize soil loss in the region and elsewhere, soil management practices involving biochar‐inorganic inputs interactions under common cropping systems within the framework of climate‐smart agriculture, have been little studied. This study aimed to assess the effect of different soil and crop management practices on soil loss characteristics under selected cropping systems, typical of the sub‐region. A two‐factor field experiment was conducted on run‐off plots under different soil amendments over three consecutive cropping seasons in the semi‐deciduous forest zone of Ghana. The treatments, consisting of three soil amendments (inorganic fertilizer, biochar, inorganic fertilizer + biochar and control) and four cropping systems (maize, soyabean, cowpea, maize intercropped with soyabean) constituted the sub‐plot and main plot factors, respectively. A bare plot was included as a soil erosion check. Seasonal soil loss was greater on the bare plots, which ranged from 9.75–14.5 Mg ha^?1. For individual crops grown alone, soil loss was 31%–40% less under cowpea than under maize. The soil management options, in addition to their direct role in plant nutrition, contributed to significant (p < 0.05) reductions in soil loss. The least soil loss (1.23–2.66 Mg ha^?1) was observed under NPK fertilizer + biochar treatment (NPK + BC) over the three consecutive cropping seasons. Biochar in combination with NPK fertilizer improved soil moisture content under cowpea crops and produced considerably smaller bulk density values than most other treatments. The NPK + BC consistently outperformed the separate mineral fertilizer and biochar treatments in biomass yield under all cropping systems. Biochar associated with inorganic fertilizers gave economic returns with value–cost ratio (VCR) > 2 under soyabean cropping system but had VCR < 2 under all other cropping systems. The study showed that biochar/NPK interactions could be exploited in minimizing soil loss from arable lands in SSA.     

Effect of buckwheat (Fagopyrum esculentum) on soil‐phosphorus availability and organic acids

As a cover crop, buckwheat (Fagopyrum esculentum) may increase soil‐P availability. Buckwheat was grown in low‐P and P‐fertilized field plots, and organic anions were measured in rhizosphere soil. Soil‐P availability was not affected by buckwheat, but the concentration of rhizosphere tartrate^2– was significantly higher (p < 0.005) in low‐P vs. P‐fertilized plots. This suggests that organic‐anion root exudation may have a role in buckwheat‐rhizosphere P dynamics.     

No‐tillage with half‐amount residue retention enhances microbial functional diversity,enzyme activity and glomalin‐related soil protein content within soil aggregates

A 3‐year field tillage and residue management experiment established in North China was used to analyse topsoil (0–15 cm) aggregation, and microbial functional diversity, enzyme activity and glomalin‐related soil protein (GRSP) content within aggregates. Compared with conventional tillage (CT), no‐tillage (NT) alone significantly (P < 0.05) increased organic C contents in 50–250 and <2 μm aggregates and decreased the proportion of C accumulated by 2–50 μm aggregates and microbial functional diversity indices in <2 μm aggregates. Regardless of tillage practice, both half‐amount (C50) and full (C100) residue retention tended to increase organic C and GRSP contents, or dehydrogenase and invertase activities, in certain aggregates. Under CT, a poorer performance of C50 than C100 was observed in maintaining Shannon index (H′) and Simpson index (D) in >250 and <2 μm aggregates, and also McIntosh index (U) in <2 μm aggregates, owing to insufficient residue and possible decreases in the distribution of decomposer micro‐organisms. Under NT, however, C50 was more effective than C100 in maintaining/elevating H′, D and U in all soil aggregates except for 50–250 μm, suggesting that surplus residue may induce worse soil conditions, decreasing heterotrophic microbial activities. Thus, NT with half‐amount residue retention improved soil physical–chemical–biological properties and could be a useful management practice in North China.     

Organic farming fosters agroecosystem functioning in Argentinian temperate soils: Evidence from litter decomposition and soil fauna

Benefits of organic farming on soil fauna have been widely observed and this has led to consider organic farming as a potential approach to reduce the environmental impact of conventional agriculture. However, there is still little evidence from field conditions about direct benefits of organic agriculture on soil ecosystem functioning. Hence, the aims of this study were to compare the effect of organic farming versus conventional farming on litter decomposition and to study how this process is affected by soil meso- and macrofauna abundances. Systems studied were: (1) organic farming with conventional tillage (ORG), (2) conventional farming with conventional tillage (CT), (3) conventional farming under no-tillage (NT), and (4) natural grassland as control system (GR). Decomposition was determined under field conditions by measuring weight loss in litterbags. Soil meso- and macrofauna contribution on decomposition was evaluated both by different mesh sizes and by assessing their abundances in the soil. Litter decomposition was always significantly higher after 9 and 12 months in ORG than in CT and NT (from 2 to 5 times in average), regardless decomposer community composition and litter type. Besides, mesofauna, macrofauna and earthworm abundances were significantly higher in ORG than in NT and CT (from 1.6 to 3.8, 1.7 to 2.3 and 16 to 25 times in average, respectively for each group). These results are especially relevant firstly because the positive effect of ORG in a key soil process has been proved under field conditions, being the first direct evidence that organic farming enhances the decomposition process. And secondly because the extensive organic system analyzed here did not include several practices which have been recognized as particularly positive for soil biota (e.g. manure use, low tillage intensity and high crop diversity). So, this research suggests that even when those practices are not applied, the non-use of agrochemicals is enough to produce positive changes in soil fauna and so in decomposition dynamics. Therefore, the adoption of organic system in an extensive way can also be suggested to farmers in order to improve ecosystem functioning and consequently to achieve better soil conditions for crop production.     

Millimetre‐scale distribution of organic matter composition at intact biopore and crack surfaces

Structured subsoil horizons are characterized by biopores and shrinkage cracks, which may serve as preferential flow paths. The surfaces of cracks and biopores may be coated by clay‐organic material. The spatially‐distributed organic matter (OM) composition at such structural surfaces was studied at the millimetre scale using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy in the mid‐infrared range (MIR). Intact biopores such as earthworm burrows and root channels, and crack surfaces of nine subsoil horizons were analysed. The samples were from arable and forest Luvisols, one Regosol, one Stagnosol and Cambisols developed from loess, till, mudstone and limestone. For better comparison between soils, the DRIFT signal intensities were corrected for the particle‐size effects. The OM was characterized by the ratio between alkyl‐ (C–H) and carbonyl (C=O) functional groups (C–H/C=O), which represent an index of the potential wettability (PWI) of the OM. The PWI was larger for biopores than for crack surfaces and the soil matrix, indicating a smaller potential wettability of OM at biopore surfaces. The millimetre‐scale spatial variability of OM was especially large for the surfaces of root channels. Samples from till‐derived Luvisols had smaller PWI (with greater potential wettability than surfaces from loess‐derived Luvisols) than other soil types. The mean PWI of the arable Luvisol crack surfaces was less than that of the forest Luvisol samples. The results suggest that the spatial distribution of OM properties at intact structural surfaces may be important for describing sorption and mass transfer processes during preferential flow.     

胸腺素家族多肽在大肠杆菌中的表达

为提高胸腺素(又名胸腺肽,thymosin)的体外表达效率,本研究采用设计融合标签的方法对胸腺素α1和β4(Tα1,Tβ4)进行体外重组表达,通过超高效液相色谱-飞行时间质谱联用(LC/MS)法,对融合蛋白的完整分子量进行验证,利用反相超高效液相色谱法对不同表达载体的单位表达量进行测定.结果 表明,A 18-KEKE、...     

甘蓝型油菜中黑芥子酶基因在大肠杆菌中重组质粒的构建和表达

实验通过RT-PCR程序从提取的油菜总RNA中扩增出硫代葡萄糖苷水解酶（又称黑芥子酶,EC3.2.1.147）基因,酶解后插入大肠杆菌表达载体（Escherichia coli）pGEX-4T-1,获得克隆菌株。基因测序在 GenBank中的登陆号为EF583560,翻译的氨基酸序列与已报道的黑芥子酶（GenBank中的登陆号为Q00326）中的一段有一个氨基酸不同,同源性达到99%。经过IPTG诱导表达,在91KDa左右处有表达量很高的一条带。     

Soil structural stability and erosion rates influenced by agricultural management practices in a semi‐arid Mediterranean agro‐ecosystem

Unsuitable agricultural practices can cause loss in soil quality and erodibility to thus increase or trigger desertification under Mediterranean conditions. A field experiment was performed at the El Teularet‐Sierra de Enguera Experimental Station (eastern Spain) to assess the influence during a 5‐yr period of different agricultural practices on physical and chemical indicators of soil quality (total and water‐soluble carbohydrates, glomalin‐related soil proteins (GRSP), total organic carbon, aggregate stability (AS), vegetation cover and soil erosion). The management practices included residual herbicide use, ploughing, ploughing + oats, addition of oat straw mulch and a control (land abandonment). Adjacent soil under natural vegetation was used as a reference for local, high‐quality soil and as a control for comparison with the agricultural soils under different management practices. Oat straw mulching led to higher levels of water‐soluble carbohydrates, GRSP and AS and lower soil erosion rates, resulting in values similar to those in the soil under native vegetation. The lowest levels of carbohydrates and GRSP were for the plots that were treated with herbicide or were ploughed. The maintenance of and increases in stable aggregates promoted by the different agricultural management practices over the years were attributed to increases in labile organic fractions such as carbohydrates and to the GRSP content. The results demonstrate that land abandonment (control plot) or the use of a cover (plants or straw) contributes to increases in soil quality and reduces the risk of erosion. The research also shows that sustainable agricultural management allows soil to recover and that the use of straw mulching is the most effective management strategy.     

人乙醛脱氢酶2的原核表达及其条件优化

为实现人乙醛脱氢酶2（ALDH2）基因在原核生物中高效表达,将含有6×His标签和SUMO融合蛋白标签的人乙醛脱氢酶2基因的表达载体转化至宿主菌BL21（DE3）中。在异丙基硫代-β-D-半乳糖苷（IPTG）诱导下,目的基因在大肠杆菌内高效表达。通过对表达条件的优化,37℃使用终浓度0.3mmol/L的IPTG诱导3h,重组大肠杆菌的表达量可占全菌蛋白的16%。SUMO融合蛋白标签的加入以及较低的诱导温度（16℃）有利于提高人乙醛脱氢酶2基因在大肠杆菌内的可溶性表达。