Fine earth soil bulk density at 0.2 m depth from Land Use and Coverage Area Frame Survey (LUCAS) soil 2018

Soil Bulk Density (BD) is an extremely important variable because it is an important site characterization parameter, and it is highly relevant for policy development because it is mandatory for calculating soil nutrient stocks. BD can influence soil chemical properties, land-use planning and agronomic management. The 2018 Land Use and Coverage Area Frame Survey (LUCAS) saw the unprecedented collection of BD core analysis in a subset of the locations in Europe and the United Kingdom where soil physical and chemical properties were analysed in the 2009 and the 2015 sampling campaigns. Here, we integrated the LUCAS 2018 BD sampling campaign with the mass fraction of coarse fragments previously determined in LUCAS 2009–2015 in order to provide a dataset of the volume fraction of coarse fragments and the BD of the fine earth and improve soil organic carbon (SOC) stock estimation accuracy for topsoil. BD data sampled at 0–10 and 10–20 cm were averaged to harmonize the BD with the mass fraction of coarse fragments measured in 2009, 2012 and 2015. Samples were from cropland, grassland and woodland soils, which accounted for 41%, 21% and 30%, respectively, of the total number of selected sites (n = 6059); ‘bareland’, and ‘shrubland’ accounted for 3% of the sites each, whereas ‘artificial land’ accounted for <1%. Only six samples were classified as ‘wetland’. The dataset was produced assuming the mass density of the coarse fraction to be constant across all LUCAS soil samples. We also estimated the SOC stocks associated with LUCAS 2018 BD and SOC content measurements and showed that correcting the BD by the coarse mass fraction instead of the coarse volume fraction generates SOC stock underestimation. We found the highest deviations in woodlands and shrublands. We showed that, when SOC stock is computed with coarse mass fraction, the error compared with the computation by volume may vary depending on the SOC and coarse mass fraction. This may imply a SOC stock underestimation for European soils. This dataset fits into the big framework of LUCAS soil properties monitoring and contributes both to soil awareness and soil research and assessments, which are two important objectives of the Soil Strategy and the European Soil Observatory (EUSO).     

退化马尾松林恢复过程中芒萁覆盖对土壤微生物生物量碳氮及其周转的影响

为探究侵蚀退化红壤马尾松林恢复过程中林下芒萁对土壤微生物生物量碳氮月动态及其周转的影响,以不同恢复年限的马尾松林为研究对象,对比分析马尾松林恢复过程中林下保留芒萁、去除芒萁处理和林下裸地土壤中12个月的土壤微生物生物量碳(MBC)和微生物量氮(MBN)含量及其周转速率、周转时间和流通量,并分析其与土壤理化性状的关系。结果表明:(1)保留芒萁覆盖处理的MBC和MBN平均含量分布比林下裸地提高26.99%~277.31%和13.54%~173.39%,而去除芒萁处理分布比保留芒萁处理降低12.29%~27.01%和5.02%~28.45%,差异均随恢复年限呈先降低后增加的趋势。(2)所有处理的土壤微生物量碳氮季节动态均表现为春夏季较高,秋冬季较低的趋势,进入生长季前的土壤微生物量碳氮含量更能反映该地区的平均水平。(3)在退化马尾松林恢复过程中,芒萁覆盖降低土壤微生物生物量碳氮周转速率,增加周转时间,提高土壤微生物生物量碳氮含量和流通量,促进土壤有机质的积累和养分释放。相关分析和逐步回归分析表明,MBC、MBN流通量分别与DOC、DON呈显著正相关,周转速率分别与铵态氮(NH₄⁺-N)和TN呈显著负相关,表明土壤碳和氮及其有效性是影响土壤微生物量周转的关键因素。     

Assessing long term effects of compost fertilization on soil fertility and nitrogen mineralization rate

Background

Fertilization with organic waste compost can close the nutrient cycles between urban and rural environments. However, its effect on yield and soil fertility must be investigated.

Aim

This study investigated the long-term effect of compost on soil nutrient and potentially toxic elements (PTEs) concentration, nutrient budgets, and nitrogen (N) mineralization and efficiency.

Methods

After 21 years of annual compost application (100/400 kg N ha^–1 year^–1 [100BC/400BC]) alone and combined with mineral fertilization, soil was analyzed for pH, organic carbon (SOC), nutrient (total N and P, N_min, extractable CAL-P, CAL-K, and Mg), and PTE (Cu, Ni, Zn) concentrations. Yields were recorded and nutrient/PTE budgets and apparent net mineralization (ANM, only 2019) were calculated.

Results

N efficiency was the highest in maize and for mineral fertilization. Compost application led to lower N efficiencies, but increased ANM, SOC, pH, and soil N, and surpluses of N, P, and all PTEs. Higher PTE concentrations were only found in 400BC for Cu. Nutrient budgets correlated with soil nutrient concentration. A surplus of 16.1 kg P ha^–1 year^–1 and 19.5 kg K ha^–1 year^–1 resulted in 1 mg kg^–1 increase in CAL-P and CAL-K over 21 years.

Conclusion

Compost application supplies nutrients to crops with a minor risk of soil-accumulation of PTEs. However, the nutrient stoichiometry provided by compost does not match crop offtakes causing imbalances. Synchronization of compost N mineralization and plant N demand does not match and limits the yield effect. In winter wheat only 65–70% of N mineralization occurred during the growth period.     

Evidence of dissolved trivalent manganese in acidic forest soils

Background

Evidence of trivalent manganese (Mn³⁺) in the aqueous phase of soils is unknown so far although this strong oxidant has large environmental implications.

Aims

We aimed to modify a spectrophotometric protocol (porphyrin method) and to discriminate between Mn²⁺ and Mn³⁺ in the aqueous phase of forest soils based on kinetic modeling.

Methods

We investigated manganese speciation in 12 forest floor solutions and 41 soil solutions from an acidic forest site by adjusting pH and correcting for absorbance.

Results

The solutions showed broad ranges in pH (3.4−6.3), dissolved organic carbon (DOC, 1.78−77.1 mg C L⁻¹), and total Mn (Mn_T, 23.9−908 µg L⁻¹). For acidic solutions, a pH-buffer was added to increase the pH of the solutions to 7.5−8.0, and background absorption was corrected for colored solutions, that is, solutions high in DOC. This was done to accelerate the reaction kinetics and avoid overestimation of Mn_T concentrations. After the pH and color adjustments, the comparison of Mn_T concentrations between the porphyrin method and optical emission spectrometry showed good agreement. Trivalent Mn, which is stabilized by organic ligands, constitutes significant proportions in both forest floor solutions (10−87%) and soil solutions (0.5−74%).

Conclusions

The dissolved Mn³⁺ is present in acidic forest soils. Thus, we revise the paradigm that this species is not stable and encourage to apply the revised method to other soils.     

不同生长年限苜蓿栽培草地CO2通量的初步研究

以种植第1年、第2年、第3年和第5年的紫花苜蓿阿尔冈金（Medicago sativa cv. Algonquin）为对象,通过研究其光合生理特性、土壤呼吸以及土壤有机碳的净通量等分析不同生长年限苜蓿草地碳通量的变化规律。结果表明,不同生长年限的苜蓿草地净光合速率呈单峰曲线,第1年和第5年在盛花期达到最大,分别为50和69 μmol/(m2·s),第2年和第3年在结荚期达到最大值,分别为60和72 μmol/(m2·s),与叶绿素a和b的含量不相关（P＞0.05）。苜蓿草地土壤呼吸的动态变化呈不规则单峰曲线变化,6月24日达到最小值,7月达到最大值,平均值为第5年＞第2年＞第3年＞第1年。土壤呼吸速率与土壤温度无明显的相关性（P＞0.05）;除第1年外,与土壤湿度显著相关（P＜0.05）,其中,第3年和第5年极显著相关（P＜0.01）。第1年、第2年、第3年和第5年的苜蓿土壤有机碳的净通量分别为3.71、-1.71、12.17和12.53 g/kg。     

新疆棉花生产综合外部性的非市场价值评估——基于棉花补贴视角

以新疆棉花生产为例,运用条件价值法(CVM),通过对新疆棉花生产正外部性补贴的支付意愿调查,估算了棉花生产的生态环境、自然景观及社会保障等正外部性非市场价值;运用分解求和法,测算了新疆棉花生产过程中,棉田吸收CO2、棉田土壤固碳、棉花生产中物资燃料使用带来的碳排放等环境外部性的非市场价值。研究结果表明,新疆棉花生产的综合外部性表现为正,其外部性的非市场总价值高达110.8573×108元。若将此作为计算棉花补贴的依据,则每公顷棉花可补贴7589.85元;并提出将其作为棉花生产补贴标准,增加补贴项目,提高补贴额度,稳定棉花生产,保障棉花产业安全。     

超高茬麦套稻的产量及低碳效应分析

通过对超高茬麦田套稻稻作方式的机理进行了介绍,分析了其低碳优势和高产原因,为现代农业生产提供参考。     

杨树伐桩嫁接与植苗林的生长及碳储量的比较

The leaf nutrient, biomass and carbon reserve of 9-year-old Populus×euramericana cv. ‘74/76’ stump grafting stand with 26-year-old P.×xiaozhuanica W.Y.Hsu et Liang cv.‘Popularis’as rootstock, 26-year-old P.×xiaozhuanica W.Y.Hsu et Liang cv.‘Popularis’ and 9-year-old P.×euramericana cv. ‘74/76’ planting stands were compared. The result showed that the average increment and the annual average increment of stump grafting stand were greater than the two planting stands. The total nitrogen content in leaves of stump grafting stand was the highest, and it was 1.26 times and 1.05 times as much as that of the planting stands of Populus×xiaozhuanica W.Y.Hsu et Liang cv.‘Popularis’ and P.×euramericana cv. ‘74/76’ separately. The total phosphorus content of stump grafting stand was 1.3 times as much as that of planting stand of 26-year-old P.×xiaozhuanica W.Y.Hsu et Liang cv.‘Popularis’, but there was little difference between stump graftin stand and planting stand of 9-year-old P.×euramericana cv. ‘74/76’. The total potassium of stump grafting stand was 46.6% and 95.8% lesser than that of the planting stands of P.×xiaozhuanica W.Y.Hsu et Liang cv.‘Popularis’ and P.×euramericana cv. ‘74/76’. The biomass of aerial parts and the biomasses of trunk, branches and leaves of stump grafting stand were 1.84, 1.80, 1.76, and 3.00 times as much as that of planting stand of P.×euramericana cv. ‘74/76’ separately. The total root biomass of the stump grafting stand was 1.42 times and 7.68 times as much as that of planting stands of 26-year-old P.×xiaozhuanica W.Y.Hsu et Liang cv.‘Popularis’ and 9-year-old P.×euramericana cv. ‘74/76’. There was an obvious advantage in carbon reserve from all the parts of the stump grafting stand and the carbon sequestration capacity was the highest, which was 2.66 times and 1.62 times as much as that of planting stands of 26-year-old P.×xiaozhuanica W.Y.Hsu et Liang cv.‘Popularis’ and 9-year-old P.×euramericana cv. ‘74/76’. These showed that the stump grafting stand had more advantages than planting stands.     

PEG/Activated Carbon Phase Change Materials of Modified Asphalt

Phase change material modified asphalt is prepared by using PEG/activated carbon composite solid-solid phase change materials for asphalt modification. Phase change materials modified asphalt with different ratios are aged and treaded alterably at high or low temperature, and then its appearance is observed. The properties of the modified asphalt, such as ductility, softening point, etc., are tested by using electronic tensile testing machine and thermal mechanical analyzer. Experiments show that when the content of PEG/activated carbon phase change material is 20%, the ductility of modified asphalt is the best; when the content of phase change material is 15% to 20%, the softening point of modified asphalt is obviously improved.     

Effect of organic carbon on nitrogen removal and microbial community in the completely autotrophic nitrogen removal process

Different synthetic wastewaters are used to analyze the effect of organic carbon on the nitrogen removal and microbial community in the completely autotrophic nitrogen removal process. Results show that the nitrogen removal performance is improved by control of DO at a reasonable C/N ratio. The NH +4-N is removed in several ways. When the influent without any organic carbon, the most of ammonium is removed in nitrification-ANAMMOX metabolic pathway; the contribution of nitrification-ANAMMOX decreases, while the conventional nitrification-denitrification process enhanced with the addition of organic carbon. PCR-DGGE and statistical analyses show that the microbial diversity in SBBR reactor fed with organic wastewater is more abundant than it fed with inorganic wastewater,and this exhibits obvious in the biofilm, which also indicate that it helps to format the aerobic-anaerobic microenvironment,so nitrogen can be removed in different ways in one reactor.