Effect of farm management on topsoil organic carbon and aggregate stability in water: A case study from Southwest England,UK

There are few reliable data sets to inspire confidence in policymakers that soil organic carbon (SOC) can be measured on farms. We worked with farmers in the Tamar Valley region of southwest England to select sampling sites under similar conditions (soil type, aspect and slope) and management types. Topsoils (2–15 cm) were sampled in autumn 2015, and percentage soil organic matter (%SOM) was determined by loss on ignition and used to calculate %SOC. We also used the stability of macroaggregates in cold water (WSA) (‘soil slaking’) as a measure of ‘soil health’ and investigated its relationship with SOC in the clay‐rich soils. %SOM was significantly different between management types in the order woodland (11.1%) = permanent pasture (9.5%) > ley‐arable rotation (7.7%) = arable (7.3%). This related directly to SOC stocks that were larger in fields under permanent pasture and woodland compared with those under arable or ley‐arable rotation whether corrected for clay content (F = 8.500, p < .0001) or not (F = 8.516, p < .0001). WSA scores were strongly correlated with SOC content whether corrected for clay content (SOC_adj R² = .571, p < .0001) or not (SOC_unadj R² = 0.490, p = .002). Time since tillage controlled SOC stocks and WSA scores, accounting for 75.5% and 51.3% of the total variation, respectively. We conclude that (1) SOC can be reliably measured in farmed soils using accepted protocols and related to land management and (2) WSA scores can be rapidly measured in clay soils and related to SOC stocks and soil management.     

土壤铅和镉溶出伏安法检测中影响因素及其削弱方法研究进展

溶出伏安法具有分析速度快、成本低、灵敏度高等优点被广泛应用于检测土壤重金属含量，但在检测土壤重金属时，溶出伏安检测精度会受到多方面因素的影响。该文在介绍溶出伏安法工作原理的基础上，从伏安参数、试验条件和土壤物质成分三方面阐述溶出伏安法检测土壤Pb2+和Cd2+为的影响因素，解析各因素的影响机理，归纳影响削弱方法的研究进展。研究结论为：方波脉冲阳极溶出伏安法最常用于检测土壤Pb2+和Cd2+，伏安参数包括脉冲幅值、电压增量和脉冲频率，试验条件包括沉积时间、沉积电压和支持电解质种类及其pH值，土壤成分主要干扰因素包括非目标重金属和有机质。针对伏安参数和试验条件的影响可以设计优化试验有效削弱。针对非目标重金属和有机质的干扰影响，目前研究还没有提出有效的削弱方法。最后，展望了溶出伏安法检测土壤重金属的未来发展方向。     

不同微喷弥雾调控方式下微气候因子对极端干旱区葡萄果实生长及糖度的影响

通过对极端干旱区葡萄在不同微喷弥雾调控方式（WP1,架上喷水1 h;WP2，架下喷水1 h；WP3，地上喷水1 h）下微气候因子与葡萄果实生长形态及糖度的监测，分析葡萄园微气候因子变化规律及其与葡萄果实生长形态和糖度的关系。结果显示：采用微喷弥雾调控可有效降低葡萄园温度和增加湿度，与CK处理（常规滴灌，不喷水）相比，白天平均温度低2.9℃~3.3℃，平均温度低2.5℃~2.9℃，夜晚平均湿度高4.7%~5.5%，同时可促进葡萄果实生长和糖度累积，WP1、WP2和WP3与CK处理相比，果粒纵茎高出2.88、1.76、0.9 mm，果粒横茎高出1.33、1.80、1.76 mm，果粒均重高出0.22、0.26、0.25 g，糖度分别高出7.75%、3.96%和5.53%。在葡萄果实生长发育过程中，白天平均温度和平均温度是影响葡萄纵径和横径的关键微气候因子，晚上平均湿度是影响葡萄果实重量和糖度的关键微气候因子，在白天平均温度为30.4℃~33.8℃、晚上平均湿度为49.5%~50.5%时接近葡萄果实纵径、横径和果粒均重拟合值最大值。根据其相互关系和建立的回归模型，得出可以用白天平均温度、平均温度和晚上平均湿度对该地区葡萄生长和糖度变化进行分析和预测。     

Change features of time-series climate variables from 1962 to 2016 in Inner Mongolia,China

Detecting change features of climate variables in arid/semi-arid areas is essential for understanding related climate change patterns and the driving and evolution mechanism between climate and arid/semi-arid ecosystems.This paper takes Inner Mongolia of China,a unique arid/semi-arid ecosystem,as the study area.We first detected trend features of climate variables using the linear trend analysis method and then detected their trend-shift features using the breaks for additive seasonal and trend method based on the time-series of monthly precipitation and monthly mean temperature datasets from 1962 to 2016.We analyzed the different change features of precipitation and temperature on a regional scale and in different ecological zones to discover the spatial heterogeneity of change features.The results showed that Inner Mongolia has become warmer-wetter during the past 54 years.The regional annual mean temperature increased 0.4°C per decade with a change rate of 56.2%.The regional annual precipitation increased 0.07 mm per decade with a slightly change rate of about 1.7%,but the trend was not statistically significant.The warmer trend was contributed by the same positive trend in each season,while the wetter trend was contributed by the negative trend of the summer precipitation and the positive trend of the other three seasons.The regional monthly precipitation series had a trend-shift pattern with a structural breakpoint in the year 1999,while the regional monthly mean temperature series showed an increasing trend without a periodical trend-shift.After the year 2000,the warmer-wetter trend of the climate in Inner Mongolia was accelerated.The late 20th century was a key period,because the acceleration of the wetter trend in some local zones(I and II)and the alleviation of the warmer trend in some local zones(Ⅶ,Ⅷand IX)occurred simultaneously.Moreover,the change features had a strong spatial heterogeneity,the southeastern and southwestern of Inner Mongolia went through a warmer-drier trend compared with the other areas.The spatio-temporal heterogeneity of the climate change features is a necessary background for various types of research,such as regional climate change,the evolution of arid/semi-arid ecosystems,and the interaction mechanisms between climate and arid/semi-arid ecosystems based on earth-system models in Inner Mongolia.     

河南省农业干旱脆弱性分析

为减轻旱灾损失,根据2005、2015年河南省统计与气象数据,采用10项指标和灰色关联分析法,以最劣值为参照系列分析了该省农业旱灾脆弱性。结果表明,豫西的济源、三门峡、洛阳,豫东的开封、漯河与豫北的鹤壁是河南省干旱脆弱性较强的区域,而豫东南的商丘、驻马店、信阳,豫北的新乡、豫西南的南阳则脆弱性较弱,其他地区居于两者之间;2005—2015年河南省干旱脆弱性呈明显的增加趋势。河南省是中国粮食生产核心区,首先要依靠科技创新,大力发展节水农业、循环农业;其次要重视水资源的节约与保护、加大农业投入以降低干旱的脆弱性,确保粮食安全。     

饲草作物对土壤健康与农业可持续发展的作用

饲草作物是指为增加土壤肥力,防止土壤侵蚀,累积和保护土层,增加土壤养分和含水率以及提高土壤质量而种植的植物。饲草作物为农田土壤提供了诸多益处,其还有助于增加和维持土壤中的微生物多样性。本文对多种饲草作物对土壤特性的作用,如土壤含水量、土壤微生物的活动、土壤碳固存、土壤硝态氮淋失、土壤水分和土壤健康等进行综述。饲草作物的选择通常取决于其自身对土壤的作用,其他考虑因素还包括天气条件,播种时间,是否为豆科植物以及杀灭饲草作物的时间和方法。研究表明,饲草作物也可用于减缓气候变化,抑制作物中的杂草,增加可交换的营养物质如Mg2+和K+,具有一定的经济性。另外,覆盖作物也会存在一些问题,包括杀灭覆盖作物的方法,其可能成为病原体的寄主,饲草作物的再生性以及短期收益不明显。尽管有一些局限,饲草作物仍被认为可以明显改善土壤整体健康状况,为主栽作物提供可持续的生态环境。     

旱地燕麦间作对土壤酶活性、微生物含量及产量的影响

本文通过研究内蒙古旱作区禾本科、豆科及茄科间作对土壤生物性状的影响，旨在揭示燕麦（Avena sativa Linn）与不同作物间作及其单作在土壤酶活性、微生物量及土地当量比（LER）等方面的优势机理。本试验设置燕麦、黑豆（Glycinemax（L.）merr）、苜蓿（Medicago sativa）、马铃薯（Solanum tuberosum L）单作和黑豆间作燕麦、苜蓿间作燕麦、马铃薯间作燕麦共7个处理，探讨各处理对上述各指标的影响。结果表明：燕麦间作黑豆土地当量比最高，2015年和2016年分别为1.62和1.65。燕麦间作黑豆土壤脲酶活性和蔗糖酶活性较苜蓿间作燕麦、马铃薯间作燕麦显著提高了5.00%~51.61%和5.73%~52.29%。2015年和2016年播种后75 d苜蓿间作燕麦土壤过氧化氢酶活性显著高于黑豆间作燕麦，分别提高了29.47%和40.56%。黑豆间作燕麦对比其他两间作处理土壤微生物的生物量碳、氮含量分别显著提高了2.70%~17.89%和11.36%~26.47%，土壤脲酶活性提高了1.51%~55.22%，蔗糖酶活性提高了5.73%~52.29%，是该地区最优的间作模式。     

北京市蔬菜专业村产业集聚测度实证研究

以北京蔬菜专业村为研究对象,选取2012—2018年北京蔬菜专业村及蔬菜产业相关数据,运用区位商指数测算方法,从时间和空间两个层面对北京市蔬菜专业村产业集聚度进行测算;运用集中度指数测算方法,从专业村主导产业总产值和从业农户数两方面对集聚度进行测算。结果显示,北京市蔬菜专业村出现了集聚现象,但存在不稳定上下波动的问题,顺义区、通州区和平谷区总体集聚程度较高,并保持稳定集聚状态,集聚区域主要集中在顺义区和房山区。研究建议完善蔬菜专业村基础设施建设,打造蔬菜专业村区域品牌效应,发挥蔬菜示范村辐射带动作用,推进专业镇、基地及园区建设。     

脱涡致振式压电风力发电机性能分析与试验

为满足农业遥感监测系统的供电需求，减少化学电池对水和土壤的污染，提出一种脱涡致振式压电风力发电机，并从理论和试验两方面进行了研究。建立了脱涡致振式压电风力发电机的理论模型，通过仿真分析研究迎风角、压电振子长度及风速对压电振子变形量的影响，并对发电机样机进行了测试试验。结果表明，不同风速下均存在两个最佳迎风角，使发电机输出电压较大，压电振子长度为60、78mm，风速为7.6、11.6、12.4m/s时的两个最佳迎风角分别为(35°,135°)、(45°,125°)、(50°,120°)和(35°,120°)、(40°,115°)、(45°,110°)。当迎风角为120°时，存在最佳风速，使发电机输出电压达到最大；随着压电振子长度的增加，最佳风速由12.4m/s降低到8.4m/s，其对应的最大输出电压由16.6V增加为16.8V。当外接电阻为150kΩ、迎风角为30°时，试验测得最大输出功率为1mW。研究表明，根据实际风速确定合理的迎风角及压电振子长度可提高发电机的发电能力。     

基于SEBAL模型评估干旱半干旱区人工灌丛植被对陆表蒸散的影响

评估人工灌丛植被重建对干旱半干旱区陆地生态系统蒸散的影响,不仅能揭示植被变化与水文过程的耦合机理,又可为区域生态治理与水资源管理提供科学指导。该研究利用Landsat-8OLI/TIR遥感影像及气象数据等驱动SEBAL模型,反演宁夏盐池县的年内不同日期的陆表蒸散,结合目视解译选取的人工灌丛区与对照草地,评估了人工灌丛植被对陆表蒸散的影响。结果表明:1)SEBAL模型的蒸散反演精度与站点观测结果较为一致,可用于干旱半干旱区蒸散反演及空间特征研究;2)盐池县人工灌丛植被区日平均蒸散为1.20mm/d,高于对照草地1.17mm/d的日平均蒸散量,即干旱半干旱区人工种植灌木林增加了生态系统水分消耗,但不同季节和不同生物地理条件下的蒸散增强作用存在差异,蒸散增强在8月份最大,而3、4月份呈现负效应;3)人工灌丛的密度越大、植被盖度越高,对陆表蒸散的增强作用越强,特别在NDVI0.4的高盖度情况下蒸散增强作用更加明显。由此可知,在水资源紧缺的干旱半干旱区开展以灌木树种为主的植被重建需在合理的生态水文阈值范围内开展,才能构建出稳定可持续的人工生态系统。