Response of the soil fungal community to multi-factor environmental changes in a temperate forest

Both environmental and climatic changes are known to influence soil microbial biomes in terrestrial ecosystems. However, there are limited data defining the interactive effects of multi-factor environmental disturbances, including N-deposition, precipitation, and air temperature, on soil fungal communities in temperate forests. A 3-year outdoor pot experiment was conducted to examine the temporal shifts of soil fungal communities in a temperate forest following N-addition, precipitation and air temperature changes. The shifts in the structure and composition of soil fungal communities were characterized by denaturing gradient gel electrophoresis and DNA sequencing. N-addition regimen induced significant alterations in the composition of soil fungal communities, and this effect was different at both higher and lower altitudes. The response of the soil fungal community to N-addition was much stronger in precipitation-reduced soils compared to soils experiencing enhanced precipitation. The combined treatment of N-addition and reduced precipitation caused more pronounced changes in the lower altitude versus those in the higher one. Certain fungal species in the subphylum Pezizomycotina and Saccharomycotina distinctively responded to N fertilization and soil water control at both altitudes. Redundancy discrimination analysis showed that changes in environmental factors and soil physicochemical properties explained 43.7% of the total variability in the soil fungal community at this forest ecosystem. Variations in the soil fungal community were significantly related to the altitude, soil temperature, total soil N content (TN) and pH value (P < 0.05). We present evidence for the interactive effects of N-addition, water manipulation and air temperature to reshape soil fungal communities in the temperate forest. Our data could provide new insights into predicting the response of soil micro-ecosystem to climatic changes.     

不同施肥处理对“稻花香”食味的影响

以"稻花香"为供试材料,研究了不同施肥处理(T1,常规处理;T2,豆饼处理;T3,豆饼+麦饭石处理)对稻米食味品质的影响。结果表明,T3处理的整精米率高于T1和T2处理,垩白粒率表现为T3T2T1,而碎米率表现为T3T2T1。从稻米的成分来看,蛋白质含量表现为T1T2T3的倾向,3种处理的直链淀粉含量无显著差异,T3处理的评分极显著高于T1和T2处理,T1和T2处理间差异不显著。淀粉糊化特性方面,最高粘度表现为T2T3T1,崩解值表现为T3T2T1,而消减值表现为T3T2T1。品尝试验中,3个处理在米饭外观上的差异不明显,T2、T3处理的香气与T1处理存在显著差异,T2、T3处理的综合评价值极显著高于T1处理。T2处理的味道、粘度和硬度与T1处理差异不显著,而T3处理的味道和粘度与T1处理存在显著差异。     

基于SPEI_PM指数的渭河流域气象干旱时空演变特征

利用渭河流域25个气象站点1980−2018年月值气象数据集，基于Penman-Monteith蒸散模型计算多个时间尺度的标准化降水蒸散发指数（SPEI），分析渭河流域气象干旱的演变、趋势、影响范围、发生频率和持续时间等时空变化特征，以期为渭河流域防灾减灾管理提供科学依据。结果表明：（1）近39a来渭河流域有明显的干湿周期变化，但整体上呈变干的趋势，干旱时段主要集中在1995−2009年，其中以2000−2009年的干旱站次比最大，平均达到36%，且干旱持续时间最长，约3.6个月，1980−1989年干旱持续时间最短，约1.6个月；（2）渭河流域秋季总体呈湿润变化趋势，而春季和夏季干旱在不断加剧，是区域年际干旱的主要驱动力；（3）渭河流域干旱以危害性较小的轻中旱为主，但2000年前后出现严重及极端干旱的站次相对较多，其中1997年研究区内发生的干旱程度较高，影响范围较广；（4）不同时间尺度各等级干旱发生频率的变化规律表现一致，均呈现出干旱等级越高发生频率越低的态势，且极端干旱在年际尺度内发生次数较为频繁，从空间上看渭河流域东北部是干旱多发区。总之，近39a来渭河流域总体干旱较为严重的时段为2000−2009年，且研究区内干旱呈北重南轻特征，因此北部地区仍需加强防灾管理。     

The optimal nutrition of maize in the hungarian national long‐term field experimental network

In Hungary, maize is grown on 1 million ha and occupies more than 20% of the arable land. The rich assortment of maize cultivars of different vegetation periods and different responses to nutritional effects, water supply etc. gives the growers the possibility to choose the cultivars suiting best the site characteristics (Jolânkai et al. 1999). Among the cereals maize has the highest genetical potential. To utilize its yield and quality potential, soil types of high nutrient content and regular nutrient supply are required (Gyõrffy, 1979). Both over‐ and under‐fertilization have an unfavourable effect on the yield and quality of maize (Debreczeni, 1985). Crops can be supplied with the appropriate nutrient amounts only with the knowledge of soil characteristics in the different agro‐ecological regions (nutrient content, water supply, soil compactness, pH, nutrient supplying capacity etc.). In Hungary, a network of long‐term field fertilization trials with uniform fertilizer treatments has been maintained at nine experimental sites representing different agro‐ecological regions of the country. This experimental network gives a basis to test the nutrient responses of our main crops and calibrate their optimal nutrient supply (Kismányoky, 1991).     

培肥措施对旱地农田土壤CO2排放和碳库管理指数的影响

阐明长期有机物料施肥下土壤CO₂排放特征及其影响机制以及碳库管理指数对黄土高原旱作农业区固碳减排及施肥模式选择的影响尤为重要。基于2012年设置在陇中黄土高原旱作区的长期定位试验,通过不施肥（CK）、氮肥（NF）、有机肥（OM）、秸秆（ST）、有机肥结合无机肥（OMNF）5个处理,测定并计算了2018年不同施肥措施下全年土壤CO₂排放、作物碳排放效率和碳库管理指数的变化,并运用结构方程模型分析了0~30 cm土壤温度、水分、微生物量碳氮、易氧化有机碳、蔗糖酶、脲酶与土壤CO₂排放速率的关系。结果表明：1）与不施肥相比,秸秆、有机结合无机肥和有机肥处理使生育期土壤CO₂排放平均速率提高了42.72%、30.82%和29.79%,秸秆、有机肥处理分别使生育期土壤CO₂排放量显著提高36.35%、32.45%（P<0.05）,有机结合无机肥处理使碳排放效率显著降低41.10%（P<0.05）;2）有机物料处理均能显著提高0~5 cm土层易氧化有机碳、微生物量碳氮、蔗糖酶活性和碳库管理指数,相比不施肥和氮肥处理,有机结合无机肥处理分别使0~30 cm土壤碳库管理指数提高127.41%,99.33%（P<0.05）;3）结构方程模型表明,环境因子对土壤CO₂排放速率的总解释度为53%,对土壤CO₂排放速率总效应较大的影响因素包括土壤温度（2.36）、微生物量碳（1.59）和土壤水分（1.18）,且均间接地影响着土壤CO₂排放速率,土壤温度促进了微生物量碳和蔗糖酶活性的提高,微生物量碳促进了微生物量氮和易氧化有机碳的增加。综合来看,有机结合无机肥处理可以提升土壤碳库管理指数,保持微生物活性,增加作物产量,降低土壤碳排放效率,是陇中黄土高原旱作农业区比较适宜的农田培肥措施。     

补播羊草和黄花苜蓿对退化草甸植物群落特征的影响

呼伦贝尔草原区是我国北方重要的生态屏障,近年来不合理的利用方式导致该地区退化草地面积不断扩大,为了探究牧草补播时间及补播比例对呼伦贝尔退化草甸草原植物群落特征的影响,为该地区退化草地修复提供依据。本研究以羊草（Leymus chinensis（Trin.） Tzvel.）和黄花苜蓿（Medicago falcata L.）为试验材料,采用双因素随机区组试验设计,通过测定幼苗数、高度、生物量等群落指标,并综合评价补播效果,结果表明：夏播羊草和黄花苜蓿幼苗数量显著高于春播和秋播（P<0.05）,夏播和秋播植物群落总生物量呈增加趋势,春播则呈减少趋势;补播措施提高了退化草地植物群落Shannon-Weiner指数、Simpson指数和Pielou指数,豆科和禾本科植物重要值呈增加趋势,其他科植物呈下降趋势。呼伦贝尔地区夏季补播羊草和黄花苜蓿以1∶3补播效果较好,而春播由于恢复时间短,需进一步观察。     

荷斯坦奶牛休息时间的群体特征及影响因素分析

为探究北京地区荷斯坦奶牛休息时间的群体规律及影响因素,本研究收集了北京地区某规模化牧场2018年4月至2020年4月共838头荷斯坦奶牛的休息时间及对应的奶牛生产性能测定记录及环境温湿度数据,利用SAS 9.2软件的GLM过程分析了年份、季节、场区、胎次和泌乳月等因素对荷斯坦奶牛休息时间的影响,并分析了休息时间对荷斯坦奶牛生产性能的影响。结果显示,荷斯坦奶牛平均休息时间为397.39 min/d,范围为87.74~707.03 min/d,变异系数为26%;休息时间随季节呈先降低后升高的趋势,夏季最低,冬季最高;随环境温湿度的升高而逐渐降低;产犊和发病对休息时间均有较大影响,产犊和发病当天奶牛休息时间均存在一个峰值,之后逐渐降低至正常水平;测定年份、季节、场区、胎次和泌乳月份对休息时间均有极显著影响（P<0.01）;荷斯坦奶牛产奶量随休息时间的升高而降低。本研究为利用自动化记录设备探究奶牛的行为规律及利用连续测定的休息时间数据提高牛群的精准管理水平提供了理论依据。     

Changes in Physical Properties of Soils with Land Use Time in the Brazilian Savanna Environment

Soils from central Brazil have been intensively used over the last decades because of the rapid conversion of savannas ( Cerrado ) into corn/soybean fields. The objective of this work is to study modifications in the physical properties of soils in the Rio Verde watershed, as a function of the land use time for agriculture, determined from classification of Landsat satellite images between 1980 and 2010. Soil samples were collected at surface (0–20 cm) and subsurface (20–40 cm) horizons for the different classes of land use time (<10, 10–20, 20–30, and >30 years). The following physical properties were measured: bulk density (BD), air permeability (K_a), penetration resistance (PR), microporosity (MI), macroporosity (MA), and total porosity (TP). Results showed a strong expansion with time of agriculture that occupied 35·3% (1980), 37·4% (1990), 51·3% (2000), and 60·9% (2010) of the watershed area. When properties were compared with those from the reference areas (preserved soils under native vegetation), significant differences were observed for all the physical attributes of soils for a land use time higher than 20 years. Overall, BD and PR increased with land use time, and the opposite was verified for K_a, MA, and TP. Some physical properties presented values (e.g., 1·54 g cm⁻³ for BD and 0.06 cm³ cm⁻³ for MA) close to the critical ones reported to affect crop development, but they were not still impacting on local soybean yield. Copyright © 2013 John Wiley & Sons, Ltd.     

基于模糊控制的水肥药一体化系统研究

为了提高目前水肥药一体化系统的自动化程度,设计了一种智能水肥药一体化系统;针对系统混肥精度不高的问题,设计了适用于营养液混合的模糊控制器,并利用Lab VIEW完成整个系统应用软件的开发。该系统不但能够实现独立灌溉、灌溉施肥一体化、灌溉施药一体化及水肥药一体化,而且还具备控制指令输入、系统工作监控和系统信息查询的功能。     

滴灌水肥管理对日光温室黄瓜产量和品质的影响

采用田间试验,研究滴灌系统运行方式和施肥频率对黄瓜产量、品质的影响。结果表明:施肥频率对黄瓜的生长、产量和品质的影响显著,在开花期与采收期,提高施肥水平能促进植株株高和叶片数的增加,产量和品质随施肥频率的增加而增加。因此,从提高产量和品质的角度看,施肥频率取两周1次较为适宜,滴灌施肥灌溉过程中的施肥时段应尽量前移。