基于林木病虫害防治的移动喷雾参数对雾滴穿透性影响分析

林木病虫害防治过程中,常采用皮卡搭载喷雾系统进行移动喷雾,以达到快速高效的目的。为了研究移动喷施农药过程中喷雾技术参数对雾滴穿透性的影响,本研究构建了由供液模块、喷雾压力调控和速度实时显示模块、喷头高度和角度调节模块、速度控制调节模块和防冲撞限位模块5大部分组成的移动喷雾测试系统。通过研制的移动喷雾测试开展试验分析,分别设置了3种喷施压力、4种搭载平台行驶速度、国产和进口不同的多个喷头,对仿真树靶标进行了喷雾试验,在仿真树冠层内设置8个采样点铺放卡纸来测定雾滴沉积覆盖率,采用iDASPRO雾滴沉积分析数据,以此来测试喷雾技术参数对雾滴穿透规律的影响。经过统计分析,得到影响喷头穿透效果大小的因素次序:喷雾压力>搭载平台移动速度>喷头孔径,采用Design Expert试验分析软件,建立以喷头孔径、搭载平台移动速度和喷雾压力为自变量、以雾滴覆盖率为应变量的多元非线性回归模型。结果表明:雾滴沉积量随着喷雾压力的增加呈现增加的趋势,当移动速度为最小的0.25m/s时,雾滴沉积量明显高于移动速度为0.50m/s和0.75m/s时的值,研究结果对于植保作业中移动喷雾参数确定和器械选择提供了理论依据与应用参考。     

畜禽粪便厌氧发酵过程抗生素抗性基因归趋及驱动因子分析

针对畜禽养殖业抗生素抗性基因(antibiotic resistance genes, ARGs)污染问题,该文选取厌氧发酵技术,对比不同厌氧发酵体系内ARGs消长与潜在宿主菌,挖掘不同因子与ARGs的相互关系。结果表明,厌氧发酵体系内微生物群落变化是ARGs消长的主要驱动因子,确定ARGs的潜在宿主菌是目前研究的难点;抗生素和重金属也是ARGs消长的重要驱动因子,控制抗生素污染和重金属污染可有效减缓ARGs污染;可移动遗传元件在ARGs水平传播过程中起着重要作用。综合而言,厌氧发酵体系内各个因子直接或间接影响ARGs消长,其中工艺参数是控制整个厌氧发酵体系的先决因素,在特定工艺参数下,微生物群落与体系物化指标相互影响与制约;微生物通过分子内部可移动遗传元件实现ARGs在不同微生物之间的水平传播。综上所述,通过综合协调各类因子实现厌氧发酵体系内ARGs消控是今后研究重点。     

甘肃省中东部农户地膜应用及回收现状

为了解甘肃省中东部地区农户地膜应用、回收状况及其主要影响因素,于2019年3月26日—4月1日采用手机问卷方式,在甘肃中东部开展了地膜应用及回收情况调查。结果显示:调查区域主要种植有玉米、小麦、蔬菜和马铃薯等作物覆膜面积占种植面积的73.2%;种植不同作物的调查农户中,99.3%玉米种植户采用覆膜技术,28.5%、77.1%、57.9%和52.1%种植户分别对小麦、蔬菜、马铃薯和其他作物采用覆膜技术;甘肃省中东部地区地膜回收方式主要为人工捡拾,占调查对象的89.3%;回收残膜的农户中47.7%的农户将残膜交给回收网点,28.3%在地头焚烧,13.8%将其堆放田间,7.9%进行填埋处理,还有2.2%采取其他方式处理;调查作物的地膜回收作业率均在80.0%以上,其中蔬菜高达99.3%;按照人工回收作业的地膜离田率为80%和90%分别估算,2018年甘肃省中东部地区地膜回收率达74.2%和83.5%,其中蔬菜上地膜回收情况最好,分别为79.4%和89.4%。目前甘肃省中东部地区地膜回收工作仍存在回收难度大、回收机械化强度不够、回收地膜处置不当,政府支持力度不够等问题。政府和相关部门应加大地膜新国家标准宣传及执行力度,制定相关扶持和奖励机制,提高地膜回收的机械化程度,快速推动农膜回收及资源化利用工作,为合理应用地膜及农膜污染防控提供数据支撑。此外,手机调查地膜应用及回收系统的启用,能快速有效地获得一手数据,为未来全面快速获取中国地膜应用回收的基础数据提供借鉴。     

Extraction of mobile element fractions in forest soils using ammonium nitrate and ammonium chloride

The extraction of earth alkaline and alkali metals (Ca, Mg, K, Na), heavy metals (Mn, Fe, Cu, Zn, Cd, Pb) and Al by 1 M NH₄NO₃ and 0.5 M NH₄Cl was compared for soil samples (texture: silt loam, clay loam) with a wide range of pH(CaCl₂) and organic carbon (OC) from a forest area in W Germany. For each of these elements, close and highly significant correlations could be observed between the results from both methods in organic and mineral soil horizons. The contents of the base cations were almost convertible one‐to‐one. However, for all heavy metals NH₄Cl extracted clearly larger amounts, which was mainly due to their tendency to form soluble chloro complexes with chloride ions from the NH₄Cl solution. This tendency is very distinct in the case of Cd, Pb, and Fe, but also influences the results of Mn and Zn. In the case of Cd and Mn, and to a lower degree also in the case of Pb, Fe, and Zn, the effect of the chloro complexes shows a significant pH dependency. Especially for Cd, but also for Pb, Fe, Mn, Zn, the agreement between both methods increased, when pH(CaCl₂) values and/or contents of OC were taken into account. In comparison to NH₄Cl, NH₄NO₃ proved to be chemically less reactive and, thus, more suitable for the extraction of comparable fractions of mobile heavy metals. Since both methods lead to similar and closely correlated results with regard to base cations and Al, the use of NH₄NO₃ is also recommended for the extraction of mobile/exchangeable alkali, earth alkaline, and Al ions in soils and for the estimation of their contribution to the effective cation‐exchange capacity (CEC). Consequently, we suggest to determine the mobile/exchangeable fraction of all elements using the NH₄NO₃ method. However, the applicability of the NH₄NO₃ method to other soils still needs to be investigated.     

Spatial pattern and heterogeneity of soil properties in sand dunes under grazing and restoration in Horqin Sandy Land, Northern China

Applying a combination of classical and geostatistical methods, we identified soil properties and their spatial variation in a 5-year grazed sand dune (GSD5) and a 20-year recovered sand dune (RSD20) in Horqin Sandy Land, northern China. The paper assesses the effect of grazing, topography and vegetation restoration on spatial heterogeneity of soil properties. The results showed that soil organic carbon, total nitrogen, very fine sand (0.1–0.05 mm) content and their coefficients of variation were lower in GSD5 than in RSD20, while soil water contents (0–20 cm and 20–40 cm depths) were higher in GSD5 than in RSD20. Geostatistical analysis revealed that the spatial structured variance accounted for the largest proportion of total sample variance in soil properties at the measured scale under grazing and restoration. The spatial autocorrelation ranges were 66.30 m for soil organic carbon and 50.80 m for total nitrogen in GSD5 less than those in RSD20 (70.00 m and 76.10 m, respectively), while the spatial autocorrelation ranges of soil particle size fractions and soil water contents in RSD20 were less than those in GSD5. Kriging-interpolated maps also showed that the heterogeneity of soil organic carbon and total nitrogen and their degree of patch fragmentation were higher in GSD5 than in RSD20. These results suggested that continuous grazing resulted in an increase in spatial variability of soil nutrient and a decrease in spatial variability of soil particle size fractions and soil water content. Soil organic carbon and total nitrogen of sand dunes are associated closely with soil particle size fractions, relative height of sampling site and vegetation cover. Spatial patterns of soil properties are most strongly related to grazing, topography and plant-induced heterogeneity in sand dune ecosystems prone to wind erosion.     

基于自主导航和全方位转向的农用机器人设计

为了提高农业作业的自动化程度,在对传感器技术、信息技术、自动导航技术等进行研究的基础上,设计了一种自动导航农用轮式移动机器人.针对目前农业机器人存在的操纵、路径跟踪等技术问题,机器人采用四轮全方位转向,操纵灵活;利用CAN总线使导航、控制等模块的通讯效率得以改善;选用模糊控制模仿人在路径跟踪控制时的控制策略,提高了移动机器人的智能化程度.仿真和试验表明机器人有较好的转向性能且在速度为1 m/s时跟踪路径的偏差为0.1 m左右.     

基于PID直流电机驱动的移动式采摘机器人设计

为了提高移动式采摘机器人的控制效率和移动精度,将直流电机驱动电路引入到采摘机器人移动控制系统的设计中,并采用PID算法对移动速度进行调节,从而避免采摘机器人在移动过程中产生较大的速度波动,提高其作业时的平稳性。为了验证PID算法在采摘机器人移动控制系统上使用的可行性,模拟葡萄采摘机器人的作业环境,对采摘机器人移动过程的速度控制进行了仿真模拟,结果表明:达到速度预定目标时,PID算法比常规算法具有更快的响应速度,调节过程也更加平稳。     

Spatio-temporal variation of soil moisture in a fixed dune at the southern edge of the Gurbantunggut Desert in Xinjiang,China

Soil moisture is critical for vegetation growth in deserts. However, detailed dataregarding the soil moisture distribution in space and time in the Gurbantunggut Desert have not yet been reported. In this study, we conducted a series ofinsitu observation experiments in a fixed sand dune at the southern edge of the GurbantunggutDesert from February 2014 to October 2016, to explore the spatio-temporal variation of soil moisture content, investigate the impact of Haloxylonammodendron (C. A. Mey.) Bungeon soil moisture content in its root zone, and examine the factors influencing the soil moisture spatial pattern. One-way analysis of variance,least significant difference testsand correlation analysis were used to analyze the data. The results revealed that the soil moisture content exhibited annual periodicity and the temporal variation of soil moisture content throughout a year could be divided into three periods, namely, a moisture-gaining period, a moisture-losing period and a moisture-stable period.According to the temporal and spatial variability, the 0-400 cm soil profile could be divided into two layers: an active layer with moderate variability and a stable layer with weak variability.The temporal variability was larger than the spatial variability in the active layer,and the mean profile soil moisture content at different slope positions displayed the trend of decreasing with increasing relative heightand mainly followed the order of interdunearea>westand east slopes>slope top.The mean profile soil moisture content in the root zone of dead H. ammodendronindividuals was significantly higher than that in the root zones of adult and young individuals, while the soil moisture content in the root zone of adult individuals was slightly higher than that in the root zone of young individuals with no significant difference.The spatial pattern of soil moisture was attributable to the combined effects of snowfall, vegetation and soil texture, whereas the effects of rainfall and evaporation were not significant. The findings may offer a foundation for the management of sandy soil moisture and vegetation restoration in arid areas.     

基于Lucid多途径检索的油茶害虫诊断APP开发与实现

油茶是亚热带地区重要的木本油料作物,近年来随着种植面积的不断扩大和集约化经营,病虫害问题日益严重,对油茶的产量和品质造成不同程度的影响。本研究通过野外调查、文献查阅、种类鉴定等工作,整理了21种油茶主要害虫的形态特征、生物学习性、为害特点、防治措施等信息,并拍摄相应害虫及为害状的高清照片1 600张。采用Lucid智能诊断系统,构建Fact Sheet Fusion基础信息数据库,并针对多途径检索方式提取害虫"为害方式"、"为害部位"、"为害高峰期"、"形态特征"等4个1级特征组,以及10个2级特征和18个3级特征,共组成102个特征状态,构建了油茶害虫的快速诊断系统。在此基础上,转换得到基于Android系统的手机应用APP,为林农和森防一线工作者对油茶害虫快速识别和防治提供便捷服务,从而促进油茶产业持续健康发展。