梳穗收获飞溅损失的分析和试验

梳穗收获时梳穗齿和穗头的梳脱位置对梳穗收获机的性能影响较大．本文对梳穗收获的飞溅损失进行了初步分析与探讨．确定降低飞溅损失的最佳梳脱区和有效梳脱区并进行了试验，找出了影响飞溅损失的主要参数。     

植树挖坑机钻头主轴扭转振动数学建模与求解

介绍国内外机械化植树造林机械发展状况,指出国内植树用挖坑机研究重点,利用空间运动学和机械振动理论以及弹性动力学原理着重分析建立钻头主轴扭转振动模型并用数值方法进行求解,同时系统地分析钻头主轴下端部件与土壤的相互作用力、钻头主轴重力及惯性力等因素的影响,给出动态的准随机边界条件和初始条件.为下一步的钻头动力学特性仿真及整机动态特性研究,合理预测和控制钻头的运动规律,改善钻头的动力学特性,提高钻头工作效率及改进设计方法提供新的理论依据.     

不同含水率对谷子籽粒压缩力学性质与摩擦特性的影响

为了探明不同含水率谷子籽粒的物理机械性质,减少谷子籽粒在播种、碾米加工及储运等过程中受到压缩载荷及摩擦而产生的机械损伤,该文针对不同含水率的谷子籽粒进行压缩力学性质与摩擦特性试验。研究了谷子籽粒的挤压破碎过程,获得不同含水率谷子籽粒的力-位移（变形）曲线,破坏力、变形量及破坏能。随着含水率升高,破坏力减小,变形量和破坏能呈现先降低后升高的变化规律。同时采用赫兹接触理论,得到谷子籽粒单向表观弹性模量和许用挤压应力,结果表明二者都随含水率升高线性降低。分别测定了谷子籽粒与钢板和铝板间的滑动摩擦系数,随含水率升高,谷子与该2种材料的摩擦系数均增大,且与铝板的摩擦系数要高于钢板。根据试验结果,分别拟合得到了压缩和摩擦力学性能指标与谷子含水率的关系方程,为谷子播种、仓储、加工等装备设计及参数优化提供了基础依据。     

鲜香菇中甲醛含量检测的样品前处理方法改进(简报)

鲜香菇分别用传统方法和改进的方法匀浆后再通过蒸馏提取甲醛,再用高效液相色谱测定甲醛含量。在改进的样品前处理方法中,除热处理外的其余操作均在冰水浴下完成,样品匀浆后增加沸水浴5min进行灭酶处理。甲醛含量测定结果显示改进后的方法的测定结果显著低于传统方法,更准确反映鲜香菇中甲醛的真实含量。改进后的方法精密度为93.53%,加标回收率为96.97%～99.00%,符合一般定量检测的要求。     

对进一步推进闽北农村科技信息化服务平台建设的思考

本文结合南平市农村科技信息化服务平台建设的现有基础和存在问题,提出进一步推进闽北农村科技信息化服务平台建设的工作思路。     

砒砂岩与沙复配土壤的冻融特征

[目的]揭示砒砂岩与沙复配土壤冻融特征及其对风蚀的影响,为毛乌素沙地土地整治可持续性提供理论依据。[方法]利用陕西省榆林市榆阳区气象资料和土壤观测数据,结合含水量变化规律,以砒砂岩与沙复配土壤为研究对象,沙土为对照,探究2种土壤冻结层形成差异、冻融过程及积雪消融特点。[结果]由于含水量的差异,复配土壤与沙冻结层形成特点具有差异,沙地表层通常会形成土壤干层,从表层之下冻结,而复配土壤的冻结层在地表形成;复配土壤的最大冻结深度为116.0cm;大于沙地的最大冻结深度96.0cm,且冻结层融解时间晚于沙地一周;积雪覆盖条件下,沙地表层存在1.0~6.4cm的土壤干层,而复配土壤表层不存在干层,复配土壤积雪盖度和厚度均大于原始沙地,阳坡尤为显著。[结论]土壤冻层和积雪在复配土壤地表形成了2层保护层,减少了休闲期的风蚀作用。     

Effects of Curtailment of Nitrogen Fertilizer on Biological Properties and Tea Leaf Yield in Acid Tea Field Soils

In Japan, the soils in tea fields are further acidified by heavy application of nitrogen fertilizer. In the long-term fertilizer application fields, available P, total carbon and nitrogen contents had the highest in the Multi-F plot, followed by the 98-D.F plot and the smallest in the 95-D.F plot. Soil enzymes activity had the highest the Multi-F plot. It was estimated that all of the enzyme activity were often corresponded with the results of the organic matter and the available P contents. The number of fungi under acidic condition had the close relation since change of these enzymes activity. It was evident that fungi were participated in carbon, nitrogen and phosphorus metabolism in acid tea field soils. It became clear that the number of fungi and enzymes activity decreased corresponding well with the available P and the organic matter contents depend on fertilization management. Moreover in case of qualities of green tea, generally difference between experimental plots and Multi-F plot were to be small. It was indicated that influence to the yields by curtailment of the amount of nitrogen fertilization was small.     

水氮耦合对滁菊产量和品质的影响

采用二因素二次回归旋转组合设计,以盆栽试验方式研究了水、氮因子对滁菊产量和品质的影响,探讨了滁菊人工栽培适宜的水氮管理模式。研究结果表明,水氮耦合对滁菊花产量、叶片水提总黄酮和氯原酸含量、滁菊花水提总黄酮和氯原酸含量均有极显著影响,水氮间存在显著交互作用。氮肥因子对滁菊花产量、总黄酮含量、氯原酸含量的影响大于水分因子。当土壤水分水平为0.284 1,氮肥水平为0.403 7时,即田间持水量80%,氮肥用量0.257g/kg时,滁菊花产量最高,达18.09g/株;当土壤水分和氮肥用量均为-1.414水平时,即田间持水量50%,氮肥用量为0g/kg时,滁菊花总黄酮含量和氯原酸含量最大。从滁菊花产量、品质角度综合考虑,滁菊生育前期水氮管理以中水中氮较为适宜,滁菊现蕾开花期以低水低氮较为适宜。     

DEM分辨率对集约化蔗区小流域水文连通性指数的影响

[目的]探究集约化蔗区小流域地表微地形特征参数与水文连通性指数随DEM不同分辨率的变化以及水文连通性指数的最佳DEM分辨率,为后续水文连通性相关研究、农业面源污染及土壤侵蚀等研究提供理论依据与参考.[方法]基于ArcGIS与无人机高分辨率影像,利用分区统计等方法,以中国南方集约化蔗区小流域为例,研究了 DEM不同分辨率...     

Deep incorporation of corn straw benefits soil organic carbon and microbial community composition in a black soil of Northeast China

‘Deep incorporation of corn straw’ (CSDI) is to concentrate the burial of corn straw into the subsurface soil layer (20–40 cm) and to break the plough pan, thereby creating a loosened plough layer (0–20 cm) and a fertile subsurface soil layer. However, its impacts on soil organic carbon (SOC) and the microbial community remain poorly understood. A field experiment was conducted to investigate the effects of 1-year CSDI (CD1), 3-year CSDI (CD3) and 5-year CSDI (CD5) on soil aggregates and aggregate-associated SOC, as well as bacterial and fungal community characteristics (examined by the high-throughput gene sequencing method). The results demonstrated that SOC and soil fungal diversity were decreased by CD1, but increased by CD3 and CD5. Compared with the control, CD5 promoted 2–0.25 mm soil macroaggregation, significantly increased SOC by 8.94% and aggregate-associated SOC by 5.96%–8.84%, consequently improving the physical protection of SOC by soil aggregates. CD3 and CD5 enhanced the richness and diversity of soil bacteria and fungi, and altered community composition. For soil bacteria, the relative abundance of Acidobacteria and Chloroflexi was increased, while that of Firmicutes, Gemmatimonadetes, Sphingomonas and Bacillus was decreased. For soil fungi, the relative abundance of Ascomycota, Zygomycota, Mortierella and Fusarium was greatly improved, but that of Basidiomycota was reduced. These obvious variations in microbial community structure were beneficial to straw degradation and SOC accumulation. Overall, the optimization of microbial community with CSDI plays a positive role in promoting soil organic matter, nutrient cycling and carbon sequestration, and thus improving soil fertility.