1LYQ-422ZF左翻驱动圆盘犁的设计及其耕作试验

论述了左翻驱动圆盘犁传动系统的设计要点.利用Visual C++语言自行编制的软件平台及测试系统进行左翻驱动圆盘犁田间耕作试验.结果表明:在适耕土壤中,其耕深大,覆盖率达85%左右,地表沟底平整,平衡性能强,耕作性能好;在干硬土壤中倾翻力矩小,能较好地平衡,但耕作质量下降;随着耕作速度的增大,倾翻力矩增大,覆盖率降低,耕深减小.     

丘陵山区耕作层剥离再利用空间配置方法

为完善耕作层剥离再利用空间配置方法与理论,指导编制专项规划,该文在利用层次分析法构建耕作层剥离适宜性与覆土优先度评价模型,筛选适宜剥离和优先覆土田块的基础上,提出基于供需平衡圈的耕作层剥离再利用空间配置思路与方法,并以福建丘陵山区光泽县为例开展实证研究。结果显示:研究区规划允许建设区内耕作层适宜剥离的面积为169.23 hm2,土方量为3.01×105m3;覆土首选与备选区耕作层需求面积分别为706.1与6 646.4 hm2,需求土方量分别为7×105和2.41×106m3;空间配置结果共划定了33个供需平衡圈,覆土总面积为559.03 hm2,其中新增耕地57.79 hm2,占剥离面积的34.1%;改良中低产田501.25 hm2,占中低产田总面积的37.6%。平均运输距离为4.65 km,小于限定的运输适宜距离。该文提出的空间配置方法兼顾成本与效益,可操作性强,具有一定的可推广性。     

田间原位试验分析长期机械作业下稻麦轮作地块土壤入渗性能

田间原位不同深度入渗试验是表达土壤分层状态、展示土层物理分异以及定量土壤剖面水功能变化的关键。为了探究不同深度水稻土的入渗能力及保水作用,该研究以华东稻麦轮作区小农户长期机械化耕整模式下代表地块的土层分异为目标,设计田间原位不同深度入渗试验。在试验地块内开挖7个不同深度的入渗坑并在坑底进行入渗试验,然后渗透48 h分层测取土壤含水率,研究不同坑底深度（坑深）土壤的入渗能力和入渗后各土层含水率的变化。结果表明,不同深度入渗试验准确表达了不同坑深土壤的水分入渗及土层持水分异,同时也能清晰地鉴别出犁底层所在位置和厚度,犁底层始于15 cm深,且耕作层与犁底层分异明显,耕作层平均紧实度为1 005.79 kPa,犁底层平均紧实度为1 910.73 kPa;土壤剖面分析表明,耕作层土壤形态疏松,根系分布稠密,犁底层土壤容重大,孔隙度小,透水性差,心土层土壤铁锰斑点较多,结构性差;土壤入渗参数随坑深的增加而减少,其中0～15 cm坑深范围内平均的平均入渗速率和累计入渗量分别为>20～30 cm的17.04倍和18.06倍;通过对比初始含水率和渗透48 h后含水率,得到坑深在15 cm范围内的...     

中国耕作层土壤剥离利用研究进展

通过分析中国耕作层土壤剥离利用研究现状,提出耕作层土壤剥离利用的关键问题和主要方向.运用文献调研法,剖析中国耕作层土壤剥离利用在类型、土壤调查评价、剥离、储存和回覆等技术环节,以及组织管理模式等方面的探索与实践.现阶段中国耕作层土壤剥离利用研究以实证分析为主,研究对象主要为试点市县和部分单独选址项目;耕作层土壤剥离利用工作暂无统一遵循的规范程序和技术体系,各技术环节均缺乏标准提炼;理论研究比较薄弱,暂未形成规律性总结.今后中国耕作层土壤剥离利用的研究重点是:健全完善规章制度,加强监督管理;规范耕作层土壤剥离利用程序,制订实施的技术标准;建立和完善耕作层土壤剥离利用相关的激励和约束机制;吸收国外耕作层土壤剥离利用的有益经验,探索在中国更具可行性和可操作性的路径和方法.以期为有效保护耕地资源,稳定粮食生产及保护生态环境提供科学指导.     

Sites and processes of nutrient accumulation in the subsoil through water percolation from the plow layer in a submerged paddy soil microcosm

The leaching of nutrients from the plow layer by water percolation and their accumulation in the subsoil observed in a Japanese paddy field (Katoh et al. 2004: Soil Sci. Plant Nutr., 50, 721-729) were determined semi-quantitatively in a soil column experiment. Ca²⁺, Mg²⁺, K⁺, Mn²⁺, Fe²⁺, and phosphate in percolating water from the plow layer soil column were retained in the subsoil columns that were connected to the plow layer soil column. Fe²⁺, K⁺, and phosphate accumulated in the uppermost part of the subsoil. Accumulation of Fe²⁺ in the uppermost part of the subsoil was presmnably due to the cation exchange process with concomitant desorption of Ca²⁺. In contrast, Ca²⁺ and Mg²⁺ in percolating water from the plow layer soil colmnn accumulated once in the subsoil, and translocated downwards slowly with successive water percolation. Considerable amounts of inorganic carbon (IC) and dissolved organic carbon (DOC) in percolating water from the plow layer soil column were also retained in the subsoil columns. IC did not accumulate a gaseous form.     

挖损农田复垦前后地力变化研究——以华北平原的曲周县为例

以曲周县为例,通过野外调查、采样和实验室分析,对挖损耕地复垦后的土壤肥力变化进行了研究。研究结果表明,挖损耕地与对照耕地相比较,土壤肥力包括土壤有机质、全氮、有效磷、速效钾含量没有显著差异,土壤容重变小。建议复垦工作必须因地制宜,在平原地区只要挖损耕地在不超过一定深度影响耕作的情况下,可以直接恢复耕种,不需要进行专门的复垦工程进行挖损耕地的复垦和培肥。     

渗碳工艺对高速液压翻转犁犁尖部件耐磨性的影响

针对在犁尖部件的局部区域堆焊硬质合金层仍无法解决现有国产犁尖整体耐磨性不足的问题,该研究对高速液压翻转犁犁尖部件整体采用渗碳-淬火-回火处理,并探讨了该工艺对犁尖微观组织与耐磨性的影响机制。研究结果表明,经渗碳-淬火-回火（Carburizing-Quenching-Tempering）工艺处理后的犁尖（CQT态犁尖）近表层最大碳质量分数约为0.70%,渗层深度约为2.5 mm,其表层组织为针状马氏体（高硬度）+残余奥氏体+少量碳化物,芯部组织则以板条马氏体（高强韧性）为主,这与经淬火-回火（Quenching-Tempering）工艺处理后的犁尖（QT态犁尖）中的板条马氏体+先共析铁素体组织明显不同,微观组织的改善使CQT态犁尖近表层的显微硬度较QT态犁尖提高56%。同时,与QT态犁尖相比,CQT态犁尖芯部的屈服强度和抗拉强度分别提升16%和20%。摩擦磨损试验及田间试验表明,CQT态犁尖的平均摩擦系数较QT态犁尖下降约22%,耕作120 hm2后的CQT态犁尖的磨损量较QT态犁尖降低37%,这主要归因于渗碳层中含有高硬度针状马氏体及残余奥氏体的应变诱导马氏体相变的综合强化作用。此外,与QT态犁尖相比,CQT态犁尖的耐磨性更高,使其具有更大的表面积,这有利于通过减小犁尖单位面积上的载荷和摩擦放热量来减轻待磨层材料蠕变软化的倾向,从而提高CQT态犁尖的耐磨性。上述研究结果可望为改善农机触土部件的耐磨性提供可行的技术方案。     

双向犁圆柱凸轮自动翻转机构

当犁体入土时,利用拖拉机的牵引力压缩弹簧贮存能量;机组耕作到地头时,拖拉机的液压提升机构将犁体提升后,通过圆柱凸轮机构即可实现双向犁的自动翻转。该机构设计合理,翻转平稳,运转可靠,结构上有创新性。     

1LF-335液压翻转犁悬挂参数优化设计

设计悬挂参数往往难于兼顾各方面性能的矛盾要求,确定重量增幅较大的液压翻转犁的悬挂参数尤其困难。为合理确定1LF-335液压翻转犁的悬挂参数,以该犁配套JDT-654拖拉机为研究对象,以较重要的耕深稳定性为目标函数,其余性能要求体现在约束条件和机组校核里,建立多约束单目标优化模型,采用非线性规划BFGS算法求解,并利用MATLAB编程实现,优化设计液压翻转犁的悬挂参数。设计结果和在1LF-335液压翻转犁上应用表明,所选悬挂参数有效实现了各项性能指标兼顾并均达到技术要求,液压翻转犁重量较大,应选用较大允许承载力的限深轮。     

Tillage and residue management effects on temporal changes in soil organic carbon and fractions of a silty loam soil in the North China Plain

Soil degradation and associated depletion of soil organic carbon (SOC) have been major concerns in intensive farming systems because of the subsequent decline in crop yields. We assessed temporal changes in SOC and its fractions under different tillage systems for wheat (Triticum aestivum L.) – maize (Zea mays L.) cropping in the North China Plain. Four tillage systems were established in 2001: plow tillage (PT), rotary tillage (RT), no‐till (NT), and plow tillage with residues removed (PT0). Concentrations of SOC, particulate organic carbon (POC), non‐POC (NPOC), labile organic carbon (LOC), non‐LOC (NLOC), heavy fraction carbon (HFC) and light fraction carbon (LFC) were determined to assess tillage‐induced changes in the top 50 cm. Concentrations of SOC and C fractions declined with soil depth and were significantly affected by tillage over time. The results showed that SOC and its fractions were enhanced under NT and RT from 0 to 10 cm depth compared with values for PT and PT0. Significant decreases were observed below 10 cm depths (P < 0.05) regardless of the tillage system. The SOC concentration under NT for 0–5 cm depth was 18%, 8%, and 10% higher than that under PT0 after 7, 9, and 12 yr of NT adoption, respectively. Apparent stratification of SOC occurred under NT compared with PT and PT0 for depths >10 cm. All parameters were positively correlated (P < 0.01); linear regressions exhibited similar patterns (P < 0.01). Therefore, to maintain and improve SOC levels, residue inputs should be complemented by the adoption of suitable tillage systems.