垂直插入式小麦覆膜穴插机的研究

针对滚轮式小麦覆膜穴插机存在的问题，设计了垂直插入式小麦覆膜穴播机。运用平行四杆机构原理，实现了成穴器－－鸭嘴的直立接种、垂直入土和出土；采用地轮传动实现了鸭嘴插入土壤后的接近水平零位移运动；鸭嘴采用了定点强制开启投种。理论分析和试验表明，该机成穴播种机构设计合理，穴粒数合格率较高，无空穴，成穴器不堵土，不挑膜，穴孔合理，易于覆土。     

船闸蘑菇头和帽接触有限元计算与优化

利用ANSYS软件计算船闸底枢蘑菇头和帽在均布外载作用下的接触应力、应变分布,分析表明:增加外载作用面积、改变接触面粗糙度对接触变形参数影响不大,增大球面半径、减小配合间隙、使用浮箱减小外载和注油孔偏移帽轴线都可有效降低接触应力以减少转动磨损。     

渭北旱塬不同覆盖对冬小麦生产综合效应研究

为了探讨旱地有效蓄水保墒对冬小麦的综合效应，从1998～2000年在渭北旱原合阳县西北农林科技大学试验基地进行实验研究。3年的试验结果表明，冬小麦在生长期采用渗水地膜、秸秆、常规地膜及不同覆盖技术，均有显著增产效果，能显著增加土壤贮水量(除常规地膜覆盖外)，使土壤上层长期保持湿润状态，提高土壤温度，降低昼夜温差，避免降雨直接冲击地面，保持良好的土壤结构。与常规地膜覆盖和秸秆覆盖比较，渗水地膜覆盖冬小麦增产分别为43.1%和40.4%。秸秆覆盖能增加土壤有机质，提高土壤肥力。渗水地膜和常规地膜具有相同的增温效果，当气温达35℃以上时，渗水地膜还具有降低极端温度的调节功能。但是，覆盖易造成有机质大量矿化物和NO^-₃-N的淋失。     

水坠坝建设中的水枪冲土及其筑坝效应

介绍了新一代冲土水枪的性能及其施工应用效果。在施工试验中系统观测了施工工效、施工成本、泥浆浓度以及高浓度泥浆的填筑效应。采用水枪冲土造泥能进一步节省工程费用,而且能造出浓度很高的泥浆,形成塑态。这种泥浆的连续上坝对水坠坝的安全稳定十分有利,同时还会产生3种效应:一是可以缩小边埂的宽度,二是可以加快冲填速度,三是可以提高重粉质壤土水坠坝的经济合理性。     

Carbon budget and seasonal carbon dioxide emission from a central Ohio Luvisol as influenced by wheat residue amendment

Enhancement of soil organic carbon (SOC) stocks through mulching has been proposed, and although this practice can alter several soil properties, its impact on the temporal variability of carbon dioxide (CO₂) emission from soils has not been widely investigated. To that end, we monitored CO₂ fluxes from a central Ohio Luvisol (fine, mixed, mesic Aeric Ochraqualf) amended with wheat (Triticum aestivum L.) straw applied at rates of 0 (M0), 8 (M8) and 16 (M16) Mg dry matter ha⁻¹ per year and supplemented with fertilizer (244 kg N ha⁻¹ per year) or without. The experimental design was a randomized complete block design with three replications. The intensity of CO₂ emission was higher in the late winter (mean: 2.79 g CO₂-C m⁻² per day) and summer seasons (2.45 g CO₂-C m⁻² per day) and lowest in the autumn (1.34 g CO₂-C m⁻² per day). While no significant effect of N fertilization on CO₂ emission was detected, soil mulching had a significant effect on the seasonal variation of CO₂ fluxes. The percentage of annual CO₂ emitted during the winter and spring was similar across treatments (17–22%); however, 43% of the annual CO₂ loss in the M0 plots occurred during the summer as opposed to 26% in the mulch treatments. A close relationship (F=0.47X+4.45, R²=0.97, P<0.001) was found between annual CO₂ flux (F, Mg CO₂-C ha⁻¹) and residue-C input (X, Mg C ha⁻¹). Litter and undecomposed residue amounted to 0.32 and 0.67 Mg C ha⁻¹ per year in the M8 and M16 plots, respectively. After 4 years of straw application, SOC stocks (0–10 cm) were 19.6, 25.6 and 26.5 Mg C ha⁻¹ in the M0, M8 and M16 treatments, respectively. The results show that soil mulching has beneficial effect on SOC sequestration and strongly influence the temporal pattern of CO₂ emission from soils.     

玉米秸秆覆盖缓冲带对细沟侵蚀及其水动力学特征的影响

玉米秸秆覆盖缓冲带是一项有效的坡面水土保持措施,为探究其减少细沟侵蚀的效果及水动力学机理,在室内人工模拟连续降雨条件下,选取黄土高原高强度侵蚀性降雨标准和细沟发育活跃的典型坡度,根据细沟发育的不同阶段,研究了不同布设部位(坡面中部5 m和坡面下部7 m)的秸秆覆盖缓冲带对细沟侵蚀及其水动力学特征的影响。结果表明:与裸露处理相比,玉米秸秆覆盖缓冲带可以减少坡面侵蚀量27.2%~54.8%,减少细沟侵蚀量40.8%~59.2%,减小细沟侵蚀量对坡面总侵蚀量的贡献率。对于细沟形态,缓冲带可减少细沟割裂度23.0%~32.0%,减少细沟平均深度6.7%~10.5%。比较2种布设部位,在坡面细沟发育后期,坡面下部7 m处布设的秸秆缓冲带可以取得更好地减少侵蚀和约束细沟形态变化的效果。对于单条细沟,裸露坡面上的细沟宽度沿坡长方向呈现约1.2 m长的周期性变化规律,而秸秆缓冲带改变了细沟宽度沿坡长方向的周期性变化趋势,此外还通过拦截淤积上方来沙减小了布设位置细沟侵蚀深度,通过拦截径流保护下方有限长度内的细沟。分析其水动力学原因可知,玉米秸秆覆盖缓冲带可使细沟水流向缓层流流态方向延伸,与缓冲带上方相比,秸秆缓冲带下方的细沟水流流速显著减小19.6%~21.9%,雷诺数和佛汝德数分别减少了29.6%~37.9%和8.3%~18.5%,而通过秸秆缓冲带后,细沟水流Darcy-weisbach阻力系数增加了22.4%~43.3%,水流剪切力、单位水流功率和断面单位能量分别减小13.6%~21.5%、20.0~21.0%和9.5%~21.0%,径流能量和侵蚀能力的降低最终导致了坡面总侵蚀量的减小。因此,在坡面上每隔5~7 m布设缓冲带可以有效的削弱坡面径流侵蚀能力,减少坡面细沟侵蚀量和总侵蚀量。该研究结果可为类似地形条件下的坡面水土保持措施合理配置提供理论基础。     

连栋塑料大棚内温湿度及番茄叶片净光合速率的垂直和水平分布特征

为探索连栋塑料大棚内气候因子的变化特征，对温室内垂直方向和水平方向的气温和相对湿度进行了连续的观测，结果表明，不同天气条件下温室内平均气温和平均相对湿度具有明显的变化特征。番茄叶片净光合速率的梯度分布特征是上部最大，中下部则迅速下降。     

残膜污染治理的对策和措施

在分析残膜污染危害的基础上，从地膜生产和使用、残膜回收及再生利用等方面阐述了治理残膜污染的措施和建议。强调指出：发展残膜回收机械是治理残膜污染的有效方法，残膜的再生利用是保护环境、变废为宝、防治残膜污染的关键所在。     

Influence of continuous plastic film mulching on yield, water use efficiency and soil properties of rice fields under non-flooding condition

Five field experiments were conducted to study the effects of continuous plastic film mulching on rice yield, water use efficiency and soil properties on different soils with great environmental variabilities in Zhejiang Province, China, under non-flooding condition. The experiment started in 2001 at five sites and ended in 2003 with one rice crop annually. Three treatments included plastic film mulching with no flooding (PM), no plastic film mulching and no flooding (UM), and traditional flooding management (TF). Soil samples were collected after the third year of the experimentation and were analyzed for soil properties. PM increased soil temperature, accelerated decomposition of organic carbon and root growth, there was a slight but statistically insignificant trend of decline in soil bulk density. PM produced the similar rice grain yield as TF at two sites, significantly higher grain yield (5.8% and 20.0% higher) at other two sites, but significantly lower (34.3% lower) yield at one site where no irrigation water was applied and rainfall was the sole water source for rice growth. PM increased water use efficiency by 69.6–106.0% and irrigation water use efficiency by 273.7–519.6%. Compared to TF, PM decreased soil organic matter content by 8.3–24.5%, soil total N by 5.2–22.0%, and available K by 9.6–50.4% at all sites. PM treatment also reduced soil available N by 8.5–26.5% at four sites. Soil total P content in PM treatments reduced by 13.5–27.8% at three sites, and increased by 6.6–8.2% at other two sites. However, PM increased soil available P by 20.9–64.7% at all sites. Systematic cluster analysis indicated the PM treatment distinctively clustered from the other treatment. These results suggested PM could gain higher yield under appropriate water condition and PM may change soil nutrient cycle.     

沙漠地区滴灌条件下地膜覆盖对玉米生长的影响

Plastic cover, as a method to minimize soil water evaporation and improve water use efficiency, was used for corn during the whole growing period in a desert area. Field studies were conducted to determine the effect of plastic covering management on corn growth and rooting pattern and its relationship with changes in climate. Four treatments, 0) bared soil without cover, 1) covering one side of the crop, 2) covering both sides of the crop, and 3) covering the surface totally, were established on a sandy loam soil. Results showed that treatment 0 was significantly different from others and revealed that plastic covering was not always good to corn growth. Improper usage of plastic cover might weaken root development and thereafter lower the total yield of the crop. Suitable practices combining different methods discussed could not only improve water use efficiency but also increase the crop yield.