腔盘式精量穴施肥装置设计与试验

施肥方式粗放是造成我国肥料利用率低的主要原因之一。与条状施肥相比,穴式施肥可有效提高肥料利用率。本文设计一种用于颗粒状肥料穴式施用的腔盘式精量穴施肥装置,通过理论分析确定了装置的主要结构和工作参数,并探讨了肥腔形状(圆弧型、直线型-钝角、直线型-锐角和抛物线型)对肥料运动的影响。运用离散元法(EDEM)对不同结构和作业参数下的排肥盘充肥性能和肥群运动进行了仿真分析,结果表明:肥腔形状、前进速度和施肥量对各穴排肥量变异系数均有显著影响,随前进速度的增大和施肥量的减少,变异系数增大,且圆弧型肥腔排肥稳定性最好;前进速度和肥腔形状对肥料扰动度有显著影响,排肥盘经过箱体的时间及其对肥料扰动的形式和扰动量是影响排肥量稳定性的主要原因。在前进速度7 km/h、排肥量300 kg/hm~2的条件下,对4种排肥盘进行台架试验,结果表明,圆弧型肥腔性能最优,排肥量合格率为94%,各穴排肥量变异系数为6.5%,与仿真结果呈现相同规律,且满足作业排肥要求。     

重力辅助充种盘室同步气吸式排种器性能分析

为探究重力辅助对盘室同步气吸式精量排种器充种性能的影响,以盘室同步气吸式精量排种器为载体,对其充种过程进行了受力分析,建立了重力辅助充种受力数学模型,结果表明：型孔充填过程中,待充种子重力在排种盘径向的分量与气流曳力方向一致;已充种子脱离种群过程中,种子重力沿径向分量与压力梯度力方向一致,种子重力对充种有辅助作用。运用EDEM(Engineering discrete element method)软件仿真分析了300、600、900、1200粒种群数量条件下,待充种子对排种盘平均法向力随低、中、高3种不同充种区域变化的影响,仿真结果表明：种群数量300粒时,各区域平均法向力随区域位置的变化不明显,种群数量为600、900、1200粒时,平均法向力随区域位置的变化规律一致,此时种群数量对充种效果影响可忽略。对仿真结果进行试验验证的结果表明,盘室同步气吸式精量排种器台架试验3个区域漏充率由大到小为：低位、中位、高位。通过盘室同步气吸式精量排种器重力辅助充种和无重力辅助充种对比试验表明：重力辅助充种下,排种器作业风压3~5.5kPa时,合格指数均高于94%;无重力辅助充种情况下,排种器作业风压6kPa才开始满足国标需要,重力辅助充种显著降低了排种器作业风压需求,提高了作业质量。     

不同腐烂病发病程度核桃根区土壤微生物多样性分析

【目的】 研究土壤微生物数量和功能多样性与核桃腐烂病之间的关系,为核桃腐烂病微生物调控技术研究奠定良好的理论基础。【方法】以健康、轻度、中度和重度4类不同病害程度的12年生核桃树为试材,采用可培养微生物计数和Biolog生态板测定其根区土壤微生物数量和功能多样性的异同,分析其与病害程度之间的相关性。【结果】不同腐烂病发病程度核桃根际土壤三大可培养微生物类群数量差异显著。与健康土壤相比,不同发病程度土壤细菌数量呈先上升后下降趋势, 轻度、中度发病土壤分别提高了15.67%和12.28%,重度发病土壤则下降了33.46%。轻度、中度和重度发病土壤放线菌数量分别下降了47.33%、32.98%和19.27%,真菌数量分别下降了49.32%、22.68%和42.68%。Biolog碳源利用表明,核桃腐烂病不同发病程度土壤微生物多样性也存在显著差异。从144 h的AWCD值可以看出,腐烂病发病较轻的核桃根区土壤中,微生物活性最高,健康土壤降低了12.03%,中、重度发病土壤分别降低了14.56%和18.42%。轻度发病土壤的Shannon丰富度指数(H)高于健康和中、重度发病土壤。健康和轻度发病的土壤微生物对糖类和氨基酸类碳源有较强的利用能力,而腐烂病发病较重的土壤中利用糖类、氨基酸类和酚酸类碳源的微生物在减少。主成分分析表明,发病程度不同的核桃根区土壤微生物群落有一定的差异。31种碳源中,糖类和氨基酸类碳源决定着主成分的分异。【结论】腐烂病发病程度较重的土壤中微生物活性低于健康和腐烂病发病程度较轻的土壤。根据土壤微生物利用的不同碳源,设计出合理的微量元素肥料,将有望减轻核桃腐烂病病害的发生。     

Nitrate leaching,nitrous oxide emission and N use efficiency of aerobic rice under different N application strategy

A field study was conducted in the sub-humid tropical region of India to examine the effect of different nitrogen (N) management strategies on nitrate leaching, nitrous oxide (N₂O) emission and N use efficiency in aerobic rice. Treatments were: control (no N), 120 kg N ha^?1 applied as prilled urea (PU) in conventional method, 120 kg N ha^?1 applied as neem coated urea (NCU) in conventional method, N applied as PU on the basis of leaf colour chart (LCC) reading, N applied as NCU on the basis of LCC reading, and 120 kg N ha^?1 applied as PU and farm yard manure (FYM) in 1:1 ratio. Results showed that 3.4–16.1 kg NO₃-N ha^?1 was leached below 45 cm depth and 0.61–1.12 kg N₂O-N ha^?1 was emitted from aerobic rice during the growing season. NCU when applied conventionally reduced nitrate-nitrogen (NO₃-N) leaching and N₂O emission by 18.6% and 21.4%, respectively However when applied on the basis of LCC reading NCU reduced NO₃-N leaching by 39.8% as compared to PU applied in conventional method. NCU when applied on the basis of LCC reading synchronized N supply with demand and reduced N loss, which resulted in higher yield and N use efficiency.     

好氧堆肥中通风工艺与参数研究进展

通风是影响好氧堆肥过程中温度变化、微生物活性、气体成分、水分去除和产品质量的重要参数,文章总结了好氧堆肥中通风工艺与参数研究进展。主要结论如下:好氧堆肥有三种通风方式,即自然通风、被动通风和强制通风,其中强制通风在堆肥科学研究和堆肥工程中应用较多。定时开-关周期循环控制、氧含量反馈控制和最大氧消耗率反馈控制是好氧堆肥中典型的三种通风控制方式,定时开-关周期循环控制和氧含量反馈控制方式被认为是在工厂化堆肥中应用的标准控制方式,最大氧消耗率反馈控制是一种新型的控制方式,控制效果较好,但在实际工程中尚未被应用。堆肥通风速率因原料和堆肥形式不同而不同,研究结果认为通风速率为0.2~0.6 L·min~(-1)·kg~(-1)有机物质具有较好的应用效果。搅拌是一种特殊的堆肥通风方式,在搅拌过程中,通过分子扩散和能量梯度驱动空气质量运动,从而为堆体供给足够的氧气,这一方式在槽式和反应器堆肥中应用较多。实际堆肥工程中,条垛式堆肥一般采取翻堆结合自然通风工艺,槽式堆肥采取分段强制通风工艺,反应器堆肥一般采取间歇式通风工艺;条垛式和槽式堆肥建议翻堆频率为1 d 1次,槽式和反应器堆肥建议通风速率为0.05~0.2 m3·min~(-1)·m~(-3)有机物质。     

Protective effect of melatonin administration on abamectin-induced immunotoxicity in Spodoptera litura (Insecta: Lepidoptera)

In vertebrates, many studies verified the immunomodulatory effect of melatonin in various tissues. Its exact role in lower organisms like insects has been very sketchy. The present study deals with understanding the immunomodulatory effect of melatonin in pesticide exposed insects. Total hemocyte count, Differential hemocyte count, Prophenoloxidase activity, and nodulation mechanism at different time intervals were studied. Results showed the abamectin results in significant increase (p < 0.01) in haemocytes numbers at 6, 48, and 72 h. Abamectin toxicity was counteracted by melatonin, with decreasing the hemocytes at 2, 4, and 12 h. Prophenoloxidase activity and protein content (p < 0.001) at 48 and 72 h of Melatonin + abamectin were slightly decreased. There was a significant decrease in nodule formation in 12–24 h in melatonin treated groups and it was clearly visible at 6 h. Increased Prohemocytes, Plasmatocytes, and Oenocytoids numbers decline in melatonin treatment. Melatonin treatment increased the survival rate on pesticide exposed insects. Results suggest that melatonin exposure significantly reduces the toxicity in pesticide exposed larvae which in turn brings back immunological profile in a time dependent manner.     

A meta‐analysis examining lactic acid bacteria inoculants for maize silage: Effects on fermentation,aerobic stability,nutritive value and livestock production

A database containing 140 articles published in journals (731 treatment means evaluated) was used to examine the effect of different lactic acid bacteria (LAB) on fermentation, chemical composition and aerobic stability of maize (corn) silage. Compared with the control, dry matter (DM) loss increased by 8% and 50% (p < .01) due to inoculation of maize silage with either homolactic LAB (^hoLAB) or heterolactic LAB (^heLAB). In vitro DM digestibility of maize silage increased only with ^hoLAB inoculation (+2.22%; p < .01). The ^heLAB inoculation increased (p < .01) the aerobic stability of maize silage by 71.3 hr. To investigate the effect of silage inoculation on livestock production, a second database comprising 35 articles [99 treatment means evaluated based on results from 648 cattle (429 beef cattle and 219 dairy cows) and 298 sheep] was used. Inoculation of maize silage with either ^hoLAB or ^heLAB did not affect milk yield (p > .05), but their combination (^mixLAB) depressed milk yield (–2.5 kg/day; p < .01). Inoculation with ^hoLAB increased DM intake in sheep (+0.15 kg/day; p = .02), but decreased it in beef cattle (–0.26 kg/day; p = .01) without affecting average daily gain for both sheep and beef cattle (p ≥ .06). In conclusion, fermentative loss increased regardless of the bacterial inoculant used, while aerobic stability increased mainly by using ^heLAB. Benefits from ^hoLAB inoculation on animal performance were noted only for feed intake in sheep, while productive performances of dairy cows and beef cattle were not improved.     

拖拉机离合器盖压盘总成试验装置开发

如何设计出结构稳定、可靠,能够进行拖拉机离合器盖压盘总成试验的试验装置,是广大科研机构和企业一直探索的问题。本课题设计了一种结构紧凑、可靠,测量过程简单,测量结果精确,自动化程度较高的拖拉机离合器盖压盘总成试验装置,可以进行拖拉机离合器盖压盘总成分离特性和负荷特性试验,且测试结果稳定可靠。     

精馏/好氧加Fenton处理制药废水

在分析了制药废水的水质特点基础上,进行了精馏/好氧加Fenton的方法处理制药废水的实验研究,结果表明:该方法对制药废水的处理出效果显著。将精馏后的制药废水混合液COD稀释到500 mg/L,再加上COD为200 mg/L的生活污水,经过好氧和Fenton处理后的COD去除率可达80%左右;且出水COD稳定在120 mg/L左右。出水水质符合(GB-T-31962-2015)中的C级排放标准。