二相流喷雾技术的研究

为了探索设施农业病虫害防治新的施药方法，该文对气液二相流喷雾作了雾化性能与药液物理特性相关性试验，得到了空气压强与气流量、喷雾量、雾滴直径、有效功率、吸液高度、喷口空气过流面积等诸参数之间相互关系，明确了药液粘性和表面张力对雾滴直径、喷雾量的影响程度，其结果为设计二相流喷头提供了依据。     

土壤有机硫矿化动力学特征及影响因素

利用开放培养系统，分别在20℃和30℃，好气和淹水条件下研究了四种土壤（黑土、褐土、黄棕壤和红壤）有机硫矿化特征。结果表明，30℃条件下土壤有机硫累积矿化量显著高于20℃下的矿化量（P＜0．01）。20℃和30℃好气条件下累积矿化量分别为17．53－24．35mg kg^-1和34．20－54．33mg kg^-1，分别占有机硫总量的2．5％－6．5％和5．－14．5％，20℃和30℃淹水条件下累积矿化量分别为18．14－21．15mg kg^-1和26．86－30．63mg kg^-1，分别占有机硫总量的2．6％－5．6％和4．0％－7．7％。好气和淹水下30℃与20℃的有机硫累积矿化量之比分别为1．85－2．23和1．28－1．71。用一级动力学方程和双倒数方程计算土壤有机硫矿化势（S0）表明，20℃好气培养时S0分别为17．82－24．88mg kg^-1和17．83－27．7mg kg^-1，S0分别为17．50－21．49mg kg^-1和19．19－22．50mg kg^-1,30℃淹水条件下S0分别为28．26－35．87mg kg^-1和26．59－34．25mg kg^-1。土壤有机硫矿化速率常数（K）和矿化量达50％矿化势（S0）所需的时间（K1）受不同土壤和培养温度的影响，都可用一级动力学方程和双倒数方程来评价。碳键硫对有机硫矿化的贡献较大，尤其在淹水条件下更明显。     

农用土地经济定级中两种方法的比较研究——以新疆一四八农场为例

以新疆一四八农场为例，对农用土地经济定级中的模拟作物产量法和综合土地质量法及其结果进行了比较，结果表明：（1）两种方法定级程序基本一致，在地方性区域内的定级结果均较为准确，且一致性较大；（2）模拟作物产量法结果的区域可比性强，但方法复杂；（3）综合土 地质量法方法简便易行，但结果的区域可比性差；（4）两种方法结合，能有效地建立便于比较和纳入全国体系的农用土地经济等级指数。     

猪排泄地点选择及其对圈栏污染程度的影响

该文论述了影响猪排泄地点的选择和圈栏内污染程度的各种环境(温度、湿度、光、气流速度、垫草)、设备布局(圈栏尺寸、形状、设备相对位置、隔栏方式)、管理(调教、喂料)等因素,并对评价圈栏内污染程度的方法进行探讨。旨在指导科学布置圈栏,将圈栏设计成长窄形,漏缝地板设在短向一侧;并尽量育成和育肥分开饲养,避免在育成阶段饲养面积偏大;通过工程手段实现漏缝地板处和躺卧区在温度和气流速度上的差异,以实现猪群在局部漏缝地板排泄。在生产管理中,避免饲养密度过大;通过通风系统控制圈栏内的温度以及空气污染;转群时进行调教,喂料有规律并对疾病进行及时诊断和治疗,都能降低圈栏污染程度,以实现真正意义的清洁生产。     

Wind erosion and sand accumulation effects on soil properties in Horqin Sandy Farmland,Inner Mongolia

Rain-fed agriculture is widespread in Inner Mongolia, northern China, where wind erosion of farmland is very common because of sandy soil and dry, windy weather. However, very little is known about the effects of wind erosion on soil physical and chemical properties in this region. A field experiment was conducted in sandy farmland, where erosional and depositional gradients were established to evaluate the effects of wind erosion and leeward sand accumulation on soil texture, nutrient content, soil water, and soil temperature. The research showed that long term wind erosion could result in significant soil coarseness, infertility and dryness. Severe erosion reduced clay by 59.6%, organic C by 71.2%, total N by 67.4%, total P by 31.4%, available N by 64.5%, available P by 38.8%, and average soil water content by 51.8%, compared with non-eroded farmland in the study region. The sand fraction (particles > 0.05 mm), pH and ground-surface temperature increased by 6.2%, 3.7%, and 2.2 °C, respectively. Accumulated sand also caused a decrease in nutrients and soil water content. Under severe sand accumulation, clay was reduced by 2.0%, organic C by 19.3%, total N by 21.7%, total P by 13.7%, available N by 52.5%, and average soil water content by 26.6%. The sand fraction, pH, available P, and ground-surface temperature increased by 0.2%, 0.9%, 5.8% and 2.8 °C, respectively.     

高寒矮嵩草草甸地面热源强度及与生物量关系的初步研究

在青藏高原海北高寒矮嵩草草甸地区,依据2002年涡度相关法观测的能量平衡各分量资料和6-10月植物地上、地下生物量测定值,分析了高寒矮嵩草草甸近地表热量平衡、地面热源强度的变化特征,讨论了地面热源强度与植物生物量季节变化过程中的相互关系。结果表明:在青藏高原海北高寒矮嵩草草甸地区,年内地面均为热源,热源强度季节变化明显,地面热源强度年平均为88.5 W/m2;地上生物量季节变化与热源强度具有显著的正相关关系,而地下生物量季节变化与热源强度关系不明显。     

粒状碎屑溜砂坡树根桩固砂防护技术

 粒状碎屑溜砂坡综合加固防护技术包含控制封闭砂源区、稳定砂坡体和保护砂坡脚3部分措施。从稳定砂坡体和保护砂坡脚的一般措施入手,通过野外调查和室内模型试验,探讨花管微型树根桩固砂机制、设计要点及固砂技术。     

高氧处理对冬枣货架期呼吸强度及品质变化的影响

该文研究了-2℃低温下用70％O₂、100％O₂分别处理冬枣7 d、15 d后，在20℃货架期期间果实的呼吸强度和品质变化。研究结果表明，70％O₂＋7 d处理促进了冬枣货架期呼吸强度的升高，100％O₂＋15 d处理能极显著抑制冬枣的呼吸强度。70％O₂处理7 d和15 d，或100％O₂处理15 d有利于冬枣果实货架期硬度的保持，但对可溶性固形物含量(SSC)的变化没有明显影响。100％O₂处理7 d和15 d均有利于Vc的保持，而70％O₂处理则促进了Vc的降解。高氧处理抑制了PPO活性的上升，100％O₂处理的效果更加明显。高氧处理15 d对抑制冬枣货架期腐烂有一定作用，但抑制效果仍不理想。总体来看，在低温下用100％O₂处理15 d，有利于提高冬枣果实在货架期期间的保鲜效果。     

1：25万土壤及地形数据库及指标体系研究

根据土壤及地形(SOTER)数据库基本原理和方法建立1：25万SOTER数据库,重点研究和修正大中比例尺SOTER主地形体划分指标体系,提出海拔高度分组指标、坡度分组指标和地势起伏强度分组指标,并利用上述3个指标组合计算出样区SOTER主地形体组分(中坡度丘陵、低坡度山体台地、山谷、中坡度山体、山前倾斜平原和冲洪积平原),以进一步发展和完善SOTER数据库理论方法体系。同时,SOTER数据库的建立使原有的历次土壤普查、国土资源详查的资料信息化,使之服务于土地资源的评价、管理与保护。     

Release and activity of allelochemicals from allelopathic rice seedlings

3-Isopropyl-5-acetoxycyclohexene-2-one-1 (1), momilactone B (2), and 5,7,4'-trihydroxy-3',5'-dimethoxyflavone (3) were isolated and identified from an allelopathic rice accession PI312777. These three compounds at low concentrations could inhibit the growth of weeds Echinochloa crusgalli and Cyperus difformis associated with rice, especially mixtures of the compounds had stronger inhibitory activity than did individual compounds. Studies with hydroponic culture, continuous root exudates trapping system (CRETS), and direct resin adsorption methods showed that a total of 7.6 n moles 1, 2, and 3 were exuded from living roots of each seedling into the environment at 10 days after seedlings were transplanted. Furthermore, 1, 2, and 3 were found in the soil growing PI312777 seedlings at day 15 after seedlings emergence and reached a total of 39.5 microg/g soil at day 30. The results indicated that PI 312777 seedlings could release sufficient quantities of 1, 2, and 3 into the environment to act as allelochemicals inhibiting the growth of associated weeds. Investigations on the distribution of 1, 2, and 3 in PI 312777 plant, and its root exudates showed that the levels of 1, 2, and 3 were significantly higher in the shoots and root exudates than in the roots, and only trace 1 was observed in the roots. The results suggest that the roots of rice seedlings are not major site of synthesis or accumulation 1, 2, and 3, but a pathway for their release into the environment. The levels of 1, 2, and 3 in the root exudates were over 2-folds higher under direct resin adsorption than under hydroponic culture and CRETS, and hence, it is the preferred method to collect and identify active allelochemicals in rice exudates in future studies on rice allelopathy.