平原农区空心村整治潜力测算模型构建及应用——以山东省禹城市为例

空心村整治是解决城乡发展转型进程中乡村地区土地资源闲置、空废及低效利用等问题的重要手段。构建符合平原农区地域功能特点的空心村整治潜力测算模型是实施平原农区空心村整治工作的基础与依据。本文以人均建设用地标准法为基础,基于平原农区的地域特色及优质耕地保育与现代商品粮基地建设重大战略需求建立了涵盖整治迫切性、自然适宜性及经济社会可行性等影响平原农区农村居民点整治理论潜力释放的评价指标体系,据此构建了空心村整治潜力测算模型,并以山东省禹城市为例进行了实证分析。结果表明:(1)禹城市的整治迫切性、自然适宜性及整治可行性存在较大的区域差异,各乡镇的整治迫切性修正系数处于0.18~0.96之间,自然适宜性修正系数处于0.69~0.84之间,整治可行性修正系数处于0.11~0.77之间;(2)禹城市空心村整治的理论潜力及现实潜力分别为3 517.86 hm2和1 853.18 hm2,新增耕地系数达16.89%。近期空心村整治需重点挖掘市中街道、十里望镇和房寺镇的整治潜力,远期需加强其他乡镇村庄整治;(3)市中街道周围的农村居民点自然适宜性较低,可考虑将该区空心村整治后复垦为建设用地,其他乡镇空心村整治后复垦为耕地,提高综合用地效益。     

Effect of Soil Organic Matter on Adsorption and Insecticidal Activity of Toxins from Bacillus thuringiensis

With the large-scale cultivation of transgenic crops expressing Bacillus thuringiensis (Bt) insecticidal toxin in the world, the problem of environmental safety caused by these Bt crops has received extensive attention. The effects of soil organic matter (SOM) on the adsorption and insecticidal activity of Bt toxin in variable- and constant-charge soils (red and brown soils, respectively) were studied. Organic carbon in the soils was removed using hydrogen peroxide (H_2O_2). After H_2O_2 treatment, the SOM in the red and brown soils decreased by 71.26% and 82.82%, respectively. Mineral composition of the H_2O_2-treated soils showed no significant changes,but soil texture showed a slight change. After SOM removal, the cation exchange capacity (CEC) and pH decreased, while the specific surface area (SSA), point of zero charge (PZC), and zeta potential increased. The adsorption isotherm experiment showed that the Bt toxin adsorption on the natural and H_2O_2-treated soils fitted both the Langmuir model (R~2≥ 0.985 7) and the Freundlich model (R~2≥ 0.984 1), and the amount of toxin adsorbed on the H_2O_2-treated soils was higher than that on the natural soils. There was a high correlation between the maximum adsorption of Bt toxin and the PZC of soils (R~2= 0.935 7); thus, Bt toxin adsorption was not only influenced by SOM content, but also by soil texture, as well as the SSA, CEC, PZC, and zeta potential. The LC_(50) (lethal concentration required to kill 50% of the larvae) values for Bt toxin in the H_2O_2-treated soils were slightly lower than those in the natural soils, suggesting that the environmental risk from Bt toxin may increase if SOM decreases. As the measurement of insecticidal activity using insects is expensive and time consuming, a rapid and convenient in vitro method of enzyme-linked immunosorbent assays is recommended for evaluating Bt toxin degradation in soils in future studies.     

秸秆覆盖对冬小麦农田土壤有机碳及其组分的影响

通过对黄土高原旱塬区冬小麦地4种覆盖方式下(无覆盖对照处理(CK)、全生育期9 000kg/hm~2秸秆覆盖(M1)、全生育期4 500kg/hm~2秸秆覆盖(M2)和夏闲期9 000kg/hm~2秸秆覆盖(SM))土壤的田间定位试验和室内分析,探讨不同秸秆覆方式对冬小麦地土壤有机碳及其组分含量以及各组分之间相关性的影响。结果表明:(1)较CK(无覆盖对照)处理,M1(全生育期9 000kg/hm~2)、M2(全生育期4 500kg/hm~2)和SM(夏闲期9 000kg/hm~2)处理,均显著增加0—10cm和10—20cm土层的土壤有机碳、微生物量碳、潜在矿化碳和颗粒有机碳含量(p0.05),而20—40cm土层差异不明显,其中M1(全生育期9 000kg/hm~2)处理效果最佳,SM(夏闲期9 000kg/hm~2)处理作用相对较弱。(2)不同覆盖方式影响土壤微生物量碳、潜在矿化碳和颗粒有机碳在总有机碳中的分配比例,土壤微生物量碳、潜在矿化碳和颗粒有机碳的相对含量变化范围分别为1.96%~3.31%,2.83%~3.78%,18.13%~37.25%。(3)各覆盖方式下土壤有机碳及其组分含量都随着土层的逐渐深入而下降,且土层越深,变化越趋于缓慢。(4)不同覆盖方式下的土壤有机碳及其组分含量两两之间均达到了极显著正相关关系(p0.01),颗粒有机碳、微生物量碳和潜在矿化碳与土壤有机碳的相关系数依次为:0.847,0.700,0.614,可见微生物量碳、潜在矿化碳、颗粒有机碳含量在一定程度上决定于土壤有机碳的贮存量。综上所述,秸秆覆盖对土壤有机碳及其组分含量具有增加效应,全生育期9 000kg/hm~2秸秆覆盖方式实际运用价值较高。颗粒有机碳和微生物量碳的动态变化更能反映土壤有机碳的早期变化,是土壤肥力变化更加敏感的指标。     

青枯劳尔氏菌潜在新寄主鉴定与青枯病防治策略的思考

为了充分发挥农业措施管理,合理轮套作技术在防治农作物青枯病的作用,结合云南当地农业生态实际情况,采用分离自雪莲果青枯病植株上的青枯劳尔氏菌,在28℃温室条件下,遵循柯赫氏法则,接种、分离、再接种和再分离该病菌,完成了植物病害验证过程。结果表明：在接种后,杜氏鼠尾草、曼陀罗和鸭趾草等3种昆明地区田间常见杂草均出现青枯病典型症状,首先在接种部位出现黑色病斑,继而植株萎蔫,并有大量的乳白色菌脓溢出。结合在自然界下尚未发现这3种杂草感染青枯病和在根部有青枯劳尔氏菌富集的研究结果,这3种杂草被推断为青枯劳尔氏菌的潜在寄主。本研究结果对农作物青枯病防治策略有重要指导意义。     

重庆市南岸区农村居民点整理潜力研究

为得出重庆市南岸区农村居民点整理潜力,对农村集体建设用地流转提供客观依据以及农村居民点用地管理提供理论支撑。采用人均农村居民点建设用地标准测算法对至2020年农村居民点整理潜力进行测算,然后采用闲置宅基地抽样调查法对其进行修正,获得农村居民点整理潜力。根据整理潜力和南岸区实际情况,对农村居民点合理布局进行了规划,并制作2020年重庆市南岸区农村居民点用地分布图。     

Subsurface drip irrigation and reclaimed water quality effects on phosphorus and salinity distribution and forage production

In the Canary Islands, water scarcity is one of the constraints for agricultural activity. Non-conventional water resources generally represent more water volume than conventional ones. The distribution of these resources frequently permits the possibility of a conjunctive use of desalinated (DW) water and reclaimed municipal wastewater (RW). Field testing with both water qualities and different irrigation systems is necessary for optimal site-specific management. The objective of this work was to evaluate soil salinity and phosphorus distribution, and alfalfa yield in a 20 month field experiment carried out in the island of Gran Canaria, using municipal RW and freshwater (FW) under subsurface drip irrigation (SDI). Phosphorus speciation was performed both in irrigation waters and in soils (Olsen's inorganic, organic, and microbial). RW had large EC values (2.4 dS m⁻¹) with a remarkable nutrient load contribution and an average total P around 3 mg L⁻¹, predominantly hydrolysable forms, while FW had very low salinity and negligible amounts of P. For the RW treatment a salt gradient was established, causing plant mortality between the irrigation lines. The study of P speciation allows describing P distribution and plant uptake in terms of P forms. Large values of microbial P were produced for the two irrigation waters around the emitters, especially for FW.A faster P-cycling could have contributed to the significantly larger inorganic P contents observed in FW irrigated soils, in spite no external sources were added by the irrigation water.     

江苏省宜农未利用地开垦土壤改良模式研究

系统分析了江苏省主要宜农未利用地类型、分布及其开垦的土壤障碍因素,探究了土壤改良的工程措施、农艺措施、生化措施及其作用,研究提出了荒草地和沿海滩涂2种主要宜农未利用地开垦的土壤改良模式,注重了各种改良措施的综合运用,对于合理制定江苏省宜农未利用地开垦土壤改良方案,提高土地开垦的质量,实现江苏省耕地总量动态平衡具有重要的指导意义。     

陕北农牧交错带牧草生产力分析

根据陕北农牧交错带的生态环境特点以及牧草生长发育过程对水热资源的要求和利用效率,运用迈阿密模型定量估算陕北农牧交错带七县区牧草自然生产力。并与牧草现实生产力进行比较。研究表明:陕北农牧交错带牧草现实生产力仅为自然生产力的30.80%。基本掌握了该区牧草生产力状况和特点,并据此提出了相应的开发战略和实施途径。     

石新733小麦的水分生理特点及节水灌溉效应

石新733是一个高产优质小麦新品种,为探明其是否适用于节水高产栽培,于2003—2004和2004—2005年度进行了节水灌溉对其水分生理性状和产量影响的田间试验。结果表明,石新733的叶片渗透调节能力比邯麦9、石麦9和衡7228的平均值高71.6%,叶水势比衡7228约高0.1 MPa。石新733的离体叶片失水速率较高;蒸腾速率、净光合速率和气孔导度与石麦9和邯麦9接近,均高于衡7228;胞间CO₂浓度和蒸腾效率品种间没有明显差别。与灌5水处理相比,灌2水处理的叶水势和叶片气体交换参数均相近而灌浆盛期的光合功能和蒸腾效率较高。石新733的产量高于其他3个品种,其中,不灌水和灌2水处理分别比其他3个品种平均产量增加11.3%和7.0%。全生育期只灌拔节和抽穗开花期2水的节水处理比灌4水的常规灌溉处理增产5.6%,说明该品种可在节水高产栽培上应用。     

玉米人工合成群体产量相关性状选择潜势及杂种优势模式分析

采用NCⅡ遗传交配设计 ,以分属于不同杂种优势群的 6个自交系做测验种 ,与 6个合成群体组配成 36个组合。结果表明 :单株产量的GCA以LBM最高 ,其次为WBM ,从株型、穗型性状的SCA分析合成群体与自交系组成了 9个优良杂种优势模式。单株产量最高的组合为HZ85×WBM ,其均值为 10 8 75g。通过对优良杂优模式内的变异参数估计 ,在群体内有丰富的变异个体 ,具有很强的选择潜势。组合内个体产量分布以及出现的频率对选系和轮回选择具有明确的指导意义。人工合成群体具有丰富的遗传变异 ,分属于不同的杂种优势类群 ,具有多元种质的特性。作为选系和轮回选择群体 ,具有明显的选择潜势