An economic evaluation of site-specific herbicide application

The objective of this study was to determine if site-specific application of postemergence herbicide was economically viable with current technologies. This objective was accomplished by: developing an algorithm that determined the economic optimal postemergence herbicide rate; creating models to determine the impact that postemergence herbicide rate has on yield; and determining whether site-specific application of postemergence herbicide has greater net returns than those from a uniform application of postemergence herbicide. Weed species identification and population counts were done on a regular grid in five fields across Kansas. A decision algorithm was developed to determine the economic optimal rate of postemergence herbicide for each grid cell. The site-specific herbicide rate and four standard herbicide rates [0, 0.5, 0.75, and full (1×) label rate] were applied according to a split-plot design. Weed population observations made three weeks after application showed that the site-specific treatment controlled the weeds present in the fields. Production functions developed to determine whether postemergence herbicide rate had an impact on yield showed that it had a positive, yet statistically insignificant, effect on yield. The difference in estimated net returns between applications of site-specific rate and uniform full-label rate covered all of the costs associated with site-specific application of postemergence herbicide. The margin between the estimated net returns for site-specific and uniform application of the economic optimal rate covered only a portion of the costs associated with site-specific application of postemergence herbicide.     

农户低碳生产行为评价指标体系构建及应用

从微观层面构建农户低碳生产行为评价指标体系,有助于引导农户进行低碳生产,从而为制定和实施更有精准性的低碳农业发展政策提供依据。从生产要素碳排放、生态效应和经济效益3个方面构建了农户低碳生产行为评价指标体系,分别基于层次分析法和碳足迹核算的生命周期评价法确定了指标权重,并根据综合评价指数划分了低碳等级。在此基础上,对辽宁省辽中县水稻种植户生产行为低碳化程度进行了评价。结果表明,碳生产率是评价农户低碳生产行为的最重要指标,其次是氮肥施用强度、土地生产率和秸秆利用率。综合评价指数平均值处于中碳区间,70%左右的农户属于中碳生产,20%左右的农户达到近低碳等级,10%左右的农户处于较高碳区间,即中碳生产占主体地位。准则层中,经济效益准则层指数较低,生产要素碳排放和生态效应准则层指数相对较高;指标层中,劳动生产率、成本收益率和有机肥施用率的标准化值较低。由此提出,促进农户低碳生产须着力提高生产要素使用效率和经济效益,同时重视农业废弃物资源化利用,提高农业生产的生态效应。     

模糊概率法在玉米品种综合评价中的应用

应用模糊概率法对中国西北地区13个试点的13个参试春玉米品种进行综合分析评价,评价结果与品种的实际表现完全吻合,表明模糊概率法应用于玉米品种的综合评价方便可行,且运算简单.     

响应面法优化棉秆水热液化生产腐植酸的运行条件

为优化棉秆水热液化生产含腐植酸液态肥的运行条件,确定反应条件间的交互作用及其反应产物的组成,采用三因素三水平的响应面分析方法,探究了反应温度（X₁,260~340℃）、反应时间（X₂,30~90 min）和物料质量分数（X₃,5%~10%）对水溶肥腐植酸产率的影响。回归模型方差分析表明,反应温度、反应时间以及物料质量分数均对腐植酸产率有较大影响。其中,物料质量分数是最重要的参数。腐植酸产率的最佳反应条件为：反应温度300℃,反应时间90 min,物料质量分数10%。在此条件下,腐植酸产率为4.10%,高于国家含腐植酸水溶肥标准（NY 1106—2010）中规定的腐植酸含量（不小于3%）,与预测值吻合较好。GC-MS分析表明,棉秆水热液化的水溶性产物主要含有酚类及其衍生物、酮类、醛类、醇类以及有机酸化合物。     

凹唇壁蜂的访花习性及必要放蜂量

凹唇壁蜂雌蜂用腹毛刷采集携带花粉 ,访花植物种类主要为苹果、梨、桃、杏、李、樱桃等北方常见落叶果树 ,也采访早春开花的十字花科及少数杂草。雌蜂访花频率为 8～1 6朵 /min,日访花数约为 5486朵 (苹果花 )。单位面积必要放蜂量为雌蜂 52 5～ 885只 /hm2 。     

杜仲茎点霉SP-16F产松脂醇二葡萄糖苷营养条件的优化

【目的】对杜仲茎点霉SP-16F发酵生产松脂醇二葡萄糖苷(PDG)的营养条件进行优化,以提高发酵液中的PDG产量。【方法】在单因素实验的基础上,通过三元二次中心组合设计和响应面分析法优化杜仲茎点霉SP-16F发酵产生PDG的最佳营养条件。【结果】在液体培养条件下,茎点霉SP-16F产PDG的最佳培养基组成为:蔗糖47.5 g/L,NaNO33.0 g/L,K2HPO42.83 g/L。在最佳培养条件下,PDG产量预测值较优化前的最大值提高了3倍以上。【结论】获得了茎点霉SP-16F的最佳产PDG培养基,有效地提高了其发酵产PDG的能力。