Uniform and Non-Uniform Second-Best Input Taxes

We investigate second-best, input-based taxes foragricultural nonpoint pollution control when marketprices are endogenous and production isheterogeneous. Theoretically, we derive the optimalforms of taxes which take account of heterogeneity(non-uniform taxes) and a tax which does not (auniform tax). Empirically, we use a multi-factor,market-equilibrium simulation model to determineoptimal tax rates and associated equity effects,particularly differences in landowner gains/lossesacross a heterogeneous region. When market prices areendogenous, second-best tax policies result inpecuniary externalities that affect existingenvironmental externalities. In particular, thepecuniary externalities amplify the effect of producerheterogeneity on determination of sub-regionaldifferences in tax rates and returns to land,particularly for the uniform policy. With endogenousprices, the uniform tax rate is considerably higherthan any of the non-uniform rates and, ironically, thenon-uniform taxes result in less dispersion oflandowner gains across sub-regions than the uniformtax.     

我国各区域农业生产资源配置效率分析

本文运用数据包络分析法测算了我国各区域农业经济的投入产出效率,指出目前我国各省市农业经济资源配置效率差异较大,其中人均化肥施用量对全国大多数省市农业劳动生产率都是最重要的,这种生产方式属于典型的“化肥农业”,并由此引发了一系列问题。文章认为,制度创新可以再造农业经济主体之间的相互关系,减少信息成本和不确定性,降低交易成本,提高生产要素配置效率,从而促进农业经济快速增长;在制度创新先行的前提下,实现农业经济组织创新与制度创新、知识创新的互动,是转变“化肥农业”生产方式,走可持续的新型农业发展道路的关键所在。     

微生物强化采油技术研究现状及应用前景

介绍了微生物强化采油技术的基本概念、机理和发展现状，讨论了该技术的研究方法、优点及应用条件，并展望了微生物强化采油技术的应用前景。     

MFC 技术处理铜、银重金属废水的研究

将具有氧化性的有机废水池作为电池的阳极,具有还原性的重金属废水池作为电池的阴极,利用微生物燃料电池（ MFC）同时处理有机废水和重金属废水．结果表明,利用铜离子溶液作阴极, MFC最大电压可达到0．277 V,最大功率密度为33．49 mW/m2,COD的去除率为31．6％,铜的去除率可达42％;利用银离子溶液作阴极,MFC最大电压可达到0．311 V,最大功率密度为42．21 mW/m2, COD的去除率为64．6％,银的去除率可达78％．即不管是从产电角度还是从废水处理角度考虑,都是以银离子废水作阴极优于铜离子．     

利用制药厂废水生产农用测土配方肥

利用制药厂的废水生产农用测土配方肥,方法可行,生产操作简单,做到废物循环利用,实现了经济、社会和环境三效益的统一.     

盆栽花卉活力剂的研究动态

简要介绍了国内外盆栽花卉培养介质，分为天然壤土堆肥和无壤土堆肥，其施肥方式也有区别；对盆栽花卉活力剂研究特点进行了综述，根据我国盆土实际情况，研制出了盆栽花卉活力剂。     

Evaluating the impact of rising fertilizer prices on crop yields

Because of tensions on fossil energy and phosphorus markets, the rise in fertilizer prices observed during the last decades may continue in the future, putting into question production pathways relying heavily on crop intensification. To evaluate how, in this context, economic choices may alter crop yields, we first construct different fertilizer price scenarios to 2050 based on an econometric relation with oil and gas prices. Other possible scenarios, such as the continuation of historical trends, are also considered. The resulting changes in fertilizer price range between +0.8% and +3.6% per year over the 2005–2050 period. These scenarios are tested in a global land‐use model incorporating an endogenous representation of the land–fertilizer substitution. We find that the supply‐side response to rising fertilizer prices could lower crop yields in 2050 from ?6% to ?13%, with a corresponding increase in global cropland area ranging between 100 and 240 Mha if the demand for food and nonfood products has to be met. The sensitivity of these results is tested with regard to assumptions on food consumption, change in potential yield and nutrient use efficiency.     

由磷肥企业副产氟硅酸制备氟化钠的研究

重点介绍了以磷肥企业副产氟硅酸为原料制备氟化钠的新工艺。首先用氨水氨化脱硅得到氟化铵溶液,再向氟化铵溶液加氯化钠合成氟化钠。对影响反应的温度、时间、物料配比等因素进行了探讨,得出具体工艺为:(1)氨化反应:H2SiF6浓度在12%～14%之间,氨水过量25%,反应温度为60～70℃,反应时间120min。(2)氟化钠合成:氯化钠过量15%～20%,反应温度85～90℃。产物氟化钠纯度大于98%,收率大于80%。     

Optimal forecast evaluation: fertilizer prices

High fertilizer price volatility makes production planning and inventory management difficult, so accurate fertilizer price forecasts would be beneficial. This article evaluates commercial forecasts for urea and diammonium phosphate (DAP) prices based on forecast accuracy and optimal forecast properties. Most forecasts pass the tests, but forecasts for the US New Orleans urea and the US Gulf DAP markets, in particular, do not and thus show potential to be improved.