Determinants of farmers’ decision to adopt or not adopt inorganic fertilizer in the savannas of northern Nigeria

Soil nutrient deficiency has hampered increased agricultural production in the savannas of northern Nigeria. It has been observed that inorganic fertilizer (IF) has the potential to reverse the situation. However, low adoption among the farmers has characterized IF in the savannas of northern Nigeria. The application rates have also fallen far lower than the rate recommended by research and extension, resulting in low crop yields. This paper investigates the factors that influence farmers' decision to adopt or not to adopt IF and to evaluate the elasticity of adoption. This information will help to prioritize the factors that affect IF adoption decisions and suggest pathways for effective promotion of IF. About 49% of the survey farmers adopted IF and the application rate ranges from 5.6 to 64.4 kg ha^–1 (with a mean of 24.1 kg ha^–1). The probability of adoption increases with increased targeting of: farmers from the Guinea savanna agroecological zone, younger farmers, better educated farmers, food secure farmers and net sellers of food grains, farmers who have diversified into many crops, farmers who perceive increase in the fertilizer needs of their crops, and farmers who apply large quantities of organic manure. Among others, the estimates of elasticity of adoption indicate that a 1% increase in the number of farmers who perceive an increase in the fertilizer needs of their crops results in 3.23% increase in the probability of IF adoption. The paper concludes with policy implications for strategies aimed at promoting IF in the savannas of Nigeria and similar ecologies elsewhere.     

柴达木盆地北缘侏罗系烃源岩生物有机相

柴达木盆地北缘地区侏罗系烃源岩的主要生烃显微组分包括藻类体、角质体和孢子体,根据这3种不同显微组分在岩石中的赋存特征、丰度,以及它们之间的相对含量,将侏罗系泥岩的成烃生物相分为4类:富集有机质型(A型)、有机质密集搬运-沉积聚集型(B型)、有机质稀疏搬运-沉积聚集型(C型)、有机质碎屑状散布型(D型).从A型到D型,有机质丰度逐渐降低,类型逐渐变差.对油气勘探和地质研究具有重要意义的优质烃源岩是A型生物相泥岩,该类烃源岩发育较高丰度的层状藻类体,有机碳含量大干4.O%,有机质类型为Ⅱ1-Ⅱ2型,一般只在下侏罗统下部和中侏罗统七段的局部层段发育,往往集中在几米至十几米厚的富集有机质层段,多形成于湖泊-三角洲沉积体系中的闭塞环境.图5表3参20     

pH and Acid Anion Time Trends in Different Elevation Ranges in the Great Smoky Mountains National Park

Quarterly base flow water quality data collected from October, 1993 to November, 2002 at 90 stream sites in the Great Smoky Mountains National Park were used in step-wise multiple linear regression models to analyze pH, acid neutralizing capacity (ANC), and sulfate and nitrate long-term time trends. The potential predictor variables included cumulative Julian day, seasonality, elevation, basin slope, stream order, precipitation, surrogate streamflows, geology, and acid depositional fluxes. Modeling revealed statistically significant decreasing trends in pH and sulfate with time at lower elevations, but generally no long-term time trends in stream nitrate or ANC. The best forecasting models were chosen based on maximizing the r2 of a holdout data set. If conditions remain the same and past trends continue, the forecasting models suggest that 30.0% of the sampling sites will reach pH values less than 6.0 in less than 10?years, 63.3% in less than 25?years, and 96.7% in less than 50?years. The pH forecasting models explain 65% of the variability in the holdout data.     

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本文主要阐述喇嘛甸气顶油田在气顶暂缓开发,先开发油区情况下,采用油区注水,采油压力平衡油、气区压力,以防止油气互窜。并在气顶区、油气界面及油区建立了一套观察系统。经十几年开发实践证明,这套观察系统和方法是行之有效的。     

山水交融,生态校园——湖南潇湘技师学院新校区方案设计

该文通过对湖南潇湘技师学院新校区规划设计方案的分析介绍,阐述了校园建筑应以人为本,与生态环境相融合。同时为现代新校园的设计提出创造性的理念。     

新疆唐巴勒孜北金矿地质特征及找矿标志

新疆青河县唐巴勒孜北金矿区位于阿尔泰山南缘东段,矿区出露地层主要为下石炭统姜巴斯套组第一段(C_1j~1)、下石炭统姜巴斯套组第二段(C_1j~2)以及第四系(Q),其中下石炭统姜巴斯套组第一段为主要含矿地层。矿体呈脉状产于蚀变破碎岩中,金矿化与蚀变岩关系密切,矿体明显受断裂构造的控制,产状较陡,矿床成因类型为蚀变岩型,强烈的围岩蚀变部位及韧性剪切带中的石英脉就是矿体或矿化体的赋存部位,是最直接的找矿标志。     

太行山石湖金矿成矿流体成分特征与演化过程

成矿流体的研究是矿床成因研究的一个非常重要的方面。本文通过石湖金矿流体包裹体的激光拉曼分析和包裹体群体分析,气相成分中发现了大量的含CO2 包裹体,可能产生碳-水反应使其在主成矿期成矿;液相成分显示了成矿流体为以岩浆热液为主同时含有大气降水的混合流体,成矿过程主体为还原环境,后期也有O2的参与使环境转换为半封闭环境甚至是开放环境,而金在成矿流体中主要以硫氢络合物的形式迁移,氯络合物次之。     

西秦岭某金矿床矿石特征及可选性研究

西秦岭地区是我国金矿床分布的主要集中区,矿床类型主要有石英脉型及构造蚀变岩型。对位于西秦岭某金矿床矿石特征及矿石的可选性进行研究表明,该金矿床类型为石英脉型,金多以粒间金和裂隙金存在于黄铁矿中,以微细粒为主,载金矿物主要为黄铁矿。在混合样研究的基础上,分别采用重选—炭浸联合流程、原矿炭浸流程两种方法进行条件试验。表明该矿为易选矿石,重选—炭浸联合流程金回收率为95.03%,推荐其作为该金矿床矿石的选矿工艺方法。     

大秦岭西安段生态环境保护规划探析

秦岭的生态环境保护具有重要的现实意义。规划以生态环境保护为纲、以实现城乡统筹为领,以促进生态安全为重、以适宜人居休闲为本,以"保一山碧绿、护八水长流"为目标,对大秦岭西安段的生态环境保护进行总体规划布局,构筑由山体保护规划、森林生态系统保护规划和水土保持规划等多项规划组成的保护体系,强化大秦岭西安段的生态环境保护、水资源保护与文化资源保护,并借助秦岭丰富的山水景观、历史遗存和宗教文化等旅游资源,强化旅游文化产业板块的建设,强化保护与发展之间的有效衔接,充分展示"山水秦岭、人文西安"的独特魅力,促进了区域生态环境的良性循环和健康发展。     

湘北住宅适宜技术策略研究

针对湘北的气候特点,提出在此气候条件下采用适宜技术的策略,争取舒适性住宅,使其具有可操作性,对今后湘北地区住宅设计有借鉴作用。