Farmer's view on soil organic matter depletion and its management in Bangladesh

Bangladesh is an agricultural country. About 80% of the total population live in rural areas. The contribution of agriculture to the gross domestic product is 30%. Rice is the major food crop while jute, sugarcane and tea are the main cash crops. Other important crops are wheat, tobacco, pulses, vegetables and fruits. Overall productivity in Bangladesh is stagnating or declining. The implication of yield stagnation or declining productivity is severe, since these trends have occurred despite rapid growth in the use of chemical fertilisers. Depletion of soil organic matter is the main cause of low productivity, which is considered one of the most serious threats to the sustainability of agriculture in Bangladesh. In Bangladesh, most soils have less than 17 g/kg and some soils have less than 10 g/kg organic matter. Farmers realise that there is a problem with soil fertility related to organic matter depletion. Farmers say that organic matter increases yield, reduces the production cost, improves crop growth and the economy, increases water-holding capacity and improves the soil structure. They recognise soil with higher organic matter content by darker brownish to black in colour. Some farmers are using fast-growing trees such as Flemingia macrophyla, Ipilipil (Leucaen leucophala), Glyricidia sepium, Boga Medula (Tephrosia candida), Dhol Kolmi (Ipomoea fistulosa), etc., as living fences, which can be used as fuel, fertiliser and fodder. To increase the soil organic matter, farmers use green manure crops, compost, quick compost, cow dung, azolla, etc. However, fuel for cooking purposes is limited and cow dung and crop residues are largely used as fuel. Crop residues are also used as fodder for livestock. Farmers expressed the wish to learn more about organic fertilizer management. However, sufficient food should be produced to keep pace with population growth. To alleviate the hunger and poverty is to increase the intensity of agricultural production and maintain favorable ecological conditions. Therefore, more organic matter should be used in the farmers' fields to sustain the soil fertility in an intensive farming system. This revised version was published online in June 2006 with corrections to the Cover Date.     

Pelletised fuel production from coal tailings and spent mushroom compost – Part II. Economic feasibility based on cost analysis

Due to the growing market for sustainable energy, in order to increase the quality of the fuels, pellets are being produced from various materials such as wood and other biomass energy crops, and municipal waste. This paper presents the results from an economic feasibility study for pellet production using blends of two residue materials: coal tailings from coal cleaning and spent mushroom compost (SMC) from mushroom production. Key variables such as the mixture composition, raw material haulage and plant scale were considered and the production costs were compared to coal and biomass energy prices. For both wet materials, the moisture content was the critical parameter that influenced the fuel energy costs. The haulage distance of the raw materials was another factor that can pose a high risk. The results showed that the pellet production from the above two materials can be viable when a less energy-intensive drying process is utilised. Potential market outlets and ways to lower the costs are also discussed in this paper.     

Co‐composting an animal fatty‐proteinaceous waste with a solid lignocellulosic by‐product from the olive oil industry (‘alperujo’)

BACKGROUND: The production of biodegradable wastes and their disposal cause a major financial problem in many industrial activities. Co‐composting was thought to be a feasible alternative for disposing of a strongly alkaline waste from the pharmaceutical industry (AW), mainly consisting of animal fats and partially hydrolysed proteins in a stable emulsion. The AW was added gradually, during the early phase of the composting process, to a substrate made up of ‘alperujo’ (AL), the wet, lignocellulosic, solid by‐product of the olive oil industry, and fresh horse manure, which was added to improve the physical structure of the composting substrate. RESULTS: The addition of AW reduced organic matter degradation during composting, enriched the amount of organic compounds in the water‐ and alkali‐soluble fractions and increased mineral salt contents. Thus, significantly higher electrical conductivity, humification indices and contents of organic matter, P, K and Na were recorded in the end‐composts resulting from AW treatments. However, the application of one AW‐based compost led to soil N immobilisation, as revealed by an incubation experiment, which must be considered in order to avoid potential N starvation in the short term. CONCLUSION: According to these results, composting can be used as a disposal alternative for AW, leading to end‐products with potential uses as organic amendments or fertilisers for agricultural systems. In addition, these composts could be used to produce alternative liquid organic fertilisers, based on the extraction of their humic‐like fraction. Copyright © 2009 Society of Chemical Industry     

一种家用小型太阳能堆肥箱的设计

针对目前市场上常见的厨余垃圾堆肥箱不易保温、堆肥时间长、沥水效果差、臭味重等问题,设计一种家用小型堆肥箱,该装置包括太阳能集热板、太阳能电池板、通风管路、投料口、沥水筛网、尾气处理等多个模块。通过对堆肥箱空间结构进行设计和优化,使其更好地满足高温好氧堆肥工艺的需求,同时由于引入了太阳能为整个系统的保温和通风供能,大大降低了能耗。该装置与自然堆肥相比缩短了堆肥时间,且整个系统移动搬运方便,不受放置地点限制,十分适合庭院内使用。     

模糊数学方法在垃圾堆肥质量评价中的应用

通过选择堆肥质量指标,制定指标评价等级,构建模糊数学评价体系,采用垃圾堆肥试验数据,在单因素评价的基础上,综合考虑各因素的影响,对堆肥质量进行模糊综合评价。结果表明运用模糊综合评价法能客观地反映堆肥质量。该法可以作为一种简单有效的城市生活垃圾堆肥质量评价方法。     

我国城市生活垃圾处理趋势的探讨

我国城市生活垃圾的数量在不断增加，成分也在不断变化。如果处理不当，它会成为污染环境的一大公害，并致使大量有用资源浪费。相反，就会变废为宝。本分析了我国城市生活垃圾变化的趋势，进而对目前的各种处理方式的利弊作了探讨；最后指出生态化处理是垃圾处理的趋势，因为它实现了垃圾的无害化、减量化和资源化处理。     

以琥珀酸二铵为原料的PBS的合成与性能

以生物质基琥珀酸二铵与丁二醇为原料,通过熔融缩聚合成相对分子量(M_w=7.0×10~4)较高的聚丁二酸丁二醇酯(PBS).运用FT-IR,~1H-NMR、WXRD、DSC、GPC和SEM对其进行表征及性能研究.结果表明:以琥珀酸二铵合成的PBS是结晶性聚合物,结晶度为64.9%,熔点为115.7℃,在可控堆肥条件下降解70 d后的生物降解率达66.71%.     

Elimination of hydrogen sulphide from odorous air by a wood bark biofilter

Wood bark, used as biofilter material, gives less back pressure than fibre peat or household compost and is therefore cheaper in variable costs than the other materials. With a filter bed height of 0.9 m and with a surface load of 65 m³ m⁻² h⁻¹, 10 ppm hydrogen sulphide is efficiently eliminated from odorous air by a wood bark biofilter. The most important parameter for a good functioning of the filter is the water content of the filter material. The optimum for wood bark is about 65%. Unnecessarily high back pressures are recorded during sprinkling water on top of the filter. Therefore, it seems preferable to condition the relative humidity of air entering the filter. If absorption and adsorption were the only factors in the biofilter mechanism, hydrogen sulphide would, in the given circumstances, break through after about 7 h. It is shown that hydrogen sulphide is oxidized to sulphate. According to literature data, chemical oxidation is too slow and therefore hydrogen sulphide oxidation in the biofilter is attributed to microbiological action.