Water use and technical efficiencies in horticultural greenhouses in Tunisia

We measure the technical efficiency of unheated greenhouse farms in Tunisia, and propose a measure for irrigation water use efficiency (IWUE) using an alternative form of the data envelopment analysis (DEA) model. Technical efficiency measures the degree to which (all) farm inputs are used efficiently. IWUE is a measure of the efficiency of irrigation water use when other inputs and output are kept constant. As a second stage, a tobit model is used to identify the degree to which technical efficiency and IWUE correlate with a set of explanatory variables. A comparison of the efficiency scores obtained from constant returns to scale (CRS) and variable returns to scale (VRS) specifications shows that most farmers in our sample are producing at an efficient scale. Under the CRS assumption, the average technical efficiency of the sample was 67.3%. A similar pattern of scores was shown for IWUE; although in this case the average IWUE was even lower (42%). This implies that when all other inputs remain constant, the current output could be produced using, on average, 58% less irrigation water. We conclude that farmers’ technical training in greenhouse management, investments in water saving technologies and the existence of a fertigation technique on farm have a significant and positive effect on their level of IWUE. However, IWUE is significantly and negatively affected by the proportion of total farm land allocated to greenhouses.     

Evapotranspiration of horticultural crops in an unheated plastic greenhouse

Large unheated greenhouse areas are located in the coastal lands of the Mediterranean Basin, based on low-cost structures covered with plastic. Water is a scarce resource in these areas and therefore it is necessary to optimise irrigation practice by applying the crop water needs, thus avoiding waste. This work was undertaken to determine the water requirements of four major horticultural crops grown in an unheated plastic greenhouse located in Almería, Spain.Drainage lysimeters were used to determine the seasonal evapotranspiration (ET) of four crops (melon, green beans, watermelon and pepper), which ranged from 170 to 371 mm and it was associated with the reference ET (ET₀). Compared to irrigated crops outdoors, the seasonal ET of the greenhouse horticultural crops is relatively low due to the lower evaporative demand inside the greenhouse and to a further reduction in solar radiation transmission by whitening in late spring and summer. Additionally, off-season greenhouse crops are grown during low evaporative demand periods, thus the low water requirements.Crop coefficient (K_c) curves were obtained for the four crops under different conditions. The K_c values varied with the crop, stage of development, and with management practices. Measured peak K_c values for crops, which were not vertically supported (melon and watermelon) were between 1 and 1.1, similar to the measured values for the same crops under field conditions. By contrast, peak K_c values for vertically supported (VS) crops (melon, green bean and sweet pepper) varied between 1.3 and 1.4, which are higher than those reported for outdoors. The tall and open canopy structures of the VS greenhouse crops, their high leaf area indices, along with the high proportion of diffuse radiation inside the greenhouse, allowed for more uniform light penetration within the canopies and ET rates in those crops higher than those of the short, non-supported crops.Management and climatic conditions combined to define an unusual K_c curve for sweet pepper. The crop is transplanted in late summer and reaches the peak K_c in early winter. Because of the low temperatures, K_c decreased thereafter down to about 1.0, until climatic conditions inside the greenhouse improved. From late winter to the end of the season, K_c was either stable or increased steadily. A simple K_c model based on thermal time for greenhouse crops with and without pruning, was proposed and validated. The model gave accurate estimates of measured K_c values for melon and pepper.     

A methodology for the management of quality in horticultural distribution

This paper presents a comprehensive methodology for the post-harvest management of quality in the distribution of horticultural produce. The methodology consists of three connected subsystems—quality prediction, price prediction and management decision making. The theoretical frameworks developed have been tested experimentally and the methodology is now available as an aid to decision making.The three main forms of deterioration—mechanical damage, physiological deterioration and pathological decay—are modelled and quality out turn is predicted from input quality and environment-event-time histories in each case. Price prediction is based on price-supply-quality relationships developed from studies of prices on wholesale markets. The price of a particular consignment is calculated from a quality index using quality-price functions. A management decision subsystem then evaluates alternative distribution strategies in terms of profit.A case study on water loss in spinach during distribution from harvest to markets shows how the methodology works.     

Pond management and water quality for drip irrigation in Mediterranean intensive horticultural systems

The influence of pond management on water quality for drip-irrigated crops was studied throughout a field survey and a mesocosm experiment. Water sources were pooled into two groups: ground or surface water (GW/SW) and recycled wastewater. Pond covering, which was limited to about a quarter of them, improved water quality by reducing phytoplankton biomass. However, biocide applications and pond dredging were ineffective at improving in-pond water quality. Dredging did not reduce the concentrations of planktonic chlorophyll a or total suspended solids (TSS) in GW/SW fed ponds, whereas biocide applications increased both parameters. Field and experimental data proved that the two predominant taxa of submerged aquatic vegetation (SAV) found in ponds (Potamogeton pectinatus and Chara spp.) improved water quality by increasing water oxygenation and decreasing chlorophyll a and TSS concentrations. Preserving SAV (especially Chara spp.) appears to be an environment-friendly, cost-effective and recommendable alternative strategy for irrigation pond management.     

An artificial capillary barrier to improve root-zone conditions for horticultural crops: response of pepper, lettuce, melon, and tomato

Capillary barriers (CBs) occur at the interface between two soil layers having distinct differences in hydraulic characteristics. In preliminary work without growing crops, it was demonstrated that CBs implemented in sandy soils increased hydrostatic volumetric water content by 20–70%, depending on soil texture and depth of barrier insertion. We hypothesized that the introduction of an artificial CB at the lower root-zone boundary of horticultural crops can increase yields as a result of increased water content and uptake efficiency. The effects of introduced CBs on soil water content, plant growth, and yields of bell peppers (Capsicum annum L), lettuce (Lactuca sativa L), tomatoes (Lycopersicon esculantum L.), and melons (Cucumis melo L.) were studied in a desert environment in southern Israel. Inclusion of a CB increased soil water content by 60% and biomass and fruit yields by 25% for pepper, and increased matric head and biomass yield by 80 and 36%, respectively, for lettuce. Neither tomatoes nor melons reacted significantly to the presence of CBs, in spite of increased soil moisture. Daily soil matric head amplitude was reduced fivefold when lettuce was grown with a CB. Spatial variability was highly reduced when a CB was present. When peppers were grown with a CB, the standard deviations of water content and biomass yield were reduced by 40% relative to control.     

Pathways to breaking the poverty trap in Ethiopia: Investments in agricultural water, education, and markets

Investments in agricultural water management should complement or strengthen the livelihood and coping systems of the rural poor, and should thus be instrumental for breaking the poverty trap in Ethiopia. Underdeveloped water resources constrain progress towards poverty reduction. We examine linkages and complementarities between agricultural water, education, markets and rural poverty through an empirical study using household level data from selected villages in southern Ethiopia. We show that investments in irrigation can contribute to poverty reduction, but the poverty reducing impacts of irrigation water are greater when human capital and rural markets are well developed. The size of landholding, access to irrigation water, on-farm land and water conservation practices, literacy of the household head, and years of education of adults are all significant determinants of household welfare, and thus potential pathways for reducing poverty. Expansion of cultivated land, particularly irrigated land, universal literacy, and an extra school year for adults all reduce poverty, but reductions in poverty are greater when irrigation is combined with universal literacy. These findings call for simultaneous investments in agricultural water, education, markets and related policy support measures for reducing poverty in smallholder agriculture in Ethiopia.     

叶城县农村水价改革中阶梯式水价的应用

本文对叶城县农村供水基本情况作了介绍,对实施阶梯性水价的必要性进行了分析,提出了农村水价的改革思路和改革方案,并对阶梯式水价改革方案的实施进行了探讨.     

Verification and application of a model for predicting damage to horticultural produce during transport

A model for predicting bruising in multilayered apple packs was subjected to an extensive experimental test progam. A specially built test rig was used to simulated pothole and bump effects. A comparison of experimental and predicted total bruise volumes and bruise distribution between interfaces in a single column of apples showed that the transport model successfully predicted the effects of varying severity of potholes and bumps, number of apples (layers) in the column, suspension spring stiffness and damping constant and the ration of load to vehicle mass. All but four of the 72 experimental conditions examined showed very good correlation between experimental and predicted results at, or better than, the 0·025 significance level. Similarly, at-test of the effect of changing one variable at a time gave excellent correlations, mostly at the 0·1 significance level.The application of the model to commercial packages is described. The model is applicable to two-and three-dimensional packing arrangements, energy absorbing packages and a wide range of produce. The model is used to evaluate the effects of important transport variables-i.e. load-vehicle mass ration, suspension spring and damping constants and severity of road irregularity.The paper concludes tha the model opens the way to the management of transport damage in horticultural distribution by providing the means of selecting optimum vehicles, roads and packaging.     

Variation in microbial communities colonizing horticultural slow sand filter beds: implications for filter function

The effect of microbial colonization on the function and rejuvenation of slow sand filters was investigated using culture-independent profiling. Colonization resulted in significant reduction in filter pore size, which may be important in order to fully remove pathogens, but was not associated with a specific microbial component. Communities were highly variable, and no common microbial groups were found in effective filters. Bacterial community composition was affected by sand particle size, although high levels of microbial turnover during filter maturation suggested that this was unlikely to have a major influence on community composition. The composition of microbial inoculum from a previous filter could not be maintained through a cycle of culture, storage and re-culture. Furthermore, no significant proportion of the inoculum persisted in filter maturity, and no advantages in terms of time to filter maturation or final filter efficiency were evident. These results may explain why filtration is such an effective and robust water treatment and emphasize the need for further research on the mechanisms involved in pathogen elimination.     

Smallholder dairy production and markets: A comparison of production systems in Zambia,Kenya and Sri Lanka

Three smallholder dairy production systems in Zambia, Sri Lanka and Kenya are analysed and compared. The focus is on the relationships between the animal production system, the farm household system, and the institutional environment. Attention is given to the valuation of marketed and non-marketed products and the intangible benefits of livestock in insurance, financing and status display. The comprehensive and comparative analysis of the production systems shows the direct relationship between type and intensity of dairy production and the presence or absence of markets for milk and other products, services and employment. The generally unobserved income components resulting from products other than milk and from the intangible benefits prove to be a substantial proportion of the total income in all three systems. The comprehensive perspective on the dairy production system results in policy suggestions that include institutional linkages.     

An analysis of agricultural price and research policies in Chile

The interactions between agricultural price and research policies are formally addressed in this article in order to avoid biased estimates of the benefits to Chile from indigenous and international agricultural research and development. Government pricing policies influenced the innovative behavior of the main Chilean public research institution and reduced the benefits from cost-reducing research benefits relative to those obtained under free trade conditions. Despite the existence of market distortions caused by commodity price policies, Chilean welfare gains from public agricultural research were positive. However, these net economic surplus changes would have been higher if output price interventions would have been aimed at reducing distortions and putting producer prices more in line with international prices.     

浅析农机产品质量现状大力加强农机质量监督

农业机械化的发展,一看农业机械的社会保有量和农业机械化的程度,二看农业机械的质量水平和有效应用水平。只有高质量的农业机械,才能提供高效的应用性能,实现农业丰产增收,才能确保农业机械的有效投入,增加经济效益。加强农机产品质量监督,严禁“假、冒、伪、劣”产品流入市场,是保证农业机械化事业健康发展、保护广大农民利益的重要措施。1我国农业机械的质量状况我国农机产品水平和世界先进国家比仍有差距,整体技术尚处在发达国家初级水平,品种单一,结构不尽合理。近几年农机产品监督抽查的平均抽样合格率都在70%左右,表明我国农机产品总…     

质量第一生产第二

企业的快速发展离不开独特的管理方法和经营理念。山东时风集团成立10年来的快速发展恰恰印证了这一点。她的发展诀窍就是不断提升产品质量,强化售后服务。山东时风集团成立于1993年,当时是一个名不见经传的社办小企业,十年来,集团坚持了不断提升产品质量,强化售后服务的理念,企业像滚雪球似地快速发展,2002年与1993年相比,产值增长94倍,销售收入增长81倍,利税增长254倍,利润增长593倍,资产增长41倍,职工总数增长26倍,产品销量增长59倍,累计上交税金15亿元。产销量连续6年位居全国同行业首位,成为国家特大型企业。董事长刘义发当选为全国人…     

统计学在股票价格指数中的应用

从股票中最基础的股票价格指数入手,着重讨论了统计学在股票价格指数编制计算过程中的相关应用,详细介绍了股票价格的三种平均数及计算公式;股票价格指数编制过程中的抽样分析和股票价格指数的四种计算方法;先后举出了国际上较有影响的几种股票价格指数在计算过程中统计学的相关应用.     

青岛市生猪价格波动规律及成因探究

为探究青岛市生猪产业的发展趋势,利用季节调整、H-P滤波等定量方法分析青岛市近10年的生猪价格波动特征,利用多元回归模型及1阶AR（1）模型实证分析供需两大方面因素对生猪价格波动产生的影响。结果表明,青岛市生猪价格波动呈现明显的周期性和季节性,主要受供给层面的影响,同时青岛市2022年下半年生猪价格会出现阶段性反弹,但总体幅度不会太大,并且在未来几年生猪价格将恢复正常,并继续升高。      

Barriers to water markets in the Heihe River basin in northwest China

Tradable water rights systems are becoming an important way to achieve distributive efficiency for water resources. However, it is not easy for countries or regions to establish water markets due to the existence of various barriers. In early 2002, the Ministry of Water Resources (MWR) of China initiated an experimental project—Building Water-saving Society in Zhangye City. This project was the first of its kind in China. The aim of the project was to establish a new water use rights (WUR) system with tradable water quotas and to reallocate water resources reasonably and efficiently through market-based instruments. This paper presents the research done on the system and water markets. It has been found that that the system is hard to implement well and that WUR trading is not popular. The barriers to implementing a WUR system are social and administrative in nature. WUR trading faces management, legal, administrative, and fiscal barriers. We discuss why these barriers exist and we provide policy recommendations to overcome them.     

素质教育与教师的自身素质

素质教育是我国一直在贯彻执行的教育方针,其实施需要诸多方面的条件得到改善。但教师作为素质教育的执行者和实施者,他们的自身素质的状况在素质教育推行的过程中起着举足轻重的作用,为此,论述了素质教育与教师自身素质的关系。     

昔阳县松溪供水工程水价分析研究

水利工程供水是一种特殊的商品.随着社会经济的发展,如今很多地区供需水矛盾日益突出,为了建立合理的收费和筹资机制,形成水利建设和用水的良性循环,缓解社会矛盾,水价改革显得尤为重要.文章以昔阳县松溪供水工程为例,对供水成本测算、用户水价承受能力和水价分析与设计进行了全面的分析研究,为同类工程水价分析提供参考依据.     

Can carbon sequestration markets benefit low-income producers in semi-arid Africa? Potentials and challenges

The Clean Development Mechanism (CDM) of the Kyoto Protocol of the United Nations Framework Convention on Climate Change allows a country that emits C above agreed-upon limits to purchase C offsets from an entity that uses biological means to absorb or reduce greenhouse emissions. The CDM is currently offered for afforestation and reforestation projects, but may apply subsequently to sequestration in agricultural soils. Additionally, markets outside of the Protocol are developing for soil C sequestration.     

A model to estimate the performance,revenues and costs of dairy cows under different production and price situations

A model was constructed and validated to determine the course of performance, revenues and costs of dairy cows with different levels of milk production and of number of days open. For each month in lactation the revenues from milk production, which are dependent on the fat and protein contents, were determined. The feed costs were calculated from consumption of roughage and concentrate, which were estimated from the energy requirements. Furthermore, the course of the carcass value, calf revenues and the probability of, and the financial loss associated with, involuntary disposal were considered. Seasonal variation in production and prices was included in the model.Parameters of, and prices in, the model were chosen to represent the Black and White cows in The Netherlands at the normalized price level of 1981–1982.In the future the model will be used in studies on replacement policies in dairy cattle.