Prospective changes in irrigation water requirements caused by agricultural expansion and climate changes in the eastern arc mountains of Kenya

Water resources and land use are closely linked with each other and with regional climate, assembling a very complex system. The understanding of the interconnecting relations involved in this system is an essential step for elaborating public policies that can effectively lead to the sustainable use of water resources. In this study, an integrated modelling framework was assembled in order to investigate potential impacts of agricultural expansion and climate changes on Irrigation Water Requirements (IWR) in the Taita Hills, Kenya. The framework comprised a land use change simulation model, a reference evapotranspiration model and synthetic precipitation datasets generated through a Monte Carlo simulation. In order to generate plausible climate change scenarios, outputs from General Climate Models were used as reference to perturbing the Monte Carlo simulations. The results indicate that throughout the next 20 years the low availability of arable lands in the hills will drive agricultural expansion to areas with higher IWR in the foothills. If current trends persist, agricultural areas will occupy roughly 60% of the study area by 2030. This expansion will increase by approximately 40% the annual water volume necessary for irrigation. Climate change may slightly decrease crops' IWR in April and November by 2030, while in May a small increase will likely be observed. The integrated assessment of these environmental changes allowed a clear identification of priority regions for land use allocation policies and water resources management.     

实施农业清洁生产势在必行

从农业生产及农业污染的特点入手，借鉴工业清洁生产的基本理念，初步界定了农业清洁生产的内涵。从农业可持续发展战略的高度，论述了实施农业清洁生产战略的必要性和可能性，并就全面推行农业清洁生产战略提出建议。     

Experimental Investigation of Convective Heat Transfer Coefficient of Various Agricultural Products Under Open Sun Drying

Abstract

In this article, the convective heat transfer coefficients of various agricultural products were investigated under open sun drying conditions. Data obtained from open sun drying experiments for eight agricultural products, namely, mulberry, strawberry, apple, garlic, potato, pumpkin, eggplant, and onion were used to determine values of convective heat transfer coefficient. The value of convective heat transfer coefficient was determined as 1.861 W/m²°C for mulberry, 6.691 W/m²°C for strawberry, 11.323 W/m²°C for apple, 1.136 W/m²°C for garlic, 8.224 W/m²°C for potato, 8.613 W/m²°C for pumpkin, 6.981 W/m²°C for eggplant, and 6.767 W/m²°C for onion. The experimental error in terms of percent uncertainty was also calculated.     

Framework and Tools for Agricultural Landscape Assessment Relating to Water Quality Protection

While many scientific studies show the influence of agricultural landscape patterns on water cycle and water quality, only a few of these have proposed scientifically based and operational methods to improve water management. Territ’eau is a framework developed to adapt agricultural landscapes to water quality protection, using components such as farmers’ fields, seminatural areas, and human infrastructures, which can act as sources, sinks, or buffers on water quality. This framework allows us to delimit active areas contributing to water quality, defined by the following three characteristics: (i) the dominant hydrological processes and their flow pathways, (ii) the characteristics of each considered pollutant, and (iii) the main landscape features. These areas are delineated by analyzing the flow connectivity from the stream to the croplands, by assessing the buffer functions of seminatural areas according to their flow pathways. Hence, this framework allows us to identify functional seminatural areas in terms of water quality and assess their limits and functions; it helps in proposing different approaches for changing agricultural landscape, acting on agricultural practices or systems, and/or conserving or rebuilding seminatural areas in controversial landscapes. Finally, it allows us to objectivize the functions of the landscape components, for adapting these components to new environmental constraints.     

Quantitative risk analysis for potentially resistant E. coli in surface waters caused by antibiotic use in agricultural systems

Antibiotics are frequently used in agricultural systems to promote livestock health and to control bacterial contaminants. Given the upsurge of the resistant fecal indicator bacteria (FIB) in the surface waters, a novel statistical method namely, microbial risk assessment (MRA) was performed, to evaluate the probability of infection by resistant FIB on populations exposed to recreational waters. Diarrheagenic Escherichia coli, except E. coli O157:H7, were selected for their prevalence in aquatic ecosystem. A comparative study between a typical E. coli pathway and a case scenario aggravated by antibiotic use has been performed via Crystal Ball® software in an effort to analyze a set of available inputs provided by the US institutions including E. coli concentrations in US Great Lakes through using random sampling and probability distributions. Results from forecasting a possible worst-case scenario dose-response, accounted for an approximate 50% chance for 20% of the exposed human populations to be infected by recreational water in the U.S. However, in a typical scenario, there is a 50% chance of infection for only 1% of the exposed human populations. The uncertain variable, E. coli concentration accounted for approximately 92.1% in a typical scenario as the major contributing factor of the dose-response model. Resistant FIB in recreational waters that are exacerbated by a low dose of antibiotic pollutants would increase the adverse health effects in exposed human populations by 10 fold.     

Analysis of livelihood security: a case study in the Kali-Khola watershed of Nepal

This paper examines household livelihoods in highland and lowland communities of the Kali-Khola agricultural watershed in western Nepal on the basis of economic, ecological and social security indicators. Significant differences were found in soil fertility status, pests and diseases management, risk and uncertainties, use of agrochemicals and access to social services. No remarkable variations were found in crop diversification, annual agricultural income and food sufficiency. However, uncertainty and risk in agricultural production is relatively low in highland communities. The findings reveal that agriculture production alone is not a viable livelihood option for agricultural watershed communities in Nepal. The households growing crops with hired labour have relatively sustainable livelihoods in Nepal's agricultural watersheds. Insufficient agricultural land, insufficient working manpower within a family, and lack of access to ecological agricultural services are prime factors in being livelihood insecure in agricultural watershed communities. Therefore, long-term policies and plans need to be developed for the empowerment of local farmers and to support rural livelihoods with adaptable and flexible income-generating strategies, resilient resource management institutions and enhancement of knowledge, skills and social capital.     

On the choice of farm management practices after the reform of the Common Agricultural Policy in 2003

The Common Agricultural Policy (CAP) was fundamentally reformed in 2003. From 2005, farmers will receive decoupled income support payments instead of production premiums if basic standards for environment, food safety, animal health and welfare are met. Farmers are likely to adjust production and management practices to the new policy framework. We describe how this reform fits into the EU strategy of making agricultural production more environmentally friendly by concentrating on the financial aspects of the reforms. Using an agricultural sector model for Austria, we show that the reform will further decrease agricultural outputs, reduce farm inputs, lessen nitrogen surpluses and make environmentally friendly management practices more attractive for farmers.     

The development and applications of a Drought Early Warning System in Botswana*

This article describes the indicators and data sources used by the Botswana Drought Early Warning System formally established in early 1984, the main uses of the indicators in the assessment of drought conditions and the design of relief programmes are outlined. Limitations of the sources of data available are discussed, as is the feasibility of adding some possible further indicators. In conclusion, the importance of a functioning Early Warning System in a country highly susceptible to repeated droughts is stressed, in the context of die current effort to elaborate a comprehensive National Food Strategy and to establish a Regional Early Warning System for Southern Africa.     

Methods of increasing food self-sufficiency following disasters in the commonwealth Caribbean*

In the Caribbean, catastrophic events take their toll on food availability through loss of food crops and livestock, disruption in the channels of distribution and loss of foreign exchange earnings from export crops, which are used to procure imported foodstuffs. Nutritional consequences such as the protein energy malnutrition among children, pregnant and lactating women and hard-working males and females are likely to follow. Choice of crops and livestock systems following disasters should be such as to allow for a rapid rehabilitation of the agricultural production and distribution system to eliminate prolonged dependence on food aid. Opportunities should be provided for balanced meal plans including staples, legumes, vegetables, food from animals, fruits, oils and fats. These issues are addressed in this article.     

田间条件下养分调控八宝景天Cd修复效率

在田间条件下,采用四因素三水平正交试验研究了N、 P、 K三因素不同水平对Cd富集植物八宝景天的生长和Cd吸收性的影响.结果表明,八宝景天生物量随施N水平的提高而增加,高N水平下(337.5 kg·hm~(-2))八宝景天地上部生物量最大,为不施肥处理的0.86～2.00倍,但对其地上部Cd含量无显著影响.K肥对八宝景天Cd吸收具有一定的促进作用,高K水平下其地上部Cd含量最高达22.05 mg·kg~(-1),较不施肥处理提高29.3%.综合分析,NPK肥料配施条件下,N肥和K肥分别是八宝景天生长和Cd吸收效率的主要影响因素,且对八宝景天Cd积累表现出明显的交互作用.肥料对八宝景天Cd提取量影响顺序为NKP,其中对八宝景天Cd修复效率的促进作用主要通过提高八宝景天生物量,高量N肥配施适量P、 K肥是提高八宝景天Cd修复效率的最佳施肥措施,其地上部Cd积累量较不施肥处理提高了0.9～2.2倍,合理增施N肥是提高八宝景天Cd修复效率的主要影响因子.