1151 92 - 6/30
Review, article, industrialized countries, developing countries, agriculture, air pollution, pollutant impact, yield losses, environmental pollution
Outlook on Agriculture, 20, 1991, 139-144
Air pollution has long been known to damage plants.
Up to the middle of this century, the problem was very largely restricted to urban and industrial regions of Europe and North America.
Over the past two decades, however, it has become evident that pollutants can be transported over long distances, and hence their impact may be felt widely over rural regions. The rapid pace of industrial development and urbanization in many developing countries means that adverse impacts on agriculture are beginning to be felt in many parts of the world.
The major pollutants of concern in relation to agriculture are summarized in this article and some important sensitive crop species and the approximate concentration at which adverse effects are observed. The pollutants may conveniently be divided into primary pollutants, such as sulphur dioxide and ammonia, which are emitted directly into the atmosphere, and secondary pollutants, such as ozone, which are formed by subsequent chemical reactions in the atmosphere.
Although particulates act primarily by reducing light interception, certain particulates (e.g.cement dust) have chemical properties which may lead to more specific injury. Other particulates may contain high concentration of heavy metals, such as lead and zinc, which may contaminate foliage directly, or contribute to an increased soil burden.
Other primary gaseous pollutants which may be of concern around industrial works include hydrogen chloride, chlorine and ammonia.
Apart from ozone, the most important secondary pollutants are acid mists and rain which contain high concentrations of nitrate and sulphate, produced from the oxidation and dissolution of nitrogen oxides and sulphur dioxide. Acid rain has been shown to cause soil and fresh-water acidification in areas with poorly buffered soils. Ozone is undoubtedly the most important gaseous secondary pollutant in terms of impact on agriculture, but other gases have local impacts on sensitive crops too.
These pollutants are photochemical and are produced in high concentrations under hot, sunny conditions.
National estimates indicate crop losses of about 5% in the USA and Netherlands, but these estimates do not take into account indirect effects, via altered pest and pathogen performance, which could substantially alter the economic loss assessment. The greatest concern in the coming decades should be the impact of air pollution on food production in the developing countries. There is a need, in particular, for an objective assessment to identify the regions and pollutants of greatest concern; improved rural monitoring of pollutant concentrations; evaluation of the pollutant sensitivity of local crops and cultivars; and field experiments to quantify impacts of air pollution. A great contribution could be made to these needs by the governments and scientists of developed countries where agricultural impacts of air pollution are of less immediate relevance for the welfare of the population.
1152 92 - 6/31
Review, book, Europe, primary production, agriculture, greenhouse effect, climatic change, crop distribution
GOUDRIANN, J. et al
PUDOC, Wageningen, The Netherlands, ISBN 90-220-1026-0, 1990, Dfl. 40, USD 23
This slim volume of 96 pages contains the proceedings of an international workshop on primary productivity of European agriculture and the greenhouse effect, held at Wageningen in April 1990. The synopses or abstracts of the 24 papers presented cover the results of recent work carried out since the Villach conference held in 1985.
Several contributors discuss the effects of climatic change expected in the future on the basis of increased concentrations of atmospheric CO2 and other gases giving rise to the 'greenhouse effect' with increasing temperatures, greater UV-radiation intensity and associated phenomena.
Geographic distribution of crops is expected to change, making wheat and even maize production possible in hitherto marginal northern areas.
Plant productivity is likely to increase through greater photosynthesis, but other aspects are less reassuring, notably accelerated development of winter cereals and possibly reduced growth periods, enhanced survival of weeds which would help pest and disease organisms to overwinter, increased weed growth due to better seed production and more life cycles, and inadequate mineral supply for increased plant growth. Crop and climate modellers have looked at possible trends, but there is a paucity of primary data and, up till now, inadequate dialogue between different groups of workers.
Several contributors discuss historical aspects and economic consequences of the greenhouse effect. There has been climatic change in the past, as shown for example by the cultivation of wheat in Iceland and of grapes in England and Belgium during the High Middle Ages, and thus a temperature rise limited to 1.5 to 2.0 C by 2050 is not considered disastrous. What is likely to be more important in Western Europe, quite apart from the cost of increased sea defences, is the likely prospect of even greater overproduction of agricultural produce which, in the face of a shrinking and ageing population, will lead to still greater surpluses of food. Future politicians will thus have to determine, how much longer local farmers can be protected and whether marginal land can be retained for agriculture or needs to revert to forest.
Many of these and other aspects were raised at the workshop, and it is valuable to have them recorded.
Abstract by R.H.M. Langer, shortened.
1153 92 - 6/32
Review, book, vegetation, atmosphere, principles, case studies, ecology, weather, soil, ecosystems, microclimate
VOL. 1 PRINCIPLES; VOL. 2 CASE STUDIES
Academic Press, London, UK, 1975
In the post war period, especially after 1950, a deliberate effort has been made to achieve a better balance between weather and soil studies in the study of vegetation in relation to its environment, in which soil conditions had been privileged for a long time. Stimulus for this work comes from, among others, (tropical) ecologists concerned with changes in the microclimate that occur when the equilibrium of an ecosystem is disturbed. The two volumes have been prepared to take stock of current knowledge and to ask whether ecological science is getting the full benefit from all the information now available about physical processes and mechanisms in plant communities. The first volume, as the introductional chapter states, deals with the main contributions of micrometeorology to ecology in terms of a matrix where mechanisms, processes and states are used against air, plants and soil. This leads to review chapters on radiative transfer in plant communities, momentum, mass and heat exchange of plant communities, the hydrological cycle in vegetation, the movement of particles in plant communities, micrometeorological models and instruments and their exposure. In the first part of the second volume chapters on relatively heavily studied crops like temperate cereals, maize and rice, sugar beet and potatoes, sunflower and finally cotton show (and occasionally state in their conclusive chapters) that much is known on (consequences of) radiation characteristics, less on (consequences of) detailed heat and water balances, appreciably less on (consequences of) momentum balances and carbon dioxide balances, overall enough to try to use some of it in relatively simple but economically useful attempts of crop climate management and manipulation, but that a synthesizing attempt for that purpose is far from possible. Only in either a modelling approach, like in the chapter on townsville stylo, or in controlling certain confined aspects (frost, solar radiation) of the microclimate, like in the chapter on citrus orchards, such simple but useful attempts are actually exemplified. The chapter on coniferous forests is one of the earliest attempts to apply in detail the same approach as for the well studied crops. In less detail, because less is known, the same is done for deciduous forests. And still more limited in scope but rather unique is the micrometeorological work reported on tropical rain forest. The last three chapters, on swamps, grassland and tundras show how micrometeorological concepts can be applied to whole ecosystems. It is important for our purposes that the following ecological topics are listed in which the potential contributions of micrometeorology have still to be realized: "measurements of states outside the temperate climates in which most micrometeorological groups have hitherto worked", "measurements of process rates over a whole growing season", "the description of plant communities as 2- or 3-dimensional systems: in particular, the application of micrometeorology to row crops and to systems of inter-cropping which are an integral part of traditional farming practice in many tropical areas; the micrometeorology of isolated trees or small groups of trees valuable for amenity or shelter; the measurement and specification of root systems", "analysis of the relation between weather and disease in terms of mechanisms, processes and states (including dispersal)", "the measurement of atmospheric pollutants in plant environments".
1154 92 - 6/33
Review, book, tropics, microclimate, environment, biometeorology, agronomic practices, yield
ROSENBERG, N.J. et al.
Wiley & Sons, New York, 1983, (2nd Ed.)
This book contains twelve chapters:
- on the radiation balance;
- soil heat flux and soil temperature;
- air temperature and sensible heat transfer;
- wind and turbulent transfer;
- atmospheric humidity and dew; modification of the soil temperature and moisture regimes;
- evaporation and evapotranspiration;
- field photosynthesis, respiration and the carbon balance;
- windbreaks and shelter effects;
- frost and frost control;
- water use efficiency in crop production;
- human and animal biometeorology.
This is a textbook close to the climate aims of understanding modification practice and potential. Especially microclimatic influences of different mulches and shelters and the manipulation of evaporation and frost climate are quantitatively dealt with. It is summarized that the literature of shelter effect is reasonably consistent in its conclusions that: shelter alters microclimate; shelter reduces potential evapotranspiration; shelter reduces actual evapotranspiration; shelter improves internal water relations, for example greater internal water potential, lower stomatal resistance; shelter provides improved opportunity for photosynthesis; shelter generally increases yield. On the one hand these benefits may be most dramatic in dry years or when moisture shortages are critical, but on the other hand the literature also suggests that benefits in terms of actual yields may be more consequential under irrigation than on dry lands. Scattered trees as shelter have not been dealt with. As methods of frost protection are treated: site selection; radiation interception; thermal insulation; air mixing; direct air and plant heating; application of water; chilling to prolong dormancy and soil manipulation. The book is full of very relevant tropical and other Third World examples from the experience of the authors and many other sources.
1155 92 - 6/34
Review, bibliography, project, microclimate management, traditional farmer, field reports
Geogr. Rev. 62, 1972, pp. 544-566
This bibliography covers the only international project existing on "Traditional Techniques of Microclimate Improvement". The paper relies on field reports in its identification of farmers' reasons for using particular management practices and wants to produce sufficient evidence to justify the nomination of (micro)climate to that group of environmental factors over which traditional farmers exercise significant control. Two aspects of field microclimate are distinguished: preservation of desirable characteristics and generation of these characteristics within the crop zone. Examples of shade management, the manipulation of albedos, surface geometry and longwave transfers are separately dealt with. In a section on heat and moisture, tillage systems, surface mulches and dew are dealt with. Sections on wind, rain and hail and on maintaining microclimates close this valuable paper. In footnotes the widely scattered existing literature on basic concepts and examples is very adequately covered. The paper nevertheless concludes that its coverage is less than comprehensive, and for good reason. Crop climate management is so widespread and assumes so many forms that a complete catalogue of practices would fill volumes. Nor can extensive quantitative evaluation be attempted, since neither field nor laboratory research has produced much data on the results achieved by traditional methods. The paper concludes that traditional farmers employ an impressive array of climate-ameliorating techniques. But information on these practices comes mostly from scattered field observations, with few indications of the results achieved. Measurement of radiation, heat, and moisture fluxes under a variety of crop and field conditions are sorely needed to determine the effectiveness and extent of these climate-control measures. Questions as growing seasons and production are affected by these practices need to be dealt with.
1156 92 - 6/35
Review, book, plants, agriculture, environmental stress, ecology, drought, salinity, temperature, heat, frost
Springer Verlag, NATO ASI Series G: Ecological Sc., 19, 1989, ISBN 3-540-18559-3, DM 188,-
Probably at no time in the past has there been a more concerted research effort aimed at improving understanding of fundamental mechanisms by which plants respond to their environment. 'Environmental Stress in Plants - Biochemical and Physiological Mechanisms' provides a recent summary of those efforts, the volume arising from a NATO-sponsored meeting held in Norwich, UK, in 1987.
The volume is divided into groups of chapters, each group dealing with a specific area of stress, namely: drought, salinity, anaerobic, low temperature and heat. Mineral nutrient deficiency and mechanical impedance are omitted but the coverage of the general area of stress in higher plants is otherwise comprehensive. Typically, each paper is brief, but well focussed, so that the reader is quickly in tune with the important issues that preoccupy investigators. Unfortunately, a few contributions comprise a single-page abstract, without references; such skimpy offerings detract from a volume that is otherwise carefully edited and printed to a high standard. It is also curious to find a paper on accumulation of metabolites by a prokaryote (Salmonella typhimurium) in a volume otherwise dedicated to higher plants - one questions its inclusion.
Although it can be argued that many of the presentations in this volume have appeared in reference journals, the value of this book is that it provides a useful collection in a single volume and reasonably current summaries of the field. The volume will be useful mainly to teachers, students and those working in other disciplines who wish to become acquainted quickly with this area of plant science; it is unlikely to appeal to the specialist researcher who is already current with the literature.
1157 92 - 6/36
Review, book, cold climate, semi-arid climate, climatic variations, agriculture, impact assessment, IIASA
PARRY, M.L. et al.
VOL. 1: ASSESSMENT IN COOL TEMPERATE AND COLD REGIONS.
VOL. 2: ASSESSMENT IN SEMI-ARID REGIONS.
Kluwer Academic Publishers, Dordrecht, 1988; Vol. 1: 876 pp., Paperback
220 Dfl.; Vol. 2: 764 pp., Hardback 200 Dfl.
These two substantial volumes arise from a project to investigate the impacts of climatic variations on the agricultural sector, carried out at the International Institute for Applied Systems Analysis (IIASA) in Austria, under the direction of Martin Parry, the leading editor.
The underlying idea, as set out in the preface, was that the impact assessments should be designed, conducted, and reported in a compatible manner even though they took place in different countries, with everything that implies in terms of economic, technical, and cultural diversity. Thus it should be possible to compare the results of one assessment with those of any other. The intention was not to look simply at the first-order (or direct) effects of climate on agriculture but also at the higher-order effects on regional and national economies.
Although the title of the book concerns climatic variations rather than climatic change, in fact much of the content, particularly in Volume 1, is devoted to impacts arising from the greenhouse effect. There are 11 case study regions altogether, with papers contributed by a team of 2-3 scientists in each. All the contributions were reviewed, and abstracts are given at the beginning of each section.
Volume 1 collects together the papers on cool temperate and cold regions: Saskatchewan, Iceland, Finland, subarctic USSR, and Japan. It opens with a set of background papers. These cover, on the one hand, discussion of regional climate scenarios for a high-CO2 world and, on the other, impacts and first-order impact models. There are two papers applying the results of a climate scenario to estimate impacts on forest productivity in Northern Hemisphere high latitudes, and the higher-order effects on the world timber trade.
Volume 2 covers semi-arid regions in Kenya, Brazil, Ecuador, India,
Australia, and European USSR. The background papers take only 120 pages as against 220 in Volume 1 and are of much less interest. One summarizes the results of the semi-arid case studies, one looks at first-order impact models, and one is a general essay on semi-arid climates.
There is a clear dislocation between the two volumes. The production of Volume 1 is much better, although potential purchasers might like to check for missing pages between 309 and 341. Volume 1 is oriented very much towards CO2-related impacts whereas Volume 2 looks almost exclusively at present-day climatic variability. On this basis we may say that the project failed in its stated aim. However, the subject matter and quality of Volume 1 is such that I would recommend people to buy it.
Abstract by J. Palutikof
1158 92 - 6/37
Review, book, Afrika, Burkina Faso, Mali, Niger, Senegal, drought occurence, dry spells, crop variety, irrigation needs, crop water requirements
ICRISAT Research Bulletin No. 13, ISBN 92-9066-182-8, 1991, Order Code RBE 013; LDCs: USD 14.31, HDCs: USD 33.11; Bilingual: English, French
This publication is bilingual (English and French). Recurring droughts and decreased agricultural productivity during the last two decades in West Africa have pointed to the need for a clearer understanding of the length of dry spells, their frequencies and probabilities. A comprehensive review of various definitions of droughts has been presented to develop the basis for analysis of droughts. Using the specific definition of onset of rains in each year as the sowing date, the length of dry spells was calculated from the historical rainfall data for 150 stations located in Burkina Faso, Mali, Niger, and Senegal.
The relationships between mean annual rainfall and average frequency of dry spells for the selected locations in West Africa showed distinct patterns and permit the prediction of the frequency of dry spells from annual rainfall totals. Applications of dry-spell analysis for the choice of a crop/variety, supplemental irrigation, and crop water requirements have been described with examples.
1159 92 - 6/38
Syria, Israel, Netherlands, study, faba beans, climate change, temperature rise, CO2 increase, yield stability, ecology
GRASHOFF, C. et al.
Publ. of the Dep. of Production Ecology, P.O.B. 430, 6700 AK Wageningen and Centre for Agrobiological Research, P.O. 14, 6700 AA Wageningen, Netherlands, 1992, 18 pp + Annex
In this paper a feasibility study of effects of climate change on growth and production of faba beans is described.
The increasing presence of atmospheric trace gases such as CO2, CH4 and N2O due mainly to human activity, directly or indirectly, may influence the Earth's climate by transmitting incoming solar radiation, while partly blocking outgoing terrestial black body radiation. The increased "greenhouse" effect may cause temperature rise. This may affect the functioning of various agro-ecosystems in general and faba bean growing more specifically.
Different processes are influenced by various factors that are affected by climate change. CO2-increase affects the stomatal conductance and increases photosynthesis rate and water use efficiency. Temperature rise may increase development rate of the crop, resulting in an adverse effect on crop production. Evaluation of the effects which work in contrary directions with direct qualitative or quantitative methods is difficult. Crop growth simulation models may be used for such an evaluation as the causal relations between rate variables and forcing variables is present in such models. The consequences of CO2-increase and temperature rise may be evaluated with these models.
Climate change may have strong effects on faba bean growing, as this crop is very sensitive to water shortage and has a high yield variability at the present climate.
A simulation study was done with a well tested and validated model for crop growth and production of faba beans.
The used model was a version of SUCROS87, including a water balance.
For three locations differing in climate (Tel Hadya, Syria; Migda, Israel; Wageningen, Netherlands) at least 8 years with detailed weather data were used to simulate the consequences of temperature rise and increase of atmosheric CO2 (based on assessment of the Intergovernmental
Panel on Climate Change IPCC), separately and combined. It appears that temperature rise causes a decrease in seed yield of rain-fed crops in Wageningen and Migda, due to a shortening of the growing season. At Tel Hadya, seed yield of rain-fed crops increases, due to an accelerated start of the reproductive phase and consequently an 'escape' from water shortage later in the season. For fully irrigated crops, temperature rise causes at all locations a decrease in seed yield, most in Migda, and smallest in Tel Hadya. CO2-enrichment causes in all situations an increase in growth and production of faba beans, which compensates the decrease due to temperature rise. The effects are not completely additive at all locations. Yield increases due to CO2-enrichment are much higher than the yield decrease due to temperature rise. In Wageningen, Tel Hadya and Migda the positive net effect of the two considered effects is respectively 12%, 68%, 28% for rain-fed crops and 5%, 16%, 13% for fully irrigated crops, assuming an increase of CO2 concentration to 460 ppm and a temperature increase of 1.7 C. Fully irrigated crops show a remarkably smaller yield variability than rain-fed crops in all these assessments. In rain-fed crops, the variation in yield over the years stays the same or is somewhat reduced due to the reduced sensitivity to water shortage. Thus the net effects on productivity and stability due to the scenarios used for global climate change are at all locations positive. Other effects, such as for example morphological effects may overrule these physiological effects.
Such effects are not taken into account in this study.
1160 92 - 6/39
Review, book, tropics, Asia rice, weather, project proceedings, workshop, physiological responses, biological stresses, cropping systems, deterministic models,
Proc. of the Int. Workshop on the Impact of Weather Parameters on Growth and Yield of Rice; IRRI, Philippines, 1987, 320 pp. + annexes
Rice is the staple food of about half of mankind. At least 1.125 billion people, comprising 225 million rural families, depend on rice as their major crop; the majority of them are subsistence farmers.
Rice is cultivated under diverse climatic, hydrological, and edaphic conditions.
Its wide adaptability is illustrated by rice cultivation at latitudes from 40 S to 53 N at elevations ranging from below sea level to more than 2,000 m; under upland conditions with no accumulated surface water and lowland conditions with no accumulated surface water and lowland conditions with 5 m deep water. Temperatures and humidity also vary widely. The importance of studies to determine the impact of weather variables on rice crop performance is apparent.
The World Meteorological Organization has implemented a number of programs, including the World Climate Impact Studies (WCIP), to which the undertaking of this workshop is relevant.
In the Philippines, specifically in the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA), a system to assess climate impact for agriculture started in January 1985. Its objective is to provide a reliable and timely, yet inexpensive, weather-based information system that will continuously monitor and assess the impact of weather (such as drought, floods, typhoons, etc.) on rainfed agriculture.
Summarizing the main recommendations of the workshop are:
- Weather and biological stresses:
The extent to which information on the prevalence of rice pests under different cultural types and climatic conditions is quantitative or qualitative needs to be reviewed.
Information on the current status of major pests in different rice-growing environments should be collected in a central data bank.
Pest monitoring should be incorporated into studies on rice- weather relationships, including data on both research plots and adjacent farmers' fields.
Provision for measuring or calculating leaf wetness, an important parameter in disease epidemiology, should be added to the basic data set. Continuous temperature and humidity records are desirable.
- Weather and rainfed rice:
The constraints to upland rice production can be grouped as environmental, environment-dependent, and site-specific.
The constraints to rainfed rice production include:
- Climate: rainfall amount and variability, solar radiation, and temperature.
- Technology: insect pests and diseases, weeds, and rats and birds; land preparation; planting methods; soil nutrient management; soil erosion and other physical problems; cropping patterns; and water conservation.
- Genotype: seed dormancy and vigor, rooting characteristics, insect and disease resistance, resistance to temperature extremes, drought resistance, and crop duration.
- Socioeconomic: production incentives, labor, markets, infrastruture, and credit.
Most of these constraints can be related directly or indirectly to climatic factors or site characteristics.
Water balance is the best tool for determining soil water availability or deficiency throughout the crop season.
Because of the socioeconomic problems in rainfed rice regions and the complexities of environmental constraints on rainfed rice, international collaboration is the only avenue with the potential to contribute significantly to increased and stabilized production.
- Rice modeling:
Several recommendations to rice modeling were made.
Because of the importance of the impact of weather on the rice crop, the major importance of the crop, and the success of the UNDP-funded Rice-Weather Project in initiating the collection of essential basic information on weather and rice crop yields, and noting that the project has already established a basis for prediction models for rice yield and shows potential for developing forecasting models for pest outbreaks, the workshop recommends that appropriate donor agencies make funds available to IRRI to continue the rice-weather project, encompassing as far as possible the recommendations of the working groups.