A critique of ethical and social issues of genetically modified crops

SUMMARY

The ethical and social issues of genetically modified crops as reported by the Nuffield Bioethics Committee are summarised. A critique of their findings is presented. It is argued that the apparent benefits are outweighed by the ecological, social and economic costs, and that the yields of some genetically modified crops are poorer when compared to conventional species. Furthermore, the current regulations are far too lax for consumer protection. There is an urgent need for a critical and disinterested review of the scientific basis of the research.     

Systemic risks of genetically modified crops: the need for new approaches to risk assessment

Background

European chemicals legislation (registration, evaluation, authorisation and restriction of chemical substances (REACH)) requires a broad assessment of chemicals with respect to, inter alia, their health-relevant properties. Due to the extreme number of substances to be assessed and the limited current toxicological knowledge on their respective properties, REACH implicitly requires a paradigm change: away from knowledge generated mainly from costly animal experiments towards the use of mechanistic findings. Moreover, effect mechanisms at the biochemical or cellular level are essential when conclusions shall be drawn about "new" endpoints and mixtures of xenobiotics. This study (funded by the German Federal Environment Agency) describes examples of biochemical processes in the mammalian organism and how xenobiotics interfere with them. Interference with physiological processes expected to lead to adverse health effects is characterised as "toxicity pathway". The study describes toxicological endpoints not usually covered in routine animal testing and the respective toxicity pathways.

Results and conclusions

Screening for chemicals which exert effects via common toxicity pathways and subsequently conducting targeted short-term tests may generate new information about the toxicity of chemicals without performing extensive substance-by-substance animal experiments. Information on common toxicity pathways may also provide input for the assessment of mixture effects. The U.S. Environmental Protection Agency is working intensely on this concept. It involves the use of enormous amounts of data on relevant biochemical and cellular processes, which are generated by "high-throughput screening" methods, and then are combined with substance-specific kinetic data, experimental apical test outcomes and modelling. Current limitations in the regulatory use of this integrated approach on risk assessment will be outlined.     

Modelling the outcrossing between genetically modified and conventional maize with equation discovery

Many studies explore the feasibility of co-existence between genetically modified (GM) and conventional (non-GM) crops. An important research topic in these studies is the process of outcrossing, i.e., the process of gene flow via pollen flow from GM to non-GM crops. In this paper, we address a new modelling approach to define the environmentally driven processes of outcrossing for maize from existing empirical datasets. In particular, we use equation discovery methodology that combines background knowledge and empirical data from several studies. We induce models that predict the degree of outcrossing rate between the donor (GM) and the recipient (non-GM) maize field from the distance between the fields and the local wind characteristics (speed, direction and duration). This results in highly accurate models, for which both variables (distance and wind) are essential and of roughly equal importance.     

Brazilian free-tailed bats as insect pest regulators in transgenic and conventional cotton crops.

During the past 12000 years agricultural systems have transitioned from natural habitats to conventional agricultural regions and recently to large areas of genetically engineered (GE) croplands. This GE revolution occurred for cotton in a span of slightly more than a decade during which a switch occurred in major cotton production areas from growing 100% conventional cotton to an environment in which 95% transgenics are grown. Ecological interactions between GE targeted insects and other insectivorous insects have been investigated. However, the relationships between ecological functions (such as herbivory and ecosystem transport) and agronomic benefits of avian or mammalian insectivores in the transgenic environment generally remain unclear, although the importance of some agricultural pest management services provided by insectivorous species such as the Brazilian free-tailed bat, Tadarida brasiliensis, have been recognized. We developed a dynamic model to predict regional-scale ecological functions in agricultural food webs by using the indicators of insect pest herbivory measured by cotton boll damage and insect emigration from cotton. In the south-central Texas Winter Garden agricultural region we find that the process of insectivory by bats has a considerable impact on both the ecology and valuation of harvest in Bacillus thuringiensis (Bt) transgenic and nontransgenic cotton crops. Predation on agricultural pests by insectivorous bats may enhance the economic value of agricultural systems by reducing the frequency of required spraying and delaying the ultimate need for new pesticides. In the Winter Garden region, the presence of large numbers of insectivorous bats yields a regional summer dispersion of adult pest insects from Bt cotton that is considerably reduced from the moth emigration when bats are absent in either transgenic or non-transgenic crops. This regional decrease of pest numbers impacts insect herbivory on a transcontinental scale. With a few exceptions, we find that the agronomics of both Bt and conventional cotton production is more profitable when large numbers of insectivorous bats are present.     

转基因植物入侵性评价指标初探

从生态学 (种子水平和成体水平 )和生理生化 (酶表达、蛋白检测、光合能力等 )层次 ,探讨转基因植物 (GMP)可能形成入侵性的一些特性 ,尝试建立GMP入侵性的评价指标体系 ,为进行转基因植物的安全性评价提供借鉴。     

植物对酞酸酯的敏感性

采用发芽试验和温室盆试验等方法，研究了酞酸酯（ＤＢＰ、ＤＥＨＰ）对番茄等１２种蔬菜以及水稻、小麦和油菜的影响。结果表明：酞酸酯（１０ｍｇ／１）对种子发芽率无明显影响，但对幼苗形态特征有一定作用。电镜观察表明：受害叶片叶绿体数量减少、结构改变。初步讨论了酞酸酯的理化性质与作物受害的关系，划分了蔬菜对酞酸酯的敏感性顺序。     

Regionalisation of flora elements in field boundaries sensitive to hybridisation with genetically modified oilseed rape

Background, aim, and scope Gene flow via pollen dispersal to neighbouring non-genetically modified (GM) and organic fields or to biotopes containing the same crop species and/or their wild relatives are among the most debated potential environmental risks of GM crops. These crosses permit ingression of GM traits and may produce viable progeny. Current GM crop monitoring plans and concepts have not considered this a critical issue. In the present study, we develop a methodology for the regionalisation of the hybridisation risk of GM oilseed rape (OSR) (Brassica napus L.) with respect to related hybridisation partners (both OSR and related species) as well as neighbouring arable fields and biotopes. This methodology should constitute an important component of future spatial GM crop monitoring designs. Materials and methods A vegetation database containing occurrence frequencies of OSR crossing partners in Brandenburg state was analysed, and literature surveys were performed on OSR outcrossing proofs with regard to different wild species, the viability of progeny and the potential establishment of crosses. We aggregated detailed biotope maps for the entire Brandenburg state in order to differentiate the nine main biotope groups relevant as habitats for OSR and hybridising Brassicaceae. We determined the types and areas of biotopes neighbouring all arable fields with an outside buffer of 50?m, and then ascertained whether the biotope composition outside the buffers was significantly different from that of the buffers. We then overlayed our buffering results with an ecoregion map of Brandenburg to upscale our results to larger regions. Results Brassica rapa presented the highest potential for hybridisation, reproduction and persistence in this environment, but Raphanus raphanistrum, Brassica oleracea, Hirschfeldia incana, Sinapis arvensis and Diplotaxis muralis are also significant potential crossing partners for OSR. The highest average frequency of species occurring in biotopes applies to arable lands, settlements and industrial areas, disturbed areas, road verges and gardens, which together cover 84.2?% of the total area and 74.6?% of the neighbouring biotopes. Related species occurring most often in Brandenburg are Descurainia sophia, feral OSR, Sinapis arvensis, Diplotaxis tenuifolia and Diplotaxis muralis. All biotopes relevant to OSR-related species are present in all Brandenburg ecoregions, but there are differences in the proportion of each biotope, especially hedgerows, arable land, gardens and road verges. The Uckermark and Oder valley can be considered slightly more critical. Discussion Hybridisation and persistence of GM OSR depends on (a) the related species’ potential to hybridise and produce viable progeny, (b) the frequency of hybridisation partners at different biotope types, and (c) the frequency of directly neighbouring arable fields with sensitive biotopes. Integration of these factors gives the following rank order of hybridisation risks for different biotopes in the agro-environment: disturbed areas > arable land > road verges > settlements and industrial areas > gardens. Extrapolation of local relevée and biotope results to larger areas such as the Brandenburg state was shown to be feasible, and may also be done nationwide and EU-wide with suitable biotope datasets. Conclusions Cultivation of GM OSR in Brandenburg carries a considerable potential of hybridisation with related species and feral OSR in biotopes neighbouring arable fields. The methodology presented here is suitable to link spatially limited but highly detailed datasets on the occurrence of potential hybridisation partners for GM OSR with regional datasets and to extrapolate hybridisation risks, and therefore could serve as a monitoring instrument. Recommendations and perspectives We suggest that populations of related species and the potential spread of GM traits should be monitored using a targeted approach. While further standardisation will be required, this methodology should be included as a regular component of GM crop monitoring.     

抗除草剂转基因作物基因流及其安全性评估方法的探讨

针对目前抗除草剂转基因作物基因流及其安全性评估方法存在的问题,提出了以亲和性为依据的抗性基因流的评估方法;同时以时间关系序列、空间关系序列和种群数量关系序列为原则,探讨了近缘种选择的标准。     

Assessment of regional capabilities for agricultural coexistence with genetically modified maize

Background

The coexistence of agricultural production with and without the use of genetically modified (GV) crops is supposed to be made possible in Germany by regulations, which include minimal distances of GV-fields to potentially susceptible crop fields and habitats. To explore the impact of these regulations on region specific coexistence potentials, we broadened the applicability of an existing method for the simulation of the spatial distribution of arable fields cropped with conventional, organic and GV-maize. We used simulations which combine a variety of minimum distances of GV-maize fields to assess regional specific options and limitations for coexistence.

Results

An existing method was extended to be applicable for different spatial scales, from the large (e.g. Federal State) to small (e.g. municipality). Input data consisted of cropping statistics, geometry of arable fields and protected areas. Scenarios of cropping situations included various minimal distances between GV-maize fields and protected areas and various proportions of maize within the areas. The results of the simulations represent possible distribution patterns of non-GV and GV-maize fields as well as the size of the remaining area in which additional GV-maize can be grown without violating the minimal distance rules. As suspected, increasing proportions of GV-maize and increasing minimal distances lower the areas suitable for additional GV-maize. However, the relation between the area of GV-maize grown and those suitable for GV-maize cultivation varied between the scenarios. Moreover, the variability between the municipalities was even more evident, due to varying landscape structure (proportion of maize, the ratio total arable land to maize, proportion of protected areas). Areas with high proportions of GV-maize, of protected areas and of maize could be problematical for coexistence. We discuss these parameters with regard to other coexistence studies.

Conclusions

Our method is suitable to simulate the spatial distribution of fields cultivated with GV-crops and non-GV-crops on various scales. Simulations on the scale of a Federal State reveals those areas, in which coexistence could be problematical. Simulations on a county scale, however, allow more insight into options and restrictions for coexistence in relation to landscape structural characteristics, which also can be transferred to larger scales. On the scale of municipalities simulations can help to analyse the limits of coexistence in areas of high conflict potential, moreover this level is more realistic with regard to practical agricultural decisions on the farm level.

Zusammenfassung

Hintergrund

Die Koexistenz verschiedener landwirtschaftlicher Produktionsformen ?C mit und ohne Anbau von gentechnisch ver?nderten Pflanzen (GVO) ?C soll durch gesetzlich fixierte Regeln erm?glicht werden, die unter anderem die Mindestabst?nde von GVO-Anbaufl?chen zu potenziell empfindlichen anderen Ackerfl?chen und Biotopen festlegen. Hier wurde eine Methode weiterentwickelt zur Simulation der r?umlichen Verteilung der Anbaufl?chen von konventionellem, ?kologischem und GV-Mais um regionsspezifische Koexistenzpotenziale von gentechnisch ver?ndertem Mais, sowie potenzielle Konfliktgebiete zu identifizieren.

Ergebnisse

Eine für Brandenburg entwickelte GIS-Simulationsmethode wurde durch die Verwendung fl?chendeckend vorhandener Daten so erweitert, dass sie bundesweit übertragbar ist und auf unterschiedlichen r?umlichen Skalenebenen angewandt werden kann, von gro?r?umig (Bundesland) bis lokal (Gemeinde). Als Eingangsdaten wurden Anbaustatistiken sowie Geometrien der Ackerfl?chen und von FFH- und Naturschutzgebieten verwendet. In den Szenarien wurden Abstandsregelungen zwischen Maisanbaufl?chen und zu Schutzgebieten und der GV-Maisanteil variiert. Die Ergebnisse der Simulation sind m?gliche r?umliche Verteilungen von Nicht-GV-Mais und GV-Mais sowie die potenziell für den Anbau von GV-Mais zur Verfügung stehende Fl?che. Mit zunehmendem GV-Maisanteil und Mindestabst?nden zu Schutzgebieten wird die für den GV-Mais zur Verfügung stehende Fl?che st?rker ausgesch?pft. Der Anteil des GV-Mais an der potenziell für den Anbau von GV-Mais zur Verfügung stehenden Fl?che variierte zwischen den Szenarien, und noch st?rker jedoch regional zwischen den Landkreisen, verursacht durch deren verschiedene agrar- und landschaftsstrukturelle Ausstattung (Maisanbauanteil, Verh?ltnis Ackerlandsanteil/Maisanbauanteil, Schutzgebietsanteil). Ein r?umliches Konfliktpotenzial bei der Umsetzung der Koexistenz ist in Gebieten hohen Nutzungsdrucks zu erwarten, d.h. in denen sowohl der Maisanbauanteil an der Ackerfl?che und der Anbauanteil von GV-Mais, als auch der Schutzgebietsanteil hoch sind. Diese Faktoren werden diskutiert in Bezug zu Ergebnissen weiterer Koexistenzstudien.

Schlussfolgerungen

Die vorgestellte Methode ist geeignet, die r?umliche Verteilung des Anbaus von Nicht-GV-Mais und GV-Mais auf unterschiedlichen Skalenebenen zu simulieren: Die Ebene eines Bundeslandes liefert Hinweise auf Gebiete, in denen die Koexistenz problematisch sein k?nnte und kann als Grundlage weiterer Berechnungen, wie zum Beispiel der Modellierung von Genflüssen auf Landesebene dienen. Die Simulation auf der Ebene eines Landkreises oder einer Gemeinde erm?glicht genauere Aussagen über die M?glichkeiten und Grenzen der Koexistenz. Auf der Ebene der Landkreise k?nnen z.B. unterschiedliche agrar- und landschaftsstrukturelle Situationen untersucht und für eine nachfolgende Regionalisierung angewandt werden. Die Ebene der Gemeinden erlaubt die Analyse der Grenzen der Koexistenz für Gebiete mit h?herem r?umlichen Konfliktpotenzial. Simulationen auf lokaler Ebene erscheinen darüber hinaus n?her an den Entscheidungsm?glichkeiten der landwirtschaftlichen Praxis.     

Environmental risk assessment of genetically modified plants - concepts and controversies

Purpose

The purpose of the study is the enhancement of criticality assessments for resources in order to address function specific factors like dissipation, recycling, bio-activity and toxicity. The developed methodology is applied to platinum-containing cytostatic drugs and automotive catalytic converters.

Methods

The study is methodically based on an analysis of resource specific factors like exploration rates, reserves-to-production ratio and regional distribution of exploration areas as well as on the investigation of product/functional depending factors like recycling rates, dissipation rates, bio-diversity and toxicity. Taking into account that economic and ecological risks may occur at any stage of the supply, consumption and dissipation processes, the whole life cycles of the two analyzed products (cytostatic drugs and automotive catalytic converters) are considered. As an approach to reduce potential economic and ecological risks the study is especially focused on recycling strategies.

Background

In order to get a better understanding of platinum as an essential resource for the development of our society the history and the cultural impact of the term "resource" are introduced.

Results & Discussion

The availability of platinum is crucial for several products of our modern society. Areas of application are e.g. jewellery, automotive catalytic converters, investments (coins, bars), computers, mobile devices, fertilizers and cytostatic drugs. Economic risks are caused by limited sources and dynamic demand of new application areas like fuel cells and drugs. Platinum-containing drugs are used for the treatment of several kinds of cancer such as testicular, breast, colon and prostate. Currently the pharmaceutical industry requires 6,9 tons per year (3 percent of the total demand of platinum). Due to the improvement of medical standards and the ageing society, especially in developing countries, the demand of platinum-containing drugs will rise significantly. The dissipation of toxic soluble salts and the lack of advanced waste-water treatment and recycling systems is a problem of the usage of platinum-containing drugs. Compared with cytostatic drugs (14.6 kg/a for Germany) the dissipation of platinum particles of mobile catalytic converters is much higher (5-20 tons/a only in North America, Europe and Japan; 184,2 kg/a in Germany). On the other hand the emission of platinum nano-particles of automotive catalytic converters seems less critical. Furthermore advanced recycling technologies are already available for them.

Conclusions

The evaluation of resources has to consider resource specific and functional depending factors. In order to reduce economic and ecological risks of the dissipation of platinum salts in cytostatic drugs three principle options can be identified: the development of ecologically compatible and cost-effective substitutes, efficient recycling systems and future-oriented sanitary-systems as well as waste-water treatment facilities, which are able to separate platinum salts. Concerning the dissipation of platinum particles of mobile converters relevant research questions are the identification of adequate substitutes as well as the extension of recycling capacities.

Recommendations and perspectives

The study demonstrates a research gap concerning substitutes for automotive catalytic converters as well as for platinum-containing cytostatic drugs. The development and implementation of recycling concepts, technologies and capacities to reuse platinum as a secondary resource is an essential issue. As a consequence the economic and ecological risks can be reduced by increasing the resource efficiency. Special research has to be done concerning the development of future-oriented sanitary-systems and waste-water treatment facilities in order to separate platinum in waste water. Furthermore, if the future demand of new products like fuel cells is considered, a resource conflict concerning the potential functional applications will be evident. In order to address these challenges the criticality assessment has to be enhanced by ethic and social factors.     

Overview of principles and implementations to deal with spatial issues in monitoring environmental effects of genetically modified organisms

Background

Sorting and disposal of waste are the last steps in the “lifetime” of a product. If products are contaminated with chemicals assessed to be hazardous for man or environment, waste management has the role of a vacuum cleaner in substance chain management working in two different ways: The hazardous compounds have to be properly separated from potential secondary resources in sorting processes. If this is not possible, those products have to be disposed safely. Starting from the experiences collected with some chemicals banned, the tools used for phasing out these chemicals from the technosphere are studied with respect to their influence on the contamination of the environment.

Results

Even if a dangerous substance has been banned, it is further used in a number of products. In the cases presented here, the substances were banned for further use. In the case of CFCs, the substitutes used have partially also been substituted because of adverse effects. Besides the prohibition of use of hazardous substances, numerous other regulations were issued to reduce unsafe handling and minimize emissions into the environment. It turned out that waste management cannot correct mistakes which already happened “upstream” in the product chain. The control of point sources works quite successfully, whereas today the overwhelming emissions stem from diffuse sources, partially caused by unsafe waste management procedures.

Conclusions

Though there are no complete balances for both groups of compounds serving as examples, some conclusions can be drawn based on the experiences collected. Hazardous compounds may be separated successfully from used products or waste,

• If they are mostly used in industry and not in households,
• if they can be identified as part of certain products,
• if their concentration in these products is rather high,
• if technical problems come up when they contaminate secondary raw materials,
• if there is international support for proper waste management.

     

Lead and potential health risks from subsistence food crops in urban Kenya

Lead, zinc and cadmium were analysed in a range of subsistence crops cultivated in and around Nairobi city centre. Lead was found to be the only contaminant of concern, being widely dispersed with elevated levels found in crops and soils from both suburban and city centre areas. Extremely high concentrations were recorded in the edible portions of a variety of crops, and high soil Pb levels were recorded within 30m of busy roads. Based on these data, it is estimated that subsistence on a diet of crops cultivated in and around Nairobi could increase Pb intake by 10–100 times the FAO/WHO maximum tolerable levels, potentially contributing substantially to existing health problems.     

The effect of wind direction on cross-pollination in wind-pollinated GM crops.

In Europe, regulatory thresholds restrict adventitious GM (genetically modified) presence in conventional crops. Minimum distances for the spatial separation of fields are often recommended to reduce field-to-field cross-pollination to an acceptable level. Field trials are typically the basis for setting separation distances. However, using records of wind direction and speed from weather stations across Europe, we predict theoretically that field-to-field windborne cross-pollination in maize, oilseed rape, sugar beet, and rice varies greatly according to the relative orientation of the GM and non-GM fields. Furthermore, at a given site and orientation from a GM field, we predict that the cross-pollination rate varies substantially from year to year. Consequently, even replicated field trials may inaccurately estimate typical levels of cross-pollination and therefore distort our perception of the separation distances required to achieve sub-threshold adventitious GM presence. We propose methods to predict the likely range in levels of cross-pollination based on the limited data typically available from field trials. Additionally, we suggest suitable time lags between peak flowering in adjacent fields that could be introduced to reduce cross-pollination to a specified level.     

Cultivation of aerobic granular sludge in a conventional,continuous flow,completely mixed activated sludge system

Aerobic granules were formed in a conventional, continuous flow, completely mixed activated sludge system (CMAS). The reactor was inoculated with seed sludge containing few filaments and fed with synthetic municipal wastewater. The settling time of the sludge and the average dissolved oxygen (DO) of the reactor were 2 h and 4.2 mg·L^-1, respectively. The reactor was agitated by a stirrer, with a speed of 250 r·min^-1, to ensure good mixing．The granular sludge had good settleability, and the sludge volume index (SVI) was between 50 and 90 mL·g^-1. The laser particle analyzer showed the diameter of the granules to be between 0.18 and 1.25 mm. A scanning electron microscope (SEM) investigation revealed the predominance of sphere-like and rod-like bacteria, and only few filaments grew in the granules. The microbial community structure of the granules was also analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Sequencing analysis indicated the dominant species were α, β, and γ-Proteobacteria, Bacteroidetes, and Firmicutes. The data from the study suggested that aerobic granules could form, if provided with sufficient number of filaments and high shear force. It was also observed that a high height-to-diameter ratio of the reactor and short settling time were not essential for the formation of aerobic granular sludge.     

Techno-economic characteristics of wastewater treatment plants retrofitted from the conventional activated sludge process to the membrane bioreactor process

• Retrofitting from CAS to MBR increased effluent quality and environmental benefits. • Retrofitting from CAS to MBR increased energy consumption but not operating cost. • Retrofitting from CAS to MBR increased the net profit and cost efficiency. • The advantage of MBR is related to the adopted effluent standard. • The techno-economy of MBR improves with stricter effluent standards. While a growing number of wastewater treatment plants (WWTPs) are being retrofitted from the conventional activated sludge (CAS) process to the membrane bioreactor (MBR) process, the debate on the techno-economy of MBR vs. CAS has continued and calls for a thorough assessment based on techno-economic valuation. In this study, we analyzed the operating data of 20 large-scale WWTPs (capacity≥10000 m³/d) and compared their techno-economy before and after the retrofitting from CAS to MBR. Through cost-benefit analysis, we evaluated the net profit by subtracting the operating cost from the environmental benefit (estimated by the shadow price of pollutant removal and water reclamation). After the retrofitting, the removal rate of pollutants increased (e.g., from 89.0% to 93.3% on average for NH₃-N), the average energy consumption increased from 0.40 to 0.57 kWh/m³, but the operating cost did not increase significantly. The average marginal environmental benefit increased remarkably (from 0.47 to 0.66 CNY/g for NH₃-N removal), leading to an increase in the average net profit from 19.4 to 24.4 CNY/m³. We further scored the technical efficiencies via data envelopment analysis based on non-radial directional distance functions. After the retrofitting, the relative cost efficiency increased from 0.70 to 0.73 (the theoretical maximum is 1), while the relative energy efficiency did not change significantly. The techno-economy is closely related to the effluent standard adopted, particularly when truncating the extra benefit of pollutant removal beyond the standard in economic modeling. The modeling results suggested that MBR is more profitable than CAS given stricter effluent standards.     

The challenge of providing environmental flow rules to sustain river ecosystems.

Accounting for natural differences in flow variability among rivers, and understanding the importance of this for the protection of freshwater biodiversity and maintenance of goods and services that rivers provide, is a great challenge for water managers and scientists. Nevertheless, despite considerable progress in understanding how flow variability sustains river ecosystems, there is a growing temptation to ignore natural system complexity in favor of simplistic, static, environmental flow "rules" to resolve pressing river management issues. We argue that such approaches are misguided and will ultimately contribute to further degradation of river ecosystems. In the absence of detailed empirical information of environmental flow requirements for rivers, we propose a generic approach that incorporates essential aspects of natural flow variability shared across particular classes of rivers that can be validated with empirical biological data and other information in a calibration process. We argue that this approach can bridge the gap between simple hydrological "rules of thumb" and more comprehensive environmental flow assessments and experimental flow restoration projects.     

The value of information on the response function of crops to soil salinity

The expected profitability to farmers from acquiring additional information on the biological response function of crop yield to soil salinity is investigated. First, a switching regression approach to estimate piecewise linear response function with critical threshold level is presented. Then, an optimization irrigation model is developed, aimed at determining the optimal use of irrigation water for soil leaching. Finally, a loss function is defined, the expected value of sample information is calculated and the optimal number of additional needed observations is determined. At each stage, an empirical analysis, using data from potato field experiments in Israel, is presented.