Prospects for improved off-crop habitat management for pollen beetle control in oilseed rape

There is an urgent need to develop sustainable and environmentally benign integrated pest management (IPM) strategies for arable crops. The enhancement and manipulation of naturally occurring populations of the natural enemies of crop pests through habitat management for ‘conservation biological control’, as well as habitat management to manipulate populations of the pests themselves, have the potential to become major components of successful IPM strategies. We review the studies that have contributed to our current understanding of how the crop margin, local landscape, and regional landscape can influence pollen beetle Brassicogethes aeneus (syn. Meligethes aeneus) (Coleoptera: Nitidulidae) abundance and damage to oilseed rape crops (Brassica napus), and the efficacy of their natural enemies. We also discuss how habitat management across these multiple scales may improve pollen beetle control, reducing the need for insecticide use and contributing towards sustainable production of this important crop which is grown on increasing areas for both food and fuel.     

Evaluation of Garden Crop Mercury Uptake and Potential Exposure from Consumption of Garden Crops Grown on Floodplain Soils

ABSTRACT

This study investigated Hg uptake from soil into garden crops to help assess the significance of human consumption of crops as a potential route of exposure to Hg. Locations for both a floodplain and a control garden were identified within the Augusta Forestry Center near Crimora, VA, USA, which is about 16 river-km downstream from the city of Waynesboro, along the South River. The floodplain garden had measured soil Hg concentrations ranging from 4.2 to 78 mg Hg kg^?1 dry weight basis in the surface to 15-cm deep layer. A total of 139 samples from the floodplain garden from 17 different crops were analyzed for Hg. All crop samples (except for nine) had less than 0.1 μg Hg g^?1 wet weight basis (ww). Many samples were less than the method detection limit (MDL) of 0.003 μg Hg g^?1 ww. Based on the measured Hg concentrations and several conservative assumptions (e.g., Hg assumed present when less than MDL; 100% consumption from the geographical area in which study was conducted; and 100% bioavailable Hg as methyl Hg), consumption of crops with these Hg levels is not expected to be a significant route of Hg exposure.     

Global food supply: land use efficiency of livestock systems

Purpose

Livestock already use most global agricultural land, whereas the demand for animal-source food (ASF) is expected to increase. To address the contribution of livestock to global food supply, we need a measure for land use efficiency of livestock systems.

Methods

Existing measures capture different aspects of the debate about land use efficiency of livestock systems, such as plant productivity and the efficiency of converting feed, especially human-inedible feed, into animal products. So far, the suitability of land for cultivation of food crops has not been accounted for. Our land use ratio (LUR) includes all above-mentioned aspects and yields a realistic insight into land use efficiency of livestock systems. LUR is defined as the maximum amount of human-digestible protein (HDP) derived from food crops on all land used to cultivate feed required to produce 1 kg ASF over the amount of HDP in that 1 kg ASF. We illustrated our concept for three case systems.

Results and discussion

The LUR for the case of laying hens equaled 2.08, implying that land required to produce 1 kg HDP from laying hens could directly yield 2.08 kg HDP from human food crops. For dairy cows, the LUR was 2.10 when kept on sandy soils and 0.67 when kept on peat soils. The LUR for dairy cows on peat soils was lower compared to cows on sandy soils because land used to grow grass and grass silage for cows on peats was unsuitable for direct production of food crops. A LUR <1.0 is considered efficient in terms of global food supply and implies that animals produce more HDP per square metre than crops.

Conclusions

Values <1.0 demonstrate that livestock produce HDP more efficiently than crops. Such livestock systems (with a LUR?<?1.0), therefore, do have a role in future food supply and therefore contribute to food security. Our LUR offers identification of livestock production systems that contribute to global food supply, i.e. systems that value land with low opportunity costs for arable production and/or by-products from crop cultivation or the food or energy industry.

     

Current status and future perspectives on natural enemies for pest control in Taiwan

ABSTRACT

In Taiwan, the agricultural policy, ‘Reduce the consumption of pesticide to half in the next 10 years’, was launched in 2017. Pesticide application, which results in contamination of food by chemical residues, pest resistance, and other adverse ecological effects, is a growing public and environmental concern. Pest control by natural predators is, thus, the best alternative. Biological control methods implemented based on insights obtained from studies on pest behaviour, rearing, and various crop management modes, increase the possibility of controlling pests in modern organic agricultural systems. More than a decade has passed since the first introduction of a predatory insect in Taiwan for pest control (in the 1990s). Predatory and parasitic natural enemies, including lacewing, predatory stink bugs, Orius, and parasitic wasps, were initially used for controlling thrips, aphids, spider mites, whiteflies, and lepidopteran pests. At present, there exists a wide range of integrated pest management (IPM) methods incorporating other non-chemical, biological, and agricultural methods. However, recently, there has been an increase in research and development on the utilisation of natural enemies of insects and the associated food safety issues. Mass production and release, storage, and handling techniques of insect predators and parasitoids have been successful in recent years. The final goal of present day research is to develop natural enemy products and provide an IPM-based model to farmers for using natural enemies in agricultural production systems, thereby reducing pesticide application and ensuring food security.     

Enhanced leaf nitrogen status stabilizes omnivore population density

Plant traits can mediate the strength of interactions between omnivorous predators and their prey through density effects and changes in the omnivores’ trophic behavior. In this study, we explored the established assumption that enhanced nutrient status in host plants strengthens the buffering effect of plant feeding for omnivorous predators, i.e., prevents rapid negative population growth during prey density decline and thereby increases and stabilizes omnivore population density. We analyzed 13 years of field data on population densities of a heteropteran omnivore on Salix cinerea stands, arranged along a measured leaf nitrogen gradient and found a 195 % increase in omnivore population density and a 63 % decrease in population variability with an increase in leaf nitrogen status from 26 to 40 mgN × g^?1. We recreated the leaf nitrogen gradient in a greenhouse experiment and found, as expected, that increasing leaf nitrogen status enhanced omnivore performance but reduced per capita prey consumption. Feeding on high nitrogen status host plants can potentially decouple omnivore–prey population dynamics and allow omnivores to persist and function effectively at low prey densities to provide “background level” control of insect herbivores. This long-term effect is expected to outweigh the short-term effect on per capita prey consumption—resulting in a net increase in population predation rates with increasing leaf nitrogen status. Conservation biological control of insect pests that makes use of omnivore background control could, as a result, be manipulated via management of crop nitrogen status.     

Indicators for the on-farm assessment of crop cultivar and livestock breed diversity: a survey-based participatory approach

Agrobiodiversity plays a fundamental role in guaranteeing food security. However, still little is known about the diversity within crop and livestock species: the genetic diversity. In this paper we present a set of indicators of crop accession and breed diversity for different farm types at farm-level, which may potentially supply a useful tool to assess and monitor farming system agrobiodiversity in a feasible and relatively affordable way. A generic questionnaire was developed to capture the information on crops and livestock in 12 European case study regions and in Uganda by 203 on-farm interviews. Through a participatory approach, which involved a number of stakeholders, eight potential indicators were selected and tested. Five of them are recommended as potentially useful indicators for agrobiodiversity monitoring per farm: (1) crop-species richness (up to 16 crop species), (2) crop-cultivar diversity (up to 15 crop cultivars, 1–2 on average), (3) type of crop accessions (landraces accounted for 3 % of all crop cultivars in Europe, 31 % in Uganda), (4) livestock-species diversity (up to 5 livestock species), and (5) breed diversity (up to five cattle and eight sheep breeds, on average 1–2).We demonstrated that the selected indicators are able to detect differences between farms, regions and dominant farm types. Given the present rate of agrobiodiversity loss and the dramatic effects that this may have on food production and food security, extensive monitoring is urgent. A consistent survey of crop cultivars and livestock breeds on-farm will detect losses and help to improve strategies for the management and conservation of on-farm genetic resources.     

Improving the accounting of field emissions in the carbon footprint of agricultural products: a comparison of default IPCC methods with readily available medium-effort modeling approaches

Purpose

The estimations of greenhouse gas (GHG) field emissions from fertilization and soil carbon changes are challenges associated with calculating the carbon footprint (CFP) of agricultural products. At the regional level, the IPCC Guidelines for National Greenhouse Gas Inventories (2006a) Tier 1 approach, based on default emission factors, insufficiently accounts for emission variability resulting from pedo-climatic conditions or management practices. However, Tier 2 and 3 approaches are usually considered too complex to be practicable. In this paper, we discuss different readily available medium-effort methods to improve the accuracy of GHG emission estimates.

Methods

We present four case studies—two wheat crops in Germany and two peach orchards in Italy—to test the performance of Tier 1, 2, and 3 methodologies and compare the estimated results with available field measurements. The methodologies selected at Tier 2 and Tier 3 level are characterized by simple implementation and data collection, for which only a medium level of effort for stakeholders is required. The Tier 2 method consists of calculating direct and indirect N₂O, emissions from fertilization with a multivariate empirical model which accounts for pedo-climatic and crop management conditions. The Tier 3 method entails simulation of soil carbon stock change using the Rothamsted carbon model.

Results and discussion

Relevant differences were found among the tested methodologies: in all case studies, the Tier 1 approach exceeded the Tier 2 estimations for fertilizer-induced emissions (up to +50 %) and the measurements. Using this higher Tier approach reduced the estimated CFP calculation of annual crops by 4 and 21 % and that of the perennial crop by 7 %. Removals related to positive soil carbon change calculated using the Tier 1 approach also exceeded the Tier 3 calculations for the studied annual crops (up to +90 %) but considerably underrated the Tier 3 estimations and measurements for perennial crops (?75 %). In this case, the impact of the selected Tier method on the final CFP results was even more relevant: an increase of 194 and 88 % for the studied annual crops and a decrease of 67 % for the perennial crop case study.

Conclusions

The use of higher Tiers for the estimation of land-based emissions is strongly recommended to improve the accuracy of the CFP results. The suggested medium-effort methods tested in this study represent a good compromise between complexity reduction and accuracy improvement and can be considered reliable for the assessment of GHG mitigation potentials.

     

Importance of plant extract formulations in managing different pests attacking beans in new reclaimed area and under storage conditions

Field evaluation of some botanical formulations like Neem Azal T/S, Neem Azal T/S + TS/fort and petroleum ether extract of Curcuma longa for the management of different pests attacking broad bean crop in a new reclaimed area at El- Noubaria and under storage conditions has been carried out. All tested formulations could be considered efficient in controlling Aphis craccivora infesting broad bean under field conditions. As to the leafminer, the number of living Liriomyza trifolii larvae decreased significantly compared to non-treated control. The number of living larvae continued to decrease until seven days post-treatment after which an increase in their number was noticed after 14 days post-treatment. Neem Azal T/S + additive (TS/fort) ranked first in comparison to other treatments for the control of aphids and leafminers attacking broad bean in the field either by killing, deterrent or antifeedant effect. The yield of treated crop increased significantly in comparison to the control. Another spray was used before harvesting the crop with the same formulations for protection of the stored crop. Neem Azal T/S with adjuvant (TS/fort) protected broad bean seeds from weevil attack for one year. Petroleum ether extract of C. longa could protect the stored crops for two months only. The percentage weight loss in one kg stored seeds treated in the field with Neem formulation + adjuvant was very small compared with those seeds treated with petroleum ether extract of C. longa and control.     

Vegetable crop irrigation with tertiary filtered municipal wastewater

Abstract

The use of tertiary membrane-filtered municipal wastewater for irrigation as an alternative to natural freshwater sources was evaluated. Membrane filtration was considered as a viable technology to reclaim wastewater for irrigation, and the microbial and heavy metal impact on crops and soil was studied. The results of 2 years of research (2003 – 2004), carried out in Cerignola in the South of Italy, are reported. Tertiary treatment was carried out using a membrane filtration pilot plant with a hollow fibre submerged system. The water produced was used for drip irrigation of three vegetable crops in succession – processing tomato, fennel and lettuce – and compared with conventional water. Microbiological analyses were performed on the water used for irrigation, on soil samples and on marketable crops. Results show that the microbial content of soil and crops did not show relevant differences in relation to the two types of water. The measured values of heavy metals concentration in crops never exceeded toxic values. The filtered wastewater never caused an increase of bacterial concentration in the soil nor on the edible part of crops. Therefore, tertiary filtered municipal wastewater can be considered a valid alternative source of water for vegetable crop irrigation.     

Maize genetic diversity in traditionally cultivated polycultures in an isolated rural community in Mexico: implications for management and sustainability

ABSTRACT

Background: Maize in Mexico exhibits great genetic diversity, maintained by traditional practices of indigenous and non-indigenous communities, the same practices that have led to crop diversification over centuries. As one of the main staple crops worldwide, safeguarding the genetic diversity of maize is paramount to food security.

Aims: This study evaluated the genetic diversity and population structure of traditionally cultured maize landraces in a rural seasonal agricultural community in Veracruz, Mexico, in order to learn how traditional practices shape these landraces, and propose strategies for their preservation.

Methods: We analysed 118 individual maize samples belonging to five morphotypes (white, yellow, black, red and mottled) with eight microsatellite markers.

Results: We encountered high genetic diversity, according to expected heterozygosity (H_e = 0.61). However, inbreeding coefficient and gene flow values suggested the existence of assortative mating, which causes low genetic differentiation. Population structure analysis identified three genetic pools, independent of grain colour. These findings suggest that all morphotypes belong to the same population, which is sub-structured due to assortative mating and gene flow related to local agronomic management.

Conclusions: Current management practices in this community could lead to genetic erosion. In order to preserve diversity, wider regional seed exchange and selection for morphological diversity could be implemented.     

GM as a route for delivery of sustainable crop protection

Modern agriculture, with its vast monocultures of lush fertilized crops, provides an ideal environment for adapted pests, weeds, and diseases. This vulnerability has implications for food security: when new pesticide-resistant pest biotypes evolve they can devastate crops. Even with existing crop protection measures, approximately one-third yield losses occur globally. Given the projected increase in demand for food (70% by 2050 according to the UN), sustainable ways of preventing these losses are needed. Development of resistant crop cultivars can make an important contribution. However, traditional crop breeding programmes are limited by the time taken to move resistance traits into elite crop genetic backgrounds and the limited gene pools in which to search for novel resistance. Furthermore, resistance based on single genes does not protect against the full spectrum of pests, weeds, and diseases, and is more likely to break down as pests evolve counter-resistance. Although not necessarily a panacea, GM (genetic modification) techniques greatly facilitate transfer of genes and thus provide a route to overcome these constraints. Effective resistance traits can be precisely and conveniently moved into mainstream crop cultivars. Resistance genes can be stacked to make it harder for pests to evolve counter-resistance and to provide multiple resistances to different attackers. GM-based crop protection could substantially reduce the need for farmers to apply pesticides to their crops and would make agricultural production more efficient in terms of resources used (land, energy, water). These benefits merit consideration by environmentalists willing to keep an open mind on the GM debate.     

Yield gaps, nutrient use efficiencies and response to fertilisers by maize across heterogeneous smallholder farms of western Kenya

The need to promote fertiliser use by African smallholder farmers to counteract the current decline in per capita food production is widely recognised. But soil heterogeneity results in variable responses of crops to fertilisers within single farms. We used existing databases on maize production under farmer (F-M) and researcher management (R-M) to analyse the effect of soil heterogeneity on the different components of nutrient use efficiency by maize growing on smallholder farms in western Kenya: nutrient availability, capture and conversion efficiencies and crop biomass partitioning. Subsequently, we used the simple model QUEFTS to calculate nutrient recovery efficiencies from the R-M plots and to calculate attainable yields with and without fertilisers based on measured soil properties across heterogeneous farms. The yield gap of maize between F-M and R-M varied from 0.5 to 3 t grain ha^?1 season^?1 across field types and localities. Poor fields under R-M yielded better than F-M, even without fertilisers. Such differences, of up to 1.1 t ha^?1 greater yields under R-M conditions are attributable to improved agronomic management and germplasm. The relative response of maize to N–P–K fertilisers tended to decrease with increasing soil quality (soil C and extractable P), from a maximum of 4.4-fold to ?0.5-fold relative to the control. Soil heterogeneity affected resource use efficiencies mainly through effects on the efficiency of resource capture. Apparent recovery efficiencies varied between 0 and 70% for N, 0 and 15% for P, and 0 to 52% for K. Resource conversion efficiencies were less variable across fields and localities, with average values of 97 kg DM kg^?1 N, 558 kg DM kg^?1 P and 111 kg DM kg^?1 K taken up. Using measured soil chemical properties QUEFTS over-estimated observed yields under F-M, indicating that variable crop performance within and across farms cannot be ascribed solely to soil nutrient availability. For the R-M plots QUEFTS predicted positive crop responses to application of 30 kg P ha^?1 and 30 kg P ha^?1 + 90 kg N ha^?1 for a wide range of soil qualities, indicating that there is room to improve current crop productivity through fertiliser use. To ensure their efficient use in sub-Saharan Africa mineral fertilisers should be: (1) targeted to specific niches of soil fertility within heterogeneous farms; and (2) go hand-in-hand with the implementation of agronomic measures to improve their capture and utilisation.     

Exploiting volatile organic compounds in crop protection: A systematic review of 1-octen-3-ol and 3-octanone

The 21st century has brought new challenges to the agri-food industry due to population growth, global warming, and greater public awareness of environmental issues. Ensuring global food security for future generations is crucial. However, pests, weeds, and diseases still significantly contribute to crop losses, and the availability of effective conventional synthetic pesticides is decreasing. To address this, new and diverse pest management tools are needed. One pest management tool showing potential for invertebrate pest management is the exploitation of volatile organic compounds (VOCs)—in particular, the compounds 1-octen-3-ol and 3-octanone. This review aims to explore the extent to which 1-octen-3-ol and 3-octanone show potential in the future management of invertebrate crop and animal pests. A significant increase in the rate of publication of literature on the use of 1-octen-3-ol and 3-octanone in crop protection since 2018 is identified by this review, therefore, showing the potential importance of these compounds for use in future pest management. This review also identifies key interactions between naturally occurring biosynthesised 1-octen-3-ol and 3-octanone, and a range of invertebrate targets. Many of these interactions with key crop pests are sourced from the taxonomic families Lamiaceae, Fabaceae, and Trichomaceae. However, analysis of the practical application of these sources in an integrated pest management programme identifies clear limitations with the use of naturally occurring biosynthesised 1-octen-3-ol and 3-octanone. Rather, future focus should be placed on the development and exploitation of synthesised nature identical 1-octen-3-ol and 3-octanone for use as a biopesticide product. Overall, 1-octen-3-ol and 3-octanone show potential for exploitation in future crop protection, being abundant in source and diversity of invertebrate interactions. However, their use as a naturally occurring biosynthesised chemical is likely not practical for direct implementation in crop protection. Rather, focus should be placed on the development and exploitation of synthesised nature identical variants of these compounds for use as a biopesticide.     

Life cycle human health impacts of 875 pesticides

Purpose

Residues in field crops grown and harvested for human consumption are the main contributor to overall human exposure toward agricultural pesticides for the general population. However, exposure from crop residues is currently not considered in life cycle assessment practice. We therefore present a consistent framework for characterizing human toxicological impacts associated with pesticides applied to agricultural crops in the frame of life cycle impact assessment based on state-of-the-art data and methods.

Methods

We combine a dynamic multicrop plant uptake model designed for evaluating human exposure to residues for a wide range of pesticide-crop combinations with latest findings of pesticide dissipation kinetics in crops and post-harvest food processing. Outcome is a set of intake fractions and characterization factors for 875 organic pesticides and six major food crops along with specific confidence intervals for each factor.

Results and discussion

Intake fractions aggregating exposure via crop residues and exposure via fractions lost to air and soil for pesticides applied to agricultural crops vary between 10^?8 and 10^?1 kg intake per kilogram applied as a function of pesticide and crop. Intake fractions are typically highest for lettuce and tomato and lowest for potato due to differences in application times before crop harvest and soil as additional barrier for uptake into potato tubers. Uncertainty in intake fractions is mainly associated with dissipation dynamics in crops, where results demonstrate that using pesticide- and crop-specific data is crucial. Combined with the uncertainty in effect modeling, characterization factors per pesticide and crop show squared geometric mean standard deviations ranging from 38 to 15,560 over a variability range across pesticide-crop combinations of 10 orders of magnitude.

Conclusions

Our framework is operational for use in current life cycle impact assessment models, is made available for USEtox, and closes an important gap in the assessment of human exposure to pesticides. For ready use in life cycle assessment studies, we present pesticide-crop combination-specific characterization factors normalized to pesticide mass applied and provide default data for application times and loss due to post-harvest food processing. When using our data, we emphasize the need to consult current pesticide regulation, since each pesticide is registered for use on certain crops only, which varies between countries.

     

Saving land to feed a growing population: consequences for consumption of crop and livestock products

Purpose

The expected increase in demand for food raises concerns about the expansion of agricultural land worldwide. To avoid expansion, we need to focus on increasing land productivity, reducing waste, and shifting human diets. Studies exploring diet shifts so far have ignored competition for land between humans and animals. Our objective was to study the relation between land use, the share of animal protein in the human diet, population size, and land availability and quality.

Methods

We used linear programming to determine minimum land required to feed a population a diet with 0–80 % of the protein derived from terrestrial domestic animals. Populations ranged from 15 million to the maximum number of people that could be supported by the system. The agricultural system in the Netherlands was used as illustration, assuming no import and export of feed and food. Daily energy and protein requirements of humans were fulfilled by a diet potentially consisting of grain (wheat), root and tuber crops (potato, sugar beet), oil crops (rapeseed), legumes (brown bean), and animal protein from ruminants (milk and meat) and monogastrics (pork).

Results and discussion

Land is used most efficiently if people would derive 12 % of dietary protein from animals (% PA), especially milk. The role of animals in such a diet is to convert co-products from crop production and the human food industry into protein-rich milk and meat. Below 12 % PA, human-inedible products were wasted (i.e., not used for food production), whereas above 12 % PA, additional crops had to be cultivated to feed livestock. Large populations (40 million or more) could be sustained only if animal protein was consumed. This results from the fact that at high population sizes, land unsuitable for crop production was necessary to meet dietary requirements of the population, and contributed to food production by providing animal protein without competing for land with crops.

Conclusions

A land use optimization model including crop and animal production enables identification of the optimal % PA in the diet. Land use per capita was lowest at 12 % PA. At this level, animals optimally consume co-products from food production. Larger populations, furthermore, can be sustained only with diets relatively high in % PA, as land unsuitable for crop production is needed to fulfil their food demand. The optimal % PA in the human diet depended on population size and the relative share of land unsuitable for crop production.

     

西北干旱区利用间套作促进能源植物的高产高效

在全球性能源紧缺和我国能源植物大规模种植困难等大背景下,优质、充足的原料供应已成为制约生物质能源产业发展的主要限制因素。在确保能源植物高效生产和克服"与粮争地、与人争粮"现实的同时,挖掘我国边际土壤高产高效生产能源植物的土地优势和增产潜力。通过筛选评价适宜西北干旱地区高抗逆的新型能源植物种类,开发应用能源植物与粮经作物间套作栽培技术,实现新型能源植物对逆境资源的高效利用和可持续规模化种植,提高能源植物的生产力和优化能源物种的区域配置,增加土地产值和农民收入,缓解能源紧缺,达到经济、生态和社会效益多赢,为我国能源和粮食安全提供技术支撑。     

Carbon losses and primary productivity decline in savannah soils under cotton-cereal rotations in semiarid Togo

Soil degradation in the savannah-derived agroecosystems of West Africa is often associated with rapid depletion of organic carbon stocks in soils of coarse texture. Field experiments were conducted over a period of more than 30 years at two sites in semiarid Togo to test the impact of agricultural management practices on soil C stocks and crop productivity. The resulting datasets were analysed using dynamic simulation models of varying complexity, to study the impact of crop rotation, fertiliser use and crop residue management on soil C dynamics. The models were then used to calculate the size of the annual C inputs necessary to restore C stocks to thresholds that would allow positive crop responses to fertilisers under continuous cultivation. Yields of all crops declined over the 30 years irrespective of crop rotation, fertiliser use or crop residue management. Both seed-cotton and cereal grain yields with fertiliser fluctuated around 1 t ha^?1 after 20 years. Rotations that included early maturing sorghum varieties provided larger C inputs to the soil through residue biomass; around 2.5 t C ha^?1?year^?1. Soil C stocks, originally of 15 t ha^?1 after woodland clearance, decreased by around 3 t ha^?1 at both sites and for virtually all treatments, reaching lower equilibrium levels after 5–10 years of cultivation. Soil C dynamics were well described with a two-pool SOM model running on an annual time step, with parameter values of 0.25 for the fraction of resistant plant material (K₁), 0.15–0.20 for the decomposition rate of labile soil C (K₂) and 8–10 t C ha^?1 for the fraction of stable C in the soil. Simulated addition of organic matter to the soil 30 years after woodland clearance indicated that additions of 3 t C ha^?1?year^?1 for 15–20 years would be necessary to build ‘threshold’ soil C stocks of around 13 t ha^?1, compatible with positive crop response to fertiliser. The simulated soil C increases of 0.5 to 1.6% per year are comparable with results from long-term experiments in the region. However, the amounts of organic matter necessary to build these soil C stocks are not readily available to resource-poor farmers. These experimental results question the assumption that crop residue removal and lack of fertiliser input are responsible for soil C decline in these soils. Even when residues were incorporated and fertilisers used at high rates, crop C inputs were insufficient to compensate for C losses from these sandy soils under continuous cultivation.     

Seasonality,crop type and crop phenology influence crop damage by wildlife herbivores in Africa and Asia

Wildlife species damaging crops can cause substantial losses to farmers and at the same time create negative attitudes against wildlife and conservation efforts that may result in negative interactions against wildlife and lead to human-wildlife conflicts (HWCs). For the analysis of negative interactions between humans and terrestrial wildlife species, a globally applicable scheme for monitoring was developed and applied over 6 years in study areas of two Asian (Nepal and India) and two African (Zambia and Tanzania) countries. Factors influencing crop consumption by eight different groups of herbivores were monitored and analyzed using generalized linear models. Seasonality, crop availability, type and the phenological stage of the crop seem to play an important role in the crop damaging behavior of herbivores. Crop consumers such as elephants (Loxodonta africana and Elephas maximus), zebra (Equus quagga spp.) and boars/hogs (Sus scrofa, Potamocherus larvatus and Phacochoerus africanus) show preferences for harvested and/or maturing crops. Rhinos (Rhinoceros unicornis) and antelopes/deer (Taurotragus oryx, Aepyceros melampus, Boselaphus tragocamelus and Axis axis) damage the highest numbers of fields with crops at an intermediate growth stage. The findings of this study can inform management of HWCs in areas where people and wildlife coexist. Furthermore, this study demonstrates the benefits of standardized HWC assessments in order to compare data from different continents and between different species to be able to draw generalized conclusions for the management of HWC.     

Water footprint and irrigation use efficiency of important crops in Northern Cyprus from an environmental,economic and dietary perspective

Availability of freshwater is currently one of the most important limiting factors for crop production and food security throughout the world. Northern Cyprus is one of the world’s most important countries that has been facing drought and salinization problems since the 1970 s. The present study aimed to determine the irrigation use efficiency (IUE), irrigation economic productivity (IEP), irrigation economic efficiency (IEE) and irrigation dietary efficiency (IDE) of some major crops in Northern Cyprus to ensure better planning for sustainable water management, not only for Northern Cyprus but also for all countries facing similar problems. The results of the present study showed that both carob and fig crops require the least amount (24 L) of irrigation to produce 1 kg of fruit, and “open field” lettuce and “greenhouse” eggplant require the least amount (10 and 16 L) of irrigation to produce 1 kg of vegetables in Northern Cyprus. The irrigation economic productivity (IEP) and irrigation dietary efficiency (IDE) of crops were also found to be significantly different and meaningful for different crops. Our results showed that reshaping the distribution of crops based on their water consumption would reduce the use of water resources while continuing to feed the population.     

转基因抗虫作物中苏云金芽孢杆菌Cry蛋白的食品安全问题

苏云金芽孢杆菌(Bt)微生物制剂是农业、林业和饮用水等领域用来控制靶标害虫幼虫的有效工具,至今已经有50余年的使用历史。同时其在美国、欧洲和其他一些国家被广泛用于经过认证的有机农业生产之中。目前已获审批的转基因Bt作物中最常使用的是Cry蛋白。Cry蛋白的作用机制、食品安全性以及致敏性已经经过啮齿类动物、农场动物和人体内试验和生物信息学研究的严格检验。Cry蛋白的杀虫作用只在靶标害虫的碱性消化道内,与中肠上皮细胞的特异蛋白受体结合才能起到杀虫作用,而其他非靶标生物体内(人类、猕猴、小鼠、大鼠和牛等)都被证明没有这种特异蛋白质受体。美国、欧洲和其他国家的管理机构都已经证实了转基因Bt作物和Cry蛋白在农作物和饮用水中残留的安全性。食物加工过程能够最大化地减少转基因作物中功能性Cry蛋白的摄入。转基因抗虫作物有利于降低农药杀虫剂的使用的同时,也能够有效防止玉米中伏马菌毒素的污染。