Sustainable Agriculture Research and Education in the Field A Proceedings (1991) / Chapter Skim
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PART FIVE: RESEARCH AND EDUCATION IN THE NORTHEASTERN REGION
PART FIVE: RESEARCH AND EDUCATION IN THE NORTHEASTERN REGION
Pages 289-384
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PART FIVE Research and Education in the Northeastern Region
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Pleasant, Steven E Peters and Mark Bohike One of the most challenging areas of research within the mandate of lowinput sustainable agriculture (LISA)
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Some of the agronomic and economic results from these studies are highlighted, although two of the three studies were established in 1988, and from a pragmatic point of view, these data should be considered preliminary results. This raises a question of concern for researchers involved with longterm studies: How are sustainable funding sources for low-input sustainable agriculture research obtained?
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rotations rely on crop rotation, cover crops, relay cropping, and mechanical cultivation for weed control and only on green manures and animal manures as nitrogen sources. Each of the three crop rotations was started at three different points in the rotation, for a total of nine treatments.
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However, because rotation entry point was a significant factor, the most profitable LIP-CO ~catmcnt resulted in a higher average annual net return than that Mom 1hc least profitable CONV lrcatmcut. 12 ~0 B 6 4 2 a 19B1-1984 19B5-19B9 a ~ # ~P-A LIP-CO CONV FIGURE 18-1 Averapc corn yields Mom the farming systems that Mom 1981 to 1984 (during conversion)
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Total biomass production and grain yields have essentially been the same in all systems since 1985. Nitrogen does not currently limit corn yield in any system, as determined by the ear leaf tissue test (Table 18-2' and by extensive testing of soil nitrate nitrogen levels during the growing season (Figure 18-3A and B)
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* Previous crop for LIP-A treatment was 2-year-old red clover-alfalfa mixture; for LIP-CO was a 1-year-old red clover stand; and CONV treatments followed either soybeans or corn.
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LONG-TERM LOW-INPUT CROPPING SYSTEMS 60 50 ~I: 30 E 7 ~ 20 o Oh 10 o 60 50 Q 40 z LO <` 30 of ~ 20 o oh 10 o 297 A ~ \ A / \ -+- LIP-A ,~ -~- LIP-CO U\, -o- CONV / ~' / \ \ / ~o/~-e s2~ \ ~\ ~a\ Apr 25 May 31 Jul 1 Jul 29 SAMPLING DATE Aug 18 Sep 15 B -+- Lip-A _ ~- Ll P-CG -o- CONV as' o- it// it// I 1 1 /,. o- \~ O ~-_6 , , 1 Apr24 Jun12 Aug3 Sep18 SAMPLING DATE FIGURE 18-3 Soil nitrate nitrogen levels in the farming systems trial at the Rodale Research Center in (A)
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The microbial activity is attributed more to the diversity of crops in the rotation, especially the legume cover crops and hay, and to the application of animal manure in the LIP-A system than it is to the absence of pesticides and chemical fertilizers. This increased biological activity may partially account for preliminary results from isN studies (Harris et al., 1989)
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manure substitution for inorganic nitrogen, (3) interseedings of cover crops, and (A band application of herbicide or cultivation for weed control.
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+ manure:> Continuous corn (ridge till) + interseeded red clover Continuous corn + interseeded red clover Continuous corn (ridge till)
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Pleasant t19904~. TABLE 18-4 Effects of Cropping System and Weed Control Treatments on Corn Silage Yields and Weed Levels, Mt.
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Analysis of variance values for weed levels: system, p = 0.1559; weed control, p = 0.0001; system x weed control interaction, p = 0.0072. This result was also observed in some early studies on cover crop interseeding conducted by the Rodale Research Center (Palada et al., 1982~.
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Ridge tillage is believed to be a promising reduced-tillage system for New York farmers, because soil in the ridge may warm up faster than soil in a high residue, flat, no-till system. Other interesting results from the Cornell study show that there are significant interaction effects of tillage system and cover crops with corn pests.
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Both LIP rotations rely primarily on cover crops for nitrogen supply and weed control in the no-till system and do not include pesticides. One LIP rotation (LIP-1)
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bu/acre. The failure of the hairy vetch and competition for moisture from the rye contributed to the agronomic and economic failure of this system in 1988.
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This was not known before this experiment was conducted, TABLE 18-7 Corn Grain Yield, Percent Nitrogen in Ear Leaf, and Weed Biomass from the Low-Input, ReducedTillage Experiment, Rodale Research Center, 1989 Grain Yield Ear LeafWeed Biomass Treatment (bu/acre)
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Expenses A_ ~ .., ~ are minimized in this system because no herbicides are used and the soybeans are drilled into the established grain crop. However, the high cost of harvesting both crops and the relatively low yield of soybeans in 1989 compared with the soybean yield in the CONV system in 1988 indicate that for the moldboard plow, chisel/disk, and ridge-till systems, monocultures of soybeans are more profitable, while in the no-till system the LIP relay crop is more profitable than the CONV monoculture crop (Wes Musser, Agricultural Economics Department, The Pennsylvania State University, University Park, personal communication of preliminary results, 1990~.
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2- to 8-inch soil layers in the low-input, reduced-tillage cropping system experiment, Rodale Research Center, 1989.
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V 1 1 1 1 1 1 1 1 1 Mar 27 Apr 18 May 31 Jun 26 Jul 24 Sep 19 SAMPLING DATE -+- Moldboard Plow _ A_ Chisel/Disk -0- Ridge-Till V No-Till _~_ Mixed-Till \ \~N \ 5N V ~+ 'I \ ' \ \ ~ ^_ _ 'I \ May 31 Jun 26 Jul 24 SAM PLI NG DATE Sep 19 FIGURE 18-6 Soil nitrate nitrogen levels in the low-input (LIP-1) cropping system (nitrogen from hairy vetch cover crop)
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LONG-TERM CROPPING SYSTEMS COMPARISONS In addition to the three experiments highlighted in this chapter, several other experiments with similar objectives have begun or are being initiated at various locations around the country. Recently, a working conference was held at the Rodale Research Center (in preparation)
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MEANINGFUL INTEGRATION OF FARMER AND RESEARCHER INFORMATION Many of the sustainable agriculture programs at various locations around the country are also linked to networks of farmers who advise researchers on the direction of on-station research and who function as research collaborators by conducting experiments and demonstration trials on their farms. Researchers involved with the cropping systems experiment at Cornell University currently conduct research on reduced-tillage techniques, cover crop overseeding, reduced herbicide use through banded applications, cultivation for weed control, and manure management with six New York State farmers (Mt.
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, and the next set of questions that need to be addressed (e.g., why do my soil phosphorus and potassium levels seem to be going up in fields with cover crops, even without manure or mineral fertilizer additions?
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The LIP reduced tillage experiment at Rodale is attempting to combine information from farmers about reduced tillage, including chisel/disk-based systems, ridge-tillage, and especially no-till (mow-sow) planting into cover crops, with what researchers have learned from the conversion experiment about how to grow crops without purchased fertilizers or pesticides (diver
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The authors also acknowledge the various funding sources that have made this research possible, including the LISA program of USDA, the Charles Stewart Mott Foundation, the Pennsylvania Energy Development Authority, the Cornell Agricultural Experiment Station and Rodale Press. REFERENCES Andrews, R
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Pp. 1-17 in Organic Farming: Current Technology and Its Role in a Sustainable Agriculture.
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1982. Association of interseeded legume cover crops and annual row crops in year-round cropping systems.
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1989. Soils of the Rodale Research Farm.
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The production of forages, especially forage legumes, and the requirements for manure handling have created the foundations for nutrient management in Pennsylvania. Although the idea of nutrient management on farms in Pennsylvania has extensive historic roots, the goals and challenges of nutrient management have not remained the same with time.
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The costs of distribution are not exclusively economic, but they could include a host of on-farm factors related to the practice. The least direct cost distribution of manure continues to be an effective foundation for nutrient management strategies on many farms in Pennsylvania.
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PLANT NUTRIENT MANAGEMENT STRATEGY IMPLICATIONS Westphal et al.
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1989. Plant nutrient management strategy implications for optimal herd size performance of a simulated dairy farm.
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1989. Plant nutrient management strategy implications for optimal herd size performance of a simulated dairy farm.
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The cultural practices for these crops require more trips across each field in a growing season than does corn production. A transition from monoculture corn to a mixed set of crops requiring different machines and field and management operations also has additional requirements for the farm that must be considered beyond the energy performance criteria of the nutrient management practices.
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The importance of animals to the whole farm nutrient flow was apparent in the primary nutrient loading of the farm from animal feed rather than from fertilizer purchased for crop production (Table 19-6~. The set of crop and animal factors contributing to the management of on- and off-farm plant nutrient sources reflects the site-specific management by the farmer in both enterprise areas and the potential productivity of the soils.
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1990. Plant nutrient flow in the managed pathways of an intensive dairy farm.
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These operational parameters of the monitoring program were considered within the context of common property or open-access water resources perspectives (Runge, 19813. Under conditions of common property, all parts of society control the use and pollution of water re
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A consensus on the appropriate precision and range of performances that define responsible management may be very critical to the potential utilization of organic sources of plant nutrients on crop and livestock farms. PLANT NUTRIENT MANAGEMENT PROCESS The difficulties in predicting the best management practices from general principles of crop nutrient supply and the need to deal with site specificity are being integrated into a nutrient management process in Pennsylvania (Figure 19-2~.
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1989. The role of on-farm nutrient balance assessments in an integrated approach to nutrient management.
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Nutrient management, on the other hand, incorporates site specificity and information richness, that is, the particular elements of place and management. It does not address the missing pieces of a management system.
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Farmers faced with nutrient management decisions are more likely to encounter a complex web of interconnections rather than a thin chain with a weak link to be stressed until it breaks. Farmers do not have the flexibility to wait until all possible hypotheses have been tested before they make each management decision.
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This perspective may be the basis for a contemporary paradigm by which to understand particular farms with their site specificity and information richness.
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CONCLUSION An approach to farm systems that is sensitive to the contributions of normal science and the opportunities of an integrative management process will be able to take advantage of both science and management alternatives. The site specificity and information richness that are essential in contemporary plant nutrient management also have been heralded as the hallmarks of sustainable agriculture.
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1989. An Economic Evaluation of a Method to Obtain Farm-Specific Nutrient Information on a Lancaster County Dairy Farm Under Two Nutrient Management Strategies.
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1989. Plant nutrient management strategy implications for optimal herd size performance of a simulated dairy farm.
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produced by the application of pesticides to residential and agricultural lands for control of insects, plant diseases, and weeds suggest that some of these control strategies have become self-defeating (Perkins, 19821. ~ ~~ Clearly, however, chemical pesticides are valuable tools that must be used wisely to combat insect pests.
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Understanding of these associations in general and more specifically on a system-by-system basis should provide a significant amount of assistance in the ability to manipulate insect pathogens for IPM purposes. Fungal pathogens are important natural biological control agents of many insects and other arthropods and frequently cause epizootics that significantly reduce host populations (Burges, 1981; Carruthers and Soper, 1987; MacLeod, 1963; McCoy et al., 1988~.
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Naturally occurring epizootics caused by fungal pathogens, particularly those caused by fungi in the order Entomophthorales, are noted frequently in both natural and managed ecosystems (Carruthers and Soper, 1987; Carruthers et al., 1985b; McCoy et al., 1988; Mohamed et al., 1977; Nordin et al., 1983; Pickford and Riegert, 1964; Soper et al., 1976; Wilding, 1975, 1981J. Because of the catastrophic impacts these pathogens have on their host populations, they hold significant potential for biological control of some ~est soecies (Carruthers and Soper, 1987; Ferron, 1978; McCoy, 1981; .
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This is not meant to be an exhaustive review but, rather, an overview of the subject. Readers interested in more comprehensive reviews on fungal pathology in general or on specific taxa of fungal pathogens are referred to Steinhaus (1963)
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. Vegetative growth in the insect hemocoel is common to most entomopathogenic fungi (Roberts and Humber, 1981)
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Fungi in the classes Ascomycetes and Deuteromycetes may produce specialized masses of hardened vegetative tissue called sclerotia or stromata, as in the genera Cordyceps and Torubiella, or modified hyphae called chlamydospores, as in the genera Beauveria and Metarhizium (McCoy et al., 1988; Roberts and Humber, 1981~. Many variations of this basic life cycle occur in different species of entomopathogenic fungi.
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Virulence refers to the intensity of the disease caused by a pathogen, whereas pathogenicity refers to an organism's ability to cause disease. Most fungal pathogens are considered highly virulent relative to other pathogenic organisms because they typically have short incubation periods, produce copious amounts of secondary inoculum, and can cause a rapid increase in disease prevalence.
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Some fungal pathogens cause their hosts to climb to aerial locations just prior to death (MacLeod, 1963~; such behavior may aid dispersal of infective conidia which may rain down on or blow to nearby hosts. Pathogen population density and spatial distribution are key factors in the development of an epizootic, as they affect the likelihood of contact with viable hosts (Tanada and Fuxa, 1987~.
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producing different levels of infection under field conditions. Although climatic conditions may be limiting for disease development, under nonlimiting conditions, host density may directly influence the rate of disease buildup (Benz, 1987; Carruthers et al., 1985b; Watanabe, 1987~.
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Transmission of fungal pathogens occurs primarily through the insect integument; this may be accomplished through direct host-to-host contact or by host contact with infective spores in the environment, such as conidia deposited on plant surfaces. Disease transmission is thus influenced by host and inoculum density and spatial distribution.
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Journal of Invertebrate Pathology 52:154.
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As it is not possible to review all the significant literature, some relevant examples have been chosen to highlight the impact of fungal pathogens on their hosts, both in natural and managed ecosystems. COWORKERS AND COOPERATORS INVOLVED IN SPECIFIC RESEARCH PROJECTS The Plant Protection Research Unit, Agricultural Research Service (ARS)
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of USDA, and cooperating ranchers and farmers in areas where actual field projects have been conducted. SPECIFIC EXAMPLES OF INSECT BIOLOGICAL CONTROL RESEARCH USING FUNGAL PATHOGENS The use of entomopathogenic fungi for biological control in managed ecosystems has followed four basic strategies: (1)
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This project has evolved into an active biological control project that is now aimed at introducing fungal pathogens (both native and exotic germ plasm) into areas where they do not currently exist.
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Upon host death, the fungus produces either resting spores, which are released into the soil to initiate infection in subsequent years, or airborne conidia, which either germinate immediately (within 24 hours) or die from adverse environmental conditions.
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If successful, this program is likely to expand into adjacent rangeland areas. Augmentation of Fungal Pathogens for Biological Control Augmentation (increasing pathogen inoculum density)
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Although B bassiana was not capable of controlling Colorado potato beetles to the same degree as chemical insecticides were, it clearly provided substantial protection against Colorado potato beetle damage under some conditions.
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353 ._ _ c5 a; .~ Cq hi hi _ do Ct I> _ Ct a; AS ·., ~ o .x.
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Most importantly, their use should be developed and managed with other control methods in mind, so that truly integrated methods of control can be established rather than just substituting microbials for chemical insecticides. Enhancement of Naturally Occurring Fungal Pathogens Depending on the specific details of the host and pathogen population and the associated ecosystem, enhancement of disease development and spread has been accomplished by a number of different methods (Hostetter and Ignoffo, 1978; McCoy et al., 19885.
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postica. Although the origin of this pathogen is still unknown (Puttler et al., 1978', the fungus has become well established as a major natural biological control agent of the alfalfa weevil throughout much of its range.
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However, a better understanding of the spatial distribution and dynamics of this pathogen is necessary to implement this strategy effectively in a statewide IPM program (Brown and Nordin, 1986 J Introduction of Exotic Fungal Pathogens Classical biological control (introduction of exotic fungi, either new species or more pathogenic strains of a species that already exists)
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Agency for International Development. The Plant Protection Research Unit, ARS, USDA, joined in an effort with the Boyce Thompson Institute for Plant Research, the Illinois Natural History Survey, and Cornell University to explore the possibility of microbial control of the potato leafhopper by using Z
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FIGURE 20-4 Laboratory dose-mortality relationship between Zoophthora radicans and the potato leafhopper Empoasca fabae.
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in sampled spotted alfalfa aphid populations (Milner and Lutton, 1986) and has spread over 186 miles from the original release sites (Milner and Lutton, 1983; Milner and Soper, 1981; Milner et al., 1980, 1982; R
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Leafhoppers in an adjacent 1.0acre field were also decimated. PLH, potato leafhoppers.
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Admittedly, fungi are limited in their ability to control insect pests. For example, not all pest species are susceptible to fungal pathogens, and even if they are susceptible, the target hosts may live in an environment that is not conducive to fungal infection and transmission.
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It must be recognized that natural populations of fungal pathogens contain high levels of genetic variation that could contribute to their ability to regulate host populations. Furthermore.
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1978. Microbial Control of Insect Pests: Future Strategies in Pest Management Systems.
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Journal of Invertebrate Pathology 52:49. Carruthers, R
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in Hype~^a postica in central Georgia. Journal of Invertebrate Pathology 40:146.
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In Microbial Control of Insect Pests: Future Strategies in Pest Management Systems, G
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Florida Agricultural Experiment Station Bulletin No.
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Journal of Invertebrate Pathology 50:78-80. Mendgen, K
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Batko: An introduced microbial control agent of the spotted alfalfa aphid Therioaphis trifolii (Monell)
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In Microbial Control of Insect Pests: Future Strategies in Pest Management Systems, G
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and their effects on germination and growth of Beauveria bassiana. Journal of Invertebrate Pathology 36:15.
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in mummified aphids at different temperatures and humidities. Journal of Invertebrate Pathology 21:309.
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Iowa's program provides substantial resources to calibrate one of the more promising sustainable agriculture technologies for statewide use, focusing on soil testing for nitrogen. Without in any way challenging the need for longer-term research, it may be useful to explore nearer-term roles for sustainable agriculture research and education programs and to compare them with other policies currently under consideration that address pollution from agriculture.
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SUSTAINABLE AGRICULTURE AS A PREVENTION STRATEGY Sustainable agriculture practices are targeted to farmers who can benefit from reductions in the use of potential pollutants. Sustainable agriculture offers an opportunity for pollution prevention because it prevents pollution from happening in the first place rather than pinpointing the source of an existing environmental problem and targeting action on the basis of where the problem has occurred.
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The low-input sustainable agriculture research and education program is proving to be effective in developing farming systems that increase net farm income while advancing a wide range of environmental goals. TIME FRAMES FOR SUSTAINABLE RESEARCH AND EDUCATION The pervasiveness of chemical contamination problems and the uncertainties regarding their health ramifications and potential costs of remediation (Wade Miller Associates, 1989b)
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Pennsylvania Agricultural Experiment Station Bulletin No.
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Sustainable Agriculture Research and Education in the Northeast James F Parr By most definitions, sustainable agriculture is viewed as a concept that comprises two major components: i.e.
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Those farming systems that currently sustain the world's population may very likely be inadequate to do so in the future. There must begin to be a more futuristic attitude about what research and education programs for sustainable agriculture are needed now, so that entirely new and sustainable farming systems can be developed for the future.
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PERSPECTIVES FOR SUSTAINABLE AGRICULTURE FROM NUTRIENT MANAGEMENT EXPERIENCES IN PENNSYLVANIA This chapter reported on the management practices of some dairy farms in the Northeast region where there has been a steady increase in nutrient levels on the farm because of a one-way flow of off-farm purchased inputs. According to the author, Les E
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164 pp. Sustainable Agriculture Research and Education in the Field Neil H
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This chapter provided a good overview of the process that was used to select components to improve the system, but it did not provide specifics about the nutrient management project. USE OF FUNGAL PATHOGENS FOR BIOLOGICAL CONTROL OF INSECT PESTS Whole-Farm Interactions: This chapter provided some of the necessary, basic information that will need to be integrated into whole-farm systems.
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382 SUSTAINABLE AGRICULTURE FIELD RESEARCH AND EDUCATION Environmental Impact: The chapter stressed the importance of evaluat~ng how alternative pest control methods are used and their interactive effects. ADDITIONAL ECONOMIC FEASIBILITY STUDIES Additional work is needed to assess adequately the ecomomic feasibility of sustainable agriculture studies and projects currently being carried out.
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REACTORS' COMMENTS 383 Environmental Analysis It is necessary to determine the economic impact of agricultural practices as they apply to environmental considerations of both on-farm and off-farm aspects of the production and marketing of food and fiber products. What are now referred to as externalities need to be incorporated into the economic modeling systems (Barlowe, 19869.
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