Sustainable Agriculture Research and Education in the Field A Proceedings (1991) / Chapter Skim
Currently Skimming:
PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION
PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION
Pages 107-162
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 107... ...
PART TWO Research and Education in the Western Region
|
From page 109... ...
Letourneau, and Fekede Workneh This chapter describes an on-going study of existing organic and conventional tomato production systems in California supported by the low-input sustainable agriculture (LISA) program of the U.S.
|
From page 110... ...
fresh market tomato production, and most importantly, a variety of management systems exist in this region, including long-term organic tomato production. The widespread adoption of intensive conventional agriculture in California has been accompanied by the appearance of symptoms of poor soil structure (Chancellor, 1977~.
|
From page 111... ...
The beneficial effects of increased organic matter on soil structure and biology have been well documented (Chancy and Swift, 1984; Oades, 1984; Tate, 1987; Tisdall and Oades, 1982~. Suppression of several plant diseases by certain soils has been attributed to high levels of microbial activity (Chen et al., 1988)
|
From page 112... ...
For example, do soils on organic and conventional farms differ with respect to nitrogen availability, structural properties, or microbial activity? If so, are these differences reflected in patterns of plant growth and nutrient acquisition?
|
From page 113... ...
. This approach offers a number of advantages by allowing whole management systems to be studied while at the same time reducing the influence of potentially confounding variables such as soil type, surrounding habitat, and microclimate and by allowing for true replication of treatments.
|
From page 114... ...
Although this is clearly of great interest, in this study the major focus is the potential for organic practices to affect attributes of the agroecosystem over the long term. By observing existing farms that have operated organically for various lengths of time, the present study provides a mechanism for doing this from the outset.
|
From page 115... ...
Provided that sites can be selected such that a similar range of these variables exists within each of the broad management categories (e.g., organic and conventional) , then the effects caused by management comparisons of interest, such as organic versus inorganic nitrogen input, can be separated from those caused by extraneous variables such as soil type or planting date.
|
From page 116... ...
However, if interactions between soil properties and plant growth are being examined, climatic variability among locations will influence the analysis and interpretation of the data that are collected. For an entomologist, the major variables of concern are surrounding habitat, microclimate, and field size, whereas for a plant pathologist, the presence of the relevant pathogens in fields of all management types is of primary importance.
|
From page 117... ...
Initially, two important vegetable-producing regions were considered as study areas: the central coastal valleys of California, which produce mainly cool season vegetables, and the Central Valley, where warm season vegetables are produced. Based on the above criteria, site visits and a questionnaire were used to gather information on organic and conventional vegetable producers in both regions.
|
From page 118... ...
ANALYTICAL APPROACHES As discussed previously, two different approaches have generally been used to compare different farming systems. Either existing organic and conventional farms have been compared in the same general area (Lockeretz et al., 1981; Niederbudde and Flessa, 1989; Niederbudde et al., 1989; Reganold, 1988; Reganold et al., 1987; Sengonca and Bruggen, 1989)
|
From page 119... ...
The growers at the 60 sites who were interviewed consisted primarily of c~r:,anic, transitional, and conventional mixed vegetable producers. Selected representative large-scale processing and fresh market tomato producers were also included In the survey.
|
From page 120... ...
Total nitrogen in the tissue, shoot and fruit dry weight, insect injury (visual scoring of feeding signs of flea beetles, thrips, chewing insects, and leaf miners) , and root rot severity scores (corky root and phytophthora root rot)
|
From page 121... ...
Theoretically, any size farm could fall into all three management designations, ranging from small-scale mixed vegetable producers to large-scale tomato growers producing either"green-gas" (fresh market varieties harvested while fruit are still green) or processing (for example, machine-harvested varieties selected for processing into tomato sauce, tomato paste)
|
From page 122... ...
Sixty mostly small-scale mixed vegetable producers were identified as potential sites in an area from Yuba City to Stockton. Approximately 30 sites from the southern part of the region were eliminated because of highly variable soil types and the considerable distances involved, leaving a pool of about 30 sites from which the 18 sites sampled by members of at least some of the disciplines were chosen (Table 6-1~.
|
From page 123... ...
tomatoes. Six of the conventional farming sites sampled in 1989 fell into the category of mixed vegetable producers; the remaining three consisted of one large green-gas tomato field and two processing tomato fields into which fresh market tomatoes were transplanted.
|
From page 124... ...
724 &~E ~E ^~ Elk ~ [~\ ~ !
|
From page 125... ...
However, confounding by transplant and sampling dates will be minimized in the future by equally dividing earlier and later planting dates over the farm types as much as possible. Preliminary examination of the data suggests that differences exist between organic and conventional farms with regard to nitrogen mineralizat~on potential, Inorganic nitrogen pools, microbial activity, corky root severity, and insect damage.
|
From page 126... ...
In addition, samples will be collected outside the designated sampling locations to target areas with visible foliar symptoms of phytophthora root rot and to aid in the determination of relationships between disease severity and soil properties. Initial analyses of field-level data suggest that pairing of organic and transitional sites with conventional sites based on geographic proximity did not add robustness to comparisons of farm-level data on arthropod community abundance.
|
From page 127... ...
This multiyear integrated interdisciplinary study of existing farms in one of the world's premier vegetable-producing regions promises to provide valuable insights into the effects of a variety of alternative and conventional management practices on the processes that function within this agroeco-system. While the results pertain most directly to central California agriculture, much of the data should also be relevant to similar irrigated production systems in semiarid irrigated regions of the world.
|
From page 128... ...
1984. The influence of organic matter on aggregate stability in some British soils.
|
From page 129... ...
1986. Soil organic matter, effects on soils and crops.
|
From page 130... ...
1984. Soil organic matter and structural stability: Mechanisms and implications for management.
|
From page 131... ...
1987. Modelling soil organic matter levels after long-term applications of crop residues and farmyard and green manures.
|
From page 132... ...
Soil Science Society of America Proceedings 30:631-634. Williams, W
|
From page 133... ...
More people are becoming sensitive to the serious consequences of soil erosion and its threat to the environment and the economic security of the region. In the future, the capability of maintaining high yields in the inherently fertile soils of the Northwest will depend largely on the ability to prevent the loss of topsoil and the depletion of soil organic matter.
|
From page 134... ...
THE STEEP PROGRAM STEEP (solutions to environmental and economic problems) is a multidisciplinary research and education program in the three Pacific Northwest states designed to focus scientific and extension efforts on the control of soil erosion on croplands (Miller and Oldenstadt, 1987; Oldenstadt et al., 1982~.
|
From page 135... ...
Develop relationships that show how erosion affects crop production over both the short and long term. All of the objectives have a common goal, that is, the development of farming systems for control of soil erosion.
|
From page 136... ...
STEEP Program Extension An extension component was added to the STEEP program in 1982 to help disseminate new research findings and to assist farmers in applying research results in the field. One specialist is located at the Columbia Plateau Conservation Research Center at Pendleton, Oregon, and the other is located on the University of Idaho campus at Moscow, Idaho.
|
From page 137... ...
The growers were largely responsible for the addition of the extension component to the STEEP program. The wheat grower organizations of the three Pacific Northwest states have done much to obtain the special grants funding that supports the research.
|
From page 138... ...
Pest Management - Conservation tillage practices and intensive cropping of small grains was found to increase root diseases of wheat and barley (Wiese et al., 1987)
|
From page 139... ...
over the past 10 years there has been a positive change in farmer attitudes toward erosion control as well as implementation of erosion control practices (Carlson et al., 1987; Dillman and Carlson, 19823. Soil Erosion-Productivity Relationships · Wheat yield losses resulting from the loss of topsoil have been masked by technological progress, that is, improved varieties, fertilizer management, and weed control (Papendick et al., 1985; Walker and Young, 1986; Young et al., 1985~.
|
From page 140... ...
Overall, the STEEP program, more so than any other program, has created increased public awareness of soil erosion and its consequences and has made growers much more receptive to implementing conservation measures on their farms. FUTURE DIRECTIONS Despite the technological advances made by the STEEP program, soil erosion is still a major environmental and economic problem for the Pacific Northwest region.
|
From page 141... ...
This revised program will build on the progress and accomplishments of the STEEP program. STEEPIIwill seek to coordinate a regional research and information delivery system designed to provide growers in the Pacific Northwest with advanced technologies for simultaneously controlling soil erosion and protecting water quality while achieving more cost-efficient crop production and increased farm profitability.
|
From page 142... ...
The STEEP II program will also give new emphasis to developing methodologies for on-farm research and providing scientific backup to research and education projects such as those supported by the USDA low-input sustainable agriculture (LISA' program that involve direct work with growers in testing treatments on large plots or whole fields. Erosion and water quality models will be developed as tools to evaluate the impacts of conservation tillage and other management options on runoff and erosion, water conservation, and water quality.
|
From page 143... ...
1982. Influence of absentee landlords on soil erosion control practices.
|
From page 144... ...
1984. Modeling agricultural productivity impacts of soil erosion and future technology.
|
From page 145... ...
Ranchers, field crop farmers, and specialty crop growers in California are also adopting the method and showing its applicability to diverse crops, soils, and farm operations and especially to surface irrigation systems like those that predominate in irrigated agriculture systems in the United States. Farmer testimony and field evidence now amply justify broader public support for soil moisture monitoring as a component of integrated conservation plans for irrigated farms.
|
From page 146... ...
Soil moisture monitoring has shown that slower rotations result in better moisture penetration, fuller utilization of storage capacity in the root zone, and less runoff. Similarly, monitoring can
|
From page 147... ...
Converting to Conservation Tillage Tillage systems that leave plant remains on field surfaces typically increase moisture retention at deep levels in the root zone and control soil erosion. With soil moisture monitoring, farmers on dryland as well as irrigated fields can see these moisture-saving benefits for themselves.
|
From page 148... ...
. Then come soil moisture monitoring, adjustments of irrigation schedules and equipment, the identification and analysis of soil compaction, year-round monitoring of dryland as well as irrigated fields, the substitution of no-till for clean fallow tillage methods, conversion to ridge-till methods on irrigated fields (with major reductions in herbicide use)
|
From page 149... ...
They are more commonly used on permanent crops. Gypsum blocks are small electrical sensors that are implanted in root zones.
|
From page 150... ...
Resource Conservation District to find a water management method that met farmers' practical needs. The director was Peter MuellerBeilschmidt, an irrigation engineer and independent consultant from Davis, California.
|
From page 151... ...
1980. Winning with Water: Soil-Moisture Monitoring for Efficient Irrigation.
|
From page 152... ...
Moreover, reduced labor time, better assessment of new field practices, better management of equipment, and other gains reported to INFORM by farmers could not be quantified, yet they appeared to be significant in persuading farmers of the benefits of monitoring soil moisture. GYPSUM BLOCK PROGRAMS IN CALIFORNIA AND COLORADO Since the mid-1980s, when INFORM completed its research, the use of gypsum blocks has spread to more than 170 farmers in California and Colorado.
|
From page 153... ...
In 1989, all but 4 of the 45 farmers who participated in the California Association of Resource Conservation Districts program in 1989 were persuaded of the benefits of soil moisture monitoring and reported their plans to continue using gypsum blocks. Of these, about half realized significant energy and water savings during the instructional period (see high and moderate water- and energy-savings categories in Table 8-2~.
|
From page 154... ...
In three growing seasons, 1987 to 1989, moisture monitoring has spread to 65,000 irrigated acres in six Colorado counties (and 10,000 additional acres of dryland wheat)
|
From page 155... ...
THE ROLE OF EDUCATIONAL ADVISERS AND AGENCIES SCS technicians in California and Colorado agree that soil moisture monitoring with gypsum blocks sells itself. However, they emphasize the importance of initial instruction that includes the following components as being essential for getting farmers to the takeoff point over one or two seasons: · demonstration on farmers' own fields; · one-on-one teaching (several meetings a year)
|
From page 156... ...
· Research is needed to establish technical standards to enable farmers and technicians to choose wisely among the available soil moisture sensors, which vary in sensitivity, uniformity, longevity, and price. Field demonstrations targeted in areas plagued by drainage and contamination problems could help to identify practical applications of soil moisture monitoring as components of regional water quality plans.
|
From page 157... ...
1988. Winning with Water: Soil-Moisture Monitoring for Efficient Irrigation.
|
From page 158... ...
, sustainable agriculture, alternative agriculture, best management practices, integrated pest management, and integrated crop management, are used by many highly efficient, profitable farm operators today. Agriculture was changing before LISA; however, the pace and intensity, as well as the focus, have quickened since LISA was introduced.
|
From page 159... ...
The following are specific responses to the chapters in this section. In their opening, John Gardner and colleagues ("Overview of Current Sustainable Agriculture Research")
|
From page 160... ...
They are valuable sources of experience and information. Gail Richardson, in "Soil Moisture Monitoring: A Practical Route to Irrigation Efficiency and Farm Resource Conservation." Provided an excellent demonstration of what appears lo be a relatively low-cost, lowtechnology, practical approach to measuring soil moisture and plant response.
|
From page 161... ...
Cook's research is a major contribution to some of the corrective solutions that can be used in a complete farm system. Gail Richardson's chapter documenting her 7 years of on-farm water conservation technology with the use of gypsum blocks is also a major key for sustainable agriculture.
|
From page 162... ...
agricultural community should move toward the complete farm research system concept, incorporating James Cook's research, Gail Richardson's water conservation research, farmers' own on-farm research, and other existing technologies. Successful sustainable agriculture can be achieved by working to increase organic matter and the microbial biomass, by correcting soil filth, and by stopping erosion while using conventional fertilizers and tillage tools.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.