Showing papers in "Renewable Agriculture and Food Systems in 1986"

Bacterial solubilization of mineral phosphates: Historical perspective and future prospects

Abstract: Maximum crop yields require sufficient phosphorus fertilization. Only phosphate in a soluble ionic form (Pi) is effective as a mineral nutrient. Current fertilizer technology supplies the soil solution with Pi via the application of large amounts of phosphate salts. Problems with this technology include energy-intensive production processes, the need for large scale mechanical application with associated environmental consequences, and reprecipitation of the phosphate into insoluble mineral complexes. It has been estimated that in some soils up to 75% of applied phosphate fertilizer may be lost to the plant because of mineral phase reprecipitation. Many approaches, ranging from cultural practices to biological inoculants such as mycorrhizal fungi, are being employed to enhance P-use efficiency. One area that is currently under-investigated is the ability of certain types of bacteria to solubilize mineral and organic phosphates. A review of the literature in the area of bacterial phosphate solubilization confirms that this trait is displayed by a wide range of bacteria. The phosphate starvation inducible (PSI) organic phosphate-solubilizing capability of E. coli is a component of a coordinately regulated gene system: the pho regulon. It has long been known that bacteria are also capable of solubilizing mineral phosphates such as hydroxyapatite. To date there has been no systematic study of the genetics of this phenomenon. Data from my laboratory indicate that the bacterial mineral phosphate-solubilizing (MPS) trait is regulated by the external level of Pi This conclusion is supported by results obtained from several types of molecular genetic studies. It is proposed that bacteria have mineral phosphate solubilizing (mps) genes. The potential agronomic applications of bacterial mineral and organic P solubilizing systems are discussed.

A hierarchical approach to sustainable agriculture

Abstract: “Sustainable agriculture” means many things to different people in agriculture. At least three different definitions of sustainability are available: sustainability as food sufficiency; sustainability as stewardship; and sustainability as community. Since increased human populations will cause demands for food to continue to grow in the foreseeable future, agricultural sustainability needs to be assessed in ways that will incorporate competing definitions. We suggest that analyzing agriculture as a hierarchical system is the appropriate way to incorporate different concepts of sustainability. Using this concept, we propose a hierarchical definition of sustainability. Agronomic sustainability refers to the ability of a tract of land to maintain productivity over a long period of time. Microeconomic sustainability is dependent on the ability of the farm, as the basic economic unit, to stay in business. Ecological sustainability depends on the maintenance of life-support systems provided by non-agricultural and non-industrial segments of a region. Macroeconomic sustainability is controlled by factors such as fiscal policies and interest rates which determine the viability of national agriculture systems. In our view, there are critical constraints to sustainability at different scales of the agricultural hierarchy. We propose that agronomic constraints are most important at the field scale; microeconomic constraints are dominant at the farm scale; ecological constraints override at the watershed or landscape scale; and macroeconomic constraints are foremost at the regional and national scale. In this paper, we describe the actions of these critical constraints, discuss interactions among various hierarchical levels, and propose ways that agricultural researchers and policy makers can integrate the various views of sustainability.

An economic analysis of alternative cropping systems for east-central Nebraska

Abstract: Thirteen cropping systems were analyzed with respect to profitability and risk for east-central Nebraska. The systems were developed from 1) a four-year rotation containing a small grain, 2) two row crop rotations, 3) three continuous cropped alternatives, and 4) combinations of continuous cropped alternatives. Three systems were developed from the four-year rotation including two alternative treatments of inorganic chemicals as well as an organic alternative. Eight years of experimental yields, historical prices, and estimated costs were combined to estimate net returns for each of the thirteen systems. Risk was analyzed as net return variability using statistical characteristics of the net return series. The stability component of rotation risk was separated from the diversification component. We found rotations to have higher average net returns than continuously cropped systems. Different chemical treatments (including organic) had little impact on profitability. Rotations had lower return variability than most continuous crops. The organic treatment did not decrease variability of returns compared to other chemical systems.

The economic implications of organic farming

Abstract: Many farmers are turning to organic or “low input” farming as a strategy for economic survival. Several comparisons of actual grain farms in the central and northern states showed that organic farming equals or exceeds conventional farming in economic performance. These findings are supported by studies that used yield data from research plots as inputs to economic models. However, models that relied more heavily on hypothetical data showed an economic disadvantage for organic farming. This may have been a result of the failure of the hypothetical models to incorporate valid assumptions on conservation and efficient utilization of water, nutrients, fuel, labor, and capital. Established organic farmers are less vulnerable to natural and economic risks than conventional farmers because their systems are more diversified. They also are less able, however, to take advantage of income tax deductions. Future trends in commodity prices, input prices, pollution regulation, and research can be expected to have mixed effects on conventional and organic farmers, but the net impact will probably favor organic farmers. On a macroeconomic (i.e. national) scale, conversion to organic farming would have many benefits. It would reduce federal costs for supporting commodity prices, reduce depletion of fossil fuels, reduce the social costs associated with erosion, improve fish and wildlife habitats, and insure the productivity of the land for future generations. However, widespread conversion to organic farming would have an undesirable impact on the balance of trade. Future research on the economics of organic farming at the farm or microeconomics level should be directed at horticultural crops, southern latitudes, marketing, and the process of conversion from conventional to organic farming. Future macroeconomic research should quantify the social benefits described above, enabling decision makers to compare organic farming with other policy options.

Urban consumers' attitudes towards locally grown produce

Abstract: In areas where farmland is under heavy development pressure but where farms are too small to compete in major marketing channels with larger farms in other regions, producers must use channels that capitalize on their proximity to consumers. This advantage is greatest for fresh fruits and vegetables, provided farmers understand their urban customers' purchasing preferences. This study interviewed more than 600 customers at farmers' markets and supermarkets in six urban and suburban communities in eastern Massachusetts and at agricultural fairs. Respondents were asked about their reasons for purchasing fruits and vegetables at various sites, about their preferences, if any, for produce grown locally, and about changes that might cause them to purchase more local produce. The results suggest that for local origin to be taken into account by consumers, the produce should be sold in a locally oriented environment, e.g., a farmers' market. Although the particular supermarkets in this study featured locally grown produce in their advertising, this seems to have had little effect on consumers' buying. Conversely, consumers' highly favorable opinion of farmers' markets involved several factors besides the localness of the produce in a purely geographic sense. These included the pleasant environment, the (presumed) short time since the produce was picked, and the opportunity to purchase directly from the producer in a face-to-face transaction.

An ecological basis for the development of alternative agricultural systems for small farmers in the Third World

Abstract: A strategy for small farm development in the Third World is suggested, emphasizing preservation of traditional farming systems while maintaining biological and genetic diversity. Basing agricultural development on indigenous knowledge, technology, and social organization can provide important guidelines for the design of cropping systems that allow low-income farmers to produce subsistence and cash crops with minimal dependence on external inputs. Suggested alternative agricultural strategies are based on diverse farming systems that achieve moderate to high levels of productivity by manipulating and exploiting resources that are internal to the farm. The resulting systems are more sustainable and economical, thus increasing the equity of the system. Several rural development programs in Third World countries, especially in Latin America, that incorporate these agroecological principles are discussed. In contrast to approaches that have been transferred from the United States without necessarily being suited to the circumstances of small farmers, and which require the purchase of expensive external inputs, these programs include sustainability, stability, and equity as goals, along with increased production. Rural development strategies based on peasant systems that are biologically and economically stable are proving to be a viable survival alternative for a great portion of the impoverished rural population in the Third World.

The transition to organic agriculture: A multi-year simulation model of a Pennsylvania farm

Abstract: Prior research has shown that an established organic farm can be as profitable as a conventional farm under certain circumstances. However, organic farming systems often require a transition period before they are fully established after a changeover from conventional farming. Yields may decrease and recover only slowly during this transition period and less profitable crop rotations may be required to establish an organic system. Previous studies have ignored the income trend during the transition phase, and comparisons of organic and conventional farms have been faulted for lack of similarity in management and other resources. The study reported here used a multi-year simulation model to investigate the trend in income of a 117-hectare crop-livestock farm in Pennsylvania (called the Kutztown farm) during this transition process. A baseline model of the Kutztown farm under conventional management (CONB) was found to earn an income (returns over cash operating cost) of $1,300), but with a larger operation (213 head) the income sacrifice increased tenfold.

Environmental consequences of modern production agriculture: How can alternative agriculture address these issues and concerns?

Abstract: Modern large-scale conventional agriculture with intensive monoculture and row-cropping practices often results in unacceptable soil erosion and runoff and in associated losses of nutrients and pesticides. It also adversely affects wildlife. Sediment from erosion is the greatest pollutant of surface water in the United States and is a major carrier of agrichemicals into the water system. Conservation tillage practices can significantly reduce soil losses in modern production systems, but pollution of surface and groundwaters from runoff and associated potential for increased use of pesticides may still present a hazard. Erosion can be reduced to tolerable levels by the use of crop rotations, meadow crops, and mulch tillage, as commonly used in alternative agriculture. These cultural practices also result in diversity in crop types and in smaller fields, with possible benefit to many wildlife species. Chemical threats to the environment and to wildlife are reduced because synthetic chemicals are used sparingly or not at all.

The potential for regenerative agriculture in the developing world

Abstract: Increased food production and greater income for farm families are primary goals of agricultural development in the Third World. Most strategies to achieve these goals are unrealistic in assuming that limited resource farmers can move out of basic food production in multiple cropping systems to high-technology monocropping for export. These strategies are based on petroleum-based inputs that demand scarce foreign exchange. They may include excessive use of chemical fertilizers and pesticides, which adds unnecessary production costs, endangers the farm family, and degrades the rural environment. Dependence on export crops and world markets is economically tenuous, especially for the small farmer. Future agricultural production systems can be designed to take better advantage of production resources found on the farm. Enhanced nitrogen fixation, greater total organic matter production, integrated pest management, genetic tolerance to pests and to stress conditions, and higher levels of biological activity all contribute to resource use efficiency. Appropriate information and management skills substituted for expensive inputs can further improve resource use efficiency. On the whole farm level, appropriate cropping on each field can be integrated with animal enterprises, leading to a highly structured and efficient system. Such systems can serve the needs of national agricultural sector planners, who in many countries are concerned with increased self-reliance in farming inputs and in production of basic food commodities. This includes a realistic focus on training of local development specialists, increased research on food crops under limited resource conditions, and providing information, incentives, and appropriate technologies for operators of both large and small farms. Well-conceived national plans include varied food production strategies and options for farmers with different resource levels.

Strip cropping corn and grain legumes: A review

Abstract: Multiple cropping systems are prevalent in many parts of the world, and alternating strips of corn and soybeans or dry beans have been used by farmers in the temperate region. Strip cropping has the potential to reduce erosion on hilly lands, to allow a crop rotation in the field if strips are changed from one season to the next, and to increase total system yields. Results from several experiments in Eastern and Midwest U.S. show considerable variation in production among years and locations. Corn grown in narrow strips has yielded from 10 to 40 percent over sole cropping, while soybeans or dry beans in narrow strips suffer yield reductions of 10 to 30 percent due to light, water and nutrient competition. There has been no definitive research to quantify the relative importance of these factors in the competitive interface between corn and legume rows. With wider strips there is less increase in corn yields and less reduction in legume yields compared to sole cropping. Changes in component crop yields also depend on rainfall, and may be influenced by the variety of each component crop and by the width of strips. Rarely does total yield in a strip crop system fall below the average monoculture performance. In years of adequate rainfall, production of strip crops may outyield sole crops by 10 to 20 percent. Potential production of strip cropping systems is reviewed, and projected soil conservation is estimated using the Universal Soil Loss Equation.

Reduced-input agricultural systems: Rationale and prospects

Abstract: In many respects the long standing and vigorous debates over alternative agriculture and organic farming are becoming less strident and less polarized. However, despite the mounting evidence that key elements of both the conventional and alternative agricultural communities are beginning to “build bridges” to each other, and to establish formal institutional programs and arrangements for improved communication and program development, important differences continue to separate the proponents and opponents of alternative agriculture. In part, these lingering differences result from the lack of adequate and reliable data, misinformation, and faulty data analyses. In order to clarify those issues which continue to divide the critics and advocates of alternative agriculture, this reappraisal of the debate begins with a methodological critique of comparison studies of conventional and organic farms. Also included is an assessment of fertilizer and pesticide use in American agriculture, the environmental impacts of conventional and reduced-input systems, the relationship between alternative agriculture and efforts to save the family farmer, and the prospects for increased public sector research on reduced-input farming systems.

Income effects of limiting soil erosion under organic, conventional, and no-till systems in eastern Pennsylvania

Abstract: A 294-acre Pennsylvania crop and livestock farm was modeled under alternative management practices using linear programming. The management practices included conventional, organic, and no-till production, with and without the use of overseeding and cover crops. For each of the management practices, soil erosion was estimated using the Universal Soil Loss Equation. Profitability was compared across the options with and without constraints on soil erosion. Prior to constraining soil erosion, no-till was found to be the most profitable option. The conventional option was next most profitable, followed closely by the organic option. The use of cover crops or overseeding was found to be unprofitable when high levels of soil erosion were allowed. When soil erosion was constrained, the relative profitability of the options changed. It was found that practices that can control erosion with the least reduction in the intensity of rotation, such as planting cover crops, overseeding and no-till, are the most profitable options when soil is constrained to below 5 tons per acre. No-till remained the most profitable option at low levels of soil erosion. The economic advantage of conventional over organic production diminished as soil erosion was constrained. Below 5 tons per acre of soil erosion, the organic system became more profitable than the conventional system. It was found that use of overseeding or cover crops makes a more profitable rotation possible at low levels of soil erosion.

Interrelationships of plant health and the sustainability of agriculture, with special reference to plant diseases

Abstract: U.S. crops have the potential routinely to produce 15–25% more, and in some cases 100% more, with no more water or fertilizer, but are prevented from doing so by diseases, nematodes, arthropod pests, and weeds. It is not compatible with the goals of a sustainable agriculture to fertilize, cultivate, and water for maximum production, but then allow diseases and pests to limit actual yields to some fraction of what was paid for with the capital investments and agronomic inputs. In eastern Washington and adjacent northern Idaho (The Palouse), wheat generally yields 4,800–6,200 kg/ha in years of normal precipitation (45–55 cm), but yields 6,900–9,000 kg/ha with the same water and fertilizer if the soil is fumigated to eliminate root disease organisms and weeds, and the plants are protected from rusts, pseudocercosporella foot rot, and aphids. Some practical alternatives to soil fumigation (depending on the value of the crop) include crop rotation, tillage, flooding the soil, heating the soil (using clear plastic tarp or by burning residue on the soil surface), and organic amendments that intensify the biological stresses on pathogen propagules in soil. Other disease controls include using pathogen-free planting material, maintaining a diversity of genetic resistance, and adjusting planting date and method of seeding to escape pathogens. Some of the emerging technologies include improved serological and molecular methods for diagnosing pathogens, microorganisms that kill pathogen propagules in soil or protect the plant, simulation models of epidemics to forecast disease outbreaks, and integrated pest management systems. Better experimental a pproaches are needed to identify and determine the priorities of the combinations of biotic and abiotic factors that limit yields, and more attention should be given to holistic plant health care.

The role of sustainable agriculture in improving the safety and quality of the food supply

Abstract: Agricultural and health policies are not integrated in the U.S. despite their obvious similarities and linkages. Sustainable agriculture can undoubtedly play an important role in joining the two sectors; however, before this can occur research is needed to answer questions in many areas. Some consumer concerns regarding the safety of the food supply can be abated through the use of sustainable practices in food production and processing which can lessen exposure to toxic contaminants and conserve resources. Among the farming issues considered here are pesticide toxicities and their synergistic interactions, yields, storability, nutrient quality, nitrates, mycotoxins, and antibiotics used in meat production. The manipulation of commodities during processing is also addressed, including the intense refining of grains, fortification and vitamin supplementation, imitation food, and food additives. Analogies between production and processing operations are drawn and specific research needs identified.

Dairy farm feeding and income effects of using Voisin grazing management of permanent pastures

Abstract: Permanent pastures produce far below their potential, as they are usually managed in the northcentral and northeastern United States. Dairy farmers in these regions generally feed their cattle year-round from stored forage and purchased concentrates, and use permanent pastures as mere holding or exercise areas, grazing them continuously. This practice involves high operating costs that, combined with lower milk prices, have resulted in greatly reduced profit margins. Farming practices that return more net income are needed. The Voisin system of rotational grazing management, which applies intensive management to forage crops on pastureland, is widely used on dairy and sheep farms in New Zealand. Farmers using the Voisin system there have low operating costs and obtain high yields of excellent quality forage over long grazing periods; increased net income results Between 1 May and 1 October 1984, 497 forage samples were taken and analyzed from permanent pastures grazed according to the Voisin management system on six Vermont dairy farms. This was done to provide farmers with current estimates of forage feeding value so that they could balance their cows' rations accordingly throughout the season, and determine if they could improve the profitability of their farms by using Voisin grazing management. Average grazingseason analyses (dry weight) were: 22.5% dry matter, 22.4% crude protein, 20.8% available protein, 28.4% acid detergent fiber, 1.18% calcium, .48% phosphorus, 1.60% potassium, .22% magnesium, and 1.58 Mcal/kg net energy lactation. Average dry forage yield was 8.9 metric tons/ha. Dry matter intake was adequate for milk production up to 36 kg/cow/day. Forage protein and energy contents were sufficient for at least 25 and 18 kg milk/day, respectively. On three farms where economic factors were calculated, net profits per cow averaged $67 more during the 5-month period from using Voisin grazing management, compared to continuous grazing of the same pastureland in the year before Voisin management was used. This profit resulted mainly from feed savings and a more favorable milk:concentrate ratio of 4.1:1 obtained with Voisin management, compared to 2.7:1 with continuous grazing and more feeding of stored or machine-harvested forage. Voisin-managed pastures can produce high yields of excellent-quality forage that can be incorporated into dairy feeding programs, thereby reducing feed costs and increasing profitability of the farming operations.

Why another journal

Abstract: Concern over the performance and future direction of American agriculture is well justified and widely shared. Although bankruptcies and foreclosures have dramatized the current farm crisis, agriculture's underlying problems extend well beyond economics to the long-term sustainability of the system itself.

Comparison of the phosphorus status of soils managed organically and conventionally

Abstract: Soils from adjoining farms, one managed organically and the other managed conventionally, were used in a greenhouse study to compare soil P status and the efficiency of concentrated superphosphate (CSP) and North Carolina rock phosphate (RP). Soil and plant parameters were measured as indicators of levels of soil P forms and availability of soil P to soybeans (Glycine max L.). Management did not affect dry matter yield of soybean plants. Conventional management resulted in higher P concentration in the plant and higher P uptake when CSP was the P source. However, when RP was the source, management effect was not significant. RP was only 15% as effective as CSP in increasing yield. When no P was applied, organic management resulted in greater total soil P, organic P, and Ca phosphate (CaP); conventional management resulted in greater Al and Fe phosphate (AlFeP) and occluded AlFeP (OcP). Addition of CSP increased AlFeP and OcP. Addition of RP increased CaP. CSP was more effective than RP in increasing extractable soil P. Multiple regression analysis showed that extractable P was related to AlFeP when CSP was the P source and to CaP when RP was the source. Yield was related to extractable P when CSP was the P source but when RP was the source, no significant regression models were found for yield.

A cropping systems approach to salinity management in California

Abstract: In irrigated cropland of the semi-arid and arid regions of California, the lack of drainage outflow requires reassessment of crop rotation patterns. As regulatory actions place limits on drainage water quality and quantity, growers will be forced to manage water more efficiently and rely more heavily on salt-tolerant crops. Improved water use efficiency depends on integrated cropping systems in which cultural practices interact to reduce leaching requirements while maintaining productivity, profitability, and the environment. The success of this approach will require a better understanding of the physiological basis of plant salt tolerance and the evolution of soil properties as influenced by crop rotation, tillage, crop residue and soil fertility management. An increased commitment to evaluate such interactions in long-term field studies is needed.