A simple method of estimating changes in biologically active soil carbon (C) could help evaluate soil quality impacts of alternative management practices. Most reports of permanganate for active C determination use highly concentrated solutions (0.333 M) that are difficult to work with and tend to react with a large fraction of soil C that is not well distinguished from total organic C. We report on a highly simplified method in which dilute, slightly alkaline KMnO4 reacts with the most readily oxidizable (active) forms of soil C, converting Mn(VII) to Mn(II), and proportionally lowering absorbance of 550 nm light. The amount of soil C that reacted increased with concentration of KMnO4 used (0.01 to 0.1 M), degree of soil drying (moist fresh soil to air-dried for 24 hour) and time of shaking (1–15 minutes). Shaking of air-diy soil in a 0.02 M KMnO4 solution for 2 minutes produced consistent and management-sensitive results, both in the laboratory and with a field kit that used a hand-held colorimeter. Addition of 0.1 M. CaCl2 to the permanganate reagent enhanced settling of the soil after shaking, eliminating the need for centrifugaron in the field kit. Results from the laboratory and field-kit protocols were nearly identical (R2 = 0.98), as were those from an inter-laboratory sample exchange (R2 = 0.91). The active soil C measured by the new procedure was more sensitive to management effects than total organic C, and more closely related to biologically mediated soil properties, such as respiration, microbial biomass and aggregation, than several other measures of soil organic C.

Effects of soil fauna on soil quality are largely unknown. Our objective was to learn whether long-term soil management has significantly affected earthworm species and populations at two Iowa locations. Soil cores were collected in fall 1989, spring 1990, and fall 1990 from a long-term tillage study in Polk County, Iowa, involving monoculture of corn (Zea mays L.) with either no-tillage, fall disking, fall chisel plowing, or fall moldboard plowing. Species found were Lumbricus terrestris (L), Octolasion tyrtaeum (Savigny), Aporrectodea trapezoides (Duges), A. turgida (Eisen), and A. tuberculata (Eisen), with O. tyrtaeum dominant across all treatments. As the amount of tillage increased, the number of earthworms generally decreased. InBoone County, Iowa, we compared the populations of mature and immature earthworms and cocoons on two adjacent fields, one managed conventionally, the other managed with an alternative farming system for more than 20 years. The predominant species was A. tuberculata. Regardless of management practice, the most worms were found in Canisteo soil on the toeslope landscape position.

Crops grown in narrow rows (NR, 0.25 to 0.38 m) shade weed seedlings more than do those grown in traditional wide rows (WR, 0.76 m). NR crops may require less herbicide and interrow cultivation than WR crops for equally effective weed control. This hypothesis was tested by comparing weed control and crop yield in NR and WR crops when the following percentages of recommended application rates (RAR) of standard herbicides were applied: soybean, 0, 50 and 100%; sunflower, 0, 25, 50, and 100%; and corn, 0, 33, and 100% in three separate sets of experiments conducted over 2, 3, and 4 years, respectively. In all treatments with 100% RAR, excellent weed control prevented reductions in crop yield. When only 25 to 50% RAR was applied, weed control was consistently high in NR (82 to 99% control), but variable in WR (42 to 99% control). Weed control and crop yields typically were lowest in NR without herbicides. Interrow cultivation controlled 0 to 81% of weeds in WR crops. In reduced herbicide treatments (25 to 50% RAR), yields of NR soybean and sunflower typically were about equal to those in WR with 100% RAR, but NR corn yields were about 10% less. Considering the reduced herbicide use and lower weed control costs, planting corn, soybean, and sunflower in narrow rows may represent a practical form of low-input production of these important crops.

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.

We evaluated the effects of free-range chickens and geese on insect pests and weeds in an experimental, nonchemical agroecosystem consisting of an apple orchard with intercropped potatoes. The objective was to assess the potential of these domestic bird species as biological control agents. Four insect pests were studied: plum curculio, apple maggot, Japanese beetle, and Colorado potato beetle. Chickens fed on several potential crop pests, including Japanese beetle. Although Japanese beetles were less abundant on apple trees when chickens were present, the proportion of damaged fruit was not reduced. Furthermore, chickens did not affect weed abundance or crop productivity. In contrast, geese were effective weeders. Their activities reduced weed abundance and increased potato plant growth and yields compared with a minimally weeded control. In addition, the activities of geese indirectly reduced apple fruit damage by plum curculio and increased the proportion of pest-free fruit, possibly because removal of vegetation by the geese reduced humidity at the soil surface and therefore reduced the activity of plum curculio.

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.

Combining cover crops and conservation tillage may result in more sustainable agricultural production practices. Objectives of this on-farm study were to quantify effects of cover crops on growth and nitrogen accumulation by soybean [Glycine max (L.) Merr,] and corn (Zea mays L.) on a Nicollet loam (fine-loamy, mixed, mesic Aquic Hapludoll) near Boone, Iowa, Our farmer-cooperator planted soybean in 1988 using ridge tillage into an undisturbed strip with a hairy vetch (Vicia villosa L. Roth) cover crop and into a strip where previous crop residue and a negligible amount of cover crop had been incorporated by autumn and spring disking. In each strip, we established four plots for soil and plant measurements. Our cooperator planted corn on the same strips in 1989 into a cover crop that consisted of both hairy vetch and winter rye (Secale cereale L.). We determined the source of N accumulated by the corn by applying 67 kg N/ha of 15N depleted NH4NO3 fertilizer. In the absence of cover crops, early season soil NO3-N levels in the top 30 cm were higher, and corn growth and N accumulation were more rapid. At harvest, the corn grain, stover, and cob together accounted for 36 and 39 percent of the 15N fertilizer for the ridge tillage and disked treatments, respectively. We suggest that lower net mineralization of organic matter or greater denitrification losses before planting reduced the availability of soil N, This created an early season Nstress in corn grown with cover crops that was not overcome by broadcast fertilizer N applied three weeks after planting. Our on-farm research study has helped focus continuing efforts to determine if non-recovered fertilizer N is being immobilized in microbial biomass, lost by denitrification, or leached below the plant root zone.

This research promotes our understanding of organic farmers' decisionmaking through individual farmers' experiences. A twofold survey was conducted to investigate characteristics of certified organic farmers in Colorado. Data from a mail survey (26 responses to 49 surveys sent) reveal patterns of farm operations and attitudes among this group of farmers. These questionnaires focused on land use, land tenure, operational change, and personal characteristics. In-depth interviews of five case study farmers provide additional insight into farmers' agricultural decisionmaking. These interviews were conversations that the farmers guided toward topics of relevance to them. Taken together, the mail and interview surveys provided information about on-farm operational factors and personal characteristics. Quantitative analysis and qualitative data reduction techniques were used to identify factors in organic farmer decisionmaking. The following eight factors help us understand organic agriculture in this region: diversity, challenge, change, businesslike approach, no formal agricultural education, love of the land, anti-”radical environmentalist,” and obstacles.

Recognition of the environmental costs of fossil fuels coupled with concern over their depletion within the next few decades has broadened the search for alternative energy resources, including biomass energy. Ethanol produced from corn (Zea mays L.) grain currently is the primary form of biomass energy produced in the Midwest, but its net energy balance commonly is negative when corn grain is produced under conventional practices. Reducing fossil fuel inputs, particularly for nitrogen fertilizer, will improve the energy balance, but more substantial improvements involve increased efficiency of ethanol production. An alternate source involves fermentation of crops such as sweet sorghum (Sorghum bicolor [L.]Moench).

Other potential biomass energy resources for the Midwest include oils extracted from seed crops, methane from waste digestion, and combustion, gasification or fermentation of woody and herbaceous crops and crop residues. These resources may serve as an energy supplement or a useful energy source for individual farms, households or rural communities. Biomass energy systems in Midwest agriculture must be evaluated regarding their long term environmental impacts and their sustainability. Externalities that must be considered include surface and ground water pollution, soil erosion, and economic and social benefits to the rural community.

In the fifth year of an agricultural conversion experiment in Pennsylvania, we studied the soil biological community under three treatment regimes planted with corn: organic-manure, organic-legume, and a conventional system. The organic treatments consisted of complex crop rotations, cultivations, and organic matter inputs to control pests and maintain soil fertility. The conventional system consisted of a simple corn/soybean rotation with synthetic fertilizer and pesticide inputs. High rates of CO2 evolution (a measure of potential microbial activity) in the organic plots corresponded with high levels of organic matter input. Soil nematodes were most abundant in organic plots, although seasonal patterns differed between the two organic treatments. Soil microarthropods were dominated by fungivorous Prostigmata mites, which reached peak abundance in organic plots two to five months after organic matter incorporation. Oribatid mites, which were rare throughout the study, followed the same pattern of abundance in each treatment and were probably most influenced by tillage disturbances. Predatory Mesostigmata were generally more abundant in organic plots. Surface-dwelling Collembola were abundant briefly in the spring, but soil-dwelling species dominated numerically throughout the cropping season. Spring tillage appeared to have a strong negative effect on earthworm populations in all plots. Small earthworm species became abundant in organic-manure plots during the summer. Larger earthworm species were abundant in organic-legume and conventional plots after the autumn harvest, when crop residues covered the undisturbed soil The systems-level nature of the Conversion Project experiment makes it difficult to identify cause-effect relationships. The data do suggest that organic amendments tend to enhance soil biological activity, while tillage disturbances tend to disrupt the biotic community.

Sustainable agriculture has gained acceptance as a conceptual approach for shaping farming systems of the future. All definitions of sustainable agriculture include food productivity, food safety, resource protection, quality of life and environmental quality. However, the sustainability of a wide range of farming systems has been judged only subjectively. Currently there are no scientific criteria to evaluate the sustainability of a specific farming system. We propose a framework for evaluating the relative sustainability of a farming system using nine attributes: profitability, productivity, soil quality, water quality, air quality, energy efficiency, fish and wildlife habitat, quality of life, and social acceptance. Each attribute is scored and then weighted in a way that is subjective and dependent on the judgment of the evaluating team, but that must be expressed numerically. The scoring must be based on quantifiable constraints within each attribute. Constraints can be quantified by direct measurement, which is already true for those related to profitability, productivity, water quality and energy efficiency. Constraints that are not readily measurable will need other evaluation techniques, including expert opinion and computer simulation models.

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 $61,900. The transitional models developed were an upper-yield case assuming no yield decline during the transition (TRANS) and a lower-yield case assuming severe yield decline in the first year after the change-over from conventional management and a subsequent linear recovery of yields over a three-year period (TRANS-L). Income was found to be severely depressed by a yield decline during the transitional phase. The first year of TRANS-L resulted in a 43% reduction in income. The scenario without a yield decline (TRANS) resulted in a 13% lower income compared to the baseline (CONB) model. Both transitional models led to an established organic situation with stable organic yields and an income of $57,400 or 7% less than under conventional management. It was found to be more profitable to sell the crops and purchase manure than to feed the crops to beef in a fattening enterprise. At small herd sizes (100 head) the reduction in income caused by the feeding operation was moderate ($1,300), but with a larger operation (213 head) the income sacrifice increased tenfold.

Sustainable cropping systems use crop diversity as a foundation to reduce the environmental impacts of agrichemicals and risks of pest and disease outbreaks. Although greater diversity in the agricultural landscape is an important goal, the decisions of individual farmers determine the diversity of crops used in each farming system. Therefore, it is essential to gain an understanding of important factors in farmers' decisions as part of any proposed solution to low crop diversity. Our objective was to develop and test an integrated socioeconomic model of farmers' decisions on crop rotations as an indicator of overall crop diversity. The model incorporated measures of farmers' attitudes, net household income, control over decisions, social norms, and regional location to address the social, economic, and environmental factors of crop diversity. Mail survey responses from 197 farmers from a western Corn Belt county in 1998 supplied the data for the analysis. Location had the strongest influence on crop diversity in the model, on the basis of a standardized beta statistic of 0.46 in the ordinary least squares regression analysis. Farmers in the region with the highest degree of sloping land had significantly higher crop diversity than farmers in the most productive, relatively flat area. Lower household net income and positive attitudes toward crop rotations were also associated with higher crop diversity. We believe social norms and control would exert more influence in uncertain decisions. The results of this study suggest that, to maintain and possibly expand crop diversity in the future, targeting farmers in sloping landscapes with positive attitudes toward rotations would be the best approach to focus economic incentives for diverse crop rotations and technical support from Extension. In any effort to support crop diversity greater than a typical cornsoybean rotation, it is also critical to preserve integrated forage/crop/livestock systems. Further adaptation and application of our behavioral model in other settings would help to better evaluate, understand, and target the integrated decisions people make relative to crop diversity.

Anticipated advances in biotechnology and sustainable land management, in combination with the availability of high-quality lands, suggest a level of food production that will sustain twice the current global population. However, lack of political will, insufficient investments in modern agriculture, and a general apathy to the tenets of sustainable land management threaten food security in Third World countries, and in some, contribute to poverty and famine. From a global land-productivity point of view, the specter of Malthusian scenarios seems unwarranted. Sadly, however, local and regional food shortages are likely to continue to occur unless mechanisms for equitable food distribution, effective technical assistance, and infusions of capital for infrastructure development are implemented in some developing countries.

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.

Two large-scale (25 ha) trials were initiated in 1989 in Wisconsin to compare six alternative production systems regarding productivity, profitability, and environmental impact. The project was designed and is managed by a coalition of farmers, extension agents and research personnel. Deliberations between production-oriented and ecologically oriented team members resulted in a factorial design, with two enterprise types (cash grain and forage-livestock) and three levels of biological complexity. Statistical methods have been used to identify the most efficient plot size, plot shape, and block shape, and the optimal procedures for sampling soil characteristics. A uniformity year was allowed before initiation of the trial, and the start was staggered. We defined treatments as production strategies rather than a specific set of inputs, which led to a more flexible plot management program.

Quantitative studies are needed to separate the real and supposed benefits of alternative farming practices. Our objective was to learn how conventional and alternative practices on adjacent farms in central Iowa affected the water stability of soil aggregates. We collected samples of Clarion loam (fine-loamy, mixed, mesic Typic Hapludoll) from adjacent 16 ha fields in fall 1990 and spring 1991. Aggregate stability was determined by wet-sieving and by measuring turbidity of soil-water suspensions. The combined effects of alternative practices resulted in greater water stability of soil aggregates, higher soil organic matter content, and lower bulk density compared with conventional practices. The components of the alternative system that were mainly responsible for these differences were: rotations that included oat and hay crops; ridge-tillage; and additions of 45 Mg/ha of a mixture of animal manure and municipal sludge during the first 3 years of each 5 year rotation. The more favorable soil physical conditions, shown by increased water stability of soil aggregates, presumably will improve soil water regimes and reduce long-term soil erosion losses from the alternatively managed fields.

We monitored emergence of morning-glory, pigweed, and prickly sida from seeded populations in no-till plots with no debris (reference plots) or with crimson clover, subterranean clover, rye, or wheat debris. Cover crops were either desiccated by glyphosate or mowed and tilled into the soil. Debris levels, soil temperature, moisture, pH, nitrate, total phenolic acid and compaction were monitored during May to August in both 1992 and 1993. Seedling emergence for all three weed species ranged from <1 to 16% of seeds sown. Surface debris treatments delayed weed seedling emergence compared with the reference plots. Rye and wheat debris consistently suppressed weed emergence; in contrast, the effects of clover debris on weed emergence ranged from suppression to stimulation. Gfyphosate application resulted in a longer delay and greater suppression of seedling emergence in May than in April. In 1993, plots in which living biomass was tilled into the soil were also included and monitored. Weed seedling emergence was stimulated when living biomass was incorporated into the soil. Covariate, correlation and principle component analyses did not identify significant relationships between weed seedling emergence and soil physical and chemical characteristics (e.g., total phenolic acid, nitrate, moisture, temperature). We hypothesize that the observed initial delay of the weed seedling emergence for all three species was likely due to low initial soil moisture. The subsequent rapid recovery of seedling emergence of morning-glory and pigweed but notprickfy sida in the clover compared with the small grain debris plots was likely due to variation in soil allelopathic agents or nitrate-N levels. The stimulation of weed seedling emergence when living biomass was incorporated into the soil was likely caused by an increase in “safe” germination sites coupled with the absence of a zone of inhibition resulting from tillage.

The logic of the Clean Development Mechanism (CDM) and other such ‘carbon (C) offsets’ rests on the notion that the opportunity cost of reducing C emissions is lower in developing countries, creating opportunities for mutually beneficial C trading. While the CDM may offer significant gross financial benefits, there has been little analysis of the opportunity costs of foregone resource exploitation and development opportunities. In addition to assessing the potential for net benefits, this paper also considers the practical implications for design and implementation of C offsets for forest conservation and agroforestation in Indonesia. Virtually nothing is known about these administrative factors, and their associated costs, which can also play a decisive role in feasibility of C offset schemes. Data are from field studies in the lowlands of the Indonesian island of Sumatra, where forests and derived land uses are broadly representative of the lowland humid tropical rainforest systems of insular South-East Asia. These data are the basis for assessing the trade-offs between natural forest protection for C sequestration and conversion to other land uses to meet national development objectives that directly affect people's livelihoods. Carbon stocks are analyzed in terms of ‘time-averaged’ C, an indicator developed for this project. Opportunity costs of land-use alternatives are estimated using standard techniques for economic assessment of investment projects in developing countries. The study finds that imputed timber values are a significant share of the opportunity costs of forest conservation, even for conservative estimates of timber prices. The question of compensating for these foregone values raises complex questions regarding the political economy of Indonesia, since property rights over these resources are highly contentious. These controversies over property rights are also examined within the context of recurrent smoke pollution from land fires in Indonesia, that (among other problems) contribute to greenhouse gas emissions. This smoke is symptomatic of deeper political and institutional problems that raise questions about the permanence of C storage through land-use practices in Indonesia. In comparison to forest conservation, C offsets through agroforestation seem more feasible in Indonesia because property rights over timber from planted trees would be easier to establish and enforce than property rights over timber from natural forests. Although results in this paper look promising, there is still much to be learned about implementation costs, even for the ‘easier’ case of agroforestation.