Floating gardening is a form of hydroponics or soil-less culture. It is an age-old practice of crop cultivation in the floodplains of southern Bangladesh, where aquatic plants such as water hyacinth (Eichhornia crassipes) are used to construct floating platforms on which seedlings are raised and vegetables and other crops cultivated in the rainy season. The platform residue is used in the preparation of beds for winter vegetable gardening. Floating gardening was introduced in 2006 on a pilot-scale in the north-east wetlands of the country, as a contribution to food security and as a supplementary income for the marginalized community. The overall experience of floating cultivation in three selected villages was encouraging. Local people became aware of this new farming system and their level of knowledge improved. Communities were mobilized into groups to make floating platforms, and platform residues were later used to establish winter gardens. Cultivation was successful on both types of plot, and vegetables were both consumed by the producers and sold in the market. The input–output analysis revealed floating gardening to be a feasible alternative livelihood option for the wetland dwellers. The method provided targeted landless people with parcels of land in the monsoon, enabling them to grow vegetables. Floating gardening and associated winter gardening appear to have the potential for introduction to other parts of the world where aquatic weed management is a major problem.

The transition away from forage-based cropping systems in Iowa to corn and soybean rotations since World War II has corresponded with degraded economic and environmental conditions in the state. Falling net incomes for farmers and concern over global warming and the effects of agriculture-related pollution on water, wildlife and human health have increased interest in diversified cropping systems. This paper reviews the benefits of diversifying Iowa corn and soybean rotations with perennial forage species such as alfalfa and red clover. Perennial forage crops improve soil quality, decrease NO3-N leaching and soil erosion, increase carbon sequestration and decrease pesticide and herbicide needs by controlling weed and insect pests. Forage legumes reduce N fertilizer needs for succeeding corn crops at a higher rate than soybeans, and corn crops following forages have higher yields than after corn or soybeans. Farmers who add alfalfa to corn and soybean rotations could realize significant economic gains. A simulated 5-year rotation in Iowa including corn–soybeans–oats/alfalfa–alfalfa–alfalfa would result in a 24% net income increase over 5 years of corn–soybean–corn–soybean–corn, even with government farm support payments for the row crops. Farm policies that encourage commodity production create little incentive for Iowa farmers to diversify their cropping systems beyond corn and soybeans, despite the clear economic and ecological benefits. We recommend increasing federal support for conservation programs that reward environmentally beneficial farm practices such as the Conservation Securities Program and we encourage land grant universities to hire researchers interested in alternative agricultural systems.

In a variety of ecosystems, interactions between soil microbiota and weedy plants can strongly affect population and community dynamics of these plants. However, weed–soil microbe interactions are not well characterized in field-crop agroecosystems. In Minnesota (USA), we repeatedly applied a fungicide (benomyl) to field plots in a corn–soybean crop rotation in each of 3 years, and sowed experimental weed communities containing host species for arbuscular-mycorrhizal fungi (AMF) and non-host species. Benomyl typically suppresses formation of mycorrhizal symbiosis in AMF-host plant species, and may also affect other soil fungi. We assessed weed density and biomass production, and monitored AMF colonization rates in each of 3 years. We found that weed density, biomass, community composition and the relative performance of AMF-host and non-host weed species were all significantly responsive to fungicide applications, although for all attributes responsiveness was variable. Fungicide application increased total weed density and biomass production in nearly all cases; most effects were modest but reached a maximum of 49%. Fungicide application also increased the relative performance of non-host species in most cases, although most effects were again modest. Our findings are the first assessment of responses by field-crop weeds to direct manipulation of soil microbial communities in a field setting, and suggest that the population and community ecology of these weeds can be strongly affected by the fungal component of soil microbiota.

Weed management is a major constraint in organic production. It can be expensive and time-consuming and severe crop yield losses may be incurred when weeds are not adequately controlled. Research on organic weed management (OWM) in herb and vegetable production is increasing internationally, although in Australia very little work has been done to assess current OWM knowledge among growers, and to test the efficacy and cost effectiveness of the weed management practices used by organic growers. The effect of hand weeding, tillage, hay mulch, pelletized paper mulch (PP) and an unweeded control treatment on weed growth, crop growth and cost effectiveness were evaluated in several field trials on the Northern Tablelands of New South Wales using lettuce (Lactuca sativa L.) and echinacea (Echinacea purpurea Moench. [L.]). In echinacea, hand weeding, hay mulch and PP reduced weed growth by at least 90% compared with the control, while tillage reduced weed levels by about 50%. The more expensive weeding methods such as hand weeding and hay mulch (AU$9600 and 8900 ha−1 respectively) produced higher yields, while the cheaper methods such as tillage ($4000 ha−1) had low crop yields and were therefore 25–50% less cost effective. In lettuce, weed growth was reduced by 96% for hand weeding and PP compared with the control, 85% for hay mulch and 66% for tillage. Weed management was cost-effectively achieved using cheaper weeding methods such as tillage ($985 ha−1) compared with more expensive methods such as hand weeding and hay mulching ($4400 and 7600 ha−1 respectively). PP had lower yields and was expensive ($12,500 ha−1) and was usually not cost effective in these trials. The results highlight several important advantages and disadvantages of currently used OWM methods in the field.

A qualitative study was conducted with a subset of a Community Supported Agriculture (CSA) membership base in Wisconsin, USA to examine attitude and behavior change associated with membership. Changes that were examined included: modified eating or cooking habits, increased consideration of food seasonality and associated consumer preferences for seasonal products, and an enhanced appreciation for farming. Although this study investigated ‘spillover’ attitude or behavior changes (e.g. reduced driving or increased use of environmentally friendly cleaning products), none were observed. This study indicates that attitude and behavior changes are generated by the structural elements of CSA including exposure to the farm, interactions with the farmer, and the constraints imposed by a pre-selected bundle of vegetables. There was no indication that changes occur due to the development and enforcement of social norms within the CSA membership base. Community, in the context of this CSA, is expressed primarily as a conceptual community of interest. Our results suggest that demonstrated attitude and behavior change increases the likelihood that a consumer will renew their CSA membership.

Soil solarization is used to manage nematodes, pathogens and weeds, but relatively few studies have examined solarization effects on soil mineral nutrients, soil properties and plant tissue nutrients. This study was designed to optimize the duration of solarization treatment for the management of soil and plant nutrients and crop biomass in an agroecosystem utilizing an organic nutrient source. The experiment was a split-plot with treatment duration as the main effect and solarization as the sub-effect. Solarization treatments of 2-, 4- and 6-week durations began on sequential dates and concluded in mid-August. Immediately post-treatment, okra (Hibiscus esculentus L.) seedlings were transplanted into subplots for tissue nutrient analysis. Freshly chopped cowpea [Vigna unguiculata (L.) Walp.] hay was applied to the soil surface directly around the okra seedlings as an organic nutrient source. Immediately following solarization treatment, concentrations of soil K and Mn were higher, while Cu and Zn concentrations were lower in solarized soils than in non-solarized soils. Soil pH was slightly lower in solarized plots. Concentrations of K, N, Mg and Mn in okra leaf tissue were higher in solarized plots than in non-solarized plots, but concentrations of P and Zn were lower in plants grown in solarized soil. Okra biomass was three and four times higher in the 4- and 6-week solarization treatments than in non-solarized treatments. Based on data from this experiment, 4- and 6-week durations of solarization were optimal for increasing crop biomass. The data indicate that solarization has significant effects on soil and plant nutrients. Results of the nutrient analyses suggest that the availability of nutrients from an organic source was not limited by solarization.

The literature implicates strongly that including energy supplements in dairy rations based on protein-rich forages increases performance and feed efficiency due to an improved and more balanced ruminal energy and protein supply. Therefore, both conventional and organic dairy farms primarily supplement roughages with concentrates, containing high proportions of cereal grains. However, considering the main principles of sustainable agricultural systems and nutrient cycles, the question of alternatives is raised. Therefore, the present study was conducted to compare grain and maize silage as energy sources in organic dairy cow rations. Two grass–clover silage-based diets, offered on an ad libitum basis, were supplemented either with 1 kg grain mixture plus 0.5 kg hay (treatment group G) or 2.1 kg maize silage (treatment group M) on a dry matter (DM) basis. The trial was carried out as a change-over design and lasted for 15 weeks. Intake of concentrates, DM and utilizable crude protein in the duodenum (uCP) were similar in both treatments. However, significant differences between treatments G and M were found for grass–clover silage dry matter intake (DMI) (13.4 versus 12.9 kg), forage DMI (14.6 versus 15.7 kg), crude protein (CP) intake (2885 versus 2801 g), ruminal nitrogen balance (RNB) (40 versus 29 g) and intake of neutral detergent fiber (NDF) (7630 versus 7900 g). Milk yield was not affected by treatment, but in treatment M, milk fat content was at 42.4 g kg−1, significantly higher, and milk urea concentration at 19.7 mg 100 ml−1, significantly lower, as compared with treatment G. Efficiency of N use (N in milk in % of N intake) tended to be improved in treatment M. Balances of energy and uCP (intake as a percentage of requirements) were unaffected by treatment.

Research has shown that agricultural professionals are one of the major influences on farmer adoption of agricultural innovations. Genetic engineering and organic farming represent two vastly different innovations in agriculture, and both assert to have important sustainability outcomes. This paper presents the views from a telephone survey of agricultural scientists, extension officers and academics in Australia (n=185) on the barriers to further adoption of organic farming and agricultural genetic engineering, as well as exploring where they obtain their information about the two innovations. Many professionals believe that market issues (in terms of small market size and the extent that consumers are willing to pay premiums) will limit the size of farmer adoption of organics in Australia, while on-farm issues (in terms of production difficulties and pest and disease problems) are named as the second largest barrier to further adoption. On the other hand, professionals from the targeted sample, who were more knowledgeable about organic farming, named information needs and lack of government support as the major barrier facing further diffusion of organic farming. In contrast, public attitudes and negative media portrayal are named as the largest barrier facing further adoption of genetic engineering in Australia. The uncertainty surrounding the research into genetic engineering (and the lack of long-term research) is believed to be the second largest barrier facing further diffusion of genetic engineering while market problems are seen as the third largest barrier.

The measurement of soil carbon dioxide respiration is a means to gauge biological soil fertility. Test methods for respiration employed in the laboratory vary somewhat, and to date the equipment and labor required have somewhat limited more widespread adoption of such methodologies. The purpose of this research is to compare the results of measured soil CO2 respiration using three methods: (1) titration method; (2) infrared gas analysis (IRGA); and (3) the Solvita gel system for soil CO2 analysis. We acquired 36 soil samples from across the USA for comparison, which ranged in pH from 4.5 to 8.5, organic C from 0.8 to 4.6% and the clay content from 6 to 62%. All three methods were highly correlated with each other after 24-h of incubation (titration and Solvita r2=0.82, respirometer and Solvita r2=0.79 and titration versus respirometer r2=0.95). The 24-h (1-day) CO2 release from all three methods was also highly correlated to both basal soil respiration (7–28 days) and cumulative 28-day CO2 respiration. An additional 24 soil samples were acquired and added to the original 36, for a total of 60 soil samples. These samples were used for calibration of the Solvita gel digital color reader results using CO2-titration results and regression analysis. Regression analysis resulted in the equation y=20.6∗(Solvita number)−16.5 with an r2 of 0.83. The data suggest that the Solvita gel system for soil CO2 analysis could be a simple and easily used method to quantify soil microbial activity. Applications may also exist for the gel system for in situ measurements in surface gas chambers. Once standardized soil sampling and laboratory analysis protocols are established, the Solvita method could be easily adapted to commercial soil testing labs as an index of soil microbial activity.