Laboratory studies were conducted to evaluate the effects of temperature and water pressure head on the degradation of the diketonitrile metabolite (DKN) of isoxaflutole during 84 d in samples collected in a loamy soil under conventional (CT) and conservation (MT) tillage systems. Soil temperature was the major factor controlling DKN degradation in the two tillage systems. The shortest half-lives (T1/2) were measured in the seedbed samples under MT at 25 °C and -33 cm water pressure head. We found that mouldboard ploughing under CT was responsible for the spatial variability of herbicide degradation properties, whereas under MT herbicide degradation was associated to the vertical distribution of organic matter. Tillage practices influence the spatial variability of diketonitrile degradation in soil and its sensitivity to pedoclimatic conditions.

The potential for storing additional C in U.S. Corn Belt soils – to offset rising atmospheric [CO2] – is large. Long-term cultivation has depleted substantial soil organic matter (SOM) stocks that once existed in the region's native ecosystems. In central Illinois, free-air CO2 enrichment technology was used to investigate the effects of elevated [CO2] on SOM pools in a conservation tilled corn–soybean rotation. After 5 and 6 y of CO2 enrichment, we investigated the distribution of C and N among soil fractions with varying ability to protect SOM from rapid decomposition. None of the isolated C or N pools, or bulk-soil C or N, was affected by CO2 treatment. However, the site has lost soil C and N, largely from unprotected pools, regardless of CO2 treatment since the experiment began. These findings suggest management practices have affected soil C and N stocks and dynamics more than the increased inputs from CO2-stimulated photosynthesis. Soil carbon from microaggregate-protected and unprotected fractions decreased in a conservation tilled corn–soybean rotation despite increases in primary production from exposure to atmospheric CO2 enrichment.

Pasture management can be effective at sequestering soil organic C. We determined the depth distribution of particulate organic C (POC), non-particulate organic C (NPOC), particulate-to-total organic C (POC-to-TOC) ratio, and particulate organic C-to-N (POC-to-N) ratio under pastures near Watkinsville, GA, USA. POC was highly related with total organic C (TOC), but became an increasingly larger portion of TOC near the soil surface, where both pools were greatest. POC and NPOC were (i) greater under pasture than under conservation-tillage cropland, (ii) greater when pasture was grazed than when hayed, (iii) marginally greater with higher fertilization of pasture, (iv) greater with higher frequency of endophyte infection of tall fescue, and (v) greater under increasing stand age of grass. Soil under pasture comparisons that had greater TOC content had (i) larger improvements in POC than in NPOC and (ii) lower POC-to-N ratios, suggesting improvement in biochemical soil quality, as well as soil C sequestration.

A plot-scale, rainfall-simulation study measured edge-of-field pollutant losses from conventional-till, strip-till, and no-till treatments in a burley tobacco production system. The field experiment results show that the conventional-till treatment yielded more total runoff than strip- and no-till treatments. Compared to the conventional-till treatment, both no-till and strip-till reduced the total mass losses of total suspended solids (TSS), total nitrogen (TN), total Kjeldahl nitrogen (TKN), nitrate (NO-N), ammonia (NH₃-N), total phosphorus (TP), orthophosphate (PO₄-P), and the insecticide chlorpyrifos in runoff. Although statistical analyses indicated that there was no significant difference between the no-till and strip-till practices, the no-till practice consistently yielded less edge-of-field pollutant loss than the strip-till practice. This research reinforces the body of knowledge documenting the effectiveness of conservation-tillage practices in reducing edge-of-field pollutant losses.

In this paper, Delphi method was used to evaluate the low-carbon technologies and measures for high agricultural carbon productivity in Taihu Lake Basin. We established the selecting process and standards and obtained the final list of low-carbon technologies and management measures of high agricultural carbon productivity in Taihu Lake Basin: (1) the initial list of low-carbon technologies and measures of planting industry included 19 items, of which 10 items were included in the final list. The 10 technologies and measures included in the final list were reducing fertilizers, mixed use of organic fertilizer and chemical fertilizer, soil testing and formulated fertilization, application of controlled release fertilizer, deep application of fertilizers, cultivation of new variety, extension of conservation tillage, extension of midseason/alternate drainage, paddy-upland rotation (rice-rape/rice-wheat), and reducing pesticides. (2) The initial list of low-carbon technologies and measures of animal husbandry included 11 items, of which 4 items were included in the final list. The 4 technologies and measures included in the final list were reasonable ratio of concentrate to roughage in ration, treatment straw feed by silage/ammoniation/shredding, application of nutritive cube/dietary additives, and promotion of high productivity livestock breeds. (3) Low-carbon agricultural technologies and management measures need to be adapted to local conditions according to different geographical, climatic, and socio-economic development characteristics, and it is necessary to form a regionally differentiated system of low-carbon agricultural technologies and management measures. The final list of low-carbon technologies and management measures of high agricultural carbon productivity can provide decision-making reference for the formulation of agricultural carbon emission reduction technology system and low-carbon agricultural development planning of provinces and cities in Taihu Lake Basin. At the same time, the final list can be considered a priority for the promotion of agricultural low-carbon technologies and measures in China and even in the world.

Background, aim, and scope The controversy over the world's first genetically modified (GM) wheat, Roundup Ready wheat (RRW), challenged the efficacy of 'science-based' risk assessment, largely because it excluded the public, particularly farmers, from meaningful input. Risk analysis, in contrast, is broader in orientation as it incorporates scientific data as well as socioeconomic, ethical, and legal concerns, and considers expert and lay input in decision-making. Local knowledge (LK) of farmers is experience-based and represents a rich and reliable source of information regarding the impacts associated with agricultural technology, thereby complementing the scientific data normally used in risk assessment. The overall goal of this study was to explore the role of farmer LK in the a priori risk analysis of RRW. Materials and methods In 2004, data were collected from farmers using mail surveys sent across the three prairie provinces (i.e., Manitoba, Saskatchewan, and Alberta) in western Canada. A stratified random sampling approach was used whereby four separate sampling districts were identified in regions where wheat was grown for each province. Rural post offices were randomly selected in each sampling district using Canada Post databases such that no one post office exceeded 80 farms and that each sampling district comprised 225-235 test farms (n = 11,040). In total, 1,814 people responded, representing an adjusted response rate for farmers of 33%. A subsequent telephone survey showed there was no non-response bias. Results The primary benefits associated with RRW were associated with weed control, whereas risks emphasized the importance of market harm, corporate control, agronomic problems, and the likelihood of contamination. Overall, risks were ranked much higher than benefits, and the great majority of farmers were highly critical of RRW commercialization. In total, 83.2% of respondents disagreed that RRW should have unconfined release into the environment. Risk was associated with distrust in government and corporations, previous experience with GM canola, and a strong belief in the importance of community and environment. Farmers were critical of expert-based risk assessment, particularly RRW field trials, and believed that their LK was valuable for assessing agbiotechnology as a whole. Discussion Over 90% of canola production across the Canadian prairies makes use of herbicide-tolerant (HT) varieties. Yet, respondents were generally uniform in their criticism of RRW, regardless whether they were HT users, non-HT-users, conservation tillage or organic in approach. They had a sophisticated understanding of how GM trait confinement was intrinsically tied to grain system segregation and, ultimately, market accessibility, and were concerned that gene flow in RRW would not be contained. Organic farmers were particularly critical of RRW, in large part because certification standards prohibit the presence of GM traits. Farmers practicing conservation tillage were also at relatively great risk, in part because their dependence on glyphosate to control weeds increases the likelihood that RRW volunteer would become more difficult and costly to control. Conclusions This research is the first of its kind to include farmer knowledge in the a priori risk analysis of GM crops and, arguably, given its prairie-wide scope, is the largest scale, independent-farmer-focused study on GM crops ever conducted. The surprising uniformity in attitudes between users and non-users of GM technology and among organic, conventional, conservation tillage and GM using farmers speaks to the ability of farmers to discriminate among HT varieties. Our results clearly show that prairie farmers recognize that the risks associated with RRW commercialization outweigh any benefits. Recommendations and perspectives Farmer knowledge systems are holistic in nature, incorporating socioeconomic, cultural, political, and agroecological factors that all can contribute meaningfully to the pre-release evaluation of GM crops. The inclusion of farmers and other stakeholders in risk assessment will also help enhance and even restore public confidence in science-focused approaches to risk assessment. Although farmers are highly knowledgeable regarding RRW and arguably any agricultural technology, their expertise continues to be overlooked by decision-makers and regulators across North America.