Encouraging farmers to retrofit tractors: a qualitative analysis of risk perceptions among a group of high-risk farmers in New York

Tractor rollovers continue to be one of the most frequent causes of agricultural fatalities. Despite knowledge of rollovers and the efficacy of rollover protective structures (ROPS), few New York farmers have considered installing ROPS on their unprotected tractors. Qualitative interviews conducted with an "at-risk" segment of the New York farming community indicate that there are a number of barriers to safety in general and to retrofitting, in particular. The following themes and categories emerged in relation to safety and risk taking: constant exposures to risk with positive outcomes normalizes risk; the modeling of risk by significant others positions risk as part of a farming identity; and the pressure to reduce costs, save time, and accept risk frames risk-taking as the cost-effective option (especially in regard to retrofitting, which farmers believe is both expensive and time-consuming). Recommendations for researchers planning retrofitting interventions would be to focus safety messages on the risk to significant others or on the financial impact of rollovers, and to provide financial incentives and assistance to farmers considering retrofitting.     

Limit cycles in predator-prey communities

Essentially all models that have been proposed for predator-prey systems are shown to possess either a stable point equilibrium or a stable limit cycle. This stable limit cycle, an explicitly nonlinear feature, is commonly overlooked in conventional analyses of these models. Such a stable limit cycle provides a satisfying explanation for those animal communities in which populations are observed to oscillate in a rather reproducible periodic manner.     

日粮蛋白质浓度和降解率对泌乳奶牛瘤胃保护蛋氨酸反应的影响

选用32头经产和16头初产荷斯坦奶牛进行不完全8×8拉丁方设计试验（4周为期,共12周）,进行评估粗蛋白（CP）、可消化瘤胃非降解蛋白（RUP）和瘤胃保护蛋氨酸（RPM,饲喂的是美国乔治亚州肯尼索德固赛公司的产品Mepron）。日粮舍（按干物质（DM）计）苜蓿青贮21％、玉米青贮34％、高水分玉米22％-26％、豆粕10％-14％、大豆皮4％、添加脂肪2％、矿物质和维生素13％、中性洗涤纤维27％-28％。添加或不添加压榨大豆粕的瘤胃降解蛋白（RUP）,配制为15.8％或17.1％日粮粗蛋白,0或9g RPM／d的2×2×2因子设计。结果表明,二向或三向交互作用都不显著。高日粮CP增加表明采食量1.1kg·d^-1 DM、产奶量1.7kg·d^-1、3.5％乳脂校正乳（FCM）2.2kg·d^-1、乳脂量0.10kg·d^-1、真蛋白0.05kg·d^-1,改善了表观氮平衡及干物质与纤维的消化率。然而,母牛采食较高日粮CP时,乳中尿素氮和估计尿液尿素氮和总氮排泄也增加,表观氮效率（牛奶中氮量,采食氮量）从33％下降到30％。饲喂较多RUP的积极效果在于提高饲料转化率和乳脂肪含量（FCM增加1.8kg·d^-1,乳脂量增加0.08kg·d^-1）,但是乳蛋白含量下降,乳中尿素氮和尿液尿素排泄增加..添加RPM增加DM采食量0.7kg·d^-1,FCM增加1.4kg·d^-1,乳脂量增加0.06kg·d^-1,并有提高乳脂率、产奶量和乳蛋白产量的趋势。     

Planting density for grafted melon as an alternative to methyl bromide use in Mexico

One of the major challenges of melon (Cucumis melo L.) yield is the decrease of fruit yield and quality caused by soil diseases. Soil disinfection with methyl bromide (MB) has been used to prevent soil-borne diseases damage; however, use of MB is being restricted because this substance damages the ozone layer. Searching for new MB alternatives, field experiments were carried out in open fields in soils infested with Fusarium oxysporum f. sp. melonis, Olpidium bornovanus, and Melon Necrotic Spot Virus (MNSV) in Colima, Mexico, where melons had only been grown previously using soil fumigation with MB. Yield and quality of melon cultivar Cruiser F1 (Harris Moran seed company) grafted on two rootstocks of Cucurbita maxima Duchesne × Cucurbita moschata Duchesne (“RS841”; Séminis seed company and “Shintosa Camelforce”; Nunhens seed company) were evaluated during two consecutive years. Each experiment had five treatments, two of which with non-grafted plants at a density of 18,519 plants/ha, with and without MB fumigation. The other three treatments consisted of grafted plants in non-fumigated soil with plant densities of 14,815, 11,111, and 9260 plants/ha. The use of melon grafted on “RS841” and “Shintosa Camelforce” rootstocks significantly increased the average fruit weight and the total yield of melons in soil without the need for MB. Grafting may be considered an alternative to MB fumigation. With the use of grafted melon plants, planting density may be reduced by 60%, obtaining higher yields than those obtained from non-grafted plants grown on fumigated land. Fruits harvested from grafted plants had equal firmness than those harvested from non-grafted plants, without affecting the content of soluble solids.