abstract using tobit model, this study investigated factors affecting on crop risk frequency of farmers in the north khorasan province. data was collected through interviewing 120 farmers of north khorasan province in 2008. results showed that age, farm ownership and off farm employment affected frequency of risk negatively. non-agricultural activity, participating in a crop supervisory plan an...

Many ecological studies have focused on the effects of transgenes in field crops, but few have considered multiple transgenes in diversified vegetable systems. We compared the epigeal, or soil surface-dwelling, communities of Coleoptera and Formicidae between transgenic and isoline vegetable systems consisting of sweet corn, potato, and acorn squash, with transgenic cultivars expressing Cry1(A)...

Estimates of climate change impacts are often characterized by large uncertainties that reflect ignorance of many physical, biological, and socio-economic processes, and which hamper efforts to anticipate and adapt to climate change. A key to reducing these uncertainties is improved understanding of the relative contributions of individual factors. We evaluated uncertainties for projections of ...

Microbial diversity can be used to assess the impact of agricultural practices on the long-term sustainability of cropping systems. The aim of this study was to investigate changes in soil bacterial diversity as a result of the impact of different soil tillage and crop rotation systems in an oxisol of southern Brazil. Bacterial diversity was examined in the 010 cm layer in two field experiments...

In a 3-year experiment, the effect of catch crop management [catch crop incorporated in autumn (A) or mulched (B) vs plots without a catch crop (C)] on soil acid (PAC) and alkaline (PAL) phosphatase activities as well as on the available phosphorus content (PAVAIL) were investigated on typical Alfisol. The catch crops were sown at the beginning of August and ploughed in the autumn in 2008, 2009...

Agricultural ecosystems are composed of genetically depauperate populations of crop plants grown at a high density and over large spatial scales, with the regional composition of crop species changing little from year to year. These environments are highly conducive for the emergence and dissemination of pathogens. The uniform host populations facilitate the specialization of pathogens to parti...

the quantitative performance of wheat crop under 1-5 year old poplar plantations in irrigated agro-ecosystem was studied to ascertain the biological yield of tree and crop. results revealed that growth and yield of wheat decreased significantly with the increase in poplar age. the per cent reduction in net grain yield was 17% under one year old poplar plantation, which increased to 52.15% under...

In a 3-year field study, population densities of Belonolaimus longicaudatus and other plant-parasitic nematodes and crop yields were compared between potato (Solanum tuberosum) cropping systems where either sorghum-sudangrass (Sorghum bicolor x S. arundinaceum) or velvetbean (Mucuna pruriens) was grown as a summer cover crop. Population densities of B. longicaudatus, Paratrichodorus minor, Tyle...

Producers are frequently most interested in economic comparisons of various cropping systems. We compared continuous corn (Zea mays L.) and continuous soybean [Glycine max (L.) Merr.] with 2-, 3-, and 5-year rotations, the latter two including wheat (Triticum aestivum L.) and alfalfa (Medicago sativa L.), using either chisel plow or no-tillage practices. Crop yield and returns to land and manag...