Heavy metals contents of soils and vegetable edible parts were studied at three crop systems （conventional, in conversion and organic） from seven traditional sites for vegetable growing in North-eastern Romania, dur...Heavy metals contents of soils and vegetable edible parts were studied at three crop systems （conventional, in conversion and organic） from seven traditional sites for vegetable growing in North-eastern Romania, during 2010. The main goal of the research was to find a correlation between the heavy metals contents and the crop systems. Determination of heavy metals was performed by atomic absorption spectrometry （AAS）, using a Shimadzu spectrophotometer, 6300 version, equipped with graphite furnace and autosampler. Heavy metals contents in the soils varied with the metals and locations, according to the crop system. The following experimental average contents were determined： Mn-262.03 mg kg1, Zn-45.60 mg kgq, Cu-28.53 mg kgl, Pb-5.20 mg kg1 and Cd-1.84 mg kg1. In vegetable edible parts, heavy metal varied with metals, sites and plant species, without a significant correlation with crop system. The trend of heavy metals in conventional and organic crops was Zn 〉 Cu 〉 Mn = Pb 〉 Cd, but in conversion crops it was Zn 〉 Mn = Pb 〉 Cu 〉 Cd. The highest content was of Zn （4.85 mg kg＇t）, at a cabbage crop in conversion. Cd was not detected in vegetable products and Pb was detected only in some vegetable samples. Research emphasized that heavy metals contents from soil and vegetable edible parts did not exceed the admitted maximum limits, according to Romanian and European Regulations. Final conclusion of research is that no correlations exist between crop systems and heavy metals contents from soil and plant.展开更多
Conservation agriculture(CA)technologies involve minimum soil disturbance,permanent soil cover through crop residues or cover crops,and crop rotations for achieving higher productivity.In India,efforts to develop,refi...Conservation agriculture(CA)technologies involve minimum soil disturbance,permanent soil cover through crop residues or cover crops,and crop rotations for achieving higher productivity.In India,efforts to develop,refine and disseminate conservation-based agricultural technologies have been underway for nearly two decades and made significant progress since then even though there are several constraints that affect adoption of CA.Particularly,tremendous efforts have been made on no-till in wheat under a rice-wheat rotation in the Indo-Gangetic plains.There are more payoffs than tradeoffs for adoption of CA but the equilibrium among the two was understood by both adopters and promoters.The technologies of CA provide opportunities to reduce the cost of production,save water and nutrients,increase yields,increase crop diversification,improve efficient use of resources,and benefit the environment.However,there are still constraints for promotion of CA technologies,such as lack of appropriate seeders especially for small and medium scale farmers,competition of crop residues between CA use and livestock feeding,burning of crop residues,availability of skilled and scientific manpower and overcoming the bias or mindset about tillage.The need to develop the policy frame and strategies is urgent to promote CA in the region.This article reviews the emerging concerns due to continuous adoption of conventional agriculture systems,and analyses the constraints,prospects,policy issues and research needs for conservation agriculture in India.展开更多
文摘Heavy metals contents of soils and vegetable edible parts were studied at three crop systems （conventional, in conversion and organic） from seven traditional sites for vegetable growing in North-eastern Romania, during 2010. The main goal of the research was to find a correlation between the heavy metals contents and the crop systems. Determination of heavy metals was performed by atomic absorption spectrometry （AAS）, using a Shimadzu spectrophotometer, 6300 version, equipped with graphite furnace and autosampler. Heavy metals contents in the soils varied with the metals and locations, according to the crop system. The following experimental average contents were determined： Mn-262.03 mg kg1, Zn-45.60 mg kgq, Cu-28.53 mg kgl, Pb-5.20 mg kg1 and Cd-1.84 mg kg1. In vegetable edible parts, heavy metal varied with metals, sites and plant species, without a significant correlation with crop system. The trend of heavy metals in conventional and organic crops was Zn 〉 Cu 〉 Mn = Pb 〉 Cd, but in conversion crops it was Zn 〉 Mn = Pb 〉 Cu 〉 Cd. The highest content was of Zn （4.85 mg kg＇t）, at a cabbage crop in conversion. Cd was not detected in vegetable products and Pb was detected only in some vegetable samples. Research emphasized that heavy metals contents from soil and vegetable edible parts did not exceed the admitted maximum limits, according to Romanian and European Regulations. Final conclusion of research is that no correlations exist between crop systems and heavy metals contents from soil and plant.
文摘Conservation agriculture(CA)technologies involve minimum soil disturbance,permanent soil cover through crop residues or cover crops,and crop rotations for achieving higher productivity.In India,efforts to develop,refine and disseminate conservation-based agricultural technologies have been underway for nearly two decades and made significant progress since then even though there are several constraints that affect adoption of CA.Particularly,tremendous efforts have been made on no-till in wheat under a rice-wheat rotation in the Indo-Gangetic plains.There are more payoffs than tradeoffs for adoption of CA but the equilibrium among the two was understood by both adopters and promoters.The technologies of CA provide opportunities to reduce the cost of production,save water and nutrients,increase yields,increase crop diversification,improve efficient use of resources,and benefit the environment.However,there are still constraints for promotion of CA technologies,such as lack of appropriate seeders especially for small and medium scale farmers,competition of crop residues between CA use and livestock feeding,burning of crop residues,availability of skilled and scientific manpower and overcoming the bias or mindset about tillage.The need to develop the policy frame and strategies is urgent to promote CA in the region.This article reviews the emerging concerns due to continuous adoption of conventional agriculture systems,and analyses the constraints,prospects,policy issues and research needs for conservation agriculture in India.
