| 1 | No-till and conservation agriculture in the United States:An example from the David Brandt farm,Carroll,Ohio显示文摘No-till(NT)farming(conservation agriculture)began in the US in the 1960s.The state of Ohio has a university research location that began no-till research in 1962.A few innovative Ohio farmers,including NT pioneers David Brandt and Bill Richards,were early adopters of the new conservation practice.Initially,no-till was most successful on sloping,well drained soils,then with improvements to the system,including cover crops,it became more widely adopted on all soil types.David Brandt was an enthusiastic learner and teacher of no-till practices,working with chemical company representatives and Cooperative Extension Specialists to demonstrate the system.David Brandt’s cooperation with Ohio State University researchers continues to provide a valuable site for studying the long term changes in soil health and ecosystem services.Results showed that total microbial biomass as one of the soil biological health indicators significantly increased with an associated decrease in carbon(C)loss under NT compared with conventional tilled soil(CT).Under NT,there was significantly higher total C and total N compared to CT.Active C,as a composite measure of soil health,significantly increased with NT.When cover crops,especially cover crop cocktail mixes,were used,NT substantially improved soil health.Long-term NT with cover crop cocktail mixes significantly increased the soil aggregate stability,compared with CT.The overall rate of C sequestration by NT suggested that the soils on the Brandt farm act as a consistent sink of atmospheric CO2 although this tends to level off after about 20 years.The Brandt farm showed that crop yields are increased under long-term NT with cover crops mixes.Results suggested that starting with a cover crop when switching from CT to NT,is more likely to ensure success and to maintain economic crop yields.Another early adopter,Bill Richards,from Circleville,Ohio,also became a national leader and promoter of no-till farming.He served as head of the United States Department of Agriculture’s Natural Resources Conservation Service in the early 1990s and instituted a program that led to rapid expansion of no-till.He advises that farmers who follow conservation agriculture principles need to be more proactive,from local level to national levels,to influence policy decisions that can lead to robust improvement in soil health. | R.Islam R.Reeder | 2014 | International Soil and Water Conservation Research2014，2，1： | 0 |
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