This is the VOA Special English Agriculture Report.
这里是美国之音慢速英语农业报道。
Farmers and gardeners have turned the soil for centuries. But many now believe in no-till or reduced tillage, a method also called conservation tillage. The Conservation Technology Information Center says forty percent of American cropland used this method at last report.
农民和园丁们耕作了几个世纪，但是现在他们中很多人开始采取少耕或免耕方法，也称保护性耕作。环保技术信息中心（Conservation Technology Information Center）在最新的报告中称，美国40%的农耕地采取了保护性耕作。
Tilling can remove weeds and the waste from last season's crops and help break down old plant material into fertilizer. But it can also increase the risk of soil erosion by rain or wind.
耕作可以清除杂草和上一季的农作物残茬，并且有助于将原来的农作物残茬分解成化肥，但它也会增加因风蚀、水蚀造成水土流失的风险。
Tilling also releases carbon dioxide from the soil into the atmosphere. No-till keeps carbon in the soil and avoids the release of heat-trapping gases from motorized equipment. It also keeps water in the soil and protects helpful organisms like earthworms. And it saves money on labor, machinery and fuel.
耕作还会将土壤中的二氧化碳释放到大气中，而免耕能够保持住土壤中的碳，并且避免机械设备释放吸热气体。免耕还能保持土壤中的水分，保护像蚯蚓这样的有益生物。而且免耕节省了人力、机械和燃料成本。
A recent study reported on almost twenty years of different tillage methods in the American states of Colorado, Kansas and Nebraska.
一项最新的研究报道了近20年在美国科罗纳多，堪萨斯和内布拉斯加这三个州不同的耕作方法。
The researchers say tillage makes soil less resistant to being broken apart by raindrops than plowed soil. They say no-till stores more soil carbon, which helps the soil particles stick together. They found that the first two and a half centimeters of topsoil are up to seven times stronger against rain than plowed soil.
研究者称，保护性耕作的土壤比传统耕作土壤更易渗入雨水。他们称，免耕土壤碳储存量更多，有助土壤颗粒黏在一起。他们发现，免耕土壤表层2.5厘米厚的表土抗雨水侵蚀的能力比传统耕作土壤强7倍。
The study also noted that when tilled soil particles come in contact with air, soil organic matter is lost through the process of oxidation.
研究还发现，当耕作的土壤颗粒在与空气接触时，土壤有机质就会在氧化过程中流失。
The findings appeared in the Soil Science Society of America Journal. Humberto Blanco-Canqui from Kansas State University and Maysoon Mikha from the Agricultural Research Service led the study.
该研究发表在美国土壤学会期刊（Soil Science Society of America Journal）上。来自堪萨斯大学的Humberto Blanco-Canqui和农业研究局（Agricultural Research Service）的Maysoon Mikha领导了该项研究。
Another recent study found that a single tillage does not harm yield or soil structure in land that is normally not tilled. Charles Wortmann at the University of Nebraska-Lincoln says a one-time tillage may be used to correct a problem like aggressive weeds. His five-year study appeared in the Agronomy Journal.
另一项最新研究发现，单独一次耕作不会对通常不耕作的土地产量或土壤结构造成破坏。内布拉斯加大学林肯分校（University of Nebraska-Lincoln）的Charles Wortmann称，一次性的耕作可以解决类似杂草猖獗等问题。他为期5年的研究发表在农学期刊上（Agronomy Journal）。
Fabian Fernandez, a soil and plant nutrition expert at the University of Illinois, says no-till means less intensive labor. But he also says it does not mean an end to preparing the ground for planting.
来自伊利诺伊大学的土壤与植物营养学专家Fabian Fernandez称，免耕意味着减少密集劳动，但是，并不意味停止土地种植预处理。
Jimmy Wagner works at the American Plant garden center in Bethesda, Maryland. He says hand tools like tilling forks, shovels and thatching rakes require more work than a rotary tiller, but they work well and cost less.
在马里兰州贝塞斯达美国植物园林中心工作的Jimmy Wagner称，像耕叉，铲子和草耙这种手工工具比翻转式耕耘机工作量大，但效率高成本低。
If you till, wait until the soil is warm and dry enough. If the soil stays together in a ball, it is too wet to till.
耕作要等到土壤充分温暖干燥。如果土壤还黏成球状，意味着土壤太湿不能耕作。