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美国太平洋西北部的帕洛斯(Palouse)地区,山势陡峭,雨水和雪水极易将这山势起伏地区破碎的土壤冲走,土壤侵蚀十分严重。在麦地里切割溪谷,并挟带成吨的沉积物冲下山麓进入江河。免耕法把前季庄稼的根茬留在农田上,是保持土壤的一个好方法。然而,帕洛斯山区的农民不愿意用这种方法,理由是免耕法引起小麦减产,多年来其原因一直不明。 最近,科学家揭开了这个秘密。由植物病理学家R. James. Cook领导的美国农业部的一组研究人员,不仅弄清了免耕土地上小麦减产的原因,而且还找到了解决问题的办法。 作为一位世界上著名的小麦根病专家,Cook发现:在比耕作土壤温度低、湿度大的免耕土壤中生长着一种称为Pythium的土壤真菌,它在这种环境条件下生长旺盛,侵染正在发芽的种子,最后破坏根系,致使小麦减产25～40％。
The Palouse area in the northwestern United States of the Pacific has steep terrain and rain and snow can easily wash away the crushed soil in this ravine and soil erosion is very serious. Cutting the valley in the cornfield, and carrying tons of sediment washed down the foothills into the river. No-Tillage leaves the stubble of the previous crop on the farmland and is a good way of keeping the soil. However, peasants in the Palos mountain area are reluctant to use this method on the grounds that no-till method has led to a decrease in the yield of wheat, which has remained unclear for many years. Recently, scientists uncovered this secret. A team of researchers from the U.S. Department of Agriculture, led by phytopathologist R. James Cook, not only uncovered the causes of wheat yield loss on no-till fields but also found a solution to the problem. Cook, a world famous Wheat Roots specialist, found that a soil fungus called Pythium grows in no-tillage soil that is cooler and more humid than tillage soil and grows vigorously under these environmental conditions, Infecting seeds that are germinating and eventually destroying the root system, resulting in a wheat cut of 25-40%.