You can usually find good clay in low areas of islands or land , especially if volcanoes helped form the land 通常你可以在小岛或陆地的低洼地找到黏土，尤其如果是火山喷发形成的陆地。
Diversity index on different terrain varied between 0 . 28 to 1 . 75 , the terrain followed the sequence of level land - plain > sloping land - medium - gradient mountain > sloping land - medium - gradient hill > level land - valley floor > sloping land - medium - gradient escarpment zone > level land - depression > steep land - high - gradient mountain ; the evenness index on different terrain varied between 发育于不同地形上的多样性指数值范围为0 . 28 1 . 75之间，从高到低依次为平原、中坡度、中坡度丘陵、山麓平原、中坡度峭壁带、低洼地和高坡度山地;均匀度指数范围为0 . 26 0 . 84之间，从高到低依次为中坡度、平原、山麓平原、中坡度丘陵、中坡度峭壁带和低洼地。
Abstract : three kinds of comparison experimental study on irrigation technique for the paddy planting and product increase have been carried out in low land area . the results showed that the “ intermit irrigation ” is an ideal irrigation technique . the problems to be tacled in utilizing this technique were also pointed out in this paper 文摘:对低洼地种稻增产灌溉技术进行了3种对比试验研究，结果表明“间歇灌溉”是理想的灌溉技术，同时指出了应用间歇灌溉技术时应注意的问题。
