Rational soil fertilization could improve soil nutrition and leaves nutritious level. 本实验的施肥试验表明，合理的土壤施肥可以提高土壤营养和叶片营养水平。
Ecologists assign every organism in an ecosystem to a feeding level,or trophic level,depending on its source of food or nutrients. 生态学家分配在生态系的每个有机体到一个哺养的水平或者食性层次，根据它的食物或营养素的来源。
