This often happens if the field is on the side of a hill. The water rushes down the hill and the river carries the humus away to the sea.
山坡上的农田经常会发生这种现象：雨水从山上急流而下，河水把腐殖土冲入大海。They generate the humus soils across the land masses of Earth .
它们产生腐殖土横跨整个地球的陆地。the top layer of a soil profile; usually contains humus.
土壤层中的顶层；通常含有腐殖土。Then the water will not rush down to the river, and the humus will stay in its place.
这样，雨水就不会直冲到河里，腐殖土也因此得以保持。Sometimes after heavy rain, the water carries the humus down to a river.
有时大雨之后，雨水会把腐殖土冲到河里。Figure 16-20 shows the good correlation observed between the magnetic field and the gold values over a muck-covered placer in this area.
图16-20表明了此地区腐殖土覆盖下砂积矿床上面的磁场和含金量之间的良好对比关系。Humus contains materials taken from dead plants, and the waste matter from animals also falls on it.
腐殖土含有枯死植物的养料，动物的粪便也掉在地上。Mixed matrix of sand and red soil give better cuttage effects than that of perlite and humus.
河沙和红土的混合基质优于珍珠岩和腐殖土的混合基质；Hydrolysis Improving and Adsorption of Chlorpyrifos by Humic Acid Extracted from Forest Soil
林地腐殖土腐植酸对毒死蜱水解影响及吸附作用