请按照nature翻译下面一句话：称取100 g风干后的土样顺次经过孔径为1 mm、05 mm和025 mm的土壤筛子将各级筛子上截留的样品分别称重精确到001 g根据重量比例计算出＞1 mm、05-1 mm、025-05 mm和＜025 mm的团聚体百分含量。

Weigh 100 g of dried soil sample, sequentially sieve it through soil sieves with pore sizes of 1 mm, 0.5 mm and 0.25 mm, and weigh the retained samples on each sieve (accurate to 0.01 g). Calculate the percentage content of aggregates with sizes >1 mm, 0.5-1 mm, 0.25-0.5 mm and <0.25 mm based on weight ratios.