1
the subsoil
作名词时指表土之下的土层，常用 the 特指。
The subsoil is usually denser than the topsoil.
底土通常比表土更密实。
底土；下层土
subsoils — plural of subsoil
先理解核心含义，再看它在真实句子里的用法。
底土；下层土
the layer of soil between the topsoil and bedrock
The subsoil is usually denser than the topsoil.
底土通常比表土更密实。
表土层以下的土层。
The layer of earth that is below the topsoil.
表土与基岩之间的土层
the layer of soil between the topsoil and bedrock
The builders had to dig through the topsoil before they reached the hard subsoil.
建筑工人必须先挖穿表土，才能到达坚硬的底土。
Farmers often add lime to the subsoil to improve drainage.
农民常常在底土中加入石灰以改善排水。
Tree roots can grow deep into the subsoil in search of water.
树根可以深扎入底土寻找水分。
作名词时指表土之下的土层，常用 the 特指。
The subsoil is usually denser than the topsoil.
底土通常比表土更密实。
作动词时是及物动词，后接田地、土地等作宾语，表示深松底土。
Farmers subsoil the ground to break up hard layers.
农民深松土地，以打碎坚硬的土层。
Not this
There are a lot of subsoils under this field.
Use this
There is a lot of subsoil under this field.
subsoil 在表示“底土”这一土层时是不可数名词，不能用复数形式或 many 修饰；表达“大量底土”应使用 a lot of 且谓语用 is。
Not this
The roots grow into the bottom soil.
Use this
The roots grow into the subsoil.
汉语“底土”不能逐字直译成 bottom soil，英语中对应的地道名词是 subsoil；bottom soil 不是表示该土层的常用说法。
Not this
The farmer subsoiled on the field.
Use this
The farmer subsoiled the field.
subsoil 作动词时是及物动词，意为“翻耕……的底土”，后面直接跟被翻耕的对象，不能加介词 on。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
底土排水
Proper subsoil drainage prevents waterlogging in heavy rain.
良好的底土排水可防止大雨时发生涝渍。
底土水分
Plant roots can draw on subsoil water during a drought.
干旱时期植物根系可以吸取底土中的水分。
黏土底土
The clay subsoil makes the ground hard to dig.
黏土底土使得地面很难挖掘。
底土压实
Repeated heavy traffic causes subsoil compaction on farmland.
重型机械反复碾压会导致农田底土压实。
深松（底土）
Deep subsoiling loosens the soil without turning it over.
深松能疏松土壤而不翻动土层。
底土层
The subsoil layer is usually richer in clay minerals.
底土层通常含有较多的黏土矿物。
Use subsoils naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
想象“sub”（下面）加“soil”（土），表土之下那一层就是底土。
语域：neutral 常见场景：农业、地质学、园艺 这里针对名词义：指表土以下的土层，通常用于农业、地质、园艺等专业语境，日常口语中较少单独使用；动词义（掘起底土）则更少见且更专业。
这些词都与 subsoil 词尾 -soil 的发音 /sɔɪl/ 押韵：topsoil, boil, coil, foil, toil, spoil。注意 subsoil 的重音在 sub- 上，-soil 为次重音。拼写以 -oil 结尾的词常读 /ɔɪl/，但不要被拼写相似的 all /ɔːl/（全部）或 aisle /aɪl/（通道）误导。
Dictionary facts from ECDICT, WIKTIONARY.