????? ??75%??????????

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??7?2??(????? ????????)?????“?”?7??????????????????2???????????????????,?,?????????????6???????????????30??7?????????2????,??,?????,????????2?15??,?????????75%??????????

?6??????30?????????,??? ?

?,7?1?????????????6?2???????????????6?,????,??????????????????????????????????????????????????????????????????????,???:?????????????????139.7????????????????105.4????????????????????99.0??

?????????7???2???????????????15??0-20cm?,???????75%???????????,25%?,??????

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????????,?10?,?,??????????????????,7??????3???6?????,??,????;7???????????8???,???????????????????????;9??13?????,?????????????????,????????????????14?????????15??????????????,????????????,??????,???????????

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