In the absence of chemical nitrogen fertilizer, the effective use of phosphate and potash fertilizers is largely limited to leguminous crops only (forage crops, green manure crops or pulses).

• 在没有氮化肥配合的条件下，磷、钾肥的有效利用仅仅局限于豆类作物如牧草、绿肥和豆类等等。