The organism of Mn loss from the surface soil for rice／wheat rotation systems in Chengdu Plain

The organisms of Mnlossfrom the surface soil of paddy rice and upland crop rotation systems and the effects of the application of N on the plant Mn accumulation are studied in this paper．The results show thatthe application of N can improve the Mn absorption of plant；a part of active Mn is absorbed by plant，the other part of Mn is deposited in deep soil layer，and only a little part of Mn is leached out from deep layer soil．Harvest is the main form of Mn loss from soil．Because of 82％ Mn in rice straw by harvesting，the important way of holding the paddy Mn fertility is to return straw to fidd．