Effects Of Long-term Application Of Edible Fungus Residue And Chemical Fertilizers On Quality Of Soil Organic Carbon Pool And Status Of Soil Microelements

As a waste of agricultural production,unreasonable utilization of edible fungus residue will not only cause resource waste,but also result in environmental pollution.The residue return to the soil,as an organic fertilizer,may improve the negative effect of single chemical fertilizer application,so that to achieve improvement of soil fertility.A total of 9 treatments was set up with three rates of fungus residue(F,0,50%,100%)and three rates of chemical fertilizers(C,0,50%,100%)in combination in a long-term rice field experiment(2010-2016).Effects of long-term fungus residue return on dynamic change of soil fertility,fractions of soil labile carbon and status of microelements were analyzed.And their relationships were discussed.The main results are as follows:(1)Compared to single application of chemical fertilizers(C100F0),long-term application of edible fungus residue and chemical fertilizers in combination(C50F50?C100F50?C50F100?C100F100)improved soil pH and content of soil organic carbon(SOC),available nitrogen(AN),available potassium(AK).The effects of fungus residue application increased with greater application rate.The treatments with greatest effect on these indices were C50F100(+0.61 pH)?C100F100(+2.92 g·kg-1)?C100F100(+28.08mg·kg-1)?C50F100(+11.01 mg·kg-1),respectively.By contrast,the application of 50% chemical fertilizer(C50)combined with edible fungus residue decreased content of available phosphorus(AP).(2)Compared to single application of chemical fertilizers(C100F0),long-term application of edible fungus residue combined with chemical fertilizers greatly increased soil carbon pool management index(CPMI),content of three types of soil labile organic carbon(LOC)and their availability(ALC).Soil LOC content at rice harvest was generally higher than preplanting.C100F100 was most effective to improve content of three types of LOC,ALC and CPMI.LOCs showed more significantly positive correlation than SOC with soil AN,AP,AK and total nitrogen(TN),respectively,LOC1 and LOC2 in three kinds of LOC are more sensitive on the response of soil fertility changes.CPMI was significantly related with soil available nutrients and TN.ALC of three kinds of LOC was related with AP,and ALC of LOC1 also showed close correlation with TN.(3)Long-term application of 100% edible fungus residue and chemical fertilizers in combination(C100F100)increased soil total Zn content.The use of edible fungus residue reduced availability of soil Fe and Cu,and increased availability of Mn in contrast,but soil Zn availability was little affected.Although long-term application of edible fungus residue combined with chemical fertilizers had no effect on transformation of Fe and Mn,it resulted in acid-soluble-fraction Cu and reducible-fraction Cu to convert to residue Cu.By contrast,it caused residue Zn transform to acid-soluble-fraction Zn and reducible-fraction Zn.(4)The availabilities of microelements were mainly related with acid-soluble-fraction,reducible-fraction and oxidizable-fraction.Soil microelements transformation was mainly affected by SOC and LOC.To sum up,returning edible fungus residue to rice field improved soil fertility and the quality of organic carbon pool,in addition to soil Zn accumulation.At the same time,the decrease of soil Fe and Cu availabilities need to be paid attention.