不同肥料配合施用土壤有机碳盈亏分布

几种施肥处理的田间试验结果表明：连续四年不施肥，土壤有机碳亏缺主要来自松结态有机无机复合体及缩合程度较低的腐殖质。因此，四年间土壤供肥能力明显降低。仅施化肥保持高产，土壤有机磷亏缺不多，亏损主要来自稳结态和紧结态腐殖质，由于残体“自然归还”的补偿，松结态碳尚有盈余，因此，对土壤复合体和供肥性能的不良影响较轻。有机肥与化肥配合施用，土壤有机碳均呈盈余平衡。土粪与化肥配合，盈余碳几乎在松结态与稳结态及

SURPLUS-DEFIClT DlSTRIBUTlON OF ORGANIC CARBON IN SOIL UNDER COMBINED FERTILIZATION

This paper reports the surplus-deficit distribution of organic carbon (0.C.) in soil obtained through a 4-year field experiment with different treatments of fertilization.Results show that there was severe deficit in the balance of soil organic carbon without fertilization,which caused the produce of loosely combined organicmineral complexes and lowly condensed humus.Application of chemical fertilizer alone temporarily kept higher productivity of soil and lost not much of organic carbon in soil.The loss of O.C.under this condition mainly came from the appearance of the stably and tightly combined organic-mineral complexes and highly condensed humus.Even though there was a decrease of total soil O.C.,because of the compensation of crop residues naturally returned to field,there still was surplus of loosely combined O.C.little loss of fulvic acid and a great loss of humic acid and humin were observed in this case.It seems that fertilizer actually promoted the renewal of soil humus and resulted in less undesirable influence on soil complex and nutrient-supplying ability in a short time.There was surplus balance of soil O.C.in field when organic materials were combined with chemical fertilizers.Large amount of manure applied in field made the surplus O.C.almost averagely distributed among loosely,stably,and tightly combined complexes.However,the increase of soil O.C.still could not markedly improve the activity of humus.The accumulation of O.C.was mainly in the form of fuvic acid distributed among loosely combined organicmineral complexes when straw was added.This promoted the activity and cycle of soil humus,and enhanced the property of nutrient supply capacity.