3.3 Aggregate SOC content
Content of organic C in aggregate fractions were significantly affected by bio-fertilizer application and tended to increase first and then decreased with increasing bio-fertilizer rates (Table 2). The 0.053-0.25 mm fraction contained the largest content of organic C while <0.053 mm fraction recorded the lowest. For the year 2018, the increases in organic C of >0.25 mm aggregate were 27.0%, 64.7%, 48.0% and 51.9% for BF30, BF50, BF70 and BF100, respectively (P <0.05), compared with BF0. In the year 2019, BF50 and BF70 significantly increased organic C content of >0.25 mm aggregate, while BF30 had no effect on it. The organic C content of <0.053 mm aggregate followed the order of BF50 = BF70 = BF100 > BF30 > BF0 in 2018 and in 2019. Generally, the organic C content in BF50 was the highest in the three soil aggregate fractions in both years.