JIA-2019-11

2612 CHEN Xu et al. Journal of Integrative Agriculture 2019, 18(11): 2605–2618 aggregates (Elliott 1986; Gregorich et al. 1989; Six et al. 1999). The higher abundance of total PLFAs in the GL- RAD soil in our study was likely a response of the microbial community to the increase in available C and nutrients (Balota et al. 2014). Bacterial PLFAs were more abundant in GL compared to FL and BF, and on average, were 17% higher in GL-RAD than GL-IAD. The degeneration of protected habitat through the breakdown of larger aggregates into microaggregates may increase microbial activity, due to the release of substrates and the exposure of 0 10 20 30 40 50 60 0 50 100 150 200 250 300 350 0 10 20 30 40 50 60 0 50 100 150 200 250 300 350 0 10 20 30 40 50 60 0 50 100 150 200 250 300 350 0 10 20 30 40 50 60 0 50 100 150 200 250 300 350 0 10 20 30 40 50 60 0 20 40 60 80 100 0 10 20 30 40 50 60 0 20 40 60 80 100 0 10 20 30 40 50 60 0 20 40 60 80 100 0 10 20 30 40 50 60 0 20 40 60 80 100 * NS * NS NS NS NS NS * * * * CK NS * NS NS NS * * NS NS * * * Inorganic N NS * * NS NS NS * NS NS NS * * * Glucose β-Glucosidase activity (µmol g –1 h –1 ) NS NS NS NS NS * NS NS NS * * * Alanine Incubation time (day) * * * NS NS NS NS NS NS NS * * CK NS NS NS NS NS NS NS * * * * * Inorganic N NS NS NS NS NS NS NS NS NS * * * Glucose N-acetyl-β-glucosaminidase activity (µmolg –1 h –1 ) NS NS NS NS NS NS NS NS NS NS NS * Alanine Incubation time (day) GL-IAD GL-RAD FL-IAD FL-RAD BF-IAD BF-RAD Fig. 3 Dynamics of β-glucosidase and N-acetyl-β-glucosaminidase activities during the incubation. Treatments included intact aggregate distribution (IAD) and reduced aggregate distribution (RAD) for grassland (GL), farmland (FL) and bare fallow (BF). The asterisks and NS indicate significant ( P <0.05) and non-significant ( P >0.05) differences between IAD and RAD, respectively. Means ( n =3) and standard errors are shown.