Crop residues used as food drive enzyme activation and enzymatic stoichiometry in casts of the earthworm Aporrectodea caliginosa (Savigny, 1826)

DOMINGUEZ A; GABBARINI L; RODRIGUEZ P; ESCUDERO J; WALL LG; BEDANO JC

APPLIED SOIL ECOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2021

0929-1393

Earthworms are drivers of soil processes as soil structure formation and organic matter cycling. Through providing soil microbiota with mucus, temperature, and organic resources within their guts, earthworms enhance their activity and organic matter decomposition. In agricultural fields, this phenomenon is linked to crop residues as trophic resources. However, very little is known about the effect of different crop rotations on soil microbiota activation mediated by earthworm activity. We aimed to evaluate the effect of diversifying crop rotation on enzymatic activity in A. caliginosa casts and on enzymatic stoichiometry patterns related to C, N, and P acquisition activities. We conducted a microcosm essay using different crop residues as food supply: soybean (S), soybean and maize (SM), vetch, maize, and soybean (VMS), and with no residue addition (NR). We measured α-glucosidase (AGLU), β-glucosidase (BGLU), cellobiohydrolase (CEL), N-acetyl-glucosaminidase (NAG), phosmonoesterase (PME), and acetylesterase (ACE) activity in A. caliginosa casts immediately before starting the essay for evaluating the initial condition (IC) and after the essay in each residue treatment. SM and VMS residues enhanced BGLU, CEL, and NAG activity regarding S, NR, and IC treatments. S had similar or lower activity than NR and IC for all the analyzed enzymes. There was a positive, strong, and significant relation among C, N, and P acquiring enzymes regardless of the treatment. We found lower ratios for C and N acquisition related to P acquisition than for C: N acquisition activity ratios. This result suggests P as the limiting nutrient for earthworm microbiomes. Our results indicate that soybean residue is unsuitable for A. caliginosa food requirements and that both diversified crop residues enhance enzymatic activity mediated by earthworms and thus organic matter decomposition. We suggest differential activation and likely changes in microbiota composition as mechanisms responsible for higher enzymatic activation when earthworms were fed with heterogeneous residues.