Land use effects on microbial biomass C, [beta]-glucosidase and [beta]-glucosaminidase activities, and availability, storage, and age of organic C in soil

• Published in: Biology and fertility of soils 2009-05, Vol.45 (5), p.487
• Main Authors: Sotomayor-ramírez, David, Espinoza, Yusmary, Acosta-martínez, Veronica
• Format: Article
• Language: English
• Subjects: Agricultural land; Agriculture; Biomass; Carbon; Effects; Enzymatic activity; Enzymes; Forests; Land use; Pasture; Soils; Studies; Sugarcane
• ISSN: 0178-2762; 1432-0789
• DOI: 10.1007/s00374-009-0359-x

Microbial biomass, β-glucosidase and β-glucosaminidase activities, and availability, storage, and age of soil organic C were investigated after 26 years of conversion from sugarcane (Saccharum officinarum) to forest (Eucaliptus robusta or Leucaena leucocephala), pasture (mixture of tropical grasses), and to vegetable cropping (agriculture) in a vertisol in Puerto Rico. Soil organic C (SOC) at 0-100 cm was similar under Leucaena (22.8 kg C/m2), Eucalyptus (18.6 kg C/m2), and pasture (17.2 kg C/m2), which were higher than under agriculture (13.0 kg C/m2). Soil organic N (SON) at 0-100 cm was similar under the land uses evaluated which ranged from 1.70 (under agriculture) to 2.28 kg N/m2 (under Leucaena forest). Microbial biomass C (MBC) and N (MBN) of the 0-15-cm soil layer could be ranked as: pasture > Leucaena = Eucalyptus > agriculture. The percentages of SOC and SON present as MBC and MBN, respectively, were nearly 1% in pasture and less than 0.50% in forest under Leucaena or Eucalyptus and agricultural soil. The activity of β-glucosidase of the 0-15-cm soil layer could be ranked as: Leucaena = Eucalyptus > pasture > agriculture; while β-glucosaminidase activity was ranked as: Eucalyptus > Leucaena = pasture > agriculture. The soil δ13C changed from 1996 to 2006 in forest under Eucalyptus (18.7[per thousand] to 21.2[per thousand]), but not under Leucaena (20.7[per thousand] to 20.8[per thousand]). The soil under Leucaena preserved a greater proportion of old C compared to the forest under Eucalyptus; the former had an increased soil mineralizable C from the current vegetation inputs. The soil under agriculture had the lowest enzyme activities associated with C cycling, lowest percentage of SOC as MBC, highest percentage of SOC present as mineralizable C, and highest percentage of MBC present as mineralizable C compared to the other land uses. (PUBLICATION ABSTRACT)