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Enzymes and C pools as indicators of C build up in short-term conservation agriculture in a savanna ecosystem in Cambodia

Hok L., De Moraes Sa J.C., Reyes M., Boulakia S., Tivet F., Leng V., Kong R., Briedis C., Da Cruz Hartman D., Ferreira L.A., Massao Inagaki T., Gonçalves D.R.P., Bressan P.T.. 2018. Soil and Tillage Research, 177 : p. 125-133.

Soil organic carbon (SOC) pools, particularly labile pools, and soil enzymes are good indicators of short-term impacts of soil management. We hypothesized that labile SOC pools drives C accumulation and enzyme activity can be an efficient indicator for C build up in short-term conservation agriculture. The aims of this study were to quantify the impacts of tillage and crop rotations with diverse crop residue inputs on changes in SOC labile pools and enzymatic activities in rice-, soybean- and cassava-based cropping systems designated as RcCS, SbCS and CsCS, respectively. The four treatments in each cropping system consisted of: conventional tillage (CT), no-till in which main crops (rice, soybean and cassava) were grown in a one-year frequency pattern (NT1) and, no-till in which the main crops were grown in bi-annual rotations with maize (NT2 and NT3). After 5 years experiment period, greater hot-water extractable organic C (HWEO-C) stocks of 61%, 55% and 53%, and permanganate oxidizable C (POX-C) stocks of 23%, 21% and 32% were attributed to NT than those in CT soils under RcCS, SbCS and CsCS, respectively, at 0¿5?cm soil layer. The pyrophosphate extractable organic C (PEO-C) and chemically stabilized organic C (CSO-C) stocks were almost constant in each depth among treatments, except 0¿5?cm in CsCS. The ?-glucosidase activity was 18%, 28% and 49% greater in NT than those in CT soils at 0¿5?cm under RcCS, SbCS, CsCS, respectively. Arylsulfatase activity was 36% and 39% greater in NT than in CT under SbCS and CsCS, respectively but no significant differences in RcCS. A strong and positive correlation (P?

Mots-clés : cambodge

Thématique : Systèmes et modes de culture; Façons culturales; Conservation de la nature et ressources foncières

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