Role of stockyard litter amendment in the short-term restoration of soil microbial efficiency in a lowland paddy

2024

Article référencé dans le Web of Science WOS:001350161900001

Koffi B. Y., Koné A. W., Koné B., Otinga A. N., Koutika L. S., Masse Dominique

Journal of Soil Science and Plant Nutrition, 2024, [Early access], p. [ p.] ISSN 0718-9508

Beneficial effects of organic fertilisers in the management of soil fertility have been proven, but their role on soil functioning in Sub Saharan savanna lowlands remains understudied. This study explores (i) the potential of stockyard litter (SYL) amendment in restoring soil microbial efficiency in a degraded lowland paddy in the short term and (ii) whether SYL amendment benefits soil spatial homogeneity. Three treatments described as no fertilisation (NF), annual mineral fertilisation with NPK + urea for four years (MinF), and annual mineral fertilisation for three years followed by SYL amendment in the fourth year (MinF-SYL) were tested. Soil samples (0-20 cm depth) were collected in the fifth year and analysed for common soil chemical properties and diverse microbial and enzyme attributes in addition to the CNP stoichiometry. Effects on the soil spatial homogeneity was assessed through the coefficient of variation (CV). Annual application of NPK + urea led to significant decreases in the microbial biomass-C (MBC) (-45.4%) and MBC: Soil organic carbon (SOC) ratio (-49%) but sharp increases in carbon mineralization rate (+ 129%), beta-glucosidase (+ 219%) and the specific microbial activities, i.e., qCO2 (+ 233%), beta-glucosidase: MBC (+ 402%) and Fluorescein diacetate hydrolysis (FDA): MBC (+ 64%). Of these attributes, one year after SYL amendment, the MBC and MBC: SOC ratio increased (+ 188.3 and + 127% respectively) to match values in the control (NF) while the opposite occurred with the specific microbial activities (-35%, -68% and - 60% for qCO2, beta-glucosidase: MBC and FDA: MBC, respectively). This indicates a return back of the soil ecosystem to equilibrium. The increase in MBC was especially associated with concentrations of exchangeable cations. Furthermore, the specific microbial activities exhibited negative correlations with soil pH while only qCO2 was positively associated with SOC and available N. Interestingly, the CVs of the microbial attributes turned low or moderate following SYL application. SYL amendment on lowland paddy soils is effective in restoring soil MBC and specific activities after one year along with a beneficial effect on soil spatial homogeneity. These findings could help future-proof an ecologically intensified rice system in humid savanna areas of Africa.

Sciences du milieu [021] ; Pédologie [068] ; Sciences du monde végétal [076]

PAR00028451