Inundation impacts on diversified pasture biomass allocation and soil particulate organic matter stocks

Abstract

Natural soil inundation caused by frequent and intense precipitation affects carbon allocation in grassland biomass, ultimately leading to changes in soil carbon storage. Increasing forage diversity could provide resiliency to inundation of grassland. The objective was to evaluate forage and root biomass and C and N stocks in the soil particulate organic matter (POM) from pastures under recurring short-term inundation. Three forage species combinations were evaluated in an inundated (typically lasting for a few days after heavy rain events) and a non-inundated pasture: (1) predominantly tall-fescue (Festuca arundinacea Schreb.); (2) mixture of cool-season perennials composed of tall-fescue, orchardgrass (Dactylis glomerata L.), bluegrass (Poa pratensis L.) and white (Trifolium repens L.) and red clover (Trifolium pratense L.); (3) and cool-season mixture of perennials overseeded with oats (Avena strigosa Schreb.) and rye (Secale cereale L.). Roots and forage biomass were sampled during the growing seasons of 2021 and 2022. Soil POM was evaluated 2.5 years after establishment. Inundation reduced forage and root biomass mainly during periods of higher inundation frequency, leading to lower C-POM stocks (p