Lupinus polyphyllus Lindl. and Rumex acetosella L. effects on nutrient accumulation and microbial activity on tephra from the Puyehue–Cordón Caulle eruption (2011)

Abstract

This study investigated the capacity of Lupinus polyphyllus (Leguminosae) and Rumex acetosella (Polygonaceae) to promote nutrient accumulation and microbial activity on tephra from the volcanic eruption of the Chilean Puyehue–Cordon Caulle complex (Northern Patagonia) in June 2011. In December 2015, February 2016 and September 2016, we sampled (1) barren substrate (‘Barren’), (2) substrate under R. acetosella (‘R. ac. substrate’), (3) substrate under L. polyphyllus (‘L. po. substrate’), (4) R. acetosella rhizosphere substrate (‘R. ac. rhizosphere’) and (5) L. polyphyllus rhizosphere substrate (‘L. po. rhizosphere’) (n = 5). Soil properties (moisture, pH, electrical conductivity, organic C, available P, inorganic N and total N) and microbial activity (enzymatic activities) were assessed. ‘Barren’ presented the lowest moisture, organic C, total N and enzymatic activities. ‘R. ac. substrate’ and ‘L. po. substrate’ showed similar levels of organic C (0.23–0.30 g kg−1), and however, R. acetosella was associated with lower inorganic N (‘R. ac. substrate’ = 0.7 and ‘L. po. substrate’ = 2.3 mg kg−1) while L. polyphyllus tended to promote higher total N, especially in the rhizosphere (‘R. ac. rhizosphere’ = 0.19 and ‘L. po. rhizosphere’ = 0.34 g kg−1). ‘L. po. substrate’ and ‘L. po. rhizosphere’ presented the highest enzymatic activities. After five years, L. polyphyllus and R. acetosella have increased tephra organic C, total N and microbial activity, and however, L. polyphyllus has maintained the best substrate N availability. Abstract in Spanish is available with online material.