Morpho-physiological responses of Italian ryegrass to volcanic ashfalls from Calbuco

Abstract

There are nearly 90 actives volcanoes in Chile that helped to shape the landscape of the country and created fertile soils. Productive pastures established on these soils are always at risk of being buried after fresh volcanic ashfalls. Therefore, our investigation aimed to characterise the physicochemical properties of the volcanic ashfalls (from the Calbuco volcano eruption) and their effect on the biomass response and morpho-physiological parameters of Lolium multiflorum Lam. The experiment considers: one control (100% soil), a mixture soil:ashfall (75:25 and 50:50) and two ashfall sizes, coarse and fine, respectively. Available nutrients, undisturbed height, number of leaves, herbage mass, and crude protein (CP) were determined. The ashfalls are low in macronutrients concentrations Ca²⁺ = 0.5 cmol₊ kg^-1, Olsen-P = 1.4 mg kg^-1 and K⁺ = 5.0 mg kg^-1, however, when mixed with soil the N concentration increases from 11.6 mg kg^-1 to 18.4 mg kg^-1. The plants growing in mixtures with 50% fine ashfall were 2 cm higher and presented 10% less leaves than the control. No differences in herbage mass were observed. However, CP increased with mineral-N content and was higher when the ashfalls made up the 25% weight in the soil-ashfall mixture. Ashfalls incorporation into the soil as a result of cultivating and sowing new species such as L. multiflorum are a viable alternative towards the recovery of the pastureland after volcanic ashfalls.