Agroenvironmental Performances of Biochar Application in the Mineral and Organic Fertilization Strategies of a Maize–Ryegrass Forage System

Abstract

Biochar, included as a soil amendment by EU Regulation 2019/1009, has been shown to increase soil organic C stock and nutrient retention. We investigated the effect of biochar incorporation alone (B) and in association with mineral (BMin), digestate (BDig) and slurry (BSlu) fertilization, compared to the respective controls without biochar (C, Min, Dig and Slu), in a silage maize–Italian ryegrass rotation, on yield, soil fertility parameters and nitrous oxide (N2O) emissions. Two types of biochar in three doses (0.2, 0.45, 0.9%) were tested in two cropping seasons. Biochar did not significantly affect maize yield; however, BDig tended to increase silage yield and the ear component compared to Dig, while BMin tended to reduce maize N uptake compared to Min. Biochar incorporation significantly increased soil organic C (+31%) and cation exchange capacity (CEC) (+13%) in all the fertilization treatments; BMin and BDig also showed an increase compared to biochar alone (B). Emission of N2O was mainly driven by fertilization, digestate exhibiting the highest emissions. Biochar addition decreased the cumulative N2O emissions consistently in all the fertilization treatments, though not significantly. The association of biochar with organic fertilizers, in particular digestate, appears promising in increasing the fertilizer efficiency and reducing N2O emissions.

The Potential of Agricultural Waste Biochar in Enhancing Soil Quality, Forage Productivity and Mitigating Greenhouse Gases Emission

“…Adding biochar did not change maize silage yield regardless of the fertilization treatments. However, adding biochar with organic fertilization (digestate from the anaerobic digestion) increased maize silage yield by 17.3% and 9.7% in the first and second years compared to the corresponding fertilization without biochar [98]. On the other hand, they did not detect a significant effect on maize silage yield between the two biochar types despite the physicochemical characteristics resulting from different processing conditions [98].…”

“…When associated with different fertilizers, crop choices and climatic characteristics influence the response to biochar application [97], Scotti et al [98] investigated the effect of two biochar types, from the gasification or pyrolysis process, with mineral and organic fertilization treatments on silage maize-Italian ryegrass yields. Adding biochar did not change maize silage yield regardless of the fertilization treatments.…”

“…However, adding biochar with organic fertilization (digestate from the anaerobic digestion) increased maize silage yield by 17.3% and 9.7% in the first and second years compared to the corresponding fertilization without biochar [98]. On the other hand, they did not detect a significant effect on maize silage yield between the two biochar types despite the physicochemical characteristics resulting from different processing conditions [98]. To clarify the impact of biochar application on soil quality and crop yield improvement, we need to focus more on the nature of soil character and the type of suitable biochar for those purposes.…”