Effects of biochar combined with n-fertilization on soil Co2 emissions, crop yields and relationships with soil properties

Abstract

Biochar is considered a valuable tool for improving soil fertility with a lower carbon footprint remaining in the background of sufficient and healthy production, particularly in tropical and subtropical conditions and especially on sandy soils. The aim of many scientists is to confirm this fact in other climatic regions of the world and on soils with different textures. Therefore, the aim of this study was to determine the effect of biochar applied separately or in combination with N-fertilizer (first to eliminate the wide C:N ratio after biochar application, which can have a priming effect on the soil organic matter and, secondly, to follow the standard N fertilization practice in Slovakia, where the amount of fertilizer applied is calculated according to the crop) to silty loam (the dominant soil texture in Slovakia) Luvisol (the most intensively used soil type in Slovakian agriculture) at Dolná Malanta, Slovakia, on (i) CO2 emissions, and (ii) grain yields in 2014-2016. The cumulative CO2 emissions from the soil for the treatments with biochar (applied with or without N-fertilizers) were from 2% to 27% lower compared to control. In 2014, grain yield was from 5% to 42% higher for the treatments with the lower biochar rate at all fertilization levels. On the contrary, a lower increase in grain yield was observed in the second year at the treatments with the higher biochar rate and higher rate of fertilizer. In 2016 – in comparison to 2014 and 2015 – no effect of biochar on CO2 flux reduction and grain yield increase was observed.