Biochar‐compost substrates in short‐rotation coppice: Effects on soil and trees in a three‐year field experiment

Abstract

Both biochar and compost may improve carbon sequestration and soil fertility; hence, it has been recommended to use a mixture of both for sustainable land management. Here, we evaluated the effects of biochar–compost substrates on soil properties and plant growth in short rotation coppice plantations (SRC). For this purpose, we planted the tree species poplar, willow, and alder in a no‐till field experiment, each of them amended in triplicate with 0 (= control) or 30 Mg ha−1 compost or biochar–compost substrates containing 15% vol. (TPS15) and 30% vol. biochar (TPS30). For three years running, we analyzed plant growth as well as soil pH, potential cation exchange capacity (CEC), stocks of soil organic carbon (SOC), total N, and plant‐available phosphate and potassium oxide.Biochar‐compost substrates affected most soil properties only in the topsoil and for a limited period of time. The CEC and total stocks of SOC were consistently elevated relative to the control. After three years the C gain of up to 6.4 Mg SOC ha−1 in the TPS30 plots was lower than the added C amount. Especially in the case of TPS30 treatment, C input was characterized by the greatest losses after application, although the black carbon of the biochar was not degraded in soil. Additionally, tree growth and woody biomass yield did not respond at all to the treatments. Overall, there were few if any indications that biochar–compost substrates improve the performance of SRC under temperate soil and climate conditions. Therefore, the use of biochar for such systems is not recommended.

Biochar-Compost Interactions as Affected by Weathering: Effects on Biological Stability and Plant Growth

“…These results are in agreement with a recent field study, showing positive growth effects on the second crop after soil application [60]. In addition, our results also showed that neutral effects of weathering depending on biochar feedstocks and/or soil type may occur [60,61]. Further studies would be needed to investigate the mechanisms controlling the variation of biochar-compost interactions on plant growth over time.…”

Short Rotation Eucalypts: Opportunities for Biochar

“…BC did not enhance survival or growth of a Eucalyptus hybrid on degraded soils in southern Amazonia [35]. Compost and BC-compost mixes did not improve the performance of poplar, willow, and alder SRWCs [36]. As evidenced by presentations at a 2018 international SRWC conference [37], the biochar-fertilizer study reported here appears to be unique.…”

Spatial Microanalysis of Natural 13C/12C Abundance in Environmental Samples Using Laser Ablation-Isotope Ratio Mass Spectrometry

“…The main soil type was a Luvic Stagnosol (Episiltic) (IUSS Working Group WRB, 2015), with a silty-loam texture (63% silt, 23% clay, and 14% sand). 31 For set 3, soil particles <2 mm from a C3/C4 vegetation change experiment at the Terrestrial Observatory TERENO, Selhausen, Germany, were sampled in 2014 (0−30 cm soil depth). Soil had been continuously cropped with maize since 2012 (Zea mays L.).…”