Short-Term Responses of Soil Respiration and C-Cycle Enzyme Activities to Additions of Biochar and Urea in a Calcareous Soil

Abstract

Biochar (BC) addition to soil is a proposed strategy to enhance soil fertility and crop productivity. However, there is limited knowledge regarding responses of soil respiration and C-cycle enzyme activities to BC and nitrogen (N) additions in a calcareous soil. A 56-day incubation experiment was conducted to investigate the combined effects of BC addition rates (0, 0.5, 1.0, 2.5 and 5.0% by mass) and urea (U) application on soil nutrients, soil respiration and C-cycle enzyme activities in a calcareous soil in the North China Plain. Our results showed soil pH values in both U-only and U plus BC treatments significantly decreased within the first 14 days and then stabilized, and CO2emission rate in all U plus BC soils decreased exponentially, while there was no significant difference in the contents of soil total organic carbon (TOC), dissolved organic carbon (DOC), total nitrogen (TN), and C/N ratio in each treatment over time. At each incubation time, soil pH, electrical conductivity (EC), TOC, TN, C/N ratio, DOC and cumulative CO2 emission significantly increased with increasing BC addition rate, while soil potential activities of the four hydrolytic enzymes increased first and then decreased with increasing BC addition rate, with the largest values in the U + 1.0%BC treatment. However, phenol oxidase activity in all U plus BC soils showed a decreasing trend with the increase of BC addition rate. Our results suggest that U plus BC application at a rate of 1% promotes increases in hydrolytic enzymes, does not highly increase C/N and C mineralization, and can improve in soil fertility.

Effects of Biochar Application on CO2 Emissions from a Cultivated Soil under Semiarid Climate Conditions in Northwest China

“…In this study, though no significant interaction of the biochar and N input appeared, our results showed that the levels of CO 2 in the biochar-amended treatments with N inputs were higher than those in the biochar alone soils and the control (Figure 3) over the short term, which was in agreement with the results reported by Wang et al and Song et al [42,43], who found that the application of biochar combined with N fertilization enhanced CO 2 emissions in the incubation experiments. A significant increase in basal and substrate-induced respiration occurred in the treatments with added biochar combined with mineral fertilization [34,39], which suggested that soil C mineralization would be stimulated in the short term.…”

Biochar increases soil microbial biomass with changes in extra- and intracellular enzyme activities: a global meta-analysis

“…Biochar application can have contrasting effects on soil enzyme activities. For instance, biochar application was found to significantly increase (Pukalchik et al 2018), decrease (Chen et al 2013;Zhang et al 2014;Zheng et al 2016;Benavente et al 2018) or not change (Yoo and Kang 2012;Song et al 2016) β-1,4-glucosidase activities in upland agricultural soils. Similarly, biochar application has been shown to increase (Song et al 2018), decrease (Bamminger et al 2014;Chen et al 2017) or have no effect (Chen et al 2019) on the activities of β-1,4-N-acetylglucosaminidase, which is involved in N-acquiring activities of microorganisms (Parham and Deng 2000).…”

“…These enzymes target different groups of substrates present in soils for SOM decomposition (Sinsabaugh 2010) and their activities are substantially influenced by biochar application (Paz-Ferreiro et al 2013;Zhang et al 2014;Song et al 2018). In biochar application studies, the most widely assayed soil hydrolytic enzymes for C cycling (C-acquisition) are β-1,4-glucosidase, β-d-cellobiohydrolase and β-1,4-xylosidase; β-1,4-N-acetylglucosaminidase, leucine amino peptidase and urease for N cycling (N-acquisition); and acid phosphatase and alkaline phosphatase for P cycling (P-acquisition) (Chen et al 2013;Song et al 2016;Pukalchik et al 2018). The phenol oxidase and peroxidase are the most studied oxidizing soil enzymes while dehydrogenase is the most studied intracellular enzyme in biochar application studies (Ouyang et al 2014;Chen et al 2017).…”

Influence of Chiken Manure Biochar on Microorganisms and Plants

“…Одним из перспективных нетрадиционных удобрений является биочар, представляющий собой продукт пиролиза органического вещества, проводимого при температурах от 300 °С до 1000 °С в условиях отсутствия кислорода. Этот материал богат углеродом, характеризуется большой удельной площадью поверхности и обладает высокоароматической структурой [3]. Сырьем для биочара могут служить различные органические отходы: растительный опад, жмых, древесина, осадки сточных вод, отходы животноводства и птицеводства и др.…”

“…Внесение в почву биочара как субстрата, содержащего органогенные элементы, определяет состав и структуру микробных сообществ, вовлеченных во многие процессы, включая трансформацию почвенного органического вещества [3]. Установлено, что различные биочары, в основном полученные из растительных отходов, влияют на метаболическую активность, микробную биомассу, активность почвенных ферментов [14,15].…”