Skip to main content

Official Journal of the Asia Oceania Geosciences Society (AOGS)

Impacts of biochar amendment and straw incorporation on soil heterotrophic respiration and desorption of soil organic carbon


While biochar amendment and straw incorporation in soil have received great attention due to the potential of carbon sequestration and improvements in soil physicochemical properties, there were limited studies addressing their impacts on soil heterotrophic respiration over a seasonal cycle. Here, we conducted a field experiment to evaluate the effects of biochar amendment and straw incorporation on the temporal variations of soil heterotrophic respiration and desorption of soil organic carbon (SOC) in the North China Plain. We measured CO2 efflux over 1-year period in the field, together with water extractable organic carbon (WEOC) and soil microbial biomass carbon (SMBC). Our study showed a significant exponential relationship (P < 0.001) between CO2 efflux and temperature, with Q10 values in a range of 2.6–3. CO2 efflux was significantly higher in summer under straw incorporation (5.66 μmol m−2 s−1) than under biochar amendments (3.54–3.92 μmol m−2 s−1) and without amendment (3.76 μmol m−2 s−1). We found significantly lower WEOC:SOC ratio and SMBC:SOC ratio under biochar amendments than with straw incorporation and without amendment. Our study indicated that biochar amendment had a greater potential for reducing SOC desorption and CO2 efflux in the cropland of North China Plain.


Soil carbon pool is the largest carbon pool on land, which is much greater than the sum of total carbon stored in the atmosphere and biosphere (Tang et al. 2018; Tifafi et al. 2018). Soil organic carbon (SOC), as a main component of soil carbon pool, acts as both a source and a sink of carbon dioxide (CO2) in the terrestrial ecosystem. In particular, soil heterotrophic respiration (decomposition of SOC) is a major CO2 source to the atmosphere.

Soil heterotrophic respiration is largely regulated by natural factors such as climate conditions and soil characteristics (Moonis et al. 2021). In general, high temperature can stimulate microbial activities thus enhances soil heterotrophic respiration (Allison et al. 2010). However, extremely high temperature may cause water stress thus decrease microbial activities, leading to low rates of soil respiration (Bradford et al. 2008). The effect of precipitation on soil respiration is complex due to its effects on various processes that regulate soil properties and microbial activity (Moyano et al. 2013; Novak et al. 2010). Generally, precipitation could increase microbial activities in drylands, which would enhance SOC decomposition (Shen et al. 2008; Wang et al. 2021b). But, sustained heavy rainfall could lead to hypoxia conditions that inhibit soil microbial activity, leading to low rates of soil respiration (Waring and Hawkes 2015).

Soil heterotrophic respiration is also affected by soil physical (e.g., porosity and texture), and chemical properties (e.g., soil pH, salinity and ion concentration) (Ferrara et al. 2017; He et al. 2009). There was evidence that high levels of clay in soils were beneficial for soil organic matter (SOM) protection (Xu et al. 2019). In addition, studies also showed that soil heterotrophic respiration was generally weak in saline–alkaline soils because of reduced soil osmotic potential and substrate availability that inhibit soil microbial activity (Ghollarata and Raiesi 2007; Wang et al. 2021a).

Land use managements can have large influences on soil heterotrophic respiration or CO2 efflux (Artemyeva et al. 2021; Guimarães et al. 2013). Straw incorporation, a comment practice, is not only beneficial for maintaining soil fertility, but also provides easily degradable organic materials (Wang et al. 2021b), which often results in more CO2 efflux. Over the past decade, biochar has been applied to improve soil physical and chemical conditions and to enhance carbon sequestration. An early study showed that biochar amendment significantly increased the numbers of macropores (> 75 μm) and medium pores (30–75 μm) in a clayey soil (Sun and Lu 2014), due to biochar’s loose and porous characteristics, which improved soil structure (Ventura et al. 2013). There was evidence that biochar amendment can increase cation exchange capacity (CEC) content in both acidic and alkaline soils due to a larger mount of anions on the biochar’s surface, and “biochar promotes the polymerization of small organic molecules through surface catalytic activity to form soil organic matter, and macropores can adsorb small organic molecules in soil” (Zhang et al. 2021). In addition, biochar addition results in improvement in soil pH (Novak et al. 2010). The improvements in soil physical and chemical conditions led to enhanced microbial activity and diversity, which can cause high rates of SOC decomposition (Zhang et al. 2021).

Our recent study revealed that long-term applications of biochar and straw led to enhanced SOM stability in wheat–maize cropping system, with greater enhancement under biochar amendment (Lu et al. 2021). Thus, one may hypothesize that biochar amendment can reduce rate of CO2 efflux, and desorption of SOC is stronger under straw incorporation than under biochar amendment. However, there were few relevant studies conducted over a seasonal cycle. The objectives of this 1-year field study were to examine the temporal variation of CO2 efflux under straw incorporation and biochar amendment in a Fluvo-aquic soil, and to evaluate the effects of soil amendments on the desorption of SOC in the main seasons.

Materials and methods

Site description

The study was conducted at the Huantai Agroecosystem Experimental Station (36° 58′ N, 117° 59′ E, elevation 17 m) of the China Agricultural University. This area is dominated by warm temperate continental monsoon climate with obvious seasonal characteristics: low temperature and drought in spring, hot and rainy in summer and autumn, cold and dry in winter. We obtained weather data from a local weather station, which showed a clear seasonality in both air temperature and precipitation (Fig. 1). Mean monthly temperature was highest in August (26.58 °C) and lowest in January (0.28 °C). Annual mean precipitation was 523 mm, with ~ 70% in summer. The soil was developed on alluvial loess, and classified as Fluvo-aquic. No crops have been planted in the experimental soil for nearly 15 years. The topsoil (0–20 cm) has 70.8% sand (0.02–2 mm), 26.9% silt (0.002–0.02 mm) and 2.3% clay (< 0.002 mm) (Du et al. 2014). Soil pH, SOC and total nitrogen (TN) were 8.29, 6.02 g kg−1 and 0.71 g kg−1, respectively.

Fig. 1
figure 1

Temperature and precipitation data for whole year from September 2019 to September 2020. The solid lines in red, blue and yellow denote the daily mean, maximum and minimum temperatures,respectively. The black columns denote daily precipitation

Experimental design

We collected topsoil (0–25 cm) from a fallow plot at the experimental station in September 2019, and mixed the soil thoroughly to ensure homogeneity, then passed through a 5-mm sieve. Empty PVC tubes (80 cm in height, 50 cm in diameter) were buried in the field (~ 50 cm deep), then filled with well-mixed soil with or without amendment. Five treatments were set up: no amendment (CK), biochar addition at 1% (B1) and 2% (B2), and wheat straw incorporation at 1% (S1) and 2% (S2). Each treatment was repeated in two sets. Wheat straw was cut into 1–2 cm in length. Application rates of soil amendments were in compliance with local agricultural practice. Biochar was produced from corncob by pyrolysis at 360 °C (by Jinfu Biochar Company in Liaoning). Basic properties of biochar were as follows: pH value 8.20, 72.0% ash content, 5.70% total carbon, 0.91% total nitrogen, 0.08% available-P and 1.60% available-K.

CO2 efflux measurements and soil sample analyses

We measured CO2 efflux every 2 weeks in summer and once a month in other seasons using Li-8100A CO2 system (20 cm chamber, Li-COR, Inc, Lincoln, NE, USA). A soil collar was inserted in the center of PVC tube. The periodic measurements were conducted from 09:00 a.m. to 11:00 a.m. We also carried out 24-h CO2 efflux measurement in July and November 2019, July and October 2020, with an interval of ~ 2 h during the day and ~ 3 h over night.

Topsoil (0–15 cm) samples were collected in April, July and October 2020, which were used to analyze relevant properties. Soils samples were air-dried, mixed thoroughly and sieved through a 2-mm screen. We prepared soil–water mixtures (1:2.5) for measurements of soil pH, and electrical conductivity (EC) using Conductivity Meter (Mettler-Toledo FE 20; Switzerland). For the measurements of WEOC and SMBC, we used 10 g 2-mm soil which was treated with 40 ml 0.05 M K2SO4 solution for 6 h at 25 °C. We shook the mixture for 40 min by oscillating machine, then followed it through centrifugation. The supernatant was filtered through a 0.45-μm membrane. Last, then analyzing WEOC and SMBC using a TOC analyzer (TOC-VCPH, Shimadzu) (Salazar et al. 2019).

Subsamples were crushed less than 0.25 mm, which were used for the measurements of SOC and TN. SOC content was determined by K2Cr2O7 oxidation titration (Walkley and Black 1934). TN content was determined by Kjeldahl method of nitrogen determination (Speirs and Mitchell 1936).

Empirical model for CO2 efflux and statistical analyses

We used observed CO2 efflux (R) and temperature (T) to derive a relationship for each treatment, using a simple empirical exponential model:

$${R=\alpha e}^{\beta T}$$

where \(\alpha\) and \(\beta\) are respiration rate at 0 °C and temperature-depend coefficients, respectively. An indicator for the temperature sensitivity to soil respiration, Q10, is calculated as:


We use one-way analysis of variance (ANOVA) and Fisher’ protected least significant difference (LSD) to assess the significance of differences in soil carbon fractions between treatments (e.g. WEOC and SMBC). The statistical tests were conducted using the SPSS Statistics 19.0 (SPSS Inc., Chicago, IL, USA). Temperature and precipitation data were obtained from local weather stations.


Temporal variations of soil CO2 efflux

Diurnal variation of CO2 efflux showed a large similarity to that of soil temperature under all treatments (Fig. 2). Despite some differences among treatments, overall, soil CO2 efflux was highest around 12 o’clock and lowest around 24 o’clock. However, there were some differences in the magnitude of diurnal variation. For example, the highest and lowest values of CO2 efflux were 2.98 and 0.62 μmol m−2 s−1 in July, 2019, but 4.57 and 1.92 μmol m−2 s−1 in July 2020 without amendment (Fig. 2a, c). Clearly, diurnal variation was greater in October (from ~ 0.8–2.1 to 3.2–5.5 μmol m−2 s−1) than in November (from ~ 0.5–1.2 to 1.4–2.9 μmol m−2 s−1), 2019 under all treatments (Fig. 2b, d). As expected, straw incorporation resulted in an increase in CO2 efflux, with greater increase under higher rate. CO2 efflux under biochar amendments showed an overall weaker diurnal variation, and/or lower rates comparing with the control.

Fig. 2
figure 2

Diurnal variation of CO2 efflux under no amendment (CK), 1% biochar (B1), 2% biochar (B2), 1% wheat straw (S1) and 2% wheat straw (S2) application. Dashed black lines denote daily mean temperature

CO2 efflux showed an obvious seasonal variation with a similar pattern under all treatments (Fig. 3). CO2 efflux was lowest in January 2020 in all treatments (< 0.20 μmol m−2 s−1), and highest in early July 2020 (3.40–3.90 μmol m−2 s−1) without straw incorporation but in September 2019 (> 5.66 μmol m−2 s−1) with straw incorporation. There was a sharp decline in CO2 efflux (by 3.07–5.42 μmol m−2 s−1) from September to December in 2019 in all treatments, and a modest increase (by 1.19–2.83 μmol m−2 s−1) from April to July in 2020. CO2 efflux was lower in September in 2020 (2.71–3.22 μmol m−2 s−1) than in 2019 (3.31–3.53 μmol m−2 s−1) without straw incorporation, which was similar to the variation of temperature (23.4 °C vs. 20.3 °C). CO2 efflux was extremely low in August 2020, without (< 0.53 μmol m−2 s−1) and with (1.70 μmol m−2 s−1) straw incorporation, which was in association with the large rainfall. Overall, there was little difference between CK and biochar treatments in terms of the seasonal variation of CO2 efflux.

Fig. 3
figure 3

Seasonal variation of CO2 efflux under no amendment (CK), 1% biochar (B1), 2% biochar (B2), 1% wheat straw (S1) and 2% wheat straw (S2) application. Dashed line denotes 7-day mean temperature prior to the day of CO2 measured (no date in February and March due to the Covid-19 epidemic)

Relationship between CO2 efflux and temperature

We evaluated the relationship of CO2 efflux with two mean temperatures (i.e., 3-day mean and 7-day mean prior to CO2 efflux measurement). Our analyses showed that CO2 efflux and temperature had a significant exponential relationship under all treatments, with R2 value ranging from 0.85 to 0.92 (P < 0.001) (Fig. 4). The respiration coefficient (α) showed the highest value (0.570) under S1 treatment and the lowest value (0.285) under B1 treatment, with relatively high values when using 3-day mean temperature. The respiration coefficient was greater under B2 treatment (0.261–0.322) than under B1 treatment (0.229–295) with two temperatures. The temperature-dependent coefficient (\(\beta\)) showed the highest value (0.108) under B1 treatment, and the lowest value under S1 treatment (0.096), with relatively high values when using 7-day mean temperature. Q10 was consistent with the change in temperature-depend coefficients under all treatments (Table 1). For example, the highest temperature-depend coefficient was 0.093 and Q10 was 2.948 under B1 treatment. While the lowest value was 0.081 and Q10 was 2.620 under straw incorporation when using 3-day mean temperature.

Fig. 4
figure 4

Relationship between CO2 efflux and temperature under no amendment (CK), 1% biochar (B1), 2% biochar (B2) and 1% wheat straw (S1) application. a Using 3-day mean temperature prior to the day of CO2 measured, and b using 7-day mean temperature prior to the day of CO2 measured

Table 1 Parameters for the relationship between CO2 efflux and temperature under no amendment (CK), 1% biochar (B1), 2% biochar (B2) and 1% wheat straw (S1) application

We estimated CO2 efflux caused by straw decomposition by calculating the difference in CO2 efflux between straw incorporation and no amendment, and found that there was also a significant exponential relationship between straw caused CO2 efflux and temperature (Fig. 5). The respiration coefficient was higher which fitted at 3-day mean temperature than 7 days (0.210 vs. 0.162), while the R2 value was lower (0.57 (P < 0.05) vs. 0.65 (P < 0.01)). The temperature-depend coefficients were higher by 7-day mean than 3 days (0.089 vs. 0.072).

Fig. 5
figure 5

Relationship between increased CO2 efflux due to straw addition and temperature. a Using 3-day mean temperature prior to the day of CO2 measured, and b using 7-day mean temperature prior to the day of CO2 measured

Seasonal variations of CO2 efflux under different organic amendments

We used the parameters derived for the relationship between CO2 efflux and 7-day temperature (Table 1) to estimate the decomposition rate of SOC, straw and biochar over an entire year (Fig. 6). The decomposition rate of SOC showed a decline from early autumn (~ 3 μmol m−2 s−1) to winter (~ 0.5 μmol m−2 s−1) in 2019, followed by a modest increase until early spring then a sharp increase from April (~ 1 μmol m−2 s−1) to June (~ 4.5 μmol m−2 s−1) in 2020 and remained high until August (Fig. 6a). The decomposition rate of straw revealed a similar but much strong seasonality, i.e., the lowest (0.15 μmol m−2 s−1) in winter 2019 and the highest (~ 2.40 μmol m−2 s−1) in summer 2020 (Fig. 6b).

Fig. 6
figure 6

Seasonal variations of estimated CO2 efflux (black lines) under no amendment (CK), 1% wheat straw (S1) application, 1% biochar (B1), and 2% biochar (B2) and decomposition rate of a soil organic carbon (i.e., CO2 efflux in CK) and b straw under 1% application (i.e., the difference in CO2 efflux between S1 and CK, red line), and changes in CO2 efflux (red lines) due to biochar amendment under c biochar 1% application (B1-CK) and (d) 2% application (B2-CK)

The seasonal change in CO2 efflux was different between low rate and high rate biochar application. There was an increase in CO2 efflux under 1% biochar application in summer 2020 (by ~ 0.1–0.3 μmol m−2 s−1), but a small decrease (~ 0.05 μmol m−2 s−1) in all other seasons (Fig. 6c). However, high rate of biochar application caused a decrease in CO2 efflux during the entire year, with the greatest decrease found in summer (~ 0.3 μmol m−2 s−1) and the smallest decrease in winter (0.02 μmol m−2 s−1) (Fig. 6d).

Effects of soil amendments on WEOC and SMBC

There was little change in WEOC content during incubation without amendment. Organic amendments led to a significant increase in WEOC content, with the greatest increase in April and the smallest increase in October (Fig. 7a). Overall, the increase of WEOC content was significantly greater under biochar amendment (by 25–31 mg kg−1) than under straw incorporation (by 17–23 mg kg−1). SMBC content showed little change in April and July but a significant increase in October without amendment (Fig. 7b). Overall, biochar amendment had no clear effect on SMBC whereas stesulted in a significant increase of SMBC content (by 29–73 mg kg−1).

Fig. 7
figure 7

Contents of (a) water extractable organic carbon (WEOC) and (b) soil microbial biomass carbon (SMBC), (c) WEOC:SOC ratio, and (d) SMBC:SOC ratio in initial samples, and under no amendment (CK), 1% biochar (B1), 2% biochar (B2) and 1% wheat straw (S1) application. Error bars denote the standard errors. Values followed by the same letter (upper case between treatments or lower case between months) are not significantly different at P < 0.05

There was a slight decrease in WEOC:SOC ratio over time without amendment (Fig. 7c). Biochar amendment led to a decrease in WEOC:SOC ratio but straw incorporation had little effect on WEOC:SOC ratio (slight increase in April and July but decrease in October). Clearly, the lowest WEOC:SOC ratio was found in October under all treatments. However, SMBC:SOC ratio was highest in October under all treatments (Fig. 7d). There was a significant decrease in SMBC:SOC ratio under biochar amendments but an increase under straw incorporation.


Response of CO2 efflux to environmental conditions

Soil respiration and CO2 efflux are regulated by environmental conditions, such as temperature and soil moisture (Delgado-Baquerizo et al. 2017; Gray et al. 2019; Rojas et al. 2017). Higher temperature can stimulate soil microbial activity, thus increase soil heterotrophic respiration (La Scala et al. 2010; Li et al. 2018). Many studies showed that soil respiration rate was significantly correlated with temperature in a certain range (Chen and Wu 2019; Kirschbaum 2006; Mahecha et al. 2010). Our study shows clear diurnal and seasonal patterns in CO2 efflux, which are largely related to the changes in temperature (Figs. 2 and 3).

There was evidence that Q10 value for soil heterotrophic respiration was generally higher in boreal and temperate regions (2.0–2.6) than in tropical and subtropical regions (1.0–2.0) (Zhou et al. 2009), reflecting temperature limitation in mid-attitudes. The Q10 value was 2.33–2.71 in our study, which was close to those (2.3–2.9) under similar soil conditions (i.e., in alkaline sandy loam) in Fierer’s study (Fierer et al. 2006). A field study conducted in arid farmland of northwest China yielded a much higher Q10 value (4.3) for SOC decomposition (Li et al. 2011). The large differences in Q10 value might reflect the influence of other factors (such as soil moisture) on soil heterotrophic respiration.

There is evidence that soil moisture has various effects on soil respiration and CO2 efflux (Inglima et al. 2009; Pabst et al. 2016). While soil respiration generally increases with the increase of soil moisture in a certain range under controled environmental conditions, such as in laboratory experiments (Zhou et al. 2014) (Moonis et al. 2021), soil respiration is low when soil moisture is too high such as in tropical forestlands, because of the water-log conditions that retard microbial activities (Zimmermann et al. 2015). The effect of precipitation on CO2 efflux is more complex (Chayawat et al. 2012; Ma et al. 2012) due to the impacts of soil moisture change on both microbial activities and soil porosity. CO2 efflux is affeted by both the timing and intensity of precipitation (Luo et al. 2017). Previous studies reported enhanced CO2 efflux with an increase of precipitation at an earlier stage or in a short period in arid and semi-arid areas and then followed by a decline, e.g., in a desert shrubland in Gansu (Song et al. 2015) and in semi-arid grasslands of Inner Mongolia (Qi et al. 2014). The initial increase of CO2 efflux was due to enhanced microbial activity that led to increased decomposition of SOM (Tan et al. 2021) whereas the decrease of CO2 efflux was probably caused by reduced soil porosity in arid and semi-arid areas (Xu et al. 2019).

On the other hand, there was evidence of reduced CO2 efflux with an increase of rainfall in humid and subhumid areas (Chen et al. 2003). Our study showed that CO2 efflux reduced to near 0 after 2-week continuous heavy rainfall in summer (Fig. 3). Similarly, other field studies also showed a decrease in CO2 efflux with an increase of rainfall, e.g., in summer and autumn at a forest site in Beijing (Zhu et al. 2020) and in summer in a coastal reed wetland (Han et al. 2018). In general, hypoxia condition induced by heavy rainfall could inhibit microbial activity (thus decrease the decomposition of SOM) in humid and subhumid regions (Yoon et al. 2014). In addition, heavy rainfall could reduce soil porosity thus restrain CO2 diffusion from soil profile to the atmosphere (Liu et al. 2017).

Effects of organic amendments on soil heterotrophic respiration and CO2 efflux

Soil management measures (straw incorporation and biochar amendment) can affect soil respiration by changing soil physicochemical properties and activity of soil microorganisms (Battaglia et al. 2021; Oertel et al. 2016). Our study showed increased CO2 efflux with straw incorporation, which was consistent with many other studies (Li et al. 2019). In general, straw incorporation can directly input organic carbon, thus increases substrate concentration for microorganisms (Feng et al. 2012; Liu et al. 2021). In addition, straw incorporation can improve soil structure and provide extra nutrients and energy for microorganisms (Singh et al. 2007; Wang et al. 2015), which facilitates microbial activity, thus increases SOC decomposition and CO2 efflux.

There were limited studies addressing the effects of biochar amendment on soil respiration and CO2 efflux, which showed inconsistent findings. For example, some indoor experiments showed enhanced CO2 efflux under biochar amendments in pH neutral soils over the duration from 3 days to ~ 3 months (Jones et al. 2011; Shah and Shah 2017; Zavalloni et al. 2011) whereas a 24-day indoor trial revealed a decrease in CO2 efflux under biochar amendment in sandy loam with a pH of 7.6 (Lu et al. 2014). Our field incubation experiment showed that despite of ~ 10% decrease in CO2 efflux under 1–2% biochar treatments, there were no significant differences over 1-year period in the sandy loam with a high pH (8.2) (Fig. 6).

The ratio of WEOC:SOC (desorption potential) showed little change under straw incorporation, but a significant decrease under biochar amendment. A number of studies also revealed that biochar amendment led to a significant decrease in WEOC:SOC ratio, including in Fluvo-aquic of North China Plain (Lu et al. 2021; Wu et al. 2021) in Hapli-Udic Cambisol soil of Northeast China (Yang et al. 2017), Solonchacks soil of East China (Ma et al. 2021) and Ferrosol soil of Southeast China (Yin et al. 2014). There was evidence that biochar amendment could increase CEC due to biochar’s negative charge, thus enhance the formation of SOC-cation complex (Chintala et al. 2014; Zhang et al. 2021). In addition, biochar amendment could also enhance the formation of macro-aggregates from micro-aggregates due to the formation of mineral-biochar-SOM complexes (Han et al. 2020) (Zhang et al. 2021). The formation of these complexes would result in enhanced protection of SOM, thus reduce soil heterotrophic respiration and CO2 efflux.

Seasonal variation of CO2 efflux from different organic materials

It is widely observed that there is a strong seasonality in soil respiration or CO2 efflux in varous ecosystems across most climate zones, which appears in association with temperature change. However, there is a large range in the temperature sensitivity parameter Q10 value for soil heterotrophic respiration (Del Grosso et al. 2005); our results show some differences in Q10 value among different treatments, with the smallest value under straw treatment. The differences in Q10 value may reflect the partial influence of other environmental conditions (such as soil moisture) on soil heterotrophic respiration (Inglima et al. 2009; Pabst et al. 2016). In addition, the characteristics of SOM and other organic materials have large influences on SOM stability (Kan et al. 2022; Wu et al. 2023) thus soil respiration with implications for the seasonal variation of CO2 efflux.

Our study showed a strong seasonality in straw decomposition (i.e., 1.9 μmol m−2 s−1 in summer, and 0.2 μmol m−2 s−1 in winter, Table 2), which was similar that of SOM decomposition. Overall, biochar application caused a reduction of CO2 efflux year-around except in summer under lower rate of biochar application. The response of CO2 efflux to straw or biochar addition was consistent with that of SMBC:SOC ratio, i.e., increase with straw and decrease with biochar (Fig. 7d), which reflected enhanced microbial activity (Singh et al. 2007; Wang et al. 2015) and reduced microbial/enzyme activity (Yang et al. 2022), respectively. The differences in magnitude and seasonality of CO2 efflux between straw and biochar were probably attributable to the differences in their own physicochemical properties and their influences on the stability of old SOM (Abiven et al. 2009; Diacono and Montemurro 2010; Han et al. 2020; Tan et al. 2017).

Table 2 Seasonal means of CO2 efflux (μmol m−2 s−1) under no amendment (CK), 1% biochar (B1), 2% biochar (B2) and 1% wheat straw (S1) application

Our previous study demonstrated that biochar amendment had a greater influence on enhancement of SOM stability than straw incorporation in cropland of North China Plain (Lu et al. 2021). There was evidence that biochar amendment could increase soil porosity due to the large surface area of biochar, which could lead to greater adsorption capacity of soil, thus more SOC trapped in soils (Burrell et al. 2016). Biochar was also able to form macroaggregates by acting as a persistent organic binder (Abel et al. 2013). Moreover, biochar amendment can increase CEC due to biochar’s negative charge, thus promote the formation of SOC-cation complex, which is beneficial to SOC stability (Chintala et al. 2014; Zhang et al. 2021). Further studies are needed to investigate the interactive responses of physical and chemical properties to various organic amendments and the subsequent effects on soil microorganisms, which aims to better understand the impacts of land use management on soil quality and carbon sequestration.


This field study showed a strong seasonality in CO2 efflux, with the lowest in January 2020 (< 0.20 μmol m−2 s−1) in all treatments, and the highest in early July 2020 (3.40–3.90 μmol m−2 s−1) without straw incorporation. CO2 efflux was significantly higher under straw incorporation, but overall lower under biochar amendment. Both WEOC:SOC ratio (an indicator for SOC desorption or SOC stability) and SMBC:SOC ratio were significantly lower under biochar amendment than under straw incorporation. The study suggested that biochar amendment had a greater potential for enhancing SOC stability, and biochar amendment was more effective than straw incorporation in soil improvement in farmland of north China. More studies are still needed to advance our understanding the complex influences of organic amendments on soil physical and chemical properties and the carbon cycle in croplands under changing environments.

Availability of data and materials

The research data of this study can be obtained upon by requesting the corresponding author.


  • Abel S, Peters A, Trinks S, Schonsky H, Facklam M, Wessolek G (2013) Impact of biochar and hydrochar addition on water retention and water repellency of sandy soil. Geoderma 202–203:183–191

    Google Scholar 

  • Abiven S, Menasseri S, Chenu C (2009) The effects of organic inputs over time on soil aggregate stability—a literature analysis. Soil Biol Biochem 41:1–12

    Google Scholar 

  • Allison SD, Wallenstein MD, Bradford MA (2010) Soil-carbon response to warming dependent on microbial physiology. Nat Geosci 3:336–340

    Google Scholar 

  • Artemyeva Z, Danchenko N, Kolyagin Y, Kirillova N, Kogut B (2021) Chemical structure of soil organic matter and its role in aggregate formation in Haplic Chernozem under the contrasting land use variants. CATENA 204:105403

    Google Scholar 

  • Battaglia M, Thomason W, Fike JH, Evanylo GK, von Cossel M, Babur E, Iqbal Y, Diatta AA (2021) The broad impacts of corn stover and wheat straw removal for biofuel production on crop productivity, soil health and greenhouse gas emissions: a review. Glob Change Biol Bioenergy 13:45–57

    Google Scholar 

  • Bradford MA, Davies CA, Frey SD, Maddox TR, Melillo JM, Mohan JE, Reynolds JF, Treseder KK, Wallenstein MD (2008) Thermal adaptation of soil microbial respiration to elevated temperature. Ecol Lett 11:1316–1327

    Google Scholar 

  • Burrell LD, Zehetner F, Rampazzo N, Wimmer B, Soja G (2016) Long-term effects of biochar on soil physical properties. Geoderma 282:96–102

    Google Scholar 

  • Chayawat C, Senthong C, Leclerc MY, Zhang G, Beasley JP Jr (2012) Seasonal and post-rainfall dynamics of soil CO2 efflux in wheat and peanut fields. Chiang Mai J Sci 39:410–428

    Google Scholar 

  • Chen S, Wu J (2019) The sensitivity of soil microbial respiration declined due to crop straw addition but did not depend on the type of crop straw. Environ Sci Pollut Res 26:30167–30176

    Google Scholar 

  • Chen Q, Li L, Han X, Yan Z (2003) Effects of water content on soil respiration and the mechanisms. Acta Ecol Sin 23:972–978

    Google Scholar 

  • Chintala R, Schumacher TE, McDonald LM, Clay DE, Malo DD, Papiernik SK, Clay SA, Julson JL (2014) Phosphorus sorption and availability from biochars and soil/biochar mixtures. Clean-Soil Air Water 42:626–634

    Google Scholar 

  • Del Grosso SJ, Parton WJ, Mosier AR, Holland EA, Pendall E, Schimel DS, Ojima DS (2005) Modeling soil CO2 emissions from ecosystems. Biogeochemistry 73:71–91

    Google Scholar 

  • Delgado-Baquerizo M, Eldridge DJ, Maestre FT, Karunaratne SB, Trivedi P, Reich PB, Singh BK (2017) Climate legacies drive global soil carbon stocks in terrestrial ecosystems. Sci Adv 3:e1602008

    Google Scholar 

  • Diacono M, Montemurro F (2010) Long-term effects of organic amendments on soil fertility. A review. Agron Sustain Dev 30:401–422

    Google Scholar 

  • Du Z, Wang Y, Huang J, Lu N, Liu X, Lou Y, Zhang Q (2014) Consecutive biochar application alters soil enzyme activities in the winter wheat-growing season. Soil Sci 179:75–83

    Google Scholar 

  • Feng Y, Zhao X, Guo Y, Yang G, Xi J, Ren G (2012) Changes in the material characteristics of maize straw during the pretreatment process of methanation. J Biomed Biotechnol.

    Article  Google Scholar 

  • Ferrara RM, Mazza G, Muschitiello C, Castellin M, Stellacci AM, Navarro A, Lagornarsino A, Vitti C, Rossi R, Rana G (2017) Short-term effects of conversion to no-tillage on respiration and chemical - physical properties of the soil: a case study in a wheat cropping system in semi-dry environment. Ital J Agrometeorol-Rivista Italiana Di Agrometeorologia 22:47–58

    Google Scholar 

  • Fierer N, Colman BP, Schimel JP, Jackson RB (2006) Predicting the temperature dependence of microbial respiration in soil: a continental-scale analysis. Glob Biogeochem Cycles 20:GB3026

    Google Scholar 

  • Ghollarata M, Raiesi F (2007) The adverse effects of soil salinization on the growth of Trifolium alexandrinum L. and associated microbial and biochemical properties in a soil from Iran. Soil Biol Biochem 39:1699–1702

    Google Scholar 

  • Gray J, Karunaratne S, Bishop T, Wilson B, Veeragathipillai M (2019) Driving factors of soil organic carbon fractions over New South Wales, Australia. Geoderma 353:213–226

    Google Scholar 

  • Guimarães DV, Gonzaga MIS, da Silva TO, da Silva TL, da Silva Dias N, Matias MIS (2013) Soil organic matter pools and carbon fractions in soil under different land uses. Soil Tillage Res 126:177–182

    Google Scholar 

  • Han G, Sun B, Chu X, Xing Q, Song W, Xia J (2018) Precipitation events reduce soil respiration in a coastal wetland based on four-year continuous field measurements. Agric for Meteorol 256–257:292–303

    Google Scholar 

  • Han L, Sun K, Yang Y, Xia X, Li F, Yang Z, Xing B (2020) Biochar’s stability and effect on the content, composition and turnover of soil organic carbon. Geoderma 364:114184

    Google Scholar 

  • He H, Chang JG, Li X (2009) Effects of environmental and biological factors on soil respiration and its components. World for Res 22:39–44

    Google Scholar 

  • Inglima I, Alberti G, Bertolini T, Vaccari FP, Gioli B, Miglietta F, Cotrufo MF, Peressotti A (2009) Precipitation pulses enhance respiration of Mediterranean ecosystems: the balance between organic and inorganic components of increased soil CO2 efflux. Glob Change Biol 15:1289–1301

    Google Scholar 

  • Jones DL, Murphy DV, Khalid M, Ahmad W, Edwards-Jones G, DeLuca TH (2011) Short-term biochar-induced increase in soil CO2 release is both biotically and abiotically mediated. Soil Biol Biochem 43:1723–1731

    Google Scholar 

  • Kan ZR, Liu WX, Liu WS, Lal R, Dang YP, Zhao X, Zhang HL (2022) Mechanisms of soil organic carbon stability and its response to no-till: a global synthesis and perspective. Glob Chang Biol 28:693–710

    Google Scholar 

  • Kirschbaum MUF (2006) The temperature dependence of organic-matter decomposition—still a topic of debate. Soil Biol Biochem 38:2510–2518

    Google Scholar 

  • La Scala N, de Sá Mendonça E, Vanir de Souza J, Panosso AR, Simas FNB, Schaefer CEGR (2010) Spatial and temporal variability in soil CO2–C emissions and relation to soil temperature at King George Island, maritime Antarctica. Polar Sci 4:479–487

    Google Scholar 

  • Li Z, Wang X, Zhang R, Zhang J, Tian C (2011) Contrasting diurnal variations in soil organic carbon decomposition and root respiration due to a hysteresis effect with soil temperature in a Gossypium s. (cotton) plantation. Plant Soil 343:347–355

    Google Scholar 

  • Li Y, Hu S, Chen J, Mueller K, Li Y, Fu W, Lin Z, Wang H (2018) Effects of biochar application in forest ecosystems on soil properties and greenhouse gas emissions: a review. J Soils Sediments 18:546–563

    Google Scholar 

  • Li H, Zhang Y, Yang S, Wang Z, Feng X, Liu H, Jiang Y (2019) Variations in soil bacterial taxonomic profiles and putative functions in response to straw incorporation combined with N fertilization during the maize growing season. Agric Ecosyst Environ 283:106578

    Google Scholar 

  • Liu Z, Zhang Y, Fa K, Qin S, She W (2017) Rainfall pulses modify soil carbon emission in a semiarid desert. CATENA 155:147–155

    Google Scholar 

  • Liu N, Li Y, Cong P, Wang J, Guo W, Pang H, Zhang L (2021) Depth of straw incorporation significantly alters crop yield, soil organic carbon and total nitrogen in the North China Plain. Soil Tillage Res 205:104772

    Google Scholar 

  • Lu W, Ding W, Zhang J, Li Y, Luo J, Bolan N, Xie Z (2014) Biochar suppressed the decomposition of organic carbon in a cultivated sandy loam soil: a negative priming effect. Soil Biol Biochem 76:12–21

    Google Scholar 

  • Lu T, Wang X, Du Z, Wu L (2021) Impacts of continuous biochar application on major carbon fractions in soil profile of North China Plain’s cropland: in comparison with straw incorporation. Agric Ecosyst Environ 315:107445

    Google Scholar 

  • Luo Y, Jiang L, Niu S, Zhou X (2017) Nonlinear responses of land ecosystems to variation in precipitation. New Phytol 214:5–7

    Google Scholar 

  • Ma J, Zheng X-J, Li Y (2012) The response of CO2 flux to rain pulses at a saline desert. Hydrol Process 26:4029–4037

    Google Scholar 

  • Ma L, Lv X, Cao N, Wang Z, Zhou Z, Meng Y (2021) Alterations of soil labile organic carbon fractions and biological properties under different residue-management methods with equivalent carbon input. Appl Soil Ecol 161:103821

    Google Scholar 

  • Mahecha MD, Reichstein M, Carvalhais N, Lasslop G, Lange H, Seneviratne SI, Vargas R, Ammann C, Arain MA, Cescatti A, Janssens IA, Migliavacca M, Montagnani L, Richardson AD (2010) Global convergence in the temperature sensitivity of respiration at ecosystem level. Science 329:838–840

    Google Scholar 

  • Moonis M, Lee J-K, Jin H, Kim D-G, Park J-H (2021) Effects of warming, wetting and nitrogen addition on substrate-induced respiration and temperature sensitivity of heterotrophic respiration in a temperate forest soil. Pedosphere 31:363–372

    Google Scholar 

  • Moyano FE, Manzoni S, Chenu C (2013) Responses of soil heterotrophic respiration to moisture availability: an exploration of processes and models. Soil Biol Biochem 59:72–85

    Google Scholar 

  • Novak JM, Busscher WJ, Watts DW, Laird DA, Ahmedna MA, Niandou MAS (2010) Short-term CO2 mineralization after additions of biochar and switchgrass to a Typic Kandiudult. Geoderma 154:281–288

    Google Scholar 

  • Oertel C, Matschullat J, Zurba K, Zimmermann F, Erasmi S (2016) Greenhouse gas emissions from soils—a review. Chem Erde-Geochem 76:327–352

    Google Scholar 

  • Pabst H, Gerschlauer F, Kiese R, Kuzyakov Y (2016) Land use and precipitation affect organic and microbial carbon stocks and the specific metabolic quotient in soils of eleven ecosystems of Mt. Kilimanjaro, Tanzania. Land Degrad Dev 27:592–602

    Google Scholar 

  • Qi Y, Liu X, Dong Y, Peng Q, He Y, Sun L, Jia J, Cao C (2014) Differential responses of short-term soil respiration dynamics to the experimental addition of nitrogen and water in the temperate semi-arid steppe of Inner Mongolia, China. J Environ Sci 26:834–845

    Google Scholar 

  • Rojas A, Matthiesen RL, Robertson AE, Urrea KE, Rupe JC, Chilvers M (2017) How changes of annual soil temperature and moisture affect rhizosphere oomycete communities. Phytopathology 107:161–161

    Google Scholar 

  • Salazar O, Balboa L, Peralta K, Rossi M, Casanova M, Tapia Y, Singh R, Quemada M (2019) Effect of cover crops on leaching of dissolved organic nitrogen and carbon in a maize-cover crop rotation in Mediterranean Central Chile. Agric Water Manage 212:399–406

    Google Scholar 

  • Shah T, Shah Z (2017) Soil respiration, pH and EC as influenced by biochar. Soil Environ 36:77–83

    Google Scholar 

  • Shen W, Jenerette GD, Hui D, Phillips RP, Ren H (2008) Effects of changing precipitation regimes on dryland soil respiration and C pool dynamics at rainfall event, seasonal and interannual scales. J Geophys Res 113:G03024

    Google Scholar 

  • Singh G, Jalota SK, Singh Y (2007) Manuring and residue management effects on physical properties of a soil under the rice-wheat system in Punjab, India. Soil Tillage Res 94:229–238

    Google Scholar 

  • Song W, Chen S, Wu B, Zhu Y, Zhou Y, Lu Q, Lin G (2015) Simulated rain addition modifies diurnal patterns and temperature sensitivities of autotrophic and heterotrophic soil respiration in an arid desert ecosystem. Soil Biol Biochem 82:143–152

    Google Scholar 

  • Speirs J, Mitchell WJ (1936) Estimation of nitrogen by Kjeldahl’s method note on the ammonia distillation. J Inst Brew 42:247–250

    Google Scholar 

  • Sun F, Lu S (2014) Biochars improve aggregate stability, water retention, and pore-space properties of clayey soil. J Plant Nutr Soil Sci 177:26–33

    Google Scholar 

  • Tan Z, Lin CSK, Ji X, Rainey TJ (2017) Returning biochar to fields: a review. Appl Soil Ecol 116:1–11

    Google Scholar 

  • Tan S, Ni X, Yue K, Liao S, Wu F (2021) Increased precipitation differentially changed soil CO2 efflux in arid and humid areas. Geoderma 388:114946

    Google Scholar 

  • Tang X, Zhao X, Bai Y, Tang Z, Wang W, Zhao Y, Wan H, Xie Z, Shi X, Wu B, Wang G, Yan J, Ma K, Du S, Li S, Han S, Ma Y, Hu H, He N, Yang Y, Han W, He H, Yu G, Fang J, Zhou G (2018) Carbon pools in China’s terrestrial ecosystems: new estimates based on an intensive field survey. Proc Natl Acad Sci USA 115:4021–4026

    Google Scholar 

  • Tifafi M, Guenet B, Hatté C (2018) Large differences in global and regional total soil carbon stock estimates based on SoilGrids, HWSD, and NCSCD: intercomparison and evaluation based on field data from USA, England, Wales, and France. Glob Biogeochem Cycles 32:42–56

    Google Scholar 

  • Ventura F, Salvatorelli F, Piana S, Pieri L, Pisa PR (2013) The effects of biochar on the physical properties of bare soil. Earth Environ Sci Trans R Soc Edinb 103:5–11

    Google Scholar 

  • Walkley A, Black IA (1934) An examination of the Degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid titration method. Soil Sci 37:29–38

    Google Scholar 

  • Wang X, Jia Z, Liang L, Yang B, Ding R, Nie J, Wang J (2015) Maize straw effects on soil aggregation and other properties in arid land. Soil Tillage Res 153:131–136

    Google Scholar 

  • Wang X, Wang J, Wang J (2021a) Seasonality of soil respiration under gypsum and straw amendments in an arid saline-alkali soil. J Environ Manage 277:111494

    Google Scholar 

  • Wang Y, Wu P, Mei F, Ling Y, Qiao Y, Liu C, Leghari SJ, Guan X, Wang T (2021b) Does continuous straw returning keep China farmland soil organic carbon continued increase? A meta-analysis. J Environ Manage 288:112391

    Google Scholar 

  • Waring BG, Hawkes CV (2015) Short-term precipitation exclusion alters microbial responses to soil moisture in a wet tropical forest. Microb Ecol 69:843–854

    Google Scholar 

  • Wu L, Zheng H, Wang X (2021) Effects of soil amendments on fractions and stability of soil organic matter in saline-alkaline paddy. J Environ Manage 294:112993

    Google Scholar 

  • Wu L, Zhang K, Zhu X, Lu T, Wang X (2023) Effects of amendments on carbon and nitrogen fractions in agricultural soils of Yellow River Delta. Geosci Lett 10:22

    Google Scholar 

  • Xu H, Liu K, Zhang W, Rui Y, Zhang J, Wu L, Colinet G, Huang Q, Chen X, Xu M (2019) Long-term fertilization and intensive cropping enhance carbon and nitrogen accumulated in soil clay-sized particles of red soil in South China. J Soils Sediments 20:1824–1833

    Google Scholar 

  • Yang X, Wang D, Lan Y, Meng J, Jiang L, Sun Q, Cao D, Sun Y, Chen W (2017) Labile organic carbon fractions and carbon pool management index in a 3-year field study with biochar amendment. J Soils Sediments 18:1569–1578

    Google Scholar 

  • Yang Y, Sun K, Liu J, Chen Y, Han L (2022) Changes in soil properties and CO(2) emissions after biochar addition: role of pyrolysis temperature and aging. Sci Total Environ 839:156333

    Google Scholar 

  • Yin Y-F, He X-H, Gao R, Ma H-L, Yang Y-S (2014) Effects of rice straw and its biochar addition on soil labile carbon and soil organic carbon. J Integr Agric 13:491–498

    Google Scholar 

  • Yoon TK, Noh NJ, Han S, Lee J, Son Y (2014) Soil moisture effects on leaf litter decomposition and soil carbon dioxide efflux in wetland and upland forests. Soil Sci Soc Am J 78:1804–1816

    Google Scholar 

  • Zavalloni C, Alberti G, Biasiol S, Delle Vedove G, Fornasier F, Liu J, Peressotti A (2011) Microbial mineralization of biochar and wheat straw mixture in soil: a short-term study. Appl Soil Ecol 50:45–51

    Google Scholar 

  • Zhang Y, Wang J, Feng Y (2021) The effects of biochar addition on soil physicochemical properties: a review. CATENA 202:105284

    Google Scholar 

  • Zhou T, Shi P, Hui D, Luo Y (2009) Global pattern of temperature sensitivity of soil heterotrophic respiration (Q(10)) and its implications for carbon-climate feedback. J Geophys Res-Biogeosci 114:G02016

    Google Scholar 

  • Zhou W, Hui D, Shen W (2014) Effects of soil moisture on the temperature sensitivity of soil heterotrophic respiration: a laboratory incubation study. PLoS ONE 9:e92531

    Google Scholar 

  • Zhu M, De Boeck HJ, Xu H, Chen Z, Lv J, Zhang Z (2020) Seasonal variations in the response of soil respiration to rainfall events in a riparian poplar plantation. Sci Tot Environ 747:141222

    Google Scholar 

  • Zimmermann M, Davies K, de Zimmermann VTVP, Bird MI (2015) Impact of temperature and moisture on heterotrophic soil respiration along a moist tropical forest gradient in Australia. Soil Res 53:286–297

    Google Scholar 

Download references


This work was supported by the Open Fund of State Key Laboratory of Remote Sensing Science (OFSLRSS202021).


Finance support of this study was from the Open Fund of State Key Laboratory of Remote Sensing Science (OFSLRSS202021).

Author information

Authors and Affiliations



XW provided supervision and financial support for this study, and corrected all the versions of the manuscript. ZZ collected field experiment and laboratory measurement, and prepared for the manuscript. NH provided financial support, and commented on later versions of the manuscript. TL and LW helped with sampling and analyses, and commented on later versions of the manuscript. ZH provided support for the field experiment.

Authors’ information

XW is a professor and chief scientist at the College of Global Change and Earth System Science, Beijing Normal University. She earned a Ph.D. in soil biochemistry from the Melbourne University (Australia) in 1994, and had nearly 20 years of research experience in soil carbon cycle.

Corresponding author

Correspondence to Xiujun Wang.

Ethics declarations

Competing interests

All authors declare that they have no conflict of interests.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Wang, X., Zhu, Z., Huang, N. et al. Impacts of biochar amendment and straw incorporation on soil heterotrophic respiration and desorption of soil organic carbon. Geosci. Lett. 10, 38 (2023).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: