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Effect of Biochar on Soil Aggregates in the Loess Plateau: Results from Incubation Experiments.

Byline: XIANG-HONG LIU, FENG-PENG HAN AND XING-CHANG ZHANG

ABSTRACT

Soil aggregates were chosen as the indices of soil structure and stability to detect the effects of biochar on the four typical types of soils in the Loess Plateau. After 11 months pot incubation experiments with four application rates i.e., 0, 4, 8 and 16 g kg-1 biochar, undisturbed soils were sampled and passed through the dry-sieving and wet-sieving, respectively. The biochar application can increase soil water-stable aggregate content of both Dark Loessial soil and Lou soil which were classified as silt loam soils, while only improved aggregate formation of Dark Loessial soil. No significant influence was detected in the soil aggregate formation and stability of the Loessal soil and Shahuang soil, which were classified as sandy loam soils. Biochar application could represent a useful practice to enhance soil aggregates of silt loam soils and a potential method to increase the soil stability and decrease the soil erosion. (c) 2012 Friends Science Publishers

Key Words: Biochar; Soil amendment; Soil aggregate distribution; Soil water-stable aggregate; Loess plateau

INTRODUCTION

Soil structure exerts important influences on soil physical, chemical, and biological processes (Bronick and Lal, 2005). It is a key factor influencing the transport of water, the germination and the growth of plants (Braunack and Dexter, 1989; Pirmoradian et al., 2005; Wei et al., 2006; An et al., 2008).

Aggregation results from the rearrangement of particles through flocculation and cementation. It is an important soil functional unit for maintaining soil porosity and providing stability against soil erosion (Barthes and Roose, 2002; Canton et al., 2009). Aggregate stability is used as an indicator of soil structure (Six et al., 2000; Bronick and Lal, 2005). Soil organic carbon (SOC) acts as a binding agent and is the key constituent in the formation of aggregates (Tisdall and Oades, 1982; Bronick and Lal, 2005; An et al., 2008). The loss of organic materials caused by long-term cultivation appears to be a primary mechanism of the degradation of soil aggregates (Jastrow, 1996). Organic matter as important soil additives have positive effects on improving soil properties. The effects of organic matter on the soil aggregation had studied intensively (Piccolo and Mbagwu, 1990; Jastrow, 1996; Wei et al., 2006; Wortmann and Shapiro, 2008; Abiven et al., 2009; Alagoz and Yilmaz, 2009).

Biochar as a kind of organic matter has been used as soil amendment to improve soil structures and fertility qualities (Glaser et al., 2002; Atkinson et al., 2010). Glaser et al. (2000) showed that a large proportion of biochar in terra preta was present in unprotected fractions. However, Brodowski et al. (2006) found that biochar was associated mainly with the very fine, sub-50 um soil fraction and Liang et al. (2008) demonstrated that biochar was predominately present in small clusters of soil particles or soil aggregates, rather than as free organic matter. Brodowski et al. (2006) also observed that the small proportion of biochar particles in soil occurred in the large macro-aggregate fractions ( greater than 2 mm) and biochar might act as a binding agent for organic matter in aggregate formation and then protect against degradation (Brodowski et al., 2006; Saran et al., 2009).

Biochar may influence soil aggregates and its stability due to the interactions with soil organic matter, microorganisms and minerals (Piccolo et al., 1997; Verheijen et al., 2009). The slow oxidation properties of biochar determine the long term effect on soil aggregation (Verheijen et al., 2009).

The effects of biochar on soil properties are influenced by many factors, such as the feedstock, procedure process, and the soil basic characteristic. Some research has shown the converse results of biochar's impact on soil aggregates. Busscher et al. (2010) found that adding biochar without switchgrass did not improve soil aggregation or infiltration rate and the interaction between the biochar and switchgrass was not significant at P less than 0.05.

Peng et al. (2011) showed that amendment of 1% biochar had no effect on soil aggregate stability and the temperature-dependent trend was not observed for aggregate stability.

The specific mechanism that biochar exerts on water retention, macro-aggregation and soil stability are poorly understood (Saran et al., 2009). Caution should be taken when applying biochar into soils, which were susceptible to water erosion (Peng et al., 2011). The Loess Plateau is the most serious region of soil erosion in the world. In the area, soil structure holds a vital role in the agriculture production and ecology restoration. Soil water-stable aggregation research is always conducted in relation to soil erosion on the Loess Plateau and the content of soil water-stable aggregates is the best factor reflecting the ability of a soil to resist erosion on the Loess Plateau (An et al., 2008).

Four typical soil types in the Loess Plateau and onetype of biochar were chosen as test materials for incubation experiments to investigate the effects of biochar on soil aggregates distribution and stability. Potential positive effects of biochar on soil stability if proved it could be widely used in the soil erosion zone to prevent soil degradation in agricultural production and to promote the ecology restoration.

MATERIALS AND METHODS

Biochar: Biochar used in the experiment was bought from Yonghong Charcoal Factory, located in Hu County, Shaanxi Province, China. The original materials, sawdust from Chinese pine and locust, were packed in a traditional charcoal kiln made of brick and mud, then pyrolysed at the final temperature of approximately 660degC. After almost 2 h carbonization, the production was allowed to cool down to ambient temperature. For the incubation experiment, the biochar mass was ground to pass 2 mm. The subsamples were ground to pass 1 mm and 0.25 mm respectively, used for the properties determination of biochar. The biochar had C and N contents of 66.27% and 2.21%, respectively, a total ash content of 12.50%, a pH (H2O) of 8.38 and CEC (cation exchange capacity) of 31.28 cmol kg-1.

Soils: Shahuang soil (M soil), Loessal soil (H soil), Dark Loessial soil (B soil) and Lou soil (L soil) in the Loess Plateau were collected from the 0-20 cm horizon. After air- drying for five days, the soil was ground to pass 2 mm sieve for the incubation experiment. The subsamples were ground to pass 1 mm and 0.25 mm respectively, used for the properties determination of the four soils. The properties of the soils used in the experiment are listed in Table I. All samples were analyzed in duplicate; the means results can be observed in the tables.

Incubation experiment and sampling: In order to compare the different effects of biochar on four different soils, pot trails with four soil treatments per soil type were designed. The pots were made by the polyvinyl chloride (160 mm diameter, 220 mm deep). The treatments were as follows: unamended soil, soil with biochar 4 g kg-1, 8 g kg-1 and 16 g kg-1. Then the pots were filled with each soil mixture to 20 cm height at bulk density designed. The bulk density of M, H, and B soils were 1.3 g cm-3, and that of L soils was 1.2 g cm-3. Each treatment was replicated in triplicate. The trial was located in the institute of soil and water conservation, Yangling, Shaanxi Province, China. Soil moisture was adjusted to 60% - 70% of water holding capacity every five to six days in all columns and no water was leached out from the pots.

We collected the soil samples from 0-10 cm depth in November, 2011. The undisturbed soil sampling used for soil aggregate analysis was divided into less than 10 mm and air-dried until analysed.

Measurements of soil aggregates: Dry-sieving method was used to assess the distribution of soil aggregates (Institute of Soil Science, 1978).

The procedure is as follows: 300 g air-dried soil was put on the top of a set of sieves with an opening of 10, 7, 5, 3, 2, 1, 0.5 and 0.25 mm diameters from top to bottom, and then shaking at about 60 times min-1 for 10 min. The weight of the soil sample on each sieve was determined. And the soil aggregate content of each size is calculated following the formula: Where Rn stands for the soil aggregate content of each size sieve (%); Wn stands for the weight of the soil aggregate of each sieve size (g).

Wet-sieving method was used to assess the stability of soil aggregates (Institute of Soil Science, 1978). After the air-dried soils were wetted for about half an hour with distilled water, the soil was immersed in water on a set of five nested sieves (5, 2, 1, 0.5 and 0.25 mm) and then shaken vertically about 3cm for 1 minute (about 30 times). The aggregates retained on each sieve were washed into the numbered bottles and dried with a sand oven. Then weighted and got the amount of aggregates in each sieve.

Three parameters were chose to evaluate the effects of biochar on soil aggregate stability: Soil water-stable aggregate content, MWD (Mean Weight Diameter), GMD (Geometric Mean Diameter). The formulas for calculating MWD and GMD are as follows:

Where xi is the mean diameter between the two sieves (mm); and wi is the weight fraction of aggregates remaining on the sieve (%).Data analysis: All data gathered in the research were recorded and classified in the Microsoft Office Excel 2003.

The effects of biochar on different soils aggregates with biochar application ratios were examined by a one-way analysis of variance (ANOVA). Analyses of variance were carried out by SPSS16.0.

RESULTS

Soil aggregates distribution: The application of biochar has the potential to influence the soil aggregation distribution. The different effects were influenced by soil types, biochar application rates and layers (Table II).

For the M and H soils, there was no difference between the control and the 4, 8, 16 g kg-1 biochar amendment treatments for all the aggregate sizes. The non-significant influences could also be found in the greater than 0.25 mm and greater than 2 mm aggregates.

For the B soil, all the biochar application treatments showed the increasing effect for the 1-2 mm, 0.5-1 mm and greater than 0.25 mm. However, significant differences were observed in 8 g kg-1 treatment only.

For the L soil, the increase in the amount of biochar resulted in decreasing aggregate content. This was significant in case of 7-10, 5-7, 3-5, 2-3 and 1-2 mm aggregates.

Soil water-stable aggregates: The effect of biochar on soil aggregation stability of different soil types is shown in Table III. Biochar application had no significant effect on the soil aggregation stability of the M soil. All the indices of the greater than 0.25 mm aggregates, MWD, GMD showed non-significant difference between the treatments means and the control.

However, the 4 and 8 g kg-1 biochar application treatments of all the aggregates sizes always got the lower water-stable aggregate content when compared with the control and 16 g kg-1 treatments.

All the biochar treatments of the H soil did not get any significant influence on the water-stable aggregate content, except the 4 g kg-1 treatment for the 2-5 mm aggregates. For the B soil, all the aggregate sizes of biochar amended soils got the increasing effect except the 2-5 mm aggregates. And the significant increasing effects were detected in all the treatments for greater than 0.25 mm aggregates, 8 and 16 g kg-1 treatments for the greater than 5 mm aggregates, 16 g kg-1 for the 0.5-1 mm aggregates and 8 g kg-1 for 1-2 mm aggregates.

The water-stable aggregate content of the greater than 5 and greater than 0.25 mm increased gradually followed by the increase of biochar application rate. The significant increasing effects of MWD and GMD were observed in the 8 and 16 g kg-1 treatments.

For the greater than 2 mm size group, the water-stable aggregate content increased followed by the increase of biochar application rate, and the 16 g kg-1 treatment showed significantly higher contents than the control.

Table I: Physico-chemical characteristics of the soils

Parameter###M###H###B###L

Sand (%)###32.48###36.18###17.35###7.97

Silt (%)###61.76###57.70###68.85###78.90

Clay(%)###5.75###6.12###13.80###13.13

Texture###Sandy loam Sandy loam Silt loam###Silt loam

OC(gkg1)###2.33###3.42###6.31###7.12

N (g kg 1)###0.30###0.42###0.69###0.76

pH(1.2.5H20)###8.76###8.82###8.71###8.66

CEC (cmoFkg')###8.05###8.60###13.95###22.43

The 8 and 16 g kg-1 biohcar application rate had the significant increasing effect on the water-stable aggregate content of greater than 5 mm and greater than 2 mm aggregates of L soil, While the 4 g kg-1 treatment decreased 2-5 mm aggregates.

DISCUSSION

Based on the basic properties of the 4 soils (Table I), the M and H soils were classified as sandy loam soils and B and L soils as silt loam soils. Biochar application has little effect on the soil aggregate distribution and the water-stable aggregate content of the M and H soils. Similar results of Busscher et al. (2010) proved that adding biochar did not improve aggregation in the loamy sands after 70 days incubation.

The biochar application only increased soil aggregation formation of the B soil. However, both of the B and L soil got the significant increasing effects on the total content of soil water-stable aggregates. Compared with that of the sandy loam soils, the biochar application could influence the condition of soil aggregation of the silt loam soils, and increase the water-stable aggregates content, especially. The effect increased with the increasing of biochar application rate (Table II and III). Higher soil aggregate stability has significant effects on reducing runoff and soil erosion hazards (Zhang et al., 2007). Thus, the biochar application into silt loam soils had the potential effect on decreasing soil erosion, especially at high biochar application rate.

The biochar used in the research is passed through the 2 mm sieve, so the content of soil aggregates which is higher than 2 mm can eliminate the influences of biochar particles and stand for the real changing of aggregate content influenced by biochar application. From Table III, we can conclude that the biochar can effectively combine with B and L soils better and form the higher content of soil water-stable aggregates at the higher biochar application rate.

The different effects of biochar on the two classes ofsoil may result from the different soil compositions which could influence the properties of biochar. Biochar in soil is refractory but not inert. Most of the effects of biochar on soil conditions are influenced by the oxidation productions of biochar, such as acidic function groups and humic materials (Cheng et al., 2006). Biochar incorporated into the soil would change gradually into stable humus (Topoliantz et al., 2006; Brodowski et al., 2007).

Table II: Effect of biochar on soil aggregation distribution (%)

###Percentage of soil aggregates (%)###greater than greater than

Treatments###Aggregate size(mm)::###7-10###5-7###3-5###2-3###1-2###0.5-1###0.25-0.5###0.25###2

###greater than

###10

M0###24.16 a###6.60 a###3.80 a###3.12 a###0.75 a###2.49 a###5.53 a###3.99 a###50.44 a###38.44 a

M4###21.72 a###5.77 a###3.90 a###3.43 a###0.87 a###2.29 a###5.20 a###4.20 a###47.39 a###35.70 a

M8###25.19 a###6.17 a###3.40 a###2.57 a###0.60 a###1.62 a###4.36 a###4.25 a###48.16 a###37.93 a

M16###22.90 a###7.61 a###3.90 a###2.93 a###0.63 a###2.08 a###4.86 a###4.14 a###49.06 a###37.98 a

H0###35.66 a###6.48 a###3.29 a###2.69 a###0.52 a###1.38 a###3.10 a###2.89 a###56.00 a###48.63 a

H4###26.43 a###5.79 a###3.07 a###2.76 a###0.58 a###1.56 a###3.85 a###3.40 a###47.44 a###38.63 a

H8###36.47 a###5.43 a###3.29 a###2.60 a###0.65 a###1.63 a###3.36 a###2.99 a###56.43 a###48.44 a

H16###33.87 a###6.52 a###3.52 a###2.79 a###0.56 a###1.43 a###3.40 a###3.27 a###55.36 a###47.27 a

B0###31.47 a###7.20 a###3.69 a###3.27 ab###1.15 a###4.50 b###10.44 a###7.22 a###68.94 a###46.78 a

B4###34.06 a###7.23 a###3.51 a###3.55 a###1.07 a###4.77 b###10.43 a###7.06 a###71.66 a###49.41 a

B8###27.48 a###8.17 a###4.37 a###3.70 a###1.19 a###5.91 a###12.17 a###7.55 a###70.55 a###44.91 a

B16###34.32 a###7.04 a###3.62 a###2.95 b###1.02 a###5.42 ab 11.16 ab###7.12 a###72.65 a###48.95 a

L0###30.19 b###7.02 a###3.64 a###3.24 a###1.35 a###9.59 a###16.87 a###9.33 a###81.24 a###45.45 a

L4###33.93 ab###5.76 ab###3.24 ab###2.52 b###0.99 b###5.49 cd 14.95 ab 10.51 a###77.38 a###46.43 a

L8###44.01 a###4.83 bc###2.22 c###2.08 c###0.63 cd###4.40 e###12.58 b###9.17 a###79.92 a###53.77 a

L16###34.08 ab###5.01 bc###2.70 bc###2.18 c###0.79 bc###6.85 bc 15.98 ab 10.73 a###78.32 a###44.76 a

Table III: Effect of biochar on soil water-stable aggregates (%)

Percentage of soil aggregates (%)###greater than

Treatments###Aggregate size(mm):###2-5###1-2###0.5-1###0.25-0.5###0.25###MWD###GMD###greater than 2

###greater

###than 2

M0###0.22 a###0.32 a###2.43 a###4.57 a###5.29 a###12.82 a###0.33 a###0.28 a###0.53 a

M4###0.05 a###0.22 a###2.18 a###4.54 a###5.10 a###12.08 a###0.32 a###0.28 a###0.26 a

M8###0.17 a###0.30 a###1.98 a###4.33 a###4.70 a###11.48 a###0.32 a###0.28 a###0.48 a

M16###0.25 a###0.50 a###2.88 a###5.16 a###4.75 a###13.54 a###0.35 a###0.29 a###0.75 a

H0###0.47 a###0.75 a###2.66 ab###4.71 a###5.30 a###13.89 a###0.36 a###0.29 a###1.22 a

H4###0.72 a###0.37 b###2.04 b###4.03 a###4.16 a###11.33 a###0.35 a###0.28 a###1.09 a

H8###0.13 a###0.71 a###3.12 a###4.61 a###4.99 a###13.57 a###0.35 a###0.29 a###0.85 a

H16###0.07 a###0.52 ab###2.09 b###4.32 a###5.27 a###12.27 a###0.32 a###0.28 a###0.59 a

B0###2.42 cd###2.52 a###7.88 b###12.70 b###9.10 a###34.62 c###0.62 c###0.40 c###4.94 b

B4###2.93 bc###2.13 a###9.67 ab###14.43 ab###9.34 a###38.50 b###0.66 bc###0.42 bc###5.05 b

B8###4.05 b###2.28 a###10.03 a###13.83 ab###9.16 a###39.35 b###0.72 b###0.43 b###6.33 b

B16###6.56 a###2.37 a###9.75 ab###15.92 a###9.45 a###44.06 a###0.85 a###0.48 a###8.93 a

L0###0.89 b###2.64 ab###12.44 a###19.24 ab###12.66 a###47.87 a###0.65 ab###0.45 a###3.53 b

L4###0.25 b###1.24 c###9.27 a###22.36 a###13.96 a###47.08 a###0.55 b###0.42 a###1.49 b

L8###4.42 a###2.54 ab###9.38 a###18.59 b###14.04 a###48.97 a###0.77 a###0.47 a###6.96 a

L16###3.66 a###2.77 a###11.82 a###20.21 ab###11.85 a###50.31 a###0.78 a###0.49 a###6.43 a

Previous research has shown that the humic substances could be used as soil conditioners to increase aggregate stability (Piccolo and Mbagwu, 1990; Piccolo et al., 1997; Imbufe et al., 2005) and that may be interpreted by the formation of soil clay-humic complex by the humic substances (Piccolo et al., 1997). The oxidation of biochar itself is slow, but some research showed that the organic matter addition can promote the oxidation of both biochar and the added organic materials (Liang et al., 2010; Novak et al., 2010; Awad et al., 2012). The oxidation of biochar in the B and L soils with the higher soil organic matter (about 2 times than that of the H and M soils, shown in Table I) may be faster, forming more humic materials in the incubation period, and increase the stability of soil aggregates.

Tisdall and Oades (1982) had reported that root and fungal hyphae as the temporary organic binding agents can initiate macroaggregate formation by enmeshing fine particles into macroaggregates and stabilize macroaggregates. The biochar application have the potential effects to promote soil microbe living (Lehmann et al.,2011) and indirect effects on mycorrhizae through effects on other soil microbes (Warnock et al., 2007). The better basic properties, such as the higher organic carbon content, would provide the better living condition for soil microbes. These can partly interpret the increasing effect of biochar on the soil aggregate formation and stability of B soil.

The improvement of soil aggregates is a long process. Although the increasing effect of soil aggregates was found in the B and L soils after 11 months incubation, the soil macro-aggregates content and water-stable aggregate content were both in the low level. The soil water-stable aggregate content of the soil with well structure should be more than 70%, but the B and L soils were just about 40%-50%. The positive effect of biochar on soil aggregates is limited in the short incubation period.

To conclude, in a short incubation period, biochar application had little effect on the improvement of soil aggregates formation, while increased the soil aggregate stability of silt loam soils (B and L soils). The higher application rate of biochar might get the significant increasing effect. But to the sandy loam soils (H and M soils), which have low organic matter content and widely spread in the Loess Plateau and easily been eroded, no positive effect was detected. The biochar application methods should be modified before using as the soil structure amendment to increase soil stability and decrease soil erosion, especially in the sandy loam soils. Further work is needed to determine the effects of other types of biochar and biochar application with plant growth.

Acknowledgement: This study was financially supported by the Knowledge Innovation Project of The Chinese Academy of Sciences (Grant no. KZCX2-YW-441), the National Natural Science Foundation of China (Grant no.41101528) and the Open Fund of State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau (Grant no. 10501-301). We thank the editors of the journal and the reviewers for their useful comments and suggestions and acknowledge Zhu-ye Shi for her assistance with measurement and analysis of the experiment.

REFERENCES

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

Alagoz, Z. and E. Yilmaz, 2009. Effects of different sources of organic matter on soil aggregate formation and stability: A laboratory study on a lithic rhodoxeralf from turkey. Soil Till. Res., 103: 419-424

An, S.S., Y.M. Huang, F.L. Zheng and J.G. Yang, 2008. Aggregate characteristics during natural revegetation on the loess plateau. Pedosphere, 18: 809-816

Atkinson, C., J. Fitzgerald and N. Hipps, 2010. Potential mechanisms for achieving agricultural benefits from biochar application to temperate soils: A review. Plant Soil, 337: 1-18

Awad, Y.M., E. Blagodatskaya, Y.S. Ok and Y. Kuzyakov, 2012. Effects of polyacrylamide, biopolymer, and biochar on decomposition of soil organic matter and plant residues as determined by 14c and enzyme activities. European J. Soil Biol., 48: 1-10

Barthes, B. and E. Roose, 2002. Aggregate stability as an indicator of soil susceptibility to runoff and erosion; validation at several levels. Catena, 47: 133-149

Braunack, M.V. and A. Dexter, 1989. Soil aggregation in the seedbed. Soil Till. Res., 14: 259-279

Brodowski, S., W. Amelung, L. Haumaier and W. Zech, 2007. Black carbon contribution to stable humus in german arable soils. Geoderma, 139:220-228

Brodowski, S., B. John, H. Flessa and W. Amelung, 2006. Aggregate- occluded black carbon in soil. European J. Soil Sci., 57: 539-546

Bronick, C.J. and R. Lal, 2005. Soil structure and management: A review. Geoderma, 124: 3-22

Busscher, W.J., J.M. Novak, D.E. Evans, D.W. Watts, M.A.S. Niandou and M. Ahmedna, 2010. Influence of pecan biochar on physical properties of a norfolk loamy sand. Soil Sci., 175: 10-14

Canton, Y., A. Sole-Benet, C. Asensio, S. Chamizo and J. Puigdefabregas, 2009. Aggregate stability in range sandy loam soils relationshipswith runoff and erosion. Catena, 77: 192-199

Cheng, C.H., J. Lehmann, J.E. Thies, S.D. Burton and M.H. Engelhard, 2006. Oxidation of black carbon by biotic and abiotic processes. Org. Geochem., 37: 1477-1488

Glaser, B., E. Balashov, L. Haumaier, G. Guggenberger and W. Zech, 2000. Black carbon in density fractions of anthropogenic soils of the brazilian amazon region. Org. Geochem., 31: 669-678

Glaser, B., J. Lehmann and W. Zech, 2002. Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal - a review. Biol. Fert. Soils, 35: 219-230

Imbufe, A.U., A.F. Patti, D. Burrow, A. Surapaneni, W.R. Jackson and A.D. Milner, 2005. Effects of potassium humate on aggregate stability of two soils from victoria australia. Geoderma, 125: 321-330

Institute of Soil Science, C.A.S., 1978. Physical and Chemical Analysis of Soil. Shanghai Science and Technology Press, Shanghai, China Jastrow, J.D., 1996. Soil aggregate formation and the accrual of particulate and mineral-associated organic matter. Soil Biol. Biochem., 28: 665- 676

Lehmann, J., M.C. Rillig, J. Thies, C.A. Masiello, W.C. Hockaday and D. Crowley, 2011. Biochar effects on soil biota - a review. Soil Biol. Biochem., 43: 1812-1836

Liang, B., J. Lehmann, S.P. Sohi, J.E. Thies, B. O'Neill, L. Trujillo, J. Gaunt, D. Solomon, J. Grossman, E.G. Neves and F.J. Luizao, 2010. Black carbon affects the cycling of non-black carbon in soil. Org.Geochem., 41: 206-213

Liang, B., J. Lehmann, D. Solomon, S. Sohi, J.E. Thies, J.O. Skjemstad, F.J. Luizao, M.H. Engelhard, E.G. Neves and S. Wirick, 2008. Stability of biomass-derived black carbon in soils. Geochim. Cosmochim. Ac., 72: 6069-6078

Novak, J.M., W.J. Busscher, D.W. Watts, D.A. Laird, M.A. Ahmedna and M.A.S. Niandou, 2010. Short-term co2 mineralization after additions of biochar and switchgrass to a typic kandiudult. Geoderma, 154: 281-288

Peng, X., L.L. Ye, C.H. Wang, H. Zhou and B. Sun, 2011. Temperature- and duration-dependent rice straw-derived biochar: Characteristics and its effects on soil properties of an ultisol in southern china. Soil Till. Res., 112: 159-166

Piccolo, A. and J.S.C. Mbagwu, 1990. Effects of different organic waste amendments on soil microaggregates stability and molecular sizes of humic substances. Plant Soil, 123: 27-37

Piccolo, A., G. Pietramellara and J.S.C. Mbagwu, 1997. Use of humic substances as soil conditioners to increase aggregate stability. Geoderma, 75: 267-277

Pirmoradian, N., A.R. Sepaskhah and M.A. Hajabbasi, 2005. Application of fractal theory to quantify soil aggregate stability as influenced by tillage treatments. Biosyst. Eng., 90: 227-234

Saran, S., L.C. Elisa, K. Evelyn and B. Roland, 2009. Biochar, climate change and soil: A review to guide future research. In: Krull, E. (ed.), Csiro Land and Water Science Report 05/09, p: 23 Six, J., E.T. Elliott and K. Paustian, 2000. Soil structure and soil organic matter ii. A normalized stability index and the effect of mineralogy.Soil Sci. Soc. American J., 64: 1042-1049

Tisdall, J.M. and J.M. Oades, 1982. Organic matter and water-stable aggregates in soils. J. Soil Sci., 33: 141-163 Topoliantz, S., J.F. Ponge and P. Lavelle, 2006. Humus components and biogenic structures under tropical slash-and-burn agriculture. European J. Soil Sci., 57: 269-278

Verheijen, F.G.A., S. Jeffery, A.C. Bastos, M. Van der Velde and I. Diafas, 2009. Biochar Application to Soils - a Critical Scientific Review of Effects on Soil Properties, Processes and Functions, pp: 63-65. EUR 24099 EN, Office for the Official Publications of the European Communities, Luxembourg Warnock, D., J. Lehmann, T. Kuyper and M. Rillig, 2007. Mycorrhizal responses to biochar in soil - concepts and mechanisms. Plant Soil, 300: 9-20

Wei, C., M. Gao, J. Shao, D. Xie and G. Pan, 2006. Soil aggregate and its response to land management practices. China Particuol., 4: 211- 119

Wortmann, C.S. and C.A. Shapiro, 2008. The effects of manure application on soil aggregation. Nutr. Cycl. Agroecosyst., 80: 173-180

Zhang, G.S., K.Y. Chan, A. Oates, D.P. Heenan and G.B. Huang, 2007.Relationship between soil structure and runoff/soil loss after 24 years of conservation tillage. Soil Till. Res., 92: 122-128
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Author:Xiang-Hong Liu; Feng-Peng Han; Xing-Chang Zhang
Publication:International Journal of Agriculture and Biology
Article Type:Report
Geographic Code:9CHIN
Date:Dec 31, 2012
Words:5045
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