The effects of greenwaste biochar on phosphorus availability in acid soils

The work in this project was undertaken in partial fulfilment of the requirements of the University of Melbourne for the degree of Master of Environment. The views expressed are those of the author and might not reflect the views of the University of Melbourne, Office for Environmental Programs.

The work in this project was undertaken in partial fulfilment of the requirements of the University of Melbourne for the degree of Master of Environment The views expressed are those of the author and might not reflect the views of the University of Melbourne, Office for Environmental Programs Content Figure Figure The chemical fraction procedure of Hedley et al (1992) Figure pH values in Poowong Low soil Figure pH values in Poowong High soil Figure The liming value of biochar on Poowong Low soil 10 Figure The liming value of biochar on Poowong High soil 10 Figure P fractions in Poowong Low and Poowong High soils (% and mg/kg) 11 Figure H2O-P values in Poowong Low soil 12 Figure H2O-P values in Poowong High soil 12 Figure Change in CHCl3/NaHCO3-P in Poowong Low soil 13 Figure 10 Change in CHCl3/NaHCO3-P in Poowong High soil 14 Figure 11 Non-labile P and residue P in Poowong Low soil 18 Figure 12 Non-labile P and residue P in Poowong High soil 18Table Table Treatments in the experiment .6 Table Characteristics of soils and biochar Table Labile P after 45 days incubation, mg P kg-1 .16 Environmental research project – ENST 90007 Table Total Pi and Po 19The effects of greenwaste biochar on phosphorus availability in acid soils Abstract Soil samples from Poowong with two levels of P were incubated at 25 oC in short term in order to determine the effects of biochar on phosphorus availability and changes in P fractions Among the treatment investigated, three were biochar addition at three levels of 10, 30 and 50 tonne -1, one was inorganic P with KH2PO4 as reference, three were NaOH addition at three levels (1, and mmol NaOH per 200 g soil) and the control Soil samples after 45 days incubated were sequential fractionation analysed for inorganic and organic P followed Hedley method, which included H 2O-P, CHCl3/NaHCO3-P, NaOH-P, HCl-P and finally residue P The results proved biochar could be used as soil amendments since it improved significantly (at p = 0.05) pH value, improved significantly labile P in low phosphorus acid soil and reduced significantly water soluble P in high phosphorus acid soil In addition, biochar could also improve microbial activity The results suggested that improving pH by adding NaOH in high P soil led to the negative effect on P availability due to it had no P amendment but increased water soluble P Introduction Agriculture has been considered as a source of greenhouse gases emissions contributing to climate change Emissions through land-use change and emissions from food production are the main causes of that However, the emissions from agricultural land, in fact, could potentially be mitigated or even reserved to store carbon in agricultural land(Sohi et al., 2010) Soils contain large amount of carbon in both inorganic and organic forms(Sanderman et al., 2010) The soil carbon sequestration has the potential to be the carbon sink for greenhouse gases with multi-benefits to profitability and farm productivity (Sanderman et al., 2010, Lal, 2004) One means of potentially permanent carbon sequestration is through the conversion of biomass to charcoal and addition to soil(Sohi et al., 2009) This process has been enhanced through the production of “biochar”, a form of charcoal produced by thermal decomposition of organic matter under limited supply of oxygen (Sohi et al., 2009, Lehmann and Joseph, 2009) The carbon in biochar could hold the carbon in soil for thousands of years (IBI, 2011) Depending on the means of production and storage this system could be carbon negative The application of biochar to agricultural soils has the potential to improve soil chemical, physical and biological conditions With high surface area,variable-charge organic material and high porosity, biochar has potential to increasecation exchange capacity (CEC), soil water-holding capacity, surface sorption capacity (Glaser et al., 2002, Keech et al., 2005, Liang et al., 2006, Chan et al., 2007a, Chan et al., 2007b, Sohi et al., 2010).Most research on pyrolysis of biomass has focussed on energy and fuel quality rather than on biochar as soil Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 amendment (Chan and Xu, 2009) Data to date has suggested a wide range of outcomes about the impacts of biochar on soil amendment Thus, the application of biochar has proved a positive, neutral and even negative effect (Grob et al., 2011) The wide range of outcomes could be due to the differences in biochar used, time scale, tested crop species and soil properties Moreover, in terms of enhance soil nutrients studies, most of them have focused on the enhance nitrogen availability in soils, while lacking study on the effect of biochar on phosphorus availability in soil, specially the interactions of biochar and available P in soils The combination of high concentrations of Al and Fe along with low pH present difficulties for the productive use of acid soils Particularly, the present of Fe in acid soils leads to available P deficiency due to the chemical adsorption to iron oxides (Hedley et al., 1994, Linquist et al., 1997) To compensate for this available P deficiency, previous study suggested that large applications of inorganic P should be required(Kamprath, 1967) However, when the inorganic P is reduced, the effects of the supply as well as available P in soils are reduced (Dobermann et al., 2002) The application of organic substances could provide many benefits such as saving inorganic fertilisersas organic fertiliser could provide variable nutrients, reducing environmental pollution caused by organic matters by transferring organic waste to organic fertiliser Especially, organic fertiliser application on acid soils could reduce many difficulties of acid soils such as improve CEC, improve SOC, reduce Al and Fe toxicity as well as improve available P(Guppy et al., 2005, Thúy and viễn, 2008, Viễn et al., 2006) The improvement of P availability due to applying organic matters shows in several ways Guppy et al (2005) illustrated that the competitive sorption of organic matter and P in soil would release P soil solution Furthermore, metal complexation and dissolution reactions could release P for plant uptake(Guppy et al., 2005, Bolan et al., 1994, Maurice et al., 1995) Depending on structure Biochar may have similar effects in soil This study aims to quantify the short term effect of greenwaste biochar on P availability in soils through the chemical fractionation of P forms This work has been conducted on an acid pasture soilswith high and low concentrations of phosphorus – incubation study KH 2PO4 was included as a reference treatment, which was used to clarify effects of inorganic fertiliser application on soils As greenwaste biochar has a potentially liming capacity, NaOH treatments were included to determine the affect of pH on P availability Materials and methods Soils Representative soils used in the study were collected from 0-10 cm depth from Poowong East in Victoria, Australia Two soil samples have high and low concentrations of phosphorus, Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 which were Poowong High (PH) and Poowong Low (PL), respectively.Soils are classified as Brown Dermosol (Isbell, 2003) Brown Dermosol soils are characterised by a gradual change in texture with depth down the soil profile (DPI, 2011) The Brown Dermosol soils used in the study are strongly acid, which pH values are 4.4 and 5.3 As most Brown Dermosol soils in the higher rainfall areas in Victoria, these soils used in the experiment have chemical problems such as strong acidity, fertility and iron and aluminium toxicity, which can cause available P efficiency Land has been long history used for pasture The soil samples were kept at field-moisture condition and removed all roots and earthworms as well as large plant materials Soils were incubated at 25 oC for 45 days and subjected to sequential fractionation for phosphorus Three levels of biochar were applied, which were 10, 30 and 50 tonne ha-1 soil Levels of biochar applied were based on biochar levels of previous studies (Chan et al., 2007b, Chan and Xu, 2009), particularly International Biochar Initiative recommends the best rate is from to 50 tonne per (IBI, 2010) Inorganic P added to soil was KH2PO4 solution (15kg Pha-1) Three levels of NaOH were selected by adding 1, and 6mmol NaOH per 200g dry soil to increase soil pH in in the reference treatments.These treatments are shown in the table below Table Treatments in the experiment Soil Treatments Soil with low concentration of P Control (soil) Biochar 10 tonne ha-1 Biochar 30 tonne ha-1 Biochar 50 tonne ha-1 Inorganic P 15kg P ha-1 Soil + NaOH level Soil + NaOH level Soil + NaOH level Soil with high concentration of P Control (soil) Biochar 10 tonne ha-1 Biochar 30 tonne ha-1 Biochar 50 tonne ha-1 Inorganic P 15kg P ha-1 Soil + NaOH level Soil + NaOH level Soil + NaOH level Biochar Biochar was supplied from Pacific Pyrolysis which contains 85 percent from green waste and 15 percent from biosolid The characteristics of biochar and soils are described in the table below Table Characteristics of soils and biochar pHH2O Biochar EC, mS/cm 7.9 Olsen P, mgkg-1 Cowell P Total C:N CEC, mgkg-1 P, % cmolkg-1 335 0.24 61 1.98 0.4 Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 PL PH 4.4 5.1 9.34 200 0.06 0.34 Sequential fractionation for inorganic and organic P P forms were extracted by Hedley method (Hedley et al., 1982) by using different extracted solutions to extract P forms in the order to analyse H 2O-P, CHCl3/NaHCO3-Pi, CHCl3/NaHCO3-Po; NaOH-Pi, NaOH-Po; HCl-Pi and residue P The procedure used to sequential fractionation P in soils is described in the figure below Add 30 ml H2O, shake 16 hours, centrifuge and filter supernatant H2O-P Soil Add ml CHCl3, shake in hour, open cap to evaporate CHCl3 Soil Add 30 ml NaHCO3, shake 16 hours, centrifuge and filter supernatant CHCl3/NaHCO3-P Add 30 ml NaOH, shake 16 hours, centrifuge and filter supernatant NaOH-P Soil Add 30 ml HCl, shake 16 hours, centrifuge and filter supernatant HCl-P Digest with ml condensed H2SO4 and H2O2, filter Soil Residue Soil Figure The chemical fraction procedure of Hedley et al (1992) First, soil samples were extracted with H 2O to determine water soluble Pi (inorganic P).Soil samples were treated with CHCl3to remove large amount of microbial P then extracted with 0.5 M NaHCO3 pH 8.5 The CHCl3/NaHCO3 extraction extracted microbial P, Pi and Po (organic P) compounds.The soil samples were followed by 0.1 M NaOH extraction step to extract Pi and Po held at the internal surfaces of soil aggregates, which mostly are iron-P (Kuo, 1996) The acid extraction (1M HCl) removed apatite-type minerals and occluded P in more weathered soils, mostly is Ca-P Finally, soil samples were digested by condensed H 2SO4 with H2O2to determine relatively insoluble Pi and more chemically stable Po.Base on several experiments, the amount of water soluble Po and HCL-Po is negligible(Viễn et al., 2006, Hedley et al., 1982), so these forms of P were not determined The extraction solution was measured Pi (A) The extraction solution was taken from to 10 ml of into the digestion tubeand then added ml 11 N H 2SO4 and 0.4 g potassium persulfate and heated at the temperature of 150 oC until the solution stops boiling Cooledsolution, added Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 H2O up to 30 ml and adjusted pH to by adding NaOH and made up to 50 ml Measured P in the solution (B) Po = B – A pHH2O with the ratio of 1:5.Method 4A1(Rayment and Higginson, 1992) CEC was analysed by using compulsive exchangemethod, method 15E1 (Rayment and Higginson, 1992) Total Pin biochar: biochar was digested by using H2SO4 and H2O2 and determined by colourmetric method (Kuo, 1996) Data analysis Statistic analysis used in the study is ANOVA one way and compare means by LSD, using Genstat as a statistical package Results and discussion 3.1 pH change With the exception of inorganic treatment, all treatments increased pH relative to the control(Figure and 3) With the Poowong High soil, both applications of biochar and NaOH increased pH value, which had significant higher pH values compared with the control There is no statistical difference between the pH values of two treatments of 50 and 30 tons biochar ha-1 The 50 and 30t biochar.ha -1 treatments are statistically significantly higher than the 10t biochar ha-1 treatment in terms of pH values The trend is nearly similar with the Poowong Low soil In this type of soil, both biochar and NaOH have a large increase in pH value Interestingly, with the lower pH soil (Poowong Low), the application of inorganic P led to the decrease in pH value while this was no effect in the higher pH soil (Figure and 3) Remark: the figure a, b and c are used to compare means between treatments, so that if two treatments have the same figure that means these two treatments are not statistically different at p = 0.05 Figure pH values in Poowong Low soil Figure pH values in Poowong High soil Biochar has a liming value as suggested by the high pH value of the char alone (pH 7.9, Table 2.) Biochar used in the study contains 15% biosolid char.That explains biochar could increase the pH value of soils in the experiment However, by applying 50 tonnes s biochar.ha -1, the pH values can increase by 0.20 and 0.26 units in Poowong High and Poowong Low soils, Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 respectively That proved that biochar can influence soil pH Adding the amount of 6mmol NaOH per 200 g soilincreased significantly the pH values The Poowong High soil showed a bigger increase, which the increase of 1.23 units compared with 1.03 units of the Poowong Low soil This illustrates that the pH buffer is different between two types of soil There is no doubt that biochar has a liming value and it seems to be linear.The liming value of biochar compares to the liming value of NaOH treatments is presented in the figure and Therefore, in the Poowong Low soil, applying 10t, 30t and 50t biochar -1 had the equal liming value as 0.64, 0.97 and 1.19 mmol OH - per 200 g soil, respectively In the Poowong High soil, application of 10t biochar -1 had a lower liming value(equal to 0.34 mmol OH per 200g soil) while the 50t biochar -1 treatment had a higher liming value (equal to 1.52 mmol OH- per 200g soil) compared with that value in Poowong Low soil (Figure and 5) Figure The liming value of biochar on Poowong Low soil Figure The liming value of biochar on Poowong High soil 3.2 Changes in P fractions P fractions in soils used in the experiment The results in the figure show that inorganic P (H 2O-P, CHCl3/NaHCO3-Pi, NaOH-Pi and HCl-Pi) was the domination forms of P in Poowong High soil (approximately 80% of total P) while this form in Poowong Low soil was only around 35% Of that total Pi in Poowong High soil, the most significant dominant was NaOH-Pi, which was more than 40% of total P It means the Poowong High soil has potentially high level of Fe causing the bone Fe-P In the Poowong Low soil, total Pi (H2O-P, CHCl3/NaHCO3-Pi, NaOH-Pi and HCl-Pi) was nearly equal total Po (CHCl3/NaHCO3-Po and NaOH-Po) The high proportion of Po in Poowong Low soil indicates that microbial activity is negligible in this soil Therefore, most phosphorus is stored in organic forms (Figure 6) Figure P fractions in Poowong Low and Poowong High soils (% and mg/kg) Water Soluble P The effects of biochar on P fractions can be easily seen in the water solubleP form results The analysis results after 45 days incubation show that biochar improved the water soluble P in low P soil (Poowong Low soil) and it appears as though there was a linear increase in H 2O-P in low P soil while it decreased this P form in high P soil (Poowong High soil) Both inorganic Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 P and the NaOH treatments resulted in increasing water soluble P in two soils Adding NaOH proved the rise of 50 percent in water soluble P in both low and high P status soils compared with the control However, while adding mmol NaOH per 200 g soil could increase only mg P kg-1 in Poowong Low soil, this increase was approximately 40 mg P kg -1 in Poowong High soil (Figure and 8) Figure H2O-P values in Poowong Low soil Figure H2O-P values in Poowong High soil The results for water soluble Pillustrate that biochar can improveavailable P through increasing water soluble P in low phosphorus soil This helps plants get more benefits from soil having P deficiency However, the high concentration of water soluble P could bring the risk for water resources when plants cannot uptake all since water soluble P could easily runoff into the water resource Therefore, the application of biochar can limit the P leaching causing eutrophication for water resources by reducing water soluble P in high phosphorus soils This results are matched with DeLuca et al (2009) study that biochar had a negative influence on P solubility in calcareous soils and Al-rich soil In the low P soil case, the application of biochar resulted in increase water soluble P, but the increase was small (only mg P kg-1) Consequently, the risk for water resources might be negligible The sorption capacity of biochar could be used to explain the difference in water-soluble P changes in two soils Biochar has its own an amount of water soluble P Therefore, with low P soil, water soluble P in biochar could contribute to water soluble P in soil However, in high P soil, the amount of water soluble P released from biochar cannot compensate the sorption capacity This led to the decrease in water soluble P in the biochar treatments (Figure 8) Increase pH by adding NaOH led to significant increase in water soluble P in both high and low phosphorus soils.This result agrees with the previous studies that increase in pH value could result in increase in available P (Kuo, 1996, DeLuca et al., 2009) Water soluble P bring with its potential risks for water resources as it can run off into water resources and causes eutrophication However, in Poowong Low soil, this increase was small (only around mg P kg-1) Therefore, the risk for water resources would be small as well The Poowong High soil Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 has different situation when the highest level of NaOH increased water soluble P significantly (by approximate 40 mg P kg-1) Consequently, the risk for water resources in the Poowong High soil case would be more serious Labile P The results show that increasing pH led to different outcomes in terms of labile P (extracted by CHCl3/NaHCO3 after extracted by H2O) in two soils In Poowong Low soil, both treatments increased statistically amount of inorganic P (CHCl 3/NaHCO3-Pi) compared with the control except the 10t biochar.ha-1treatment The 50t biocharha-1treatment showed the most significant increase compared with others, approximate 20 mgPkg -1higher than the control The 30t biocharha-1treatment showed the similar result with the 15kg Pha -1 Although higher values were showed in three NaOH treatments, both three levels of NaOH application gave the same CHCl3/NaHCO3-Pi value (Figure 9) The CHCl3/NaHCO3-Po results gave the nearly similar trend compared with the CHCl3/NaHCO3-Pi results, but the NaOH treatments While added NaOH provided the higher CHCl3/NaHCO3-Pi, the NaOH treatments had lower values of CHCl3/NaHCO3-Po compared with the control, except the NaOH level treatment The 50t biocharha-1treatment again showed the highest value, statistically different compared with others (Figure 9) Figure Change in CHCl3/NaHCO3-P in Poowong Low soil The CHCl3/NaHCO3-Pi and CHCl3/NaHCO3-Po forms have a close relationship While the NaHCO3-Pi is a part of labile P for plant uptake, NaHCO 3-Po will be used by microbial activity to release labile P for plant (Lehmann and Joseph, 2009, Kuo, 1996) NaHCO3-Po could be called potential labile P The application of biochar led to the increase in both labile NaHCO3-P and potential labile NaHCO3-P and the amount of both those forms of P had a positive correlation with the amount of biochar This result shows that biochar has a similar function that influences NaHCO3-P in acid soil as other organic substances such as compost from sugarcane filter cake, vermicompost, pig manure and biogas slude (Viễn et al., 2006, Thúy and viễn, 2008).Increase pH value by NaOH helped to transfer potential labile P to labile form As can be seen from the figure 8, NaHCO labile P values of treatments added NaOH were statistically higher than the control while NaHCO potential labile values of these treatments were statistically smaller compared with the control The microbial activities could be used to explain that In Poowong High soil, the trend differs from the Poowong Low soil’s trend in terms of CHCl3/NaHCO3-P form Except from the 50t biochar -1treatment, the biochar application Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 and inorganic supply did not have statistically different values of CHCl 3/NaHCO3-Pi with the control While they increased the amount of water soluble P, the NaOH treatments gave the adverse results in CHCl3/NaHCO3-Pi with the decreasing trend when increasing concentration of NaOH The results in CHCl3/NaHCO3-Po had a similar trend with the water soluble P results except the 50t biochar -1 treatment While the biochar application tended to reduce CHCl3/NaHCO3-Po, the more amount of NaOH resulted in the higher value of CHCl3/NaHCO3-Po (Figure 10) Figure 10 Change in CHCl3/NaHCO3-P in Poowong High soil Surprisingly, although the total CHCl3/NaHCO3-P of the 50t biocharha-1 treatment gave the similar result compared with other biochar treatments, the smaller amount of CHCl 3/NaHCO3Pi led to the higher amount of CHCl 3/NaHCO3-Po Another reason can be used to explain why biochar had bigger effects on CHCl3/NaHCO3-Pi in Poowong Low soil could be due to the lower pH value of this soil Brown Dermosol soil has difficulties with pH and some other toxicants such as aluminium and iron The present of alumium could limit the available P The lower pH value, the higher concentration of exchangeable aluminium is expected(Kuo, 1996) The lower pH value of Poowong Low soil could result in higher concentration of exchangeable Al The sorption of chelates might have negative influence on available P (Lehmann and Joseph, 2009) Biochar application then can increase significantly available P in Al-rich soil(Lehmann and Joseph, 2009, Shen et al., 2001) Consequently, P could be release from the Al-P link While in the low phosphorus soil, NaOH had a positive effect on improving microbial activity that transfers CHCl3/NaHCO3-Po to CHCl3/NaHCO3-Pi, the high phosphorus soil gave a reverse trend by keeping more potential labile P Moreover, in the Poowong High soil, the increase amount of water soluble P when increasing the amount of NaOH could result in the decrease amount of CHCl3/NaHCO3-Pi The overall change in labile P in two soils is presented in the table below The total labile P could be the total H2O-P and CHCl3/NaHCO3-Pi (Lehmann and Joseph, 2009, Kuo, 1996) Therefore, with Poowong Low soil, the incubation with biochar led to the significant increase 10 Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 *** Standard errors of means *** Table treatments_PH rep d.f 15 e.s.e 4.33 (Not adjusted for missing values) *** Standard errors of differences of means *** Table rep d.f s.e.d treatments_PH 15 6.13 (Not adjusted for missing values) *** Least significant differences of means (5% level) *** Table treatments_PH rep d.f 15 l.s.d 13.06 (Not adjusted for missing values) ***** Stratum standard errors and coefficients of variation ***** Variate: CHCl3_NaHCO3_Po_PH d.f 15 s.e 7.50 cv% 7.1 ***** Missing values ***** Variate: CHCl3_NaHCO3_Po_PH Unit estimate 51.7 Max no iterations 344 "One-way ANOVA (no Blocking)." 345 BLOCK "No Blocking" 346 TREATMENTS treatments_PH 347 COVARIATE "No Covariate" 348 ANOVA [PRINT=aovtable,information,means,%cv,missingvalues; FPROB=yes; PSE=diff,lsd,\ 349 means; LSDLEVEL=5] NaOH_Pi_PH 349 ***** Analysis of variance ***** Variate: NaOH_Pi_PH Source of variation treatments_PH Residual Total d.f 16 23 s.s 33042 18831 51873 m.s 4720 1177 v.r 4.01 F pr 0.010 * MESSAGE: the following units have large residuals *units* 16 *units* 18 57.7 -56.4 s.e 28.0 s.e 28.0 ***** Tables of means ***** Variate: NaOH_Pi_PH Grand mean 1465.8 29 Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 treatments_PH 9.00 1484.5 treatments_PH 16.00 1414.2 10.00 1465.1 11.00 1528.1 12.00 1499.5 13.00 1462.0 14.00 1411.5 15.00 1461.6 *** Standard errors of means *** Table rep d.f e.s.e treatments_PH 16 19.81 *** Standard errors of differences of means *** Table rep d.f s.e.d treatments_PH 16 28.01 *** Least significant differences of means (5% level) *** Table rep d.f l.s.d treatments_PH 16 59.38 ***** Stratum standard errors and coefficients of variation ***** Variate: NaOH_Pi_PH d.f 16 s.e 34.31 cv% 2.3 350 "One-way ANOVA (no Blocking)." 351 BLOCK "No Blocking" 352 TREATMENTS treatments_PH 353 COVARIATE "No Covariate" 354 ANOVA [PRINT=aovtable,information,means,%cv,missingvalues; FPROB=yes; PSE=diff,lsd,\ 355 means; LSDLEVEL=5] NaOH_Po_PH 355 ***** Analysis of variance ***** Variate: NaOH_Po_PH Source of variation treatments_PH Residual Total d.f 16 23 s.s 22151.3 10498.2 32649.4 m.s 3164.5 656.1 v.r 4.82 F pr 0.004 * MESSAGE: the following units have large residuals *units* -56.5 s.e 20.9 ***** Tables of means ***** Variate: NaOH_Po_PH Grand mean 157.1 treatments_PH 9.00 195.5 10.00 195.4 11.00 130.5 30 12.00 190.9 13.00 124.2 14.00 160.8 15.00 132.2 Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 treatments_PH 16.00 127.5 *** Standard errors of means *** Table rep d.f e.s.e treatments_PH 16 14.79 *** Standard errors of differences of means *** Table rep d.f s.e.d treatments_PH 16 20.91 *** Least significant differences of means (5% level) *** Table rep d.f l.s.d treatments_PH 16 44.34 ***** Stratum standard errors and coefficients of variation ***** Variate: NaOH_Po_PH d.f 16 s.e 25.62 cv% 16.3 356 "One-way ANOVA (no Blocking)." 357 BLOCK "No Blocking" 358 TREATMENTS treatments_PH 359 COVARIATE "No Covariate" 360 ANOVA [PRINT=aovtable,information,means,%cv,missingvalues; FPROB=yes; PSE=diff,lsd,\ 361 means; LSDLEVEL=5] HCl_Pi_PH 361 ***** Analysis of variance ***** Variate: HCl_Pi_PH Source of variation treatments_PH Residual Total d.f 16 23 s.s 17584 19264 36848 m.s 2512 1204 v.r 2.09 F pr 0.106 * MESSAGE: the following units have large residuals *units* 13 71.4 s.e 28.3 ***** Tables of means ***** Variate: HCl_Pi_PH Grand mean 610.0 treatments_PH 9.00 608.0 10.00 608.2 11.00 662.9 31 12.00 639.6 13.00 604.9 14.00 570.5 15.00 590.1 Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 treatments_PH 16.00 596.0 *** Standard errors of means *** Table rep d.f e.s.e treatments_PH 16 20.03 *** Standard errors of differences of means *** Table rep d.f s.e.d treatments_PH 16 28.33 *** Least significant differences of means (5% level) *** Table rep d.f l.s.d treatments_PH 16 60.06 ***** Stratum standard errors and coefficients of variation ***** Variate: HCl_Pi_PH d.f 16 s.e 34.70 cv% 5.7 362 "One-way ANOVA (no Blocking)." 363 BLOCK "No Blocking" 364 TREATMENTS treatments_PH 365 COVARIATE "No Covariate" 366 ANOVA [PRINT=aovtable,information,means,%cv,missingvalues; FPROB=yes; PSE=diff,lsd,\ 367 means; LSDLEVEL=5] Residue_P_PH 367 ***** Analysis of variance ***** Variate: Residue_P_PH Source of variation treatments_PH Residual Total d.f 16 23 s.s 3769.2 2066.1 5835.3 m.s 538.5 129.1 v.r 4.17 F pr 0.009 * MESSAGE: the following units have large residuals *units* 10 *units* 11 -29.8 21.9 s.e 9.3 s.e 9.3 ***** Tables of means ***** Variate: Residue_P_PH Grand mean 334.8 treatments_PH 9.00 318.6 treatments_PH 16.00 332.4 10.00 324.7 11.00 338.2 32 12.00 340.0 13.00 360.4 14.00 322.6 15.00 341.1 Thi Kim Phuong Nguyen – 376329 Environmental research project – ENST 90007 *** Standard errors of means *** Table rep d.f e.s.e treatments_PH 16 6.56 *** Standard errors of differences of means *** Table rep d.f s.e.d treatments_PH 16 9.28 *** Least significant differences of means (5% level) *** Table rep d.f l.s.d treatments_PH 16 19.67 ***** Stratum standard errors and coefficients of variation ***** Variate: Residue_P_PH d.f 16 s.e 11.36 cv% 3.4 ***** Analysis of variance ***** Variate: H2O_PL Source of variation d.f.(m.v.) s.s m.s PL 15.0397 2.1485 Residual 15(1) 1.5604 0.1040 Total 22(1) 16.5578 * MESSAGE: the following units have large residuals *units* 0.620 v.r 20.65 F pr [...]... 3.4 The results showed that biochar application increased the extractable Pi fractions in low phosphorus soil In addition, extractable Po fractions in this soil were also increased in the biochar treatments It can be explained due to the concentration of phosphorus in this soil is low, therefore, the adding biochar is going with the adding P sources That led to the increase in phosphorus fractions In. .. Poowong High soil was high Due to different characteristics of soils, the effects of biochar and adding NaOH on these soils were different .Biochar had liming value and resulted in increase pH values in both soils The application of biochar on Poowong Low soil increased water soluble P with a linear trend Labile P in Poowong Low soil was also significantly increased by biochar application Similarly, biochar. .. fractions In high phosphorus soil, because the concentration of phosphorus in this soil is high and even higher than the concentration of phosphorus in biochar, the application of biochar had a negligible effect on total Pi and Po fractions Adding NaOH led to the decrease in total pi fractions in this soil Although the Poowong High soil has far higher 14 Thi Kim Phuong Nguyen – 376329 Environmental research... was smaller than others and got the lowest position The control treatment got the lowest values in both extractable Pi fractions and extractable Po fractions (Table 4) In the Poowong High soil, the trend was different with the trend in the Poowong Low soil Adding NaOH to increase pH led to the decrease in extractable Pi fractions in all NaOH treatments, total Pi in these treatments got the lowest values,...Environmental research project – ENST 90007 in labile P with the large increase There was a positive correlation between the amount of applied biochar and the labile P values (Table 3).This increase came from the change of P fractions in soil as well as from labile P in biochar The results show that in Poowong Low soil, biochar increased labile P and this source is from the mineralisation P in soil... mg Pkg -1 after incubation Since the concentration of labile P in biochar is extremely smaller than that concentration in Poowong High soil (335 mg Pkg -1 compared with 715 mg Pkg -1) Consequently, the more application of biochar, the more diluted labile P in the soils Although the experiment showed that both treatments reduced labile P values compared to the control, those reductions were not followed... extractable Pi fractions in the 50 t biocharha-1treatment was higher than the control (325 mg Pkg-1 compared with 217 mg Pkg-1) and was the highest values The proportion of extractable Pi fractions in this treatment also had the highest ranking, which was 43.4% Although the extractable Pi fractions in the 50t biocharha-1 ranked the highest proportion, the proportion of extractable Po fractions in this treatment... Biochar Application to Field Soil in Various Soil Management Systems International Biochar Initiative IBI 2011, What is biochar? [Online]: International Biochar Intinative Available: http:/ /biochar- international.org /biochar [Viewed: 08/9/201] Isbell, R F 2003, The Australia soil classification, COLLLINGWOOD, CSIRO Ishii, T & Kadoya, K 1994, 'Effects of charcoal as a soil conditioner on citrus growth... value of total P compared with the Poowong Low soil, which were around 3,430 mgPkg -1 and 590 mgPkg-1, respectively (approximately 6 times higher), the residue P of two types of soil were slightly different That means the difference in P concentrations in soils would go to P fractions 4 Conclusion and recommendation Poowong Low soil had a low concentration of phosphorus while that concentration in the. .. Figure 12 Non-labile P and residue P in Poowong High soil NaOH-P fraction is the iron-P form when extracted by NaOH This P form is non-labile and not available for plant uptake High concentration of NaOH-Pi in Poowong High soil (around 1,400 mg P kg-1) ilustrated this soil might has high concentration of iron oxidesand this source of iron would keep P in the Fe-P bone.Again, the organic form of NaOH-P