Effects of biochar and/or dolomitic limestone application on the properties of Ultisol cropped to maize under glasshouse conditions

Transcription

1 Effects of biochar and/or dolomitic limestone application on the properties of Ultisol cropped to maize under glasshouse conditions M. A. Rabileh 1, J. Shamshuddin 1,3, Q. A. Panhwar 1,2, A. B. Rosenani 1, and A. R. Anuar 1 1 Department of Land Management, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; and 2 Soil Chemistry Section (SF), Agriculture Research Institute Tandojam, Sindh, Pakistan. Received 15 July 2014, accepted 6 November Published on the web 28 November Rabileh, M. A., Shamshuddin, J., Panhwar, Q. A., Rosenani, A. B. and Anuar, A. R Effects of biochar and/or dolomitic limestone application on the properties of Ultisol cropped to maize under glasshouse conditions. Can. J. Soil Sci. 95: Ultisols in the tropics are characterized by low ph and high exchangeable Al. Maize grown on them produces low yield. A study was conducted to determine changes in soil properties and their subsequent effects on maize growth, resulting from oil palm empty fruit bunch (EFB) biochar and/or dolomitic limestone application. The results show that the application of the EFB biochar improved soil fertility by increasing soil ph. The Al 3 activities in the soil solution decreased exponentially with increasing rate of the biochar application. The decrease in Al in the biochar-treated soil occurred because: (1) at the rate of5tha 1, soil solution ph increased significantly, precipitating Al as gibbsite; and (2) the biochar was able to fix some of the Al by chelation. Application of the biochar alone or in combination with lime significantly improved maize growth. The critical Al 3 activity for maize grown on Ultisol was 10 mm, while critical ph was Maize grown on the EFB biochar-amended soils produced greater root length compared with that of the control. The optimal rate of EFB biochar application to improve the productivity of the Ultisol for maize production under glasshouse condition was 510 t ha 1. Key words: Acidic soil, empty fruit bunch, biochar, dolomitic limestone, maize, Ultisol Rabileh, M. A., Shamshuddin, J., Panhwar, Q. A., Rosenani, A. B. et Anuar, A. R Effets de l application de biocharbon ou de chaux dolomitique sur les propriétés des urtisols employe s pour cultiver le maı s en serre. Can. J. Soil Sci. 95: Dans les tropiques, les ultisols se caracte risent par un faible ph et une forte concentration d ions aluminium échangeables. Le maïs cultive sur de tels sols donne un faible rendement. Les auteurs ont entrepris une e tude pour de terminer comment l application de biocharbon venant de la masse des fruits vides (MFV) du palmier a` huile ou de chaux dolomitique, ou des deux, modifie les proprie tés du sol et la croissance du maı s. Les résultats indiquent que l application de biocharbon MFV rend le sol plus fertile en augmentant son ph. L activite des ions Al 3 dans la solution de sol diminue de fac on exponentielle avec la quantite de biocharbon applique e. La baisse de la concentration d ions Al dans le sol amendé avec du biocharbon est attribuable à deux phénome` nes: 1) quand le taux d application de passe 5 t par hectare, le ph de la solution de sol augmente de manie` re significative, ce qui entraıˆne la précipitation des ions Al sous forme de gibbsite; 2) le biocharbon fixe une partie de l aluminium par che lation. Appliquer du biocharbon seul ou avec de la chaux ame liore significativement la croissance du maı s. Le seuil critique en ce qui concerne l activite des ions Al 3 pour la culture du maïs sur les ultisols est de 10 mm, le ph critique se situant, lui, a` 4,7-4,8. Le maïs cultivé sur les sols amende s avec du biocharbon MFV forme des racines plus longues que celui cultivé sur la parcelle te moin. Le taux d application optimal du biocharbon MFV pour la culture du maïs en serre se situe entre 5 et 10 t par hectare. Mots clés: Sol acide, masse de fruits vides, biocharbon, chaux dolomitique, maı s, ultisol Ultisols, the soils identified by the presence of argillic horizon, are widespread in Southeast Asia, especially in Malaysia, Thailand and Indonesia. They are the most dominant soil type in the region, where acid-tolerant oil palm and rubber are mostly grown with great success. Ultisols are characterized by high acidity, low cation exchange capacity (CEC) and high exchangeable aluminum throughout their profiles, and their clay fraction is dominated by kaolinite and sesquioxides (Tessens and Shamshuddin 1983; Shamshuddin and Fauziah 2010). 3 Corresponding author ( shamshud@upm.edu.my). During the replanting phase of oil palm and rubber cultivation in Malaysia, maize is often grown by smallholders in the inter-rows to get some income, but the yield is low (both grain and fodder yield). Studies indicate that maize production on Ultisols in the tropics is low due to the low ph, Al and/or Mn toxicities, and Ca and Mg deficiencies in addition to lack of P. Because of the relatively large area of Ultisols in the tropics, and thus the high potential for maize Abbreviations: EFB, empty fruit bunch; CEC, cation exchange capacity; ICP-AES, inductively coupled plasma atomic emission spectroscopy Can. J. Soil Sci. (2015) 95: 3747 doi: /cjss

2 38 CANADIAN JOURNAL OF SOIL SCIENCE cultivation, it is important to develop measures to ameliorate the soil acidity for sustainable maize production. Due to the low ph of Ultisols, good crops of maize could only be produced after adequate application of dolomitic limestone (Shamshuddin et al. 1991; Shamshuddin and Fauziah 2010). Al 3 and AlSO 4 are the dominant Al species in the untreated Ultisols of Malaysia (Ismail et al. 1993). The former is toxic to maize, but the latter is not. It is believed that organically bound Al is also non-toxic (Hue and Graddock 1986). Shamshuddin et al. (1991) found that the critical Al and Mn concentrations for maize grown on Ultisols were 22 and 39 mm, respectively. The current study, using Geochem-EZ, established that 5055% of the Al and Mn in soil solution existed in the form of their activity. So, the respective critical Al 3 and Mn 2 activities for the maize studied by Shamshuddin et al. (1991) would have been about 11 and 19 mm. The same researchers found that the lime requirement of Ultisols (using dolomitic limestone) was 2 t ha 1. Applying lime to the soils at this rate reduced Al activities in the soil solution from 115 to 8 mm (Shamshuddin et al. 1991). Research conducted in recent years has indicated that biochar can also be used as an effective amendment to improve the productivity of poor soils (Lehmann et al. 2003; Ibrahim et al. 2013). Biochar is a carbon-rich product formed by pyrolysis process of organic wastes under oxygen-limited conditions (Sohi et al. 2010). Biochar is a form of organic matter; therefore, theoretically, its application can reduce Al concentration in the soil via a process called chelation (Hue and Amien 1989). It has been shown that biochar is recalcitrant; hence, it may persist in soil for a long period of time (Seiler and Crutzen 1980). Biochar has an alkaline property (Chan et al. 2007) which could reduce soil acidity (Topoliantz et al. 2005) and increase CEC (Glaser et al. 2002) because of its high surface area and high negative charge (Liang et al. 2006; Singh et al. 2010). Application of biochar can alleviate Al toxicity by increasing soil ph, which precipitates Al existing in the soil solution (Gensemer and Playle 1999). In Malaysia and Indonesia, the area cultivated to oil palm is 5 and 15 million ha, respectively. Oil palm factories in these countries produce huge amount of empty fruit bunch every year. These agricultural wastes can be used as feedstock for production of biochar that can be land applied to improve the productivity of Ultisols. Claoston et al. (2013) reported that the ph of empty fruit bunch (EFB) biochar was 7. According to Shamshuddin et al. (1998), palm oil mill effluents derived from EFB contained 2.20% N, 0.96% P, 0.93% K and 0.64% Ca, and they enhanced crop yield. Hence, the biochar so produced from EFB can be used to ameliorate the infertility of Ultisols. This study was conducted to determine the effects of EFB biochar and/ or dolomitic limestone application on the chemical properties of Ultisol and the growth of maize. MATERIALS AND METHODS Site Description and Planting Material A glasshouse experiment was conducted at the Faculty of Agriculture, Universiti Putra Malaysia (UPM), Serdang, Malaysia (lat N, long E; 30 m above sea level). Mas Madu maize cultivar (Zea mays L.) was the test crop used in this study. Soil of the Study The soil under investigation was Bungor Series, belonging to the clayey, kaolinitic, isohyperthermic family of Typic Paleudult (Tessens and Shamshuddin 1983). The topsoil (020 cm depth) was collected from Universiti Putra Malaysia farm at Serdang, Malaysia. The site was left barren without planting any crop for a long period of time. Biochar for the Study The feedstock of the biochar production was oil palm EFB. It was produced by Nasmech Technologies Sdn Bhd (Malaysia) via slow pyrolysis of the EFB (size 25 mm, moisture content of 5%) in the absence of O 2 at the temperature of C. The biochar was homogenized, ground to pass through 1-mm sieve and kept for this study. Treatments and Experimental Procedures A factorial experiment consisting of four levels (0, 5, 10 and 20 t ha 1 ) of EFB and two levels of EFB0DL0 (0 t ha 1 EFB0 tha 1 dolomitic lime), EFB0DL2 (0 t ha 1 EFB2 tha 1 dolomitic lime), EFB5DL0, EFB5DL2, EFB10DL0, EFB10DL2, EFB20DL0, EFB20DL2 with total of eight treatments were laid out in completely randomized design (CRD) with four replications. The treatments are shown in Table 1. The Bungor soil was ground sieved (2.0 mm) and mixed thoroughly with the biochar, either in the presence or absence of 2 t dolomitic limestone ha 1 in each polybag. This limestone contains: Ca 18.5%, Mg 6.7% and K 1.7 mg kg 1 (Shamshuddin and Ismail 1995). Then, the recommended rate of NPK fertilizers for maize cultivation was respectively applied uniformly in all the treatments in the form of urea (120 kg ha 1 N), Table 1. Experimental treatments [Author: please confirm] No. Code of treatments Description of treatments 1 EFB0 z DL0 0 t ha 1 EFB0 tha 1 dolomitic lime 2 EFB0DL2 0 t ha 1 EFB2 tha 1 dolomitic lime 3 EFB5DL0 5 t ha 1 EFB0 tha 1 dolomitic lime 4 EF5DL2 5 t ha 1 EFB2 tha 1 dolomitic lime 5 EFB10DL0 10 t ha 1 EFB0 tha 1 dolomitic lime 6 EFB10DL2 10 t ha 1 EFB2 tha 1 dolomitic lime 7 EFB20DL0 20 t ha 1 EFB0 tha 1 dolomitic lime 8 EFB20DL2 20 t ha 1 EFB2 tha 1 dolomitic lime z Dolomitic limestone. Each of the above treatments was mixed with 20 kg of Bungor soil thoroughly and transferred into 50-cm45-cm polybag.

3 RABILEH ET AL. * BIOCHAR APPLICATION ON ULTISOLS 39 triple superphosphate (60 kg ha 1 P 2 O 5 ) and muriate of potash (90 kg ha 1 K 2 O). Before sowing, the soils were watered frequently to maintain moisture level at the field capacity (10 kpa) and left for 2 wk for incubation under glasshouse conditions. Four maize seeds were sown in each polybag at 3-cm depth. Based on height uniformity and healthy appearance after 7 d, of these four plants, one plant was allowed to grow in each pot. The experiment was conducted for 50 d and treatments were arranged in a CRD with four replications. Biochar Analysis and Characterization The ph of biochar was determined with a Beckman Digital ph meter using a ratio of air-dried sample to distilled water of 1:2.5, according to Ahmedna et al. (1998). Total carbon and N in the biochar were determined using a CNS analyzer (TrueMac CNS Analyser). CEC and exchangeable cations were determined using 1MNH 4 OAc buffered at ph 7 (Schollenberger and Simon 1945). The K, Ca and Mg in the extracts were then measured by atomic absorption spectrophotometry (Perkin-Elmer, 5100 PC, USA). One gram of the biochar was digested with 1 N H 2 SO 4 and P was determined using auto-analyzer (Lachat Instrument USA). The ash content was measured by heating 1 g of ground biochar at 2008C for 1 h, followed by another 4 h of heating in a muffle furnace at 5008C (Slattery et al. 1991). After cooling at room temperature, the sample was removed and weighed immediately, and this weight was considered as the ash mass of the biochar. Liming potential of the biochar (in terms of its calcium carbonate equivalence) was determined by the titration method of Erich and Ohno (1992). Soil Analysis and Characterization Soil ph was determined in water (1:2.5) using a ph meter. Exchangeable Al was determined by the method of Kamprath (1970) in which the extracted Al was analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Total phosphorus was determined by (Muir 1952) and available P was determined by Bray and Kurtz II method (Bray and Kurtz 1945). Leaching method was used to determine exchangeable K, Ca and Mg (Schollenberger and Simon 1945). Cation exchange capacity was measured using the NH 4 replacement method (Schollenberger and Simon 1945) by determining from the same soil, which was previously leached with 1 M NH 4 OAc for the determination of exchangeable bases. Total carbon and nitrogen were determined by CNS analyzer. Soil texture was determined by the pipette method of Teh and Jamal (2006). Post-harvest soil samples were collected from each polybag. Chemical analyses carried out were ph, total C, total N, exchangeable bases (K, Ca and Mg), CEC and exchangeable Al using the methods mentioned above. Mn in the soil was measured using diluted double acid method. Five grams of air-dried soil was placed into conical flask and 25 ml of diluted double acid extracting reagent (0.05 N HCl0.025 N H 2 SO 4 ) was added. The solution was shaken well for 15 min. on a mechanical shaker at 180 rpm. The solution was filtered with Whatman no. 42 filter paper and the filtrate was analyzed for Mn content by atomic absorption spectrophotometry. Soil Solution Extraction and Analysis At harvest, soil solution (it is also called pore water) was extracted from each pot using a Rhizon soil moisture sampler (Eijelkemp, Holland). Prior to the extraction, each polybag was first irrigated to 90% of available water and a Rhizon soil moisture sampler was inserted diagonally at a 458 angle inside the polybag. During sampling, when pulling the plunger back, the partial vacuum created inside the tube caused the solution from the soil to move into the vacuum tube. After 48 h, the soil solution was extracted and the tube was filled. The extracted soil solution was then taken to the soil laboratory for analysis. Five millilitres of the soil solution was immediately analyzed for ph. The remaining solution was stored at 58C for the measurement of Al, Ca, Mg, K, and Mn using ICP-AES. The concentration of phosphate (PO 4 3 ) and sulfate (SO 4 2 ) was determined by ion chromatography (ICS-2100 Ion Chromatography System, USA). The activities of free ions in the soil solution and soluble complexes were determined using GeochemEZ (Shaff et al. 2010). Measurement of Maize Growth Parameters Analysis of NPK in Maize Plant Tissues Determination of macronutrients was carried out using the modified method of Wolf (1982). Plant root and leaf samples were placed into envelopes and then dried in the oven at 658C for 72 h. The dried plant tissues were ground and 0.25 g was used for the digestion. For the digestion process, the samples were transferred into clean digestion flasks and 5 ml of concentrated H 2 SO 4 was added to each flask for 2 h. Thereafter, the flasks were heated for 45 min at 2858C and 2 ml of 50% (H 2 O 2 ) was added to complete the process. The process was repeated several times until the samples became white and clear. The flasks were removed from the digestion plate, cooled at room temperature and then diluted to make up to 100 ml volume with distilled water. Then, N P and K in the solution were determined using an auto-analyzer, while Ca, Mg and Al were determined by ICP-AES. The plant uptake from leaves and roots was calculating by following formula: Uptake total nutrient concentrationbiomass After harvesting the above-ground plant parts, the polybags were saturated with water and left overnight in order to remove the roots the next day. Then, the roots were slowly removed by loosening the soil. After removing the roots, they were placed in containers with sieves of several mesh sizes to prevent the loss of fine

4 40 CANADIAN JOURNAL OF SOIL SCIENCE roots during washing, and water was gently poured onto the roots, which were carefully washed by hand until they were clean. The roots were immediately taken to the laboratory. Root length was determined using root scanner, model Win RHIZO 2008a software. Fixation of Al by Biochar Fixation of Al by the EFB biochar was determined by the method of Shaheen et al. (2008). The experiment was carried out at the optimum temperature of 298C andph of 4. Fifty millilitres of 10 mg L 1 Al solute was added into the adsorbent in a falcon tube. The mixture was shaken on an orbital shaker for about 2 h, followed by centrifugation for 15 min. The supernatant was filtered using 0.22 mm Milipores filter and exchangeable Al in the filtrate was analyzed using ICP-AES. The relative shoot and root dry weights were determined by calculating the shoot and dry weight of each treatment compared with the highest shoot and dry weight as the maximum i.e., as 100%. The calculation formula of (RRL) was as follows: Relative shoot=dry weight shoot=dry weight=maximum shoot=dry weight 100%: Statistical Analysis Data collected from the experiments were statistically subjected to analysis of variance (ANOVA). The treatments means were compared by Tukeys test at 5% level of confidence using SAS software version 9.2 (SAS Institute Inc. 2008). Correlation and regression analyses were used to estimate the relationships and trends between the selected parameters. RESULTS AND DISCUSSION Physico-chemical Properties of the Original Soil from the Field The soil for this study was defined by Paramananthan (2000) as the Bungor Series, which was classified as Typic Paleudult (Soil Survey Staff 2010). Shamshuddin et al. (1991) conducted a liming experiment at the site where the samples were taken. The clay content in the topsoil was 34% (Table 2), but in the argillic horizon it was 35% (Shamshuddin and Fauziah 2010). The ph and exchangeable Al of the topsoil were 4.30 and 2.30 cmol c kg 1, respectively, while the exchangeable basic cations were very low. The exchangeable Al was above the toxic level and the exchangeable basic cations were below the sufficiency range for healthy growth of maize (Reuter and Robinson 1997). According to Shamshuddin et al. (1991), least 2 tons of dolomitic limestone ha 1 were required to alleviate the infertility of this soil for maize cultivation. The clay fraction of the benchmark Bungor soil in Malaysia is dominated by kaolinite and sesquioxides Table 2. Physico-chemical properties of the topsoil of Bungor Series and EFB biochar Properties Soil EFB biochar Bungor soil series Sand 60% Silt 6% Clay 34% ph Available P (mg kg 1 ) CEC (cmol c kg 1 ) Exchangeable Ca (cmol c kg 1 ) Exchangeable K (cmol c kg 1 ) Exchangeable Mg (cmol c kg 1 ) Exch Al (cmol c kg 1 ) 2.30 Total carbon (%) Total nitrogen (%) Total phosphorus z (mg kg 1 ) Ash content (%) Acid neutralising ability (%CaCO 3 ) z Total P was analysed by Muir (1952). (Tessens and Shamshuddin 1983; Shamshuddin and Fauziah 2010), which are considered as variable charge minerals (Anda et al. 2008). This means that the CEC of the Bungor soil under study will be increased if the soil ph is increased to a value above 4.3 due to treatment with biochar and/or lime. The increase in CEC, considered as an improvement in the productivity of the soil, depends on the rate of the amendments applied. Chemical Composition of the Biochar The chemical properties of EFB biochar of the current study are given in Table 2. This biochar was alkaline in nature with a ph of 9, due to the presence of ash produced during the pyrolysis process. Biochar typically contains some Ca, Mg, K and Na oxides/carbonates (Yuan et al. 2011). The biochar used in this study contained 50% C with 1.21% N. Like any other organic materials, its CEC was very high (61 cmol c kg 1 ), which was consistent with the finding of Singh et al. (2010). Thus, land application of this biochar would improve the fertility of Ultisols tremendously and eventually translate into improved maize growth and yield. Effects of EFB Biochar and/or Dolomitic Limestone on Soil Properties The chemical properties of the Bungor soil under study as affected by biochar and/or lime application are given in Table 3. By and large, soil ph, exchangeable bases, CEC, total C and total N increased with increasing rate of biochar and/or dolomitic limestone application, while, without biochar application, the soil ph was Increasing the rate to 5 and 10 t ha 1 resulted in a significant increase in soil ph to 4.82 and 5.17, respectively. The ph of the biochar itself was 9 and, therefore, to some extent, helped raised soil ph. The increase in soil ph was consistent with the finding of Claoston et al. (2013). We know that basic cations (such as Ca, K and Mg) can form alkaline oxides or carbonates during the pyrolysis

5 RABILEH ET AL. * BIOCHAR APPLICATION ON ULTISOLS 41 Table 3. Effects of biochar and/or dolomitic limestone application on the chemical properties of Bungor soil Exchangeable cations Mg K Ca Al CEC Treatments Rate of Biochar (t ha 1 ) ph (cmol c kg 1 ) Total C (%) Total N (%) Biochar without lime z d 0.40c 0.23c 0.62c 2.20a 10.00c 1.04c 0.060b c 0.37c 0.81b 1.23a 1.25b 11.30c 1.13c 0.065b b 0.68b 1.12b 1.54a 0.61c 13.30b 1.66b 0.080a a 0.81a 1.85a 1.55a 0.16d 15.30a 2.07a 0.089a Biochar with lime z d 1.05d 0.24c 2.10b 0.41a 14.00c 1.06c 0.063b c 1.20c 0.62b 2.34b 0.21b 14.30c 1.23c 0.066b b 1.35b 1.55a 3.17a 0.02c 17.00b 1.68b 0.080a a 1.48a 1.47a 3.17a 0.00c 19.53a 2.10a 0.090a z Dolomitic limestone (2 t ha 1 ). ad Means with in the same column followed by the same letters are not significantly different at PB0.05. process. Following the release of these oxides into the soils, H and Al 3 in the soil solution will be neutralized, subsequently raising soil ph and decreasing acidity (Novak et al. 2009). These researchers proposed that CaO neutralized soil acidity according to the following reaction: 2Alsoil3CaO3H 2 O 0 3Casoil2Al(OH) 3 This reaction describes the reduction in soil acidity whereby Ca 2 replaces the Al 3 on the soil exchangeable sites, generating alkalinity. Thus, there is an increase in soil ph as a result of the reduction of the readily hydrolysable Al 3 and the subsequent formation of inert Al-hydroxides (Sparks 2003). When ph go above 5, Al in the soil solution precipitates as Al-hydroxides, rendering it inactive and therefore unavailable to the maize (Shamshuddin et al. 2011). Under normal condition, soil solution ph should be raised to a level above 5 in order to eliminate Al toxicity for maize cultivation. This study found that applying EFB biochar at the rate of 5 t ha 1 significantly increased exchangeable K and Ca to 0.81 and 1.23 cmol c kg 1 soil, respectively. At this rate of biochar application, the treated soil contained total C of greater than 1% (equivalent to 1.7% organic matter). This level of organic matter content in the soil is considered sufficient for maize production (Shamshuddin et al. 1991). Applying dolomitic limestone at a rate of 2 t ha 1 resulted in an increase in soil ph to about 5 and a decrease in exchangeable Al tob1 cmol c kg 1 soil. Soil under these conditions is considered to be suitable for maize production (Shamshuddin et al. 1991). The result of the current study is consistent with that conducted earlier by Ismail and Shamshuddin (1993). Dolomitic limestone applied at 2 t ha 1 can reduce H stress and Al 3 toxicity in the long run and is less costly than biochar. However, lime application did not increase soil organic matter, which is needed for the improvement of both the chemical and physical properties of the soil. This means that EFB biochar is a superior soil amendment compared with dolomitic limestone. The results of the current study show that it is not necessary to apply biochar in combination with lime to alleviate the infertility of Ultisols for sustainable maize cultivation. Considering the improvement in soil fertility, improved growth and the cost of maize production, the suitable rate of EFB biochar application affordable by the farmers in the tropics is 510 t ha 1. One of the parameters to consider when evaluating soil fertility and the ability of soils to hold nutrients is the CEC. In this study, it was found that the CEC was significantly (P ) increased by applying EFB biochar with or without lime. Biochar application at 10 t ha 1 increased the CEC from to cmo1 c kg 1. The highest CEC value, cmol c kg 1 soil, was obtained in the 20 t biochar ha 1 treatment. The increase in CEC was due to two factors: first, the addition of biochar into the soils, as it was negatively-charged (Singh et al. 2010); second, the ph increase as a result of biochar application (Table 3) (the EFB biochar contained alkaline ash of ph 9). Note that the soil of the Bungor Series is dominated by kaolinite and sesquioxides in the clay fraction (Tessens and Shamshuddin 1983; Shamshuddin and Fauziah 2010), so it has the capacity to increase its CEC if soil ph is increased (Anda et al. 2008). The increase in CEC means that the soil is able to retain more cations than it otherwise was under the heavy rainfall prevailing in the tropics. This means that EFB biochar application significantly improved the productivity of the Ultisol under investigation. Effects of ETB Biochar and Dolomitic Limestone on Soil Solution Properties The effects of biochar and/or lime application on the soil solution properties are presented in Table 4. Applying dolomitic limestone alone also increased soil solution ph to a value above 5. In the biochar treatment, soil solution ph of the control treatment was The values were increased to 4.83 and 5.17 due the respective application of 5 and 10 t EFB biochar ha 1. The respective activities of Al 3 in the soil solution due to application of biochar

6 42 CANADIAN JOURNAL OF SOIL SCIENCE Table 4. Effects of biochar and/or dolomitic limestone application on the soil solution of Bungor soil Mg 2 K Al 3 Ca 2 Mn 2 Treatments Rate of biochar (t ha 1 ) ph Activities (mm) Biochar without lime z d c c 71.60a c 87.00a c d b 29.00b c 35.80b b b a 9.30c b 11.80c a a a 0.72c a 5.60d Biochar with lime z d d c 10.20a d 7.00a c c b 1.20b c 1.42b b b a 0.01c b 2.98b a a a 0.00c a 2.95b z Dolomitic limestone (2 t ha 1 ). ad Means with in the same column followed by the same letters are not significantly different at PB0.05. at the rate of 5 and 10 t ha 1 were and 9.30 mm, while those of Mn 2 were and mm (Table 5). It was also observed that the activities of Ca 2 increased significantly due to application of 10 t EFB biochar ha 1. Dolomitic limestone also played a significant role in eliminating Al and Mn toxicity where applying it at 2 t ha 1 had reduced Al 3 and Mn 2 to and 7.00 mm, respectively. Figure 1 shows the relationship between Al 3 activities and ph and Mn 2 activities and ph. The activities of Al 3 decreased exponentially as soil solution ph increased (y317000e 1.96x ) (Fig. 1a). The decrease in Al 3 activities was dependent on the rate of biochar applied. The critical Al activity for maize growth on Ultisols was 12 mm (Shamshuddin et al. 1991). To lower the Al 3 activities to a value less than that of the critical level, the ph should at least be 5 (Fig. 1a). Shamshuddin et al. (1991) found that the critical soil solution ph for maize grown on Ultisols in Malaysia was 4.7. Based on the data given in Table 4, the rate of EFB biochar to be applied onto the soil so that soil solution ph can be increased to this value is slightly above 5 t ha 1. Like Al 3,Mn 2 activities decreased exponentially with increasing soil solution ph (y e 2.19x ; R ) (Fig. 1b). Due to applying EFB biochar at the rate of 5 t ha 1,Mn 2 activities were decreased from to mm (Table 4). According to Shamshuddin Table 5. Plant nutrient uptake in maize et al. (1991), the critical Mn activities for maize grown on common Ultisols in Malaysia was 20 mm. Using Fig. 1b, the estimated soil solution ph to bring Mn 2 activities below the critical level was about 5. The rate of EFB biochar needed to decrease Mn 2 activities to less than the critical level was also slightly above 5 t ha 1. Effects of ETB Biochar and Dolomitic Limestone on the Growth of Maize in the Greenhouse Application of EFB biochar and/or dolomitic limestone has been shown to improve maize growth. The application of biochar and/or lime significantly increased (P0.042) the height of maize, as shown in Fig. 2a. Dry matter yield of maize grown in biochar-treated soils was significantly higher (P ) compared with that of the untreated soils. The maize grew poorly in the untreated soils as shown clearly by its low dry weight. It was observed that biochar applied at 5 t ha 1 was able to increase the maize dry weight significantly compared with that of the control (Fig. 2b). The higher the rate of biochar application, the higher the dry weight. A similar trend was also observed for biochar in combination with lime, except for the 10 biochar ha 1 treatment, where it reached the highest biomass production. The low maize dry weight for the untreated soil was attributed to the low soil ph and the presence of high exchangeable Al (Table 3). N P K Ca Mg Treatments Rate of biochar (t ha 1 ) (g plant 1 ) Biochar without lime z d 0.057c 0.097c 0.022c 0.015c c 0.094b 0.949b 0.052c 0.049b b 0.150a 1.376b 0.141b 0.159a a 0.170a 2.304a 0.250a 0.182a Biochar with lime z d 0.071d 0.711b 0.121d 0.097c c 0.128c 1.336b 0.224c 0.134c a 0.244a 2.927a 0.526a 0.394a b 0.195b 3.171a 0.348b 0.281b z Dolomitic limestone (2 t ha 1 ). ad Means with in the same column followed by the same letters are not significantly different at PB0.05.

7 RABILEH ET AL. * BIOCHAR APPLICATION ON ULTISOLS 43 Fig. 1. Relationship between Al 3 (a) and Mn 2 (b) activities and soil solution ph. Significant level: **PB0.01. It was observed that root dry weight was linearly increased with increasing soil solution ph (Fig. 3a), and a similar trend was observed for total dry weight and soil solution ph (Fig. 3b). Figure 4 shows that the root length of maize increased linearly with increasing rate of biochar application, and the equation representing the relationship is given by y x (R ). Relative root length was linearly decreased with increasing Al 3 activities (Fig. 5a). The equation representing the relationship is given by y x (R ). The Al 3 activities corresponding to 90% relative root length was 10 mm; this value is the critical level for maize growth, which is almost similar to that obtained by Shamshuddin et al. (1991). Likewise, the relative dry matter weight decreased with increasing Al 3 activities (Fig. 5b). Relative dry weight was also decreased with increasing Mn 2 activity, with the equation representing the relationship given by y x (R ) (Fig. 6a). The critical level of Mn 2 activities obtained was 10 mm; the value was slight lower than that obtained by Shamshuddin et al. (1991). It was probably due to fixation of some of the Mn 2 in the soil solution by the EFB biochar. On the contrary, relative root length increased linearly with increasing soil solution ph as shown by the equation y x (R ) (Fig. 6b). The soil solution corresponding to 90% relative root length at ph 5.3. The amount of the EFB biochar with dolomitic limestone needed to raise soil solution ph to this level was 510 t ha 1. At this ph level, most of the Al 3 existing in the soil solution was precipitated as inert Al-hydroxides (Shamshuddin et al. 1991) and Mn toxicity was also eliminated when soil solution reached this ph level (Shamshuddin et al. 2011). The current study showed clearly that Mn 2 toxicity in the Ultisol can also be eliminated by applying dolomitic limestone at 2 t ha 1 with EFB biochar. Aluminum in the Roots Maize plants took in Al from soil solution through their roots. Hence, Al taken up by the maize depended on its activities in the soil solution. This is clearly shown in Fig. 6c where Al in maize roots was linearly increased with the increase in Al 3 activities in the soil solution. The equation representing the relationship between Al in the root and Al 3 activities in the soil solution is: y x (R ) (Fig. 6c). The Al in the root was relatively high at the low rate of EFB biochar application. The high amount of Al in the maize root would cause Al 3 toxicity. The activity of Al 3 was considerably high in the control treatment, above the critical level of 10 mm. The increase of Al in root was therefore closely related to its high activity in the soil solution. As the Al 3 activity in the soil solution increased, more Al was taken up by the maize roots. This finding is consistent with that of Pintro et al. (1995). They also found that Al was higher in the root of Fig. 2. Effects of biochar and/or GML application on (a) maize height and (b) total dry weight. Note: limedolmitic limestone (2 t ha 1 ). Means within the same column followed by the same letter are not significantly different at PB0.05.

8 44 CANADIAN JOURNAL OF SOIL SCIENCE Fig. 3. Relationship between root and shoot dry weight and (a) solution ph and (b) total dry weight and solution ph. Significant level: *PB0.05. maize compared with that in its shoot and that the effect of Al toxicity was much stronger in the root, suggesting that the maize root is more sensitive to Al toxicity than the shoot. Nutrient Uptake by Maize As more nutrients were added to the soils due to application of biochar and/or dolomitic limestone (Table 5), more of them were taken up by the maize. It was found that the uptake of nutrients by maize increased significantly by the EFB biochar and/or lime treatments. The uptake of N by maize increased with the increased rate of biochar application; the increase was in the order of 20 t10 t5 t0 t biochar ha 1, which is consistent with the study of Van Zwieten et al. (2010). The uptake of P was significantly higher in the EFB biochar- and/or lime-amended soils, at 10 t biochar ha 1 biochar, followed by 20 t biochar ha 1 rates of application. Acidic soils usually have toxic levels of Al, which are associated with P deficiencies, and these greatly limit plant growth (Clark 1977; Olsen and Sommers 1982). The relatively increased P uptake by Fig. 4. Relationship between total root length and rate of biochar. Significant level: **PB0.01. maize for the biochar-amended soils could be due to reduced Al toxicity. Significant differences were observed in K uptake by maize between the control and the other treatments. This trend was also observed for Ca and Mg uptake. However, it was observed that EFB biochar and/or dolomitic limestone were only effective in increasing Ca and Mg uptake at the high rates of their application. The increase in K uptake by the maize as a result of EFB biochar application could be partly related to its high K content, which is similar to the finding of Uzoma et al. (2011) and Lehmann et al. (2006). Mechanisms for Eliminating H and Al 3 Stress The growth of maize was affected by the presence of high Al 3 activities in the soil solution. For sustainable production of maize on Ultisol, soil solution ph should be normally raised to a value above 5; the pka of Al is 5. However, this study showed that maize could grow satisfactorily even though the solution ph was , the critical level found by Shamshuddin et al. (1991). Under stress, the root of maize secreted oxalic acid that resulted in the chelation of some of the toxic Al 3 (Rabileh et al. 2013). This chelation reaction had, to some extent, reduced the Al 3 toxicity. When this reaction occurred less Al 3 was present in the soil solution. This was probably the main reason why maize in this study was able to grow at a soil solution ph below 5. This study showed clearly that the soil solution ph can be increased to a value above the critical ph level by applying EFB biochar at the rate of slightly more than 5tha 1. It is believed that the reduction of Al 3 toxicity by biochar application happened via another mechanism. The surface of the EFB biochar was negatively charged (Singh et al. 2010) and so the positively charged Al was readily adsorbed on its surfaces. This phenomenon would eventually result in the formation of Al-organo complex as explained in detail by Hue and Amien (1989).

9 RABILEH ET AL. * BIOCHAR APPLICATION ON ULTISOLS 45 Fig. 5. Relationship between relative root length Al 3 activity (a) and relative total dry weight and Al 3 activity (b). Significant level: **PB0.01. Hence, some Al 3 in the soil solution was deactivated by the biochar application. Due to this complexation process, Al 3 activities in the soil solution decreased, with the amount depending on the rate of biochar applied (Table 4). Like inert Al-hydroxides, Al-organo complex occurring in the soil was not toxic to maize growth (Hue and Graddock 1986). Fixation of Al by Biochar The current study showed that as the amount of biochar (adsorbent) increased, the adsorption of the Al in the solution linearly increased, and the relationship is given by the equation y x (R ) (Fig. 6d). This result is consistent with the findings of the study by Shaheen et al. (2008). Fig. 6. Relationship between (a) relative total dry weight and Mn 2 activities, (b) relative root length and soil solution ph, (c) Al in the roots and Al 3 activities in the soil solution, and (d) adsorbent dosage (g L 1 ) and Al adsorbed (%) onto EFB biochar. Significant level: *PB0.05, **PB0.01.

10 46 CANADIAN JOURNAL OF SOIL SCIENCE Agricultural and Environmental Implication This study proves beyond doubt that EFB biochar is a good soil amendment, being able to increase soil ph, which resulted in the reduction of soil acidity and Al 3 and/or Mn 2 toxicity prevailing in the Ultisols of the tropics. The CEC of biochar-amended soils is significantly increased by application of biochar at the rate 5 tha 1. Additionally, soil fertility can be improved somewhat by way of increased organic matter and N, P, K Ca and Mg nutrients released by the biochar. Therefore, the soils can be used to grow maize after being amended with EFB biochar at a suitable rate. It is known that biochar is resistant to decomposition by microorganisms in soils and thus it has long-term benefit as a carbon sink (Ibrahim et al. 2013). Note that the area under oil palm cultivation in Malaysia is close to 5 million ha and in Indonesia the area is larger (about 15 million ha). This is not to mention the oil palm areas in West Africa and South America. It means that oil palm factories in these countries are producing huge amounts of empty fruit bunches annually that can be converted into stable C source, such as biochar. If these empty fruit bunches so produced by the oil palm plantations worldwide are land applied or left to rot in the open they can cause environmental damages, such as global warming. It is, therefore, a good idea to use the empty fruit bunches as feedstock for the production of environment-friendly biochar to be applied on agricultural land in the tropics. Application of EFB biochar with or without dolomitic limestone improved soil fertility by way of increasing plant nutrients, ph, carbon and cation exchange capacity, with concomitant suppression of Al 3 and Mn 2 activities in the soil solution. The increase in soil ph resulted in the precipitation of Al as inert Al-hydroxides. The increase in ph of the biochar-treated soils was attributed to the alkaline ash present in the biochar. It was observed that Al 3 activities decreased exponentially with increasing rate of biochar and/or lime application. The decrease in Al 3 activity in the biochartreated soil occurred via two mechanisms: (1) At the rate5 tha 1, soil solution ph increased significantly, precipitating Al as Al-hydroxides, making it inactive; and (2) EFB biochar was able to fix some of the Al in the soil solution by chelation processes. Application of EFB biochar in combination with dolomitic limestone significantly improved maize growth, shown by the increase in maize height, nutrient uptake and dry matter weight of shoots and roots. Relative maize dry matter weight increased linearly with increasing soil solution ph, while it decreased as Al 3 and Mn 2 activities increased. This study found that the critical Al 3 activity for maize grown on Ultisol under tropical condition was 10 mm. For sustainable maize production, the optimal rate of EFB biochar application to improve the productivity of the Ultisol was between 5 and 10 t ha 1. These findings were observed in the controlled conditions of the polybags but in the field study the impacts of biochar or lime on corn growth and production may differ. ACKNOWLEDGEMENTS The authors acknowledge Universiti Putra Malaysia, the Ministry of Science, Technology and Innovation Malaysia for financial and technical support for this study. Ahmedna, M., Marshall, W. E. and Rao, R. M Production of granular activated carbon from select agricultural by-products and evaluation of their physical, chemical, and adsorption properties. Bioresour. Technol. 71: Anda, M., Shamshuddin, J., Fauziah, I. and Syed Omar, S. R Mineralogy and factors controlling charge development of three Oxisols developed from different parent materials. Geoderma 143: Bray, R. H. and Kurtz, L. T Determination of total, organic and available forms of phosphorus in soils. Soil Sci. 59: Chan, K. Y., Van Zwieten, L., Meszaros, I., Downie, A. and Joseph, S Agronomic values of green waste biochar as a soil amendment. Aust. J. Soil Res. 45: Claoston, N., Samsuri, A. W., Ahmad Husni, M. H. and Mohd Amran, M. S Quality of biochars derived from empty fruit bunch and rice husk produced at different hydrolysis temperature. In K. Wan Rasidah et al., eds. Proc. Soil Apr Malays. Soc. Soil Sci. Bukit Gambang Resort City, Pahang, Malaysia. Clark, R. B Effect of aluminum on growth and mineral elements of Al-tolerant and Al-intolerant corn. Plant Soil 47: Erich, M. S. and Ohno, T Titrimetric determination of calcium carbonate equivalence of wood ash. Analyst 117: Gensemer, R. W. and Playle, R. C The bioavailability and toxicity of aluminum in aquatic environments. Crit. Rev. Environ. Sci. Technol. 29: Glaser, B., Lehmann, J. and Zech, W Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal a review. Biol. Fertil. Soils. 35: Hue, N. V. and Amien, I Aluminum detoxification with green manures. Commun Soil Sci. Plant Anal. 20: Hue, N. V., Craddock, G. R. and Adams, F Effects of organic acids on aluminum toxicity in subsoil. Soil Sci. Soc. Am. J. 50: Ibrahim, H. M., Al-Wabel, M. I., Usman, A. R. A. and Al-Omran, A Effects of Conacarpus biochar application on the hydraulic properties of sandy loam soil. Soil Sci. 178: Ismail, H., Shamshuddin, J. and Syed Omar, S. R Alleviation of soil acidity in a Malaysian Ultisol and Oxisol for corn growth. Plant Soil. 151: Kamprath, E. J Exchangeable Al as a criterion for liming leached mineral soils. Soil Sci. Soc. Am. Proc. 34: Lehmann, J., Gaunt, J. and Rondon, M Biochar sequestration in terrestrial ecosystems a review. Mitig. Adapt. Strat. Global Change 11: Lehmann, J., da Silva, J. P., Steiner, C., Nehls, T., Zech, W. and Glaser, B Nutrient availability and and leaching in archeological Anthrosol and a Ferralsol of the Central Amazon basin. Plant Soil. 249:

11 RABILEH ET AL. * BIOCHAR APPLICATION ON ULTISOLS 47 Liang, B., Lehmann, J., Kinyangi, D., Grossman, J., O Neill, B., Skjemstad, J. O., Thies, J., Luizao, F. J., Peterson, J. and Neves, E. G Black carbon increases cation exchange capacity in soils. Soil Sci. Soc. Am. J. 70: Muir, J. W The determination of total phosphorus in soil. Analyst 77: Novak, J. M., Busscher, W. J., Laird, D. L., Ahmedna, M., Watts, D. W. and Niandou, M. A. S Impact of biochar amendment on fertility of a southeastern coastal plain soil. Soil Sci. 174: Olsen, S. R. and Sommers, L. E Phosphorus. Pages in A. L. Page, R. H. Miller, and D. R. Keeney, eds. Methods of soil analysis. 2nd ed. Agronomy Series No. 9, Part 2. SSSA, Madison, WI. Paramananthan, S Soils of Malaysia: Their characteristics and identification. Academy of Sciences Malaysia, Kuala Lumpur, Malaysia. Pintro, J., Barloy, J. and Fallavier, P Aluminum toxicity in corn plants cultivated in a low ionic strength nutrient solution. I. Discrimination of two corn cultivars. R. Bras. Fisiol. Veg. 7: Rabileh, M. A., Shamshuddin, J., Anuar., A. R., Rosenani, A. B. and Panhwar, Q. A Early root growth of maize seedlings in nutrient solution as affected by Al3 toxicity and H stress. Jokull 63 (10): Reuter, D. J. and Robinson J. B Plant analysis. An interpretation manual. CSIRO Publishing, Collingwood, Australia. SAS Institute Inc. 2008a. SAS/STAT 9.2 user s guide. Version 9.2. SAS Institute Inc., Cary, NC. Schollenberger, C. J. and Simon, R. H Determination of exchange capacity and exchangeable bases in soil-ammonium acetate method. Soil Sci. 59: Seiler, W. and Crutzen, P. J Estimates of gross and net fluxes of carbon between the biosphere and the atmosphere from biomass burning. Clim. Change 2: Shaff, J. E., Schultz, B. A., Craft, E. J., Clark, R. T. and Kochian, L. V GEOCHEM-EZ: a chemical speciation program with greater power and flexibility. Plant Soil 330: Shaheen, A. M., El-Naas, M. H. and Abdallah, S Removal of aluminum from aqueous solutions by adsorption on date-pit and BDH activated carbon. J. Hazard. Material 158: Shamshuddin, J., Fauziah, C. I., Anda, M., Kapok, J. and Shazana, M. A. R. S Using ground basalt and/or organic fertilizer to enhance the productivity of soils in Malaysia for crop production. Malays. J. Soil Sci. 15: Shamshuddin, J. and Fauziah, C. I Weathered tropical soils: The Ultisol and Oxisol. UPM Press, Serdang, Malaysia. Shamshuddin, J., Sharifuddin, H. A. H. and Bell, L. C Changes in chemical properties of an Ultisol as affected by palm oil mill effluent application. Commun. Soil Sci. Plant Anal. 29: Shamshuddin, J., Fauziah, C. I. and Sharifuddin, H. A. H Effects of limestone and gypsum applications to a Malaysian Ultisol on soil solution composition and yield of maize and groundnut. Plant Soil 134: Shamshuddin, J. and Ismail, H Reaction of ground magnesium limestone and gypsum in soils with variable-charge minerals. Soil Sci. Soc. Am. J. 59: Singh, B., Singh, B. P. and Cowie, A. L Characterization and evaluation of biochars for their application as a soil amendment. Soil Res. 48: Slattery, W. J., Ridley, A. M. and Windsor, S. M Ash alkalinity of animal and plant products. Aust. J. Exp. Agric. 31: Sohi, S. P., Krull, E., Lopez-Kapel, E. and Bol, R A review of biochar and its use and function in soil. Pages 4782 D. L. Sparks, ed. Adv. Agron. Academic Press, Burlington, VT. Soil Survey Staff Keys to SOIL TAXONOMY. United States Department of Agriculture, Washington, DC. Sparks, D. L Environmental soil chemistry. Academic Press, San Diego, CA. Teh, C. B. S. and Jamal, T Soil physics analyses. Vol. 1. Uni. Putra Malaysia, Serdang, Malaysia. Tessens, E. and Shamshuddin, J Quantitative relationship between mineralogy and properties of tropical soils. UPM Press, Serdang, Malaysia. Topoliantz, S., Ponge, J. F. and Ballof, S Manioc peel and charcoal: a potential organic amendment for sustainable soil fertility in the tropics. Biol. Fert. Soils 41: Uzoma, K. C., Inoue, M., Andry, H., Fujimaki, H., Zahoor, A. and Nishihara, E Effect of cow manure biochar on maize productivity under sandy soil condition. Soil Use Manage. 27: Van Zwieten, L., Kimber, S., Morris, S., Chan, K. Y., Downie, A., Rust, J., Joseph, S. and Cowie, A Effects of biochar from slow pyrolysis of paper mill waste on agronomic performance and soil fertility. Plant Soil 327: Wolf, B A comprehensive system of leaf analysis and its use for diagnosing crop nutrients status. Commun. Soil Sci. Plant Anal. 13: Yuan, J. H., Xu, R. K. and Zhang, H The forms of alkalis in the biochar produced from crop residues at different temperatures. Bioresour. Technol. 102: