The Biochar Option to Improve Plant Yields: First Results From Some Field and Pot Experiments in Italy

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1 Itl. J. Agron. / Riv. Agron., 2010, 5:3-11 The Biochr Option to Improve Plnt Yields: First Results From Some Field nd Pot Experiments in Itly Silvi Bronti 1*, Giorgio Alerti 2, Gemini Delle Vedove 2, Filippo Di Gennro 1, Guido Fellet 2, Lorenzo Genesio 1, Frnco Migliett 1, Alessndro Peressotti 2, Frncesco Primo Vccri 1 1 IBIMET-CNR Istituto di Biometeorologi, Consiglio Nzionle delle Ricerche Vi Giovnni Cproni 8, Firenze, Itly 2 Diprtimento di Scienze Agrrie ed Amientli, Università di Udine Vi delle Scienze 208, Udine, Itly Received: 22 August Accepted: 9 Novemer Astrct The pyrolysis conversion of griculturl residues into iochr nd its incorportion in griculturl soil, voids CO 2 emissions providing sfe long-term soil cron sequestrtion. Furthermore, iochr ppliction to soil seems to increse nutrient stocks in the rooting zone, to reduce nutrient leching nd to improve crop yields. This study reports some preliminry results otined using iochr in two typicl Itlin griculturl crops. Two field experiments were mde on durum whet (Triticum durum L.) in Centrl Itly nd mize (Ze mys L.) in Northern Itly. In oth the field experiments, n increse in yields (+ 10% nd + 6% in terms of grin production, respectively) ws detected fter iochr ppliction of 10 t h -1. A further increse in grin production (+24%) ws detected when iochr ws dded with mize residues. The iochr dose-effect curve ws studied on perennil ryegrss (Lolium perenne L.) in pot experiment. The highest increse of dry mtter (+120%) ws otined t iochr rte of 60 t h -1 nd ove this threshold, generl reduction of iomss ws oserved. Results demonstrte the potentil of iochr pplictions to improve in terms of dry mtter production, while pointing out the needs for long-term field studies to etter understnd the effects of iochr on soil. Key-words: Blck cron, crop yield, durum whet, mize, sustinle griculture Introduction Biochr is fine-grined nd porous sustnce, similr in its ppernce to chrcol produced y nturl urning. It is produced y pyrolysis, thermo-chemicl process where iomss is heted in the sence of oxygen. As results, iooil, synthesis gs with different energy vlues nd lck cron (iochr) re otined. Biochr cn e used s soil mendment to improve soil qulity, crop yield nd s cron (C) sequestrtion method. It my improve the physicl structure of the soil (Chn et l., 2007) nd cn lso modify soil hydrulic properties (Chn et l., 2007; Gskin et l., 2007). Given tht the pore size of iochr is reltively fixed, it increses ville moisture in sndy soils while hs neutrl effect in medium textured soils nd decreses moisture vilility in cly soils. In generl, soil orgnic mtter increses soil wter holding cpcity. In iochr-enriched terr pret with their ssocited high levels of orgnic mtter, Glser et l. (2002) found wter retention cpcity tht ws 18% higher thn in the djcent soils. Biochr hs een found to decrese nutrient leching thus enhncing nutrient vilility (Chn et l., 2007; Ymto et l., 2006). Evidence suggests tht iochr porosity contriutes to nutrient dsorption or covlent interction on lrge surfce re. Furthermore, its ction exhnge cpcity (CEC) is consistently higher thn tht of the whole soil (Ling et l., 2006, Lehmnn et l., 2003, Skjemstd et l, 1996; Lehmnn et l., 2005). In fct, the concentrtion of negtive chrges on iochr surfces increses with ge (Cheng et * Corresponding Author: Tel ; Fx E-mil ddress: s.ronti@iimet.cnr.it 3

2 Bronti S., Alerti G., Delle Vedove G., Di Gennro F., Fellet G., Genesio L., Migliett F., Peressotti A., Vccri F.P. l., 2006) s well s the dsorption of chrged orgnic mtter (Ling et l., 2006). According to Lehmnn et l. (2003), leching of mmonium fter iochr ddition to soil ws reduced y more thn 60% over four dys of cropping rice compred to control tretments. Furthermore, these uthors mesured decrese in C, Mg nd nitrte-n leching. Field experiments involving iochr ppliction hve een mde for some crops nd t different loctions, nd positive yield responses hve een often reported (Lehmnn et l., 2003; Ymto et l., 2006; Chn et l., 2007; Rondon et l., 2006; Rondon et l., 2007; Vn Zwieten et l., 2008). Most of these studies ttriuted the positive plnt response to the effects of iochr on nutrients vilility (i.e. nutrient svings in terms of fertilizers or improved fertilizer use-efficiency). Some studies (Ymto et l., 2006; Rondon et l., 2006; Vn Zwieten et l., 2008) ttriuted the positive plnt response to the ility of iochr to increse or mintin the ph of soil, through liming. However, most of studies mde so fr hve een conducted in tropicl, semi-tropicl nd svnnh environments (Kimetu et l., 2008; Vn Zwieten et l., 2008; Sinclir et l., 2008) while there is sustntil lck of studies t mid-ltitudes nd in temperte climtes. Agriculturl mngement my ply role in reducing the net greenhouse gs (UNFCCC, 2008) nd different gronomic strtegies hve een suggested nd tested to reduce soil respirtion rtes nd to increse soil orgnic cron. Those mesures include the conversion of rle lnd to grsslnds, forest plnttions nd the implementtion of crop mngement prctices, such s conservtion tillge nd the introduction of rottions sed on nitrogen fixing crops (Ll nd Bruce, 1999; Ll et l., 1999; Ll, 2002). Recently, Lehmnn et l. (2002) nd Steiner et l. (2004) introduced the concept of converting residues to iochr s n lterntive griculturl method to reduce cron dioxide (CO 2 ) emissions. In fct, iochr cn remin into soil for long time (Glser et l., 2001) due to its stle structure nd complex romtic polycyclic form (Bldock nd Smernik, 2002) thus enhncing the resistnce of C to microil decy (Shindo, 1991; Cheng et l., 2008). Although informtion out turnover time of iochr is scrce nd mostly comes from shortterm decomposition experiments, it hs een suggested tht iochr stores tmospheric C from millennil (Kuzykov et l., 2009) to centennil timescles (Hmer et l., 2004). Bsed on those results, iochr is currently considered s n interesting option to meet mitigtion trgets discussed y United Ntionl Frmework Convention on Climte Chnge (UNFCCC). The ojectives of the present study were to ssess: 1) the effect of iochr doses on ryegrss (Lolium perenne L.) production; 2) the effect of iochr ppliction on durum whet (Triticum durum L.) nd mize (Ze mys L.) yields; 3) the effect on mize yield of iochr ppliction with or without mize s crop residues. Mterils nd methods Biochr Both field nd pot experiments descried in this pper were mde using commercil horticulturl chrcol y Lkelnd Coppice Products (Englnd) otined from coppiced woodlnds (eech, hzel, ok, irch). Biochr ws prepred t pyrolysis tempertures of 500 C in trnsportle ring kiln (215 cm in dimeter nd holding round 2 t of hrdwood). The mteril used ws crushed into prticles smller thn 1 cm efore ppliction to the soil in order to increse the re: volume rtio nd to enhnce its expected effects on soil properties. C nd N iochr contents were determined using CHN Elementl Anlyzer (Crlo Er Instruments, mod 1500 series 2). Smples of iochr were screened y mens of 2 mm sieve nd finlly oven dried t 105 C for 24 h. The dry smples were cid digested with microwve oven (CEM, MARSXpress) ccording to the EPA method 3052 (USEPA, 1995). The solutions otined fter the minerliztion were filtered (0.45µm PTFE) nd diluted. The Aville N ws determined y KCl extrction technique. Totl contents of P, K, S, C, Mg were determined y n ICP opticl spectrometer (Vrin Inc., Vist MPX) using scndium s internl stndrd. The ph ws mesured in soil/wter solution t 1/2.5 rtio. The min chemicl chrcteristics of the iochr used in the present study re reported on Tle 1. 4

3 Itl. J. Agron. / Riv. Agron., 2010, 5:3-11 Tle 1. Chrcteristics of the iochr used in this study. Chemicl Element Biochr Chrcteristics Vlue* Totl C (g kg -1 ) 840 Totl N (g kg -1 ) 12 Aville N (g kg -1 ) 0.03 P (g kg -1 ) 0.5 K (g kg -1 ) 4.3 C (g kg -1 ) 2.6 S (g kg -1 ) 1.1 Mg (g kg -1 ) 2.8 C:N 70 ph (1:2.5 H 2 O) 7.2 * ll concentrtions re on DM sis. Pot experiment In order to sses the dose-response curve of iochr, pot experiment ws mde with perennil ryegrss. Seeds were sown in pots of 5 l (0.2 m of dimeter; 0.2 m of height) filled with sndy-lom soil t rte of 60 seeds per pot corresponding to 24 kg seeds h -1. Six ppliction rtes of 0%, 0.3%, 0.8%, 1.7%, 2.8%, 3.3% (kg of iochr per kg of soil) where tested in fully rndomized experimentl design with three replictes. The iochr doses were equivlent to ppliction rtes of 0, 10, 30, 60, 100 nd 120 t iochr h -1 ssuming soil ulk density of 1.2 g cm -3 up to depth of 30 cm. After mixing, the pots were filled in order to ensure the sme soil ulk density. Min soil chrcteristics re reported in Tle 2. Biochr ws dded efore sowing nd the pots were regulrly irrigted to prevent wter stress, ut not fertilized. Aoveground iomss production ws determined for two growth cycles (one nd two months fter plnt emergence) y mnul clipping. Dry mtter ws determined on oven-dried smples. Field experiments Two field experiments were performed in The first experiment ws mde in griculturl frm ner Empoli (Toscn, Centrl Itly) with durum whet (cv. SOLEX). The field ws locted t n ltitude of 50 m.s.l. with su-humid typicl Mediterrnen climte. According to long term wether dt, totl rinfll ws 750 mm nd the men nnul temperture ws 14 C (ARSIA Toscn, Itly). Min soil chrcteristics of the site re reported in Tle 2. A fully rndomised experiment ws mde in 1.5 m 2 plots with two tretments (control C- nd iochr C+) nd four replictes. Biochr ddition corresponded to n overll rte of 10 t h -1 tht ws incorported in Decemer 2007, n hlf (5 t h -1 ) immeditely efore sowing nd hlf fter germintion. Whet ws sown on 17 th Decemer with seeds density of 450 seeds m -2. A NP fertilizer ws distriuted t this time (22 kg N h -1 nd 50 kg h -1 of P 2 O 5 ) nd second nitrogen fertiliztion using ure (92 kg N h -1 ) ws mde in Ferury Plots were mnully hrvested on 30 th June 2008 in centrl suplot of 0.7 m 2 to minimize edge effects. Totl oveground dry mtter ws oven-dried t 105 C for 48 hours. Then, whet ers were seprted using lortory thresher (LD 350, Wintersteiger, Ried, Austri). Nitrogen concentrtion of seeds ws determined y Kjeldhl nlysis. The second field experiment ws performed in Beno (Friuli Venezi Giuli, Itly) on soil cropped with irrigted continuous mize rottion. The men nnul temperture ws 13.5 C Tle 2. Texture nd chemicl Chrcteristics of the experimentl soils. Pot experiment Empoli Beno Grvel (% of dry ulk soil) > 2mm n.. n.. 32 Snd (g kg -1 ) 2 mm > > 0.05mm Silt (g kg -1 ) 0.05 mm> > 0.002mm Cly (g kg -1 ) < mm Bulk density (Mg m -3 ) 1.6 n OC (g kg -1 ) n N (g kg -1 ) n CEC (meq/100g) n.. 16 n.. ph c ) Orgnic Cron (OC) content ws determined using CHN uto-nlyser (CHN 1500, Crlo Er). ) Ction Exchnge Cpcity (CEC) ws determined using NH 4 OAc method. c) The ph ws mesured in 1:2.5 (mss/vol) soil solution. 5

4 Bronti S., Alerti G., Delle Vedove G., Di Gennro F., Fellet G., Genesio L., Migliett F., Peressotti A., Vccri F.P. with totl rinfll of 1216 mm (OSMER Friuli Venezi Giuli). The tretments were control (C-) nd iochr ddition (10 t h -1 ) with (CR) or without (C+) residues of preceding mize. The three tretments where rrnged in rndomized lock experiment with three replictes. Ech experimentl plot hd n re of 20 m 2. On April 4th the cv Kermess (from KWS mturity FAO clss. 600) ws sown t 7.2 seeds m -2. Fertiliztion ws mde t sowing dding 54 kg N h -1 nd 138 kg P 2 O 5 h -1 in the form of di-mmonium phosphte. Ure ws then dded t two dtes for totl of 359 kg h -1 of N (83 nd 276 kg N h -1 on 09/05/2008 nd 03/06/2008, respectively). The plots were weekly irrigted nd no wter stresses were detected. Aoveground dry mtter nd yield were mesured t hrvest in re of 9 m 2 voiding order effects of ech plot. Min soil chrcteristics of the site re reported in Tle 2. Sttisticl nlyses Tretment effects were nlysed y nlysis of vrince (ANOVA) using SAS 9.1 (SAS Institute Inc., Cry, NC, USA). The ANOVA included tretment C- nd C+ in the durum whet experiment nd C-, C+ nd CR in the mize experiment. Since the experiment ws lock design, lock effect ws lso included. Significnt tretment effects (p < 0.05) were explored further vi posteriori tretment comprison using the Lest-Squres mens (LSMEANS) test with Bonferroni djustment for multiple comprison. Results Pot experiment The higher ws the rte of iochr dded to the soil, the higher ws the dry mtter of ryegrss up to threshold of 60 t iochr h -1 (Fig. 1). A significnt difference mong tretments ws detected (p = 0.012). The ryegrss iomss incresed y +29% nd +120% t first clipping nd +40% nd 140% t second clipping in 0.8% of iochr (30 t h -1 ) nd 1.7% (60 t h -1 ) tretments, respectively. Germintion ws ccelerted in the pots were iochr ws dded s likely consequence of incresed soil temperture (dt not shown). Negtive effects of iochr were oserved ove 1.7% of iochr (60 t h -1 ). Field experiments In the field experiment with durum whet, the phenologicl development of the whet ws not ffected y iochr ddition. In fct, no differences were found etween the tretments nd no mjor iotic nd iotic stresses were oserved during the experimentl period (dt not shown). The oveground iomss ws insted enhnced y iochr. The oserved stimultion ws 23% respect to control with vlue of 10.4 t h -1 nd 8.6 t h -1 in C+ nd C-, respectively (Fig. 2; p = 0.054). Similrly, grin production ws stimulted y 10% with vlue 3.1 t h -1 nd 2.4 t h -1 in C+ nd C-, respectively, ut the significnce of difference ws low (p = 0.082). The nitrogen content of the whet grins ws not pprecily different etween treted nd First growth cycle Second growth cycle 0.6 Figure 1. Aoveground iomss of Lolium perenne in the lortory experiment in the first nd second growth cycle t different rtes of iochr (t h -1 ). Ech vlue is the verge of 3 replictes. Verticl rs indicte +/- stndrd error. Different letters indicte significnt difference respect to control (rte of iochr corresponding to 0) (p < 0.05). Dry Mtter (t h -1 ) Biochr Rte (t h -1 ) 6

5 Itl. J. Agron. / Riv. Agron., 2010, 5: Aoveground iomss Grin iomss Dry Mtter (t h -1 ) C- C+ Figure 2. Aoveground iomss (open rs) nd grin production (solid rs) of durum whet in the field experiment in Empoli (Centrl Itly). C+ is the iochr, C- is the control. Ech vlue is the verge of 4 replictes. Verticl rs indicte +/- stndrd error. Different letters indicte significnt difference (p < 0.05). un-treted plots (1.8% for control nd 1.84% for iochr tretment). In the field experiment on mize, plnt density t the end of the growing seson ws not significntly different mong tretments (dt not shown). Aoveground iomss ws lso not significnt (p = 0.068): 17.9, 22.5 nd 25.8 t h -1 in C-, C+ nd CR, respectively. Grin production, insted, ws significntly different (p < 0.01) (Fig. 3). In fct, reltive increse of grin yield in C+ nd CR in comprison to C- (+6% nd +24%, respectively) ws mesured: 9.7, 10.3 nd 12.1 t h -1 in C-, C+ nd CR, respectively. However, Bonferroni test showed significnt difference in grin yield etween C+ nd CR (p < 0.05) nd etween C- nd CR (p < 0.01), while no difference ws detected etween C+ nd C- (p > 0.05). Discussion Agriculturl productivity is often reported to increse with iochr ppliction to soil, ut lwys not consistently. It is not yet cler wht re the soil climtic conditions tht fvour incresed yields, nd wht re the most responsive species (Lehmnn nd Rondon, 2006). Our results in the lortory experiment showed tht the rte of iochr ppliction of 1.7%, corresponding to 60 t h -1, cused the mximum stimultion in terms of dry mtter production in perennil ryegrss. Aoveground production stimultion y iochr ddition ws lredy oserved for grsses (Rondon et l., 2006; Lehmnn nd Rondon, 2006) nd this ws interpreted s n overll meliortion of growth condition. In our study incresed vilility of nitrogen ws supposed to e responsile for in- 30 Aoveground iomss Grin iomss 25 Dry Mtter (t h -1 ) C- C+ CR Figure 3. Aoveground iomss (open rs) nd grin production (solid rs) of mize in the field experiment in Beno (Northern Itly). C+ is the iochr, C- is the control nd CR is the iochr + residues, respectively. Ech vlue is the verge of 3 replictes. Verticl rs indicte +/- stndrd error. Different letters indicte significnt difference (p < 0.05). 7

6 Bronti S., Alerti G., Delle Vedove G., Di Gennro F., Fellet G., Genesio L., Migliett F., Peressotti A., Vccri F.P. cresed dry mtter production (Gthorne- Hrdy et l., 2009) s improved wter vilility ssocited to iochr ddition cnnot e considered ecuse the pots were mintined t the field cpcity throughout the experiment y mens of mple irrigtion. Aove the 1.7% (60 t h -1 ) threshold, the dry mtter production of perennil ryegrss strted to decline, proly ecuse some chemicl nd physicl properties of the soil were modified y the high rte of iochr pplied. A possile explntion ws given y Kishimoto nd Sugiur (1985) nd Mikn nd Arms (1995) who oserved generl decrese of the iomss t high rte of the iochr ppliction due to micronutrient deficiency induced y the incresing soil ph. Direct toxicity effects my lso provide n explntion, lthough these were not specificlly investigted. Even smll iochr rte of 10 t h -1 incresed oveground iomss (23%) nd grin yield (10%) of durum whet compred to control. Comprle results were otined y Steiner et l. (2007). A strict correltion etween totl iomss production nd grin yield is well known to exist in whet s the hrvest index is hrdly ffected y different mngement nd yield levels (Speth nd Sinclir, 1995; Bindi et l., 1998). The oserved yield stimultion ws likely due to comintion of improved soil wter conditions (Lehmnn nd Steiner, 2009), reduced nutrient leching (Yni et l., 2007) improved soil structure nd ggregte formtion in the soil (Lehmnn nd Steiner, 2009). Incresed nutrient vilility following iochr ddition ws oserved in other field studies (Rondon et l., 2007). In our experiment, the lck of difference etween the N-content of the grins of treted nd untreted plnts cnnot support the soil incresed nutrient vilility. A positive effect on oth oveground iomss nd grin ws lso oserved in the field experiment on mize. An increse of 26% nd 6% in C+ nd 44% nd 24% in CR for oveground iomss nd grin, respectively, ws oserved. A similr response ws lso oteined y Oguntunde et l. (2004). The higher increse oserved in CR in comprison to C+, even though not significnt, is in greement with other studies (Glser et l., 2002) nd cn e interpreted s result of the positive effect of mize stover residues of previous crop on the micro-scle physicl properties of soil ggregtes, promoting their formtion nd stility (Blnco-Cnqui nd Ll, 2008). Beneficil effects of iochr in terms of incresed crop yield nd improved soil qulity hve een reported in severl other studies (Iswrn et l., 1980; Glser et l., 2002). However, Glser et l. (2002) underlined the fct tht crop yields cn e incresed only if iochr is pplied together with inorgnic or orgnic fertilizer s in the present study. In fct, Steiner et l. (2008) mesured oth higher soil N retention nd n enhnced N cycling in fertilized plots tht received iochr. This could e due to reduction in N leching (higher retention of NH 4+ ; N immoiliztion in microil iomss) or to reduction of denitrifiction (Yni et l., 2007) nd we suppose tht this is the min mechnism tht cn explin the oserved yields increse in oth our field experiments. However, there could e other importnt interctions to explin the iochr stimultion of crop yield mostly relted to its higher stility in comprison to other orgnic mendments s well s the ntive soil orgnic mtter (SOM) (Steiner et l., 2007). Biochr cn cpture high mounts of exchnge ctions (Lehmnn et l., 2003) ecuse of its high porosity nd surfce/volume rtio nd cn improve plnt nutrients uptke nd P, C, K vilility (Chn et l., 2007; Ymto et l., 2006). Biochr should no longer e seen s n inert mteril tht remins unltered in the soil where it is deposited. In fct, during its permnence in soils, iochr is slowly oxidized, croxylic groups re produced, ction exchnge cpcity nd oxygen cron rtio on the iochr surfce increses (Brodowski et l., 2005), improving the cpcity of iochr to retin nutrients in the long term. However, chemicl nd physicl chrcteristics of iochr depends on the nture of the feedstocks used nd on the operting conditions of pyrolysis process (Gundle nd De Luc, 2006). Therefore, yield responses re currently difficult to predict, nd glol ptterns need to e identified to move towrds n understnding of the crop production potentil using iochr. Conclusions The results shown in this pper highlight numer of conclusions tht cn hve prcticl im- 8

7 Itl. J. Agron. / Riv. Agron., 2010, 5:3-11 portnce for future experiment nd rel-world ppliction of iochr in griculture. A. Positive effect on growth nd yield re sustined even t very high rtes of iochr ddition to the soil. In the pot experiment, negtive effects were oserved when more thn 1.7% (60 t h -1 ) of iochr were dded. The preliminrily type of investigtion nd the limited prediction cpcity of the pot experiment do not llow excessive generliztion, ut outline the fct tht negtive effects re unlikely under-relistic ppliction scenrios. The ddition of t h -1 of iochr, to 30 cm deep soil would in fct correspond to % rte, elow the 1.7% rte over which negtive effect were oserved; B. Even reltively smll rtes of iochr ddition cn hve positive effects on crop growth nd yield. Although the limited scope of our initil tril does not llow to properly understnd the mechnism underlying the oserved increse in yield, there re convincing indictions tht iochr cts s soil mendnt cple of enhncing resource vilility for the crop. Higher soil N-retention cn e responsile for incresed productivity (Steiner et l., 2008) ut lso enhnced N-cycling (reduction of denitrifiction) cn contriute (Yni et l., 2007). Incresed soil wter cpcity, mechnicl chrcteristics promoting soil orgnic mtter stiliztion (Steiner et l., 2007), the vilility of high mounts of exchnge ctions ssocited to high porosity of iochr (Lehmnn et l., 2003) re dditionl fctors tht require further specific investigtion in field experiments; C. Enhnced yield nd soil meliortion due to iochr ppliction is lwys ccompnied y long-term C-sequestrtion. When plnt residues re trnsformed into chr y pyrolisis they rech very stle condition tht cn only e prtly decomposed y soil micro-orgnisms. There is evidence in literture tht the lrgest prt of cron contined in the iochr cn remin undecomposed for hundred yers or even millenni; D. The positive effects of iochr ppliction nd its potentil for C-sequestrtion re ccompnied y the production of therml-energy during the pyrolisis. When such energy is efficiently used it cn replce the use of fossil fuels nd therefore further contriute to n overll reduction of net emission of greenhouse gses to the tmosphere. Our study must e seen s first ttempt to frme the reserch of iochr within coherent scientific pproch in Itly. More studies re definitely required to expnd phenomenologicl oservtion nd to improve our mechnistic understnding of processes. Acknowledgment Diego Chià (University of Udine) is cknowledged for vlule technicl ssistnce during the field experiment. This study contriutes to the y the Itlin Biochr Assocition (ICHAR References Bldock J.A., Smernik R.J Chemicl composition nd iovilility of thermlly ltered Pinus resinos (Red pine) wood. Org. Geochem., 33: Bindi M., Sinclir T.R., Hrrison J Anlysis of seed growth y increse in hrvest index. Crop Science, 39: Blnco-Cnqui H., Ll R Corn Stover removl impcts on micro-scle soil physicl properties. Geoderm, 145: Brodowski S., Amelung W., Humier L., Aetz C., Zec W Morphologicl nd chemicl properties of lck cron in physicl soil frctions s reveled y scnning electron microscopy nd energy-dispersive X-ry spectroscopy. Geoderm, 128: Chn K.Y., Vn Zwieten L., Meszros I., Downie A., Joseph S Agronomic vlues of greenwste iochr s soil mendment. Aust. J. Soil Res., 45: Cheng C.H., Lehmnn J., Engelhrd M.H Nturl oxidtion of lck cron in soils: Chnges in moleculr form nd surfce chrge long climosequence. Geochim. Cosmochim. Ac., 72: Cheng C.H., Lehmnn J., Thies J.E., Burton S.D., Engelhrd M.H Oxidtion of lck cron y iotic nd iotic processes, Org. Geochem., 37: Gskin J.W., Speir A., Morris L.M., Ogden L., Hrris K., Lee D., Ds K.C Potentil for pyrolysis chr to ffect soil moisture nd nutrient sttus of lomy snd soil. In: Georgi Wter Resources Conference. University of Georgi. Gthorne-Hrdy A., Knight J., Woods J Biochr s soil mendnt positively intercts with nitrogen fertilizer to improve rley yields in the UK. IOP Conf.Series: Erth nd Environmentl Sciences 6 doi / /6/7/

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