Effect of Humic Substances Extracted from Compost to Plant Growth and Soil Microorganisms

Transcription

1 Dynmi Soil, Dynmi Plnt Glol Siene Books Effet of Humi Sustnes Extrted from Compost to Plnt Growth nd Soil Miroorgnisms Frnis Suárez-Estrell * Mrí del Crmen Vrgs-Grí Mrí José López Joquín Moreno Deprtment of Applied Biology, Miroiology Division, CITE IIB, University of Almerí, L Cñd de Sn Urno s/n, Almerí, Spin Corresponding uthor: * fsurez@ul.es ABSTRACT There re mny produts ville for griulturl use flling into the rod tegory of iologil soil onditioners, stimulnts or dditives. These produt kinds enhne rop growth nd yield through severl mehnisms, suh s miroil inoultion into soil, stimultion of soil miroil tivity, inresing the tivity of ritil enzymes, prodution of phytohormones or supplementing mironutrients. Between these produts, humi ids re nowdys eing used s liquid orgni mendment, sine lose reltionship exists etween soil fertility nd its orgni mtter ontent. In our work, the response of tomto plnts to mendment with humi ompounds (HCs) from severl origins is reported in pot tril. The different sustrtes used were sndy soil (SS) nd nother inert sustrte (IS). The HCs used were potssium humtes from ompost sed on hortiulturl wste () nd leonrdite () were used. Two different ultivrs of tomto (Solnum lyopersium v. Rf type Mrmnde or Durint ) were tested in two pot sustrtes. Results were evluted in terms of plnt growth nd iomss prodution. The effet of these HCs on soil miroil popultions ws lso investigted. Results showed tht the pplition of low rtes of HCs hd n overll stimultory effet on heterotrophi eroi teri, fungi nd nitrogen fixing-teri growth. The ddition hd positive influene on nitrogen fixing-teri nd nitrifying teri popultion when Rf or Durint were used, respetively. Both groups were fvoured when IS ws used. On the other hnd, lower nd thiker plnts were oserved when were pplied to rops. Therefore, results showed the potentil for improving the utiliztion of HCs extrted from ompost sed on plnt wste (). The extrtion of these sustnes () y the proess here desried produed n extrt whih ehved s stimultory sustne on soil-plnt eosystems nd some miroorgnisms relted to the plnt roots. Keywords: humi ids, soil fertility, soil miroil popultions INTRODUCTION The effets of humi ompounds (HCs), the mjor omponent of soil orgni mtter, on plnt growth hve een exmined in reent works (Clpp et l. ; Vrnini nd Pinton ; Nrdi et l. ). The enefiil effets of these sustnes my e either indiret, inresing fertilizer effiieny or reduing soil omption, nd diret, improving plnt iomss prodution (Vughn nd Mlom 9). In this sense, their diret effets on plnts pper to e minly exerted on ell memrne funtions, promoting nutrient uptke, or plnt development, y ting s hormone-like sustnes (Vughn nd Mlom 9; Visser 9, 9; Nrdi et l. 99). On the other hnd, humi olloids lso ffet the growth of soil miroil popultions. Mny soil miroorgnisms from different txonomi nd funtionl groups respond fvourly to the presene of HCs in in vivo or in vitro experiments (Visser 9, 9; Vllini et l. 993; Vldrighi et l. 99; Vllini et l. 997). To explin the stimultory effets of humi moleules on miroes, severl uthors hve proposed the modifition of ell memrne permeility to nutrients s the min mehnism involved (Shisler nd Lindermn 99). Composting onsists of the eroi iologil deomposition of orgni solid sustrtes, in whih mterils re onverted to stle end-produt nmed ompost (Goyl et l. ). This proess is employed world-wide s tretment for orgni wstes suh s sewge sludge nd niml or griulturl residues (Gsser 9; Hung et l. ; Lhdi et l. ). During omposting, orgni mtter is prtilly trnsformed into humus-like sustnes (de Bertoldi et l. 93). Compost n therefore e used diretly in griulture s n orgni mendment to enhne soil fertility. This proess is of inresing importne in southest Spin, where over t of hortiulturl plnt wste is produed nnully (Cr nd River 99). The loss of orgni mtter in most griulturl soils, often to the level of % or less, implies the need to serh for solutions suh s the pplition of HCs to inrese soil qulity. The urrent present mrket for this produt kind hs therefore turned to ompost s possile eonomi soure for the extrtion of suh sustnes (Vldrighi et l. 99, 99; Filip et l. ) insted of reline on expensive fossil mtries suh s leonrdite. The present study ompres the effets of HCs extrted from ompost sed on hortiulturl wste nd those from ommeril liquid fertilizer on plnt growth nd soil miroil popultions using pot experiment rried out with tomto plnts (Solnum lyopersium L.). The oservtion of the long-term response of soil miroil ommunities to the ddition of HCs ws one of the min ojetives of the present work. The effet of these sustnes on plnt growth nd iomss were lso investigted. MATERIALS AND METHODS Humi-like sustnes A onentrted humi extrt from leonrdite () provided from n griulturl ompny (JISA, Jilo Industril, S.A) were used to represent humtes of fossil origin. On the other hnd, HCs from ompost sed on hortiulturl wste () were prepred s follows. Dried nd omposted vegetle residues were digested with KOH.3% for h t C, in the rtio of : (w/v). The Reeived: 9 July,. Aepted: Septemer,. Originl Reserh Pper

2 Dynmi Soil, Dynmi Plnt (Speil Issue ), 9- Glol Siene Books solute frtion ws then seprted from the undigested residue y sedimenttion nd denting nd onentrted times y evportion. KOH ws used s n extrtnt insted of NOH, sine it is more suitle for the industril prodution of humi mendments for griulturl pplitions. The use of KOH to otin humi extrt hs een ove hieved y severl uthors (Vldrighi et l. 99, 99; Vllini et l. 997; Chrest et l. ). Some hemil hrteristis of humi extrts re shown in Tle. In this sense, the humi ontent in ws higher thn the oserved in. However, on the sis of other reserh in whih enefiil spets were oserved when these extrts were used under % (Prdo-Prr 3), oth produts were pplied in queous solution t.7%. Plnts nd sustrtes used in pot trils Two vrieties of tomto were used to determine plnt growth nd prodution in ultivtion experiments nd they re ertified v. Rf, type Mrmnde nd ertified v. Durint (Almeriplnt Semilleros, Almerí, Spin). Pot trils were rried out in the experimentl greenhouse of the Plnt Prodution Deprtment, University of Almerí (Spin). Both sndy soil (SS) nd semi-inert sustrte (IS) on the sis of minly vermiulite (PROJAR, S.A., El Ejido, Almerí, Spin) were used seprtely to ompre the effet of HCs on plnt nd miroil growth. Experimentl design Tomto plnts were grown on seeded during 3 dys up to pproximtely m high. These were lined inside polyethylene gs ( m ) previously filled with SS or IS. The si irrigtion solution ws prepred s desried y Guzmán (3) in Tle eing pplied throughout the experiment on ll tomto plnts. The finl experimentl design onsisted of six loks with replites (plnts) per lok. Plnts were supplied weekly with nd in queous solutions t.7% ut ontrol plnts were not mended with HCs. The weekly ontriution of humtes in queous solution ws plnned s desried in Tle 3 sed on wter onsumption y the plnts. Plnts were loted in rndomized lok in the greenhouse nd grown for dys t onstnt temperture of ± C nd reltive humidity of 7%. Tle Some hemil hrteristis of the humtes tested. Humis extrt C o C ex ph CE 3.%.%.3.9% 3.3% Oxidizle ron (g/ g of onentrted extrt) Alkline-extrtle ron (g/ g of dry mtter) 3 Eletril ondutivity (ms/m) Tle Bsi irrigtion solution (Guzmán 3). Chemil omposition - NO 3 - H PO SO - Cl - + NH K + C + Mg + K+/ (C + +Mg + ) meq/l Tle 3 Contriution of humi extrts in queous solution throughout the smpling time. Week - Wter L/plnt Humi extrt Humi extrt onsuming (L/m ) IS SS ontriution (/m ) ontriution (/plnt) Estimtion of miroil growth After 7,,, nd dys, miroil ounts were tken on 3 seprte soil smples from eh experimentl lok. Totl numer of eroi teri (TB), tinomyetes (TA) nd fungi (TF) were determined on nutrient gr, engle rose nd sodium seinte gr pltes, respetively. Cellulolyti popultion (CEL) ws determined on niline lue lk gr (Krui nd Kushner 9), hemiellulolyti miroorgnisms (HEM) were estimted on xilne-gr medium (He et l. 993) nd ligninolyti miroorgnisms (LIG) were isolted using Poly-R-7 gr pltes (Feritg nd Morrell 99). On the other hnd, nitrogen-fixing teri (NF) were ultured in nitrogen-defiient medium (Burk 93). The other miroil groups were determined y the most prole numer tehnique. Ammonifiers (AM) were evluted in Winogrdsky s sline solution plus oligoelements nd L-sprgine s the only N nd C soure, s reommended y Pohon nd Trdieux (9); Nessler s regent ws used for ssessing the presene of NH 3. The medium for nitrifying teri (NIT) ontined Winogrdsky s sline solution plus CCO 3 nd (NH ) SO. Diphenylmine-sulfuri id regent ws utilized to hek positives tues. The inoulted tues nd pltes were inuted t C for nd -7 dys, respetively. Estimtion of plnt growth nd iomss To ssess tomto growth, six plnts from eh lok were hrvested pproximtely every 3- dys for two months. The prmeters mesured were top height (H), lef numer (L) nd fruit (F) numer, stem dimeter (D), infloresene (I) numer nd height/dimeter rtio (H/D). Additionlly, fresh nd dry weights of root, leves, stem, infloresenes nd fruits were lso determined every dys, pproximtely. All reported vlues were men of six mesurements per tretment nd smpling. Sttistil nlysis In reltion to the effet of the humi extrts on plnt growth nd iomss, ll vlues were expressed s the men of six mesurements for eh prmeter investigted (H, L, F, D, I, H/D rtio, RFB, SFB, LFB, IFB, FFB, RDB, SDB, LDB, IDB nd FDB). Dt were sujeted to one multiftoril nlysis of vrine (ANOVA) in whih men vlues were ompred for the different levels of humi tretment (, nd ), smpling time nd pot sustrte type (IS nd SS). On the other hnd, relting to miroil growth experiment, ounts of the different groups were ompred for the different levels ove ited. Sttistil intertions etween the different levels for eh prmeter were esides investigted (humi tretment X smpling time, humi tretment X sustrte type nd smpling time X sustrte type). Only the most interesting intertions hve een shown in Figs.,,, 7 nd. Sine Rf nd Durint showed notiele differenes, results were nlysed irrespetive of ultivr. In order to determine whih mens were signifintly different (), multiple omprison tests (Fisher s lest signifint differene) were used (Dowdy nd Werden 99). All experiments were rried out twie. RESULTS AND DISCUSSION Effets of humi ompounds on miroil popultions from plnt-soil system Miroil popultions were ffeted when different HCs were dded to ll experimentl loks. The effet oserved depended on the origin of the mendment pplied ( or ) s well s the tomto ultivr used ( Rf or Durint ). Tle shows the signifint influene of the different ftors on ll miroil groups nlysed s well s the influene of the intertions etween them. In generl, severl differenes were oserved when humi extrts were dded to different ultivrs. In this sense, the humi tretment signifintly influened on TB, TF, CEL, LIG nd NF popultions when Rf ws used while this effet ws oserved 97

3 Humi extrt from ompost: effet on plnt nd miroil growth. Suárez-Estrell et l. Tle Effet of Smpling time, Sustrte kind nd Humi tretment on miroil popultions from plnt-soil system. Signifint differenes re oserved t 9% onfidene level (). Rf Ftors TB TA TF 3 CEL HEM LIG NF 7 NIT AM 9 Smpling time Sustrte kind Humi tretment.7 ns.9. ns.. ns ns Intertions Smpling time X Sustrte kind Smpling time X Humi tretment ns ns ns. Humi tretment X Sustrte kind ns ns ns... ns..9 Durint Ftors TB TA TF 3 CEL HEM LIG NF 7 NIT AM 9 Smpling time Sustrte kind Humi tretment. ns. ns. ns.. ns Intertions Smpling time X Sustrte kind Smpling time X Humi tretment.393 ns ns Humi tretment X Sustrte kind ns ns ns. ns. ns. ns Totl Bteri Totl Atinomyetes Totl Fungi Cellulolyti Miroorgnisms Hemiellulolyti Miroorgnisms Ligninolyti Miroorgnisms Nitrogen-Fixing Bteri Ammonifiers Miroorgnisms Nitrifying Bteri non signifint log CFU / g of soil 7 3 TB TF NF CEL LIG Fig. Miroiologil nlyses of Solnum lyopersium v. Rf -soil system treted with two humi ompounds, or. For eh miroil group, olumns with the sme letter(s) re not signifintly different (P <.). CEL: ellulolyti miroorgnisms; LIG: lignoellulolyti miroorgnisms; NF: nitrogen-fixing teri; TB: totl eroi teri; TF: totl fungi. on TB, TF, HEM, NF nd NIT when Durint ws used (Tle ). On the other hnd, in oth ultivrs, the intertions etween the different ftors signifintly influened TA, TF, CEL, LIG nd NF popultions. Figs. nd 3 show the results previously treted s whole, irrespetive of the smpling time. The most interesting intertions etween the different ftors re shown in Figs. nd. In the Rf -soil system, when HCs were dded to the soil, popultions of TA, HEM, AM nd NIT did not differ from those oserved in the ontrol tretment (dt not shown). On the other hnd, ounts of TB, TF, NF nd CEL popultions in nd tretments were, in generl, higher thn those otined in ontrol soils (Fig. ). The popultion of nitrogen-fixing teri (NF) ws prtiulrly higher in the tretment thn in the, nd vlues from ontrol fell in etween them (Fig. ). This effet ws more evident from dys nd when IS ws used (Fig. ). In the Durint -soil system, miroil ounts of TA, CEL, LIG nd AM were not ffeted y the ddition of HCs to the soil. On the other hnd, s oserved in the se of Rf, ounts of TB, TF nd NF popultions were higher Nitrogen-fixing teri (i) 7 Dys Nitrogen-fixing teri (ii) IS Sustrte Fig. Effet of the intertions etween humi ompounds nd time (i) or sustrte (ii) on nitrogen-fixing teri (NF) popultion: Solnum lyopersium v. Rf -soil system. The ANOVA test deomposes the vriility of NF into ontriutions due to the intertions etween vrious ftors. Sine P-vlues re less thn., these intertions hve sttistilly signifint effet on NF t the 9.% onfidene level. when or were dded (Fig. 3). Contrry to the results otined from the Rf -soil system, miroil ounts of HEM nd NIT were lso higher in mended sustrtes (Fig. 3). NIT showed higher ounts thn those otined in the se of sustrtes dded with. These differenes were higher during the seond month nd when IS ws used rther thn SS (Fig. ). Soil degrdtion used y intensive griulture, the use of inpproprite tehnologies or the pplition of gret quntities of pestiides nd fertilizers represents mjor environmentl prolem. Indeed, urrent hortiulturl methods SS 9

4 Dynmi Soil, Dynmi Plnt (Speil Issue ), 9- Glol Siene Books log CFU / g of soil Nitrifying teri (i) TB TF NF HEM NIT Fig. 3 Miroiologil nlyses of Solnum lyopersium v. Durint - soil system treted with two humi ompounds, or. For eh miroil group, olumns with the sme letter(s) re not signifintly different (P <.). HEM: hemiellulolyti miroorgnisms; NF: nitrogen-fixing teri; NIT: nitrifying miroorgnisms; TB: totl eroi teri; TF: totl fungi Dys Nitrifying teri (ii). IS Sustrte Fig. Effet of the intertions etween humi ompounds nd time (i) or sustrte (ii) on nitrifying teri (NIT) popultion: Solnum lyopersium v. Durint -soil system. The ANOVA test deomposes the vriility of NIT into ontriutions due to the intertions etween vrious ftors. Sine P-vlues re less thn., these intertions hve sttistilly signifint effet on NIT t the 9.% onfidene level. led to deteriortion of the physil, hemil nd iologil properties of soil (Alih et l. ). The use of orgni mendments in deteriorted soils improves soil struture nd is soure of ron, nitrogen nd other nutrients, thus fvouring the miroil diversity nd tivity. The preservtion of soil miroil groups is essentil, s they ply n importnt role in ron nd nitrogen yling, the deomposition of orgni mtter nd mintenne of soil fertility (Potter nd Meyer 99). The results otined in this work hve shown tht the pplition of HCs hs signifint impt on severl soil miroil groups. This response ould e ttriuted to the nutritive vlue of humtes from nd. Also, Vldrighi et l. (99) suggest tht potssium dded to hs no stimultory effets on miroil popultions. Severl uthors hve onfirmed tht moleulr hrteristis of HCs my result in higher iologil tivity due to enzymti tivtion of nutrient uptke or modifition of teril ell permeility to nutrients (Vldrighi et l. 99; Tejd et l. ). Counts of totl eroi teri, fungi nd nitrogen-fixing teri were higher in soils treted with HCs thn in ontrol soils (Figs. -3). This effet ws oserved in oth plnt ultivrs tested ( Rf nd Durint ). However, tretment with promoted the highest ounts of nitrogen-fixing (NF) teri with Rf (Fig. ), while the highest ounts of nitrifying teri were otined with Durint (Fig. 3). It is therefore possile tht different plntsoil systems ret differently to the presene of HCs (Vughn nd Mlom 9). Soil miroorgnisms involved in nitrogen yling hve previously een studied s regrds their response to the pplition of HCs. Popultions of utotrophi mmoni nd nitrite oxidizers inresed in soil or xeni ultures mended with humtes from omposted vegetle wste, espeilly t high rtes (Vldrighi et l. 99, 997). On the other hnd, Ae et l. (3) onfirmed the importne of nitrogen-fixing teri to promote miroil rust form- SS Tle Effet of Smpling time, Sustrte kind nd Humi tretment on prmeters relted to plnt growth. Signifint differenes re oserved t 9% onfidene level (). Rf Ftors H L F 3 D I H/D Smpling time Sustrte kind Humi tretment..7 ns... Intertions Smpling time X Sustrte kind Smpling time X Humi tretment. ns ns. ns ns Humi tretment X Sustrte kind.. ns..3. Durint Ftors H L F 3 D I H/D Smpling time Sustrte kind Humi tretment.. ns ns.. Intertions Smpling time X Sustrte kind Smpling time X Humi tretment ns ns ns ns. ns Humi tretment X Sustrte kind ns Top Height Lef Numer Fruit Numer Stem Dimeter Infloresene Numer Height/Dimeter rtio non signifint 99

5 Humi extrt from ompost: effet on plnt nd miroil growth. Suárez-Estrell et l. tion, enhning C nd N yling miroorgnisms nd inresing orgni mtter nd nutrient ontent in deteriorted soils. Effets of humi ompounds on plnt growth nd iomss Tle shows the signifint influene of the different ftors on ll prmeters relted to plnt growth (H, L, F, D, I nd H/D) s well s the sttistil influene of the intertions etween them. In this sense, exepting Fruit Numer nd Stem Dimeter ftors, signifint influenes were in generl oserved when the humi tretment ws independently nlysed. Severl differenes etween oth ultivrs were deteted when sttistilly signifint intertions were nlysed (Tle ). On the other hnd, Fig. shows the results previously treted s whole, irrespetive of the smpling time. The most interesting intertions etween the different ftors were esides shown in Figs. -. Therefore, plnt growth ws ffeted when tomto plnts were mended with HCs depending on the plnt ultivr nd sustrte used. Contrry to expettions, for severl prmeters tretments showed no effet in omprison with ontrol plnts (Fig. ). In Rf, lef (L) nd infloresene (I) numer nd top height (H) inresed when plnts were mended with rther thn plnts. However, signifint differenes were not oserved respet to ontrol plnts (Fig. ). On the ontrry, mesure of stem dimeter (D) ws highest in plnt treted with, espeilly in IS (Fig. ), nd s result these plnts lso hd the lowest H/D vlues (Fig. ). This lst oservtion ourred in oth sndy soil (SS) nd inert sustrte (IS) with dded (Fig. 7). The results otined were different to Durint, exept for H/D. These vlues were lower when were pplied in oth sustrtes, ut espeilly so in IS (Fig. ). Lef (L) nd infloresene (I) numer nd top height (H) were lower when plnts were mended with, ut stem dimeter (D) ws not ffeted y either of the HCs in this ultivr (Fig. ). Finlly, Tle shows the signifint influene of the different ftors on ll prmeters relted to fresh nd dry vegetle iomss (RFB, SFB, LFB, IFB, FFB, RDB, SDB, LDB, IDB nd FDB) s well s the sttistil influene of the intertions etween them. In this se, results otined oth in Rf nd Durint were in generl signifintly influened y the smpling time nd sustrte kind. Opposite to expeted, vegetle iomss prmeters were not ffeted y the humi tretment (Tle ). Therefore, these results show wek effet of HCs on vegetle iomss prmeters. This effet ws surely due to the low onentrtions pplied. However, iomss vlues of plnts mended with were very similr to those of smples treted with. Indeed, for Rf, only stem fresh iomss (SFB) ws higher for tretment thn tretment (Fig. 9). The opposite effet ws oserved for Durint. We must emphsize tht Fig. 9 show the results previously treted s whole, irrespetive of the smpling time. Although neither nor dded to the soil t.7% showed mrked enefiil influene on tomto growth (Fig. ), n interesting effet ws oserved with respet to H/D. The thikest plnts were oserved when were pplied (Fig. ), possily mking less rekle plnts. In Durint, H/D ws signifintly lower for tretment thn (Fig. ). The other prmeters relting to plnt growth or iomss prodution were only slightly ffeted y the pplition of HCs. This my e explined y the low onentrtion of HCs dded to the rop. Indeed, severl uthors hve onfirmed the sene of stimultory effets when humtes were dded to soil t rtes elow - mg.kg - (Vldrighi et l. 99, 99). The physiologil effets of HCs on some spets of plnt growth hve een extensively exmined (Nrdi et l. L. esulentum v. Rf L. esulentum v. Rf L. esulentum v. Rf 3 3 Centimetres H/D Rtio Numer of leves or infloresenes H D L I L. esulentum v. Durint ). These effets minly depend on the soure, onentrtion nd moleulr weight of the HCs pplied. However, mny of the importnt funtions of these sustnes remin osure s their nture is not ler. In this sense, low moleulr size frtion is the mjor ndidte for determining the positive effets of HCs on plnt growth, sine this fr- L. esulentum v. Durint L. esulentum v. Durint 3 3 Centimetres H/D Rtio Numer of leves or infloresenes Fig. Effets of two humi ompounds, nd, on the growth of tomto plnts. For eh growth prmeter, olumns with the sme letter(s) re not signifintly different (P <.). H: top height; L: lef numer; F: fruit numer; D: stem dimeter; I: infloresene; H/D: height/dimeter rtio. H D L I

6 Dynmi Soil, Dynmi Plnt (Speil Issue ), 9- Glol Siene Books Tle Effet of Smpling time, Sustrte kind nd Humi tretment on prmeters relted to fresh nd dry vegetle iomss. Signifint differenes re oserved t 9% onfidene level (). Rf Ftors RFB SFB LFB 3 IFB FFB RDB SDB 7 LDB IDB 9 FDB Smpling time Sustrte kind Humi tretment ns.3 ns ns ns ns ns ns ns ns Intertions Smpling time X Sustrte kind ns. Smpling time X Humi tretment ns ns ns ns ns ns ns ns ns ns Humi tretment X Sustrte kind ns ns ns ns ns ns ns ns ns ns Durint Ftors RFB SFB LFB 3 IFB FFB RDB SDB 7 LDB IDB 9 FDB Smpling time Sustrte kind Humi tretment ns ns.39 ns ns ns ns ns ns ns Intertions Smpling time X Sustrte kind Smpling time X Humi tretment ns ns ns ns ns ns ns ns ns ns Humi tretment X Sustrte kind ns.97. ns ns ns ns ns ns ns Root Fresh Biomss Stem Fresh Biomss Lef Fresh Biomss Infloresene Fresh Biomss Fruit Fresh Biomss Root Dry Biomss Stem Dry Biomss Lef Dry Biomss Infloresene Dry Biomss Fruit Dry Biomss non signifint Stem dimeter (m) perlit IS Sustrte suelo SS Fig. Effet of the intertions etween humi ompounds nd sustrte on stem dimeter: Solnum lyopersium v. Rf -soil system. The ANOVA test deomposes the vriility of stem Dimeter into ontriutions due to the intertions etween vrious ftors. Sine P-vlues re less thn., these intertions hve sttistilly signifint effet on stem dimeter t the 9.% onfidene level. H/D rtio IS Sustrte Fig. 7 Effet of the intertions etween humi ompounds nd sustrte on H/D rtio: Solnum lyopersium v. Rf -soil system. The ANOVA test deomposes the vriility of H/D rtio into ontriutions due to the intertions etween vrious ftors. Sine P-vlues re less thn., these intertions hve sttistilly signifint effet on H/D rtio t the 9.% onfidene level. SS H/D rtio tion esily rehes the inside of plnt ells. Humtes extrted from mture ompost usully hve smller moleulr size thn those extrted from fossil or soil smples (Guzmán 3). Our results hve shown tht soil miroorgnisms esily use these mendments s nutrient soure using the quik loss of these sustnes from the soil. Sine they were dded t low rte, the susequent vilility of these sustnes for plnts ws miniml. CONCLUSIONS perlit IS suelo SS Sustrte Fig. Effet of the intertions etween humi ompounds nd sustrte on H/D rtio: Solnum lyopersium v. Durint -soil system. The ANOVA test deomposes the vriility of H/D rtio into ontriutions due to the intertions etween vrious ftors. Sine P-vlues re less thn., these intertions hve sttistilly signifint effet on H/D rtio t the 9.% onfidene level. The pplition of low rtes of HCs hs n overll stimultory effet on heterotrophi eroi teri, fungi nd nitrogen fixing-teri growth. The ddition hs positive influene on nitrogen fixing-teri nd nitrifying teri popultion when Rf or Durint were used, respetively. Both groups were fvoured when IS ws used nd generlly during the seond month of the ssy. On the whole, lower nd thiker plnts were oserved when were pplied to rops. Therefore, results derived from this preliminry work showed the potentil for improving the utiliztion of HCs extrted from ompost sed on plnt wste (). The extrtion of these sustnes () y the proess here desried produed n extrt whih ehved s stimultory sustne on soil-plnt eosystems nd some miroorgnisms relted to the plnt roots.

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