Long-term Effect of No-tillage on Soil Organic Matter Fractions in

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1 Long-term Effect of No-tillge on Soil Orgnic Mtter Frctions in Rinfed Argon (NE Spin) Efecto lrgo plzo del no loreo sore frcciones de mteri orgánic del suelo en grosistems de secno en Argón (NE Espñ) Efeito longo przo do plntio direto em frções de mtéri orgânic do solo no sequeiro de Argon (NE Espnh) AUTHORS Received: Revised: Accepted: Blnco-Moure N. csic.es Grci R. 1 Biels A. 1 López M.V. 1 strct This pper ssesses the long-term effect of no-tillge (NT) on soil orgnic cron (OC) content nd its distriution mong different orgnic mtter frctions in rinfed grosystems of Argón (NE Spin). Adjcent fields of NT, conventionl tillge (CT) nd nturl soils (NAT) were compred in three different cerel production res. In the soil surfce, the higher OC content found in the NAT soils ws due to the prticulte orgnic mtter. In the cse of griculturl soils, in generl, the frctions responsile for the OC increse under NT were the fine prticulte orgnic mtter nd the minerl-ssocited orgnic mtter occluded within stle Corresponding Author 1 Deprtmento de Suelo y Agu, Estción Experimentl de Aul Dei, Consejo Superior de Investigciones Científics (CSIC). Apdo. 202, Zrgoz. Spin. resumen En este trjo se evlú el efecto lrgo plzo del no loreo (NT) en el contenido de crono orgánico del suelo (OC) y su distriución en diferentes frcciones de mteri orgánic en grosistems de secno en Argón (NE Espñ). En tres diferentes zons cerelists se comprron cmpos dycentes de NT, loreo trdicionl (CT) y suelo nturl (NAT). En l superficie del suelo, el myor contenido en CO encontrdo en los suelos NAT se deió l mteri orgánic prticuld. En el cso de los suelos grícols ls frcciones responsles del incremento de OC en NL fueron, en generl, l mteri orgánic prticuld fin y l frcción orgno-minerl de los microgregdos estles. resumo Este trlho vli o efeito longo przo do plntio direto (NT) no conteúdo de crono orgânico no solo (OC) e su distriuição em diferentes frções d mtéri orgânic em sistems grícols de sequeiro em Argon (NE Espnh). Cmpos djcentes do NT, plntio convencionl (CT) e solos nturis (NAT) form comprdos em três diferentes áres de produção de cereis. N superfície do solo, o mior teor de OC encontrdo nos solos NAT deveu-se à mtéri orgânic prticuld. No cso dos solos grícols, s frções responsáveis pelo umento de OC em NL form, em gerl, à mtéri orgânic prticuld fin e frção orgno-minerl de microgregdos estáveis. DOI: /SJSS.2011.V1.N1.08 sjss. spnish journl of soil science yer 2011 VOLUME 1 issue 1 116

2 1. Introduction The loss of physicl protection of orgnic cron (OC) y soil ggregtes (Denef et l. 2007), chnges in soil oxygention nd microclimte (Blesdent et l. 2000) nd reduced C inputs to the system (Golchin et l. 1995) hve een identified s the min cuses of the OC decrese in griculturl soils. However, conservtion tillge nd, more specificlly, no-tillge (NT) my enhnce OC ccumultion in the soil surfce compred with CT systems. Recently, López et l. (2009) evluted the ility of NT to increse the soil OC content compring 22 pirs of djcent fields of NT nd CT in different drylnd cerel-growing res of Argon (NE Spin). In this work, soil OC under NT ws etween 8% lower (only in one field) nd 55% higher thn tht found under CT in the 0-20 cm lyer. The higher impct of the NT durtion s well s of other griculture prctices (cropping system, crop residues mngement, etc.) could msk the effect of other influentil fctors s climte nd soil type. The im of the present study ws to further understnding of the contriution of different soil orgnic mtter frctions to the OC increse oserved under NT nd, especilly, of the role of soil microggregtes in the physicl protection of OC in these frming systems. 2. Mteril nd Methods Fields of commercil frms with lrge numer of yers under NT (9-21 yers) were compred with djcent CT fields in three different rinfed cerel res of Argon (Tle 1). At ech site, NAT soil ws lso selected s control soil. Soil smpling (0-5, 5-20 nd cm depths) ws mde in three different zones within ech field (NT, CT nd NAT) where two soil smples were collected nd mixed to mke composite smple. A totl of 27 soil smples were tken from ech site (3 fields x 3 depths x 3 replictes). Once in the lortory, soil smples were sujected to physicl frctiontion, following the method of Six et l. (2000), to otined 4 orgnic mtter frctions: corse prticulte orgnic mtter (cpom, >250 µm in size), fine prticulte orgnic mtter (fpom, µm), minerl-ssocited orgnic mtter occluded within stle microggregtes (Min-µgg, <53 µm) nd esily dispersed minerl ssocited frction (Min-d, <53 µm). Soil OC content ws determined y dry comustion with LECO nlyzer. Soil prticle size distriution ws otined y lser diffrction nlysis with Coulter LS230 lser grin-sizer. Within ech study site, sttisticl comprisons mong tretments were mde using one-wy ANOVA, ssuming rndomized experiment with the three smpling loctions (i.e. smpling zones within ech field) s pseudoreplictes (Christopher et l. 2009). Duncn s multiple rnge test ws used to compre tretment mens (P < 0.05). KEY WORDS Soil orgnic cron, conservtion tillge, prticulte orgnic mtter, minerl-ssocited orgnic mtter PALABRAS CLAVE Crono orgánico del suelo, loreo de conservción, mteri orgánic prticuld, frcción orgno-minerl PALAVRAS- CHAVE Crono orgânico do solo,prepro conservcionist do solo, mtéri orgânic prticuld, frção orgno-minerl sjss. sjss. spnish journl of of soil soil science yer yer issue VOLUME 1 1 specil issue issue 1 117

3 [ Long-term effect of no-tillge on soil orgnic mtter frctions in rinfed Argon (NE Spin) ] 3. Results nd Discussion Tillge effect on totl soil orgnic cron As expected, the highest OC contents were found in the soil surfce of the NAT soils (Figure 1) nd especilly in the Artied site where more rinfll is received (Tle 1). The fct tht the NAT soil of Lnj hs een developed on n ndoned crop terrce (> 40 yers) nd the current pssge of sheep cn explin the reltively low OC content long the soil profile. In the griculturl soils, OC in the first 5 cm of soil ws higher under NT thn under CT in two of the study sites (Lnj nd Torres) with vlues of g kg -1 vs. 10 g kg -1 in CT (Figure 1). In the Artied site, the lck of differences etween oth tretments ws due to the excessive removl of crop residues from the NT field nd the use of the chisel plough in the CT tretment (Tle 1). The differences mong tretments decresed with soil depth due to oth the homogeniztion of soil profile y mouldord ploughing (CT) nd the OC concentrtion grdient in undistured soils (NT nd NAT soils). No effect of soil type ws found on soil OC contents. This ws proly due to the nrrow texture rnge of the study soils (ll medium textured soils). Likewise, men nnul precipittion did not seem to explin the differences in SOC under NT nd CT mong the study sites. Similr results were reported y Alvrez (2005) nd Angers nd Eriksen-Hmel (2008) for wide rnge of soils, climte nd tillge prctices. In our study conditions, proly, higher impct of other griculturl prctices, s crop residues mngement or cropping intensity, could e msking the effect of other site chrcteristics. Tillge effects on soil orgnic cron frctions The esily dispersed minerl-ssocited frction (Min-d) contriuted most to the totl OC content with percentges of % (Figure 1). However, this frction ws not ffected y tillge nd no differences were found etween NT nd CT in ny cse. In contrst, t the surfce lyer, the fpom-c nd the Min-µgg-C were higher under NT thn under CT, lthough not lwys these differences were sttisticlly significnt. The cpom nd fpom frctions hve een considered the first steps on the degrdtion of orgnic deris (Six et l. 2001). Once gin, the lower effect of tillge on the fpom-c in Artied with respect to the other sites cn e ttriuted to the low OC inputs from crop residues in NT nd the use of the Ch plough in the CT tretment. As in the cse of the totl OC content, the fpom- C ws reduced with depth in ll tretments nd Tle 1. Chrcteristics of the griculturl fields. NT, no-tillge; CT, conventionl tillge. M, mouldord plough; Ch, chisel; S, susoiler Site (Province) Men nnul precipittion (mm) Soil type Tretment Soil nd crop residue mngement Lnj (Huesc) 433 Silt lom Clcric cmisol* NT (14 yers) CT Crop residue retention M. No crop residue retention Artied (Zrgoz) 741 Lom Hplic regosol NT (21 yers) CT No crop residue retention Ch. No crop residue retention Torres (Huesc) 468 Sndy lom Clcric cmisol NT (9 yers) CT Crop residue retention M/S/Ch. No crop residue retention * WRB (2007). sjss. spnish journl of soil science yer 2011 VOLUME 1 issue 1 118

4 [ Blnco-Moure N., Grci R., Biels A. & López M.V. ] sites especilly in NT tht showed similr OC contents thn CT in the cm lyer. Numerous studies point to n effect of tillge on the decy of fpom due to the increse of rte of destruction of the ggregtes (Blesdent et l. 2000) nd, thus, the orgnic mtter degrdtion (Denef et l. 2007). Likewise, decrese in the formtion of orgno-minerl complexes within soil ggregtes is often ssocited with the depletion of the fpom frction (Golchin et l. 1995). In fct, in the present study, the seprtion of the Min-µgg-C from the Min-d-C llowed us to ssess the cpcity of NT to enhnce physicl protection of OC within stle microggregtes in the soil surfce. cpom CT cpom NT cpom NAT fpom CT fpom NT fpom NAT Min-μgg CT Min-μgg NT Min-μgg NAT Min-d CT Min-d NT Min-d NAT Totl CT Totl NT Totl NAT 30 Lnj 20 OC (g C kg -1 totl soil) Artied Torres c Soil depth (cm) Figure 1. Soil orgnic cron (OC) frctions s ffected y soil mngement (CT, conventionl tillge; NT, no-tillge; NAT, nturl soil). For the sme frction nd soil depth, different letters indicte significnt differences mong tretments (P < 0.05). sjss. spnish journl of soil science yer 2011 VOLUME 1 issue 1 119

5 [ Long-term effect of no-tillge on soil orgnic mtter frctions in rinfed Argon (NE Spin) ] 4. Conclusions In rinfed cerel res of Argon, the higher OC content found in the soil surfce under NT thn under CT is minly due to the increse of fpom nd Min-µgg frctions. The physicl protection tht stle microggregtes offer to OC seems to e min cuse for long-term soil enrichment in orgnic mtter resulting from the doption of NT in these environments. Results from this onfrm study lso indicte tht proper mngement of crop residues is essentil for successful NT in rinfed Argon, whose influence cn e even greter thn other fctors such s precipittion or soil texture. However, further reserch in roder scenrio of soil type nd climte is necessry to n ccurte evlution of the effect of NT on long-term OC stiliztion in soils. 5. Acknowledgements The uthors wish to thnk M. José Slvdor for lortory ssistnce. This reserch ws supported y the Comisión Interministeril de Cienci y Tecnologí of Spin (Grnts AGL CO2-02/AGR nd AGL CO3-02/AGR) nd the Europen Union (FEDER funds). The first uthor ws wrded with FPI fellowship y the Spnish Ministry of Science nd Innovtion. sjss. spnish journl of soil science yer 2011 VOLUME 1 issue 1 120

6 [ Blnco-Moure N., Grci R., Biels A. & López M.V. ] References Alvrez R A review of nitrogen fertilizer nd conservtion tillge effects on soil orgnic cron storge. Soil Use Mnge. 21(1): Angers DA, Eriksen-Hmel NS Full-inversion tillge nd orgnic cron distriution in soil profiles: A met-nlysis. Soil Sci Soc Am J. 72(5): Blesdent J, Chenu C, Blne M Reltionship of soil orgnic mtter dynmics to physicl protection nd tillge. Soil Till Res. 53(3-4): Christopher SF, Ll R, Mishr, U Regionl study of no-till effects on cron sequestrtion in the Midwestern United Sttes. Soil Sci Soc Am J. 73(1): Denef K, Zotrelli L, Boddey RM, Six J Microggregte-ssocited cron s dignostic frction for mngement-induced chnges in soil orgnic cron in two oxisols. Soil Biol Biochem. 39(5): Golchin A, Clrke P, Odes JM, Skjemstd JO The effects of cultivtion on the composition of orgnic mtter nd structurl stility of soils. Aust J Soil Res. 33(6): López MV, Blnco N, Limón MA, Grci R Siemr direct en el secno rgonés: Efecto sore el crono orgánico en el horizonte superficil del suelo. No Loreo 4: Six J, Elliot ET, Pustin K Soil mcroggregte turnover nd microggregte formtion: A mechnism for C sequestrtion under no-tillge griculture. Soil Biol Biochem. 32(14): Six J, Guggenerger G, Pustin K, Humier L, Elliott ET, Zech W Sources nd composition of soil orgnic mtter frctions etween nd within soil ggregtes. Eur J Soil Sci. 52(4): WRB World Reference Bse for Soil Resources 2006, first updte World Soil Resources Reports No Rome: FAO. sjss. spnish journl of soil science yer 2011 VOLUME 1 issue 1 121