Inorganic Phosphorus Fractions Dynamics Following Phosphorus Application on Maize in Acid Soils

Transcription

1 Amerin-Eursin J. Agri. & Environ. Si., 8 (6): 793-8, ISSN IDOSI Pulitions, Inorgni Phosphorus Frtions Dynmis Following Phosphorus Applition on Mize in Aid Soils 3 Thienkou, Wolfgng, Zeh nd Nterngy Snging Institute of Agriulturl Reserh for Development P.O. Box 67 Youndé, Cmeroon University of Byreuth, University of Byreuth D-9544 Byreuth Germny 3 Tropil Soil Biology nd Fertility, P.O. Box 3667 Niroi Niroi, Keny Astrt: Soil properties influene phosphorus prtitioning into funtionl pools nd plnt response to fertilizer pplition. A greenhouse experiment ws onduted using three id soils from southern Cmeroon in order to i) hve etter understnding of soil properties intertions with inputted P on mize performne nd ii) ssess hnges in oneptul inorgni soil P pools. The soils whih lssified s Typi Kndiudox (), Rhodi Kndiudult () nd Typi Kndiudults () reeived 5 P rtes rnging from to 98.6 mg P pot. Soil hrteriztion reveled gret differenes in terms of physil soil properties nd inorgni oneptul P pools. For ll soils, NHCO3-Pi represented less thn % of totl inorgni P (TIP) while NOH-Pi nd HSO4- Pi pools emerged s the lrgest ounting for 3. nd 85.% of TIP, respetively. The oserved P pools trend in the order HCl-Pi<NHCO3-Pi<NOH-Pi <HSO 4-Pi onfirmed the Wlker nd Syers model of P trnsformtion over time. All soils were P-responsive with dry mtter yield (DMY) inresing in the order >>. Phosphorus fertiliztion indued differentil inreses in inorgni P pools with exponentil models est explining the dynmis of NHCO3-Pi pool with R etween.87 nd.94. The HCl-P showed no onsistent trend while NOH-Pi nd HSO4-Pi s the most enrihed pools followed liner models. Soil plnt-system ordintion through prinipl omponent nlysis indited tht C nd other si tion levels influened signifintly P nd N uptke nd photosynthte llotion. Key words: Aid soil South Cmeroon Greenhouse Inorgni P frtions Ze mys L INTRODUCTION suh s minerlogy of the prent mteril, soil texture []. In Cmeroon, soil fertility is evluted through trditionl Ferrlsols ound on stle lndspes of the soil tests suh s Bry or Olsen P [3]. Phosphorus humid tropis. These re inherently infertile soils with ville to plnts for uptke is perpetully in equilirium low levels ville phosphorus (P), si tions nd with other P forms not mesured y trditionl soil P tests nitrogen []. They re trditionlly ropped using shifting [4]. This highlights the neessity to mesure these other ultivtion tehniques whih mke use of no fertilizers. soures known to ontriute to plnt P nutrition. Different In the perspetive of stilizing lnd use in these regions, sequentil frtiontion proedures hve een developed strtegies for enhning soil fertility re needed. tht extrt different forms of P in the soil [5,6]. These If nitrogen n e replenished iologilly through proedures ssign differentil liility to hemil P pools symioti fixtion, P vilility depends on inherent soil nd hve een used to investigte lndspe pedologil ondition imposed y prent mteril geohemistry, soil evolution [7], fte of P fertilizers in soils [8,4,9] nd development stge nd mngement prties. In reent funtionl reltionships mong pools []. The min yers, with the eonomi development of the ountry, ojetives of this study were to hve omprehensive mize ultivtion hs gined importne evolving into understnding of soil properties intertions with ommerilly-oriented systems. Soil phosphorus inputted P on mize growth response to phosphorus nd hemistry is omplex; its vilility in most eosystems hnges in P sttus using oneptul P pools of three depends on soil properties tht regulte P vilility, id soils from Southern Cmeroon. Corresponding Author: Thienkou, Institute of Agriulturl Reserh for Development P.O. Box 67 Youndé, Cmeroon, Tel , E-mil: mthienko@yhoo.om, 793

2 Am-Eurs. J. Agri. & Environ. Si., 8 (6): 793-8, MATERIALS AND METHODS nd N ontents in shoot nd root mize smples were determined following [3]. A simplified four-step Greenhouse Experimenttion: The soils used for the sequentil extrtion proedure dpted from [6] ws used iossy were olleted from 3 sites in southern to evlute the soil P sttus efore nd fter pot Cmeroon: Minkomeyos ( 5 5 E, N), experimenttion. Aout g of soil ws weighed in 5-ml Ang ( 3 34 E, 3 34 N) nd Mengomo entrifuge tue nd 3 ml of suessive extrtions were ( 45 E, 35 5 N). These sites re representtive dded. The tues were shken overnight for 6 hours with of rnge of id soils developed from Premrin the suessive extrting solutions (i).5 M NHCO3 t sement roks nd overing extensive res in southern ph 8.5 [4], (ii). M NOH, (iii).5 M HCl nd finlly with Cmeroon nd the whole Congo sin. They re M HSO4fter ignition t 55 C. At eh step of the respetively lssified, t the sugroup level of the US sequentil extrtion proedure, entrifugtion ws soil txonomy (Soil Survey Stff, 994) s Rhodi rried out t 3 rpm for 5 min. Totl inorgni P ws Kndiudult (), Typi Kndiudult () nd Typi lulted s the sum of P forms mesured sequentilly. Kndiudox (). These soils hve koliniti ly All phosphorus nlyses were done using the minerlogy with only tres of hlorites, qurtz nd molydenum lue method []. interstrtified minerls minly in the soils. A omprehensive desription of these soils nd their setting Dt Proessing nd Sttistil Anlyses: n e found elsewhere (). In eh of the 3 sites, surfe Phosphorus uptke in shoot nd umultion in horizon (- m) ws olleted in 4 fields under to roots (PAR) were lulted s the produt of P yers- Chromolen odort fllow. The greenhouse onentrtion times shoot or root iomss dry mtter experiment ws rried out t the Interntionl Institute yield (DMY). Phosphorus uptke effiieny (PUE) ws for Tropil Agriulture, Youndé (Cmeroon). Plsti defined s the verge hnge in shoots DMY otined pots were filed with 5 kg of sun-dried soil mteril rushed per unit of hnge in P input. One wy nlysis of to pss 4-mm sieve. Phosphorus ws pplied in the vrine ws used to ssess wht soil properties nd form of simple superphosphte t rtes of, 33.9, 66.8, inorgni P pool vried ross soil types. In se of 3.36 nd mg P pot. These rtes orresponded sttistil signifine (P<.5), mens were seprted to, 7.5, 5., 3. nd 45. kg P h respetively. A sl using the DIFF option of the LSMEANS sttement. A pplition of mg of K in the form of KCl nd 8 two-wy nlysis of vrine (ANOVA) ws lso used to mg N in the form of ure ws pplied in eh pot to evlute P rte nd soil type effets on soil P frtion insure dequte supply of N nd K. Six lirted mize dynmis, mize growth nd P uptke ssessment (Ze mys L. v CMS 874) seeds were sown initilly nd vriles. The predited mximum ttinle DMY ws thinned to 4 plnts 6 dys fter plnting (DAP). Pots were otined y tking the first derivtive of the DMY s rrnged in ompletely rndomized lok design with expressed y the qudrti polynomil models set t P 4 replites. The pots were rought to 6% field pity rte =. In order to explore the omplex intertions dily y wtering with deionized wter. At hrvest 4 etween soil properties, P rte nd plnt growth DAP, shoots were ut off t the soil surfe nd weighed. prmeters, prinipl omponent nlysis (PCA) ws The roots were hnd-sorted from the soil, wshed with used. Nturlly, some degree of orreltion were found wter on -mm sieve. Root nd shoot weights were etween soil nd plnt growth vriles used ut they determined fter drying in the oven t 65 C for 3 dys. were mintined in redundnt model in order to pture Soils from pots were removed, ir-dried nd smpled for hidden spets of soil-plnt system funtioning. P sequentil frtiontion nlyses. Component retention ws sed on the riteri of eigen vlue more thn nd intuitive interprettion mde tking Lortory Anlyses: All routine physio-hemil into onsidertion underlying vriles with loding nlyses were rried out on ir-dried soil smples ground solute vlue more thn.4. Regression nd stepwise to pss -mm sieve following onventionl methods. regression nlyses were used to fine-tune reltionships Oxlte-extrtle Fe ws determined ording to highlighted y PCA nd determine whih soil vriles Shwertmnn []. Lile P ws mesured following the nd/or P pools optimise DMY nd P uptke estimtions. Bry- P method (.3 M NH4F nd. M HCl) nd P All sttistil nlyses were performed using SAS sorption ording to Blkemore et l. []. Phosphorus sttistil pkge [5]. 794

3 Am-Eurs. J. Agri. & Environ. Si., 8 (6): 793-8, RESULTS Inherent Soil Properties nd Ntive Inorgni Frtions: The one-wy ANOVA indited tht the studied soils ontrsted y most of their properties (Tle ). The soils hd signifintly higher ly ontent, lower level of exhngele C, Mg nd K, higher level of P sorption nd exhngele Al. The soils hve reltively higher mounts of snd nd silt. The soils hve higher soil retion nd morphous iron. The trends in inorgni P pools were similr ross the investigted with the greter proportion P eing found in the residul nd NOH-P extrtle pools. The NHCO3-P pool onsidered s plnt ville ws signifintly higher in while higher vlues of NOH-P nd residul P were found in the. Soil Properties nd Inorgni P Reltionships to Mize Growth: Shoot nd root DMY differed signifintly ross soil type nd P rte. The intertion term ws however not signifint (Fig. ). Shoot DMY trends s funtion of P rte were est explined y qudrti polynomil models with oeffiients of determintion etween 66.6 nd 89.7%. The highest shoot DMY ws oserved in with ontrol vlue of.4 g pot. The lowest vlue ws oserved in with ontrol DM of 6.8 g pot. Tle : Men ± S.E of seleted properties nd inorgni P frtions of the studied soilsof the soil used. Soil properties Snd (%) 4.8 ± ± ±3. Silt (%). ± ±.9.4 ±.9 Cly (%) 48.9 ± ± ± 3.8 ph wter 4.5 ±. 5.4 ±. 5. ±. OC (g kg ).5 ±.9 6. ±. 9. ±. TN (g kg ). ±..6 ±.. ±. C (mol(+) kg ). ±..35 ±.7.9 ±.4 Mg (mol(+) kg ).33 ±..64 ±.6.7 ±.3 K (mol(+) kg ).8 ±..6 ±.4.4±. Al (mol(+) kg ).63 ±.3. ±..6±.7 P sorption (%) 88.3 ± ± ± 5.6 FeOx (%).69 ±.4.3 ±.7.86±.5 NHCO3-Pi.7 ±.3 3. ±.5. ±.3 NOH-Pi (mg kg ) 5.4 ±3. 9. ±. 3. ± 3.8 HCl-P (mg kg ). ±.5.86 ±.38.8 ±. Residul P (mg kg ) 54. ± ±. 9.9 ± 3.8 For eh property, vlues long the sme row not followed y the sme letter re sttistilly different t P<.5. Predited mximum ttinle DMY ws signifintly lower in (6. g pot ) ompred to 35.6 nd 36.7 g pot for nd, respetively. Phosphorus rte nd soil type hve signifint impted on root/shoot 5 4 DMY = -.8P +.33P +.43 R =.9 Shoot DMY(g/pot) 3 DMY = -.6P +.538P R =.85 DMY = -.5P +.97P R = P rte (mg/pot) Fig. : Dry mtter yield response s relted to pplied P rte. Oserved (symols) nd fitted regression models 795

4 Am-Eurs. J. Agri. & Environ. Si., 8 (6): 793-8,.. Root/shoot rtio Root/shoot rtio Soil ph Exhngele Al (mol(+)/kg) Root/shoot rtio.6.4. Root/shoot rtio C (mol(+)/kg) Mg (moll(+)/kg)..8 Root/shoot rtio K (mol(+)/kg) Fig. : Stter digrms showing the vrition in root/shoot rtio s funtion of ph, exhngele Al nd exhngele ses rtio with 88.% of the vrine eing ounted for y soil type. Root/shoot rtio ws relted to severl soil properties. Those tht were negtively orrelted with the root/shoot rtio were soil ph, exhngele C, Mg nd K (Fig. ). Fertiliztion Effets on P Pools: Phosphorus fertiliztion improved the soil P sttus with signifint differenes ross oneptul inorgni P pools. All pools were inresed with inresing P rte exept for the HCl Pool whih yielded no onsistent trend. (Fig. 3). Exponentil models est explined the dynmis of NHCO3-Pi pool with R etween.87 nd.94. The HCl-P frtion seemed to pek following the seond nd third rte of P input. Using urviliner models ounted for 76.8 % of vrition in HCl-P in nd only 38.8 nd 4. for nd, respetively. NOH-Pi nd residul P inresed linerly with inresing P rte One-wy ANOVA results in ontrol pots whih reeived no P fertilizer pointed t differentil hnges in inorgni P frtions ross soil 796

5 Am-Eurs. J. Agri. & Environ. Si., 8 (6): 793-8, NHCO3- P (mg P/kg) 8 4 y =.48e.74 R =.94 y =.958e.73 R =.8699 y =.483e.7 R = P input rte (mg P/pot) HCl-P (m P/kg) P input rte (mg P/pot) d NOH-P (mg P/kg) 4 y =.44x R =.955 y =.39x R =.963 y =.36x R = P input rte (mg P/pot) Residul P (mg P/kg) 5 5 y =.348x R =.9 y =.86x R =.94 5 y =.54x R = P input rte (mg P/pot) Fig. 3: Soil P pool responses to P input s ffeted y soil types types (Fig. 4). The gretest vritions in NHCO3-Pi stepwise regression nlysis with C, Mg, K nd pool were oserved in nd with 47 nd exhngele Al s independent vriles explined 67. 9%, respetively. In soils, the NHCO3-Pi pool % of vrition in root shoot rtio. The seond omponent ws signifintly depleted, giving vlues lose to (PC) ws highly weighted on shoot DMY, P nd N detetion limits y trditionl olorimetri determintion uptke, N umultion in roots. Also signifintly loded proedures. to PC were idity-relted vriles (soil ph nd exhngele Al) nd the lile NHCO3-Pi frtion. Using Prinipl Component Anlysis of the Soil-mize System: stepwise regression nlysis with NHCO3-P i, Prinipl omponent nlysis of the soil-mize system ws exhngele Al nd OC s independent vriles sed on the omplete dt set model nd yielded 5- explined 63.4% of vrition in shoot DMY. The third omponents whih ounted for 88.% of totl system omponent ws highly loded on soil orgni mtter vrine (TSV) (Tle ). The first omponent ssoited omponents, morphous Fe nd exhngele K, P rte with 3.% of TSV ws underlin y wide rnge of nd their effet on P uptke. Other signifint ontriutors vriles tht inluded C nd other si tions (Mg to PC3 inluded the silt frtion, soil ph, exhngele Al, nd K), the root/shoot rtio, inorgni soil P pool th P uptke nd shoot dry mss. The 4 omponent frtions, P soring pity, soil texturl frtions nd highlighted soil texturl seprtes vrition ross soil ph wter. All plnt-relted vriles ontriuted types ut lso morphous Fe. The lst omponent signifintly to PC exept DMY nd P uptke. A unidimensionl trgeted HC extrtle P. 797

6 Am-Eurs. J. Agri. & Environ. Si., 8 (6): 793-8, Bironte P (mg/kg) 4 3 Initil 4 DAP C HCl-P (mg/kg).5.5 Initil 4 DAP Soil type Soil type NOH-P Soil type Initil 4 DAP d Residul P (mg/kg) Soil type Initil 4 DAP Fig. 4: Chnges in P pools in exhustive ropping Tle : Prinipl omponent (PC) nlysis of the greenhouse experiment Soil vriles PC PC PC3 PC4 PC5 P rte (g P pot ) DMY shoot (g pot ) DMY root (g pot ) root/shoot rtio P uptke (g P pot ) N uptke (g N pot ) PAR (g P pot ) NAR (g P pot ) NHCO3-Pi (mg kg ) NOH-Pi (mg kg ) HCl-P (mg kg ) Residul P (mg kg ) Snd (%) Silt (%) Cly (%) ph wter Totl N (g kg ) Totl C (g kg ) C (mol(+) kg ) Mg (mol(+) kg ) K (mol(+) kg ) Exh. Al (mol(+) kg ) Feox (%) P sorption (%) Eigen vlue Proportion (%) Highlighted lodings re signifint ontriutors to eh omponent. PAR : P umultion in roots NAR : N umultion in roots DISCUSSION Soil Properties nd Phosphorus Intertions on Mize Growth: Prtitioning soil P into oneptul pools of different iovilility is importnt for following hnges in soil P sttus over time nd understnding P pool intertions with soil properties on mize growth. To this extend, the first omponent of the PCA with signifint lodings on most soil vriles is quite informtive. The reltionships mong soil vriles indites tht with inresing soil idifition, si tions re lehed nd greter frtion of primry P mesured with HCl extrtnt trnsformed into NOH nd residul pools of lower iovilility. The smll size of NHCO3-Pi nd HCl pools oserved ross ll soils trnsltes therefore the deep hemil wethering in tropil environment nd low P vilility [6]. As reveled y PC, the differenes of NOH nd HSO4-P pools sizes ross soils reflet geohemil differenes in prent mterils nd soil ge ut lso the reltive undne of Al- nd Fe-rih minerls. The trends in inorgni P forms in the order HCl- P<NHCO3-P< NOH <HSO4-P onfirms the Wlker nd Syers [7] model of P trnsformtion over time. The iossy positive responsiveness to P input for ll soils onfirm soil P defiieny results otined from hemil frtiontion proedures. The differentil P use effiieny nd dry mtter yield potentil ross soil types trnslte signifint intertions of inputted P nd soil physiohemil properties. Phosphorus sorption hs een 798

7 Am-Eurs. J. Agri. & Environ. Si., 8 (6): 793-8, shown to e highly orrelted with the ontents of ly fertilizer on HCl-P pool on Brzilin oxi Hplustults. The nd totl free Fe-oxide ontent [4]. As reveled y PCA men slopes of NOH-Pi lines ws lower thn those of (Tle ), exhngele Al nd soil ph hd signifint HSO4-P inditing tht it ws the gretest sink in id negtive effets on the uptke, trnsport nd effiient tropil soils. The grdul uild-up of residul P upon utiliztion of N nd P nd overll ltertion in fertiliztion nd its deline in exhustive ropping hs photosynthte llotion. Similr oservtions hve een een desried y Guo et l [4]. reported y Cl et l [8] nd Shumn et l[9].the enhned root growth oserved n e onsidered s CONCLUSION mize physiologil response ttriuted to root phosphtse tivity [] for etter explortion of the The present pot experimentl study indites id soil volume. The soils derived from Premrin soils in southern Cmeroon re inherently low in lile P metluminous grnite with men ph wter vlues of 4.5 ut present the sme trend in P pools. They differed ±., low levels of C nd Mg nd high Al level represent signifintly in their seondry nd residul pools P. soils with mrginl potentil for mize prodution []. Phosphorus fertilitistion indued differentil hnges in Component 3 with the highest loding on totl nitrogen inorgni pools the most enrihed eing the NOH-Pi nd nd totl C expresses iologil nd physil spets of HSO4-Pi. The multivrite sttistil pproh permitted soils with respet to soil orgni mtter iominerliztion more syntheti interprettion, providing informtion on rtes ross soil types s influened y soil ph, ly, edphi onstrints ffeting phosphorus use effiieny oxlte-extrtle Fe nd their effets on N nd K nd orreltively mize potentil growth in id soils. vililities s shown y Frossrd et l []. These onstrints inlude i) C nd other si tions defiienies onduive to enhned root growth, redued Fertiliztion Effets on Soil P Sttus: The P fertility P uptke nd overll ltertion in photosynthte sttus of id soils is generlly ffeted y fertiliztion, llotion, ii) soil idity nd Al toxiity tht redues the moility nd umultion of P eing ontrolled y nutrient uptke nd iomss prodution nd lstly iii). N sorption pity depending on ly nd Fe nd Al oxides vilility s relted to orgni mtter deomposition. ontent of the soils. The hnge rte given y the slopes The highlighted onstrints re ute in oxisols derived of the regression models expresses hnges in P pools per from metluminous grniti mterils nd need to e unit of dded P. The exponentil models fitted to NHCO3- llevited in order to improve P fertilizer effiieny. Liming P pool indite tht hnges re initilly low in reltion to ppers s the lssil solution for rising soil ph while the initil fst dsorption retions on minerl surfes t t the sme time preipitting exhngele Al. This lower P rtes. At higher P input, the dsorption sites re prtie my revel finnilly prohiitive for most progressively sturted resulting in shrp inrese in soil resoure-poor frmers of the humid tropis. To this P onentrtions. Comprisons ross soils indite tht respet, indigenous prties omining fllowing nd mount of inputted P were reorded from the NHCO3-Pi prtil urning of the vegettion remins n eologilly nd NOH-Pi pools in nd soils with lighter sound prtie in the short run in low populted res. texture. Similr oservtions were reported from soils from Sreening for Al-tolernt plnt genotypes remins the Rothmsted experimentl sttion [4]. The emergene sound reserh pthwy for enhning food rop of NOH-Pi nd residul P s the lrgest P pools reflets prodution in vst res of id soils of the humid tropis. the overll geohemil dominne on P yling proesses. The enrihment of these two pools during ACKNOWLEDGMENTS fertiliztion indites tht sustntil portion of P fertilizers is rpidly onverted under id soil onditions The uthors grtefully knowledge the funding from to pools of lower iovilility. This finding is in line IITA through the E-projet, the tehnil ssistne for with most previous P studies y Selles et l [3]. The lortory nlyses y lte Moning Stephne. derese in NOH-Pi ross ll ontrol tretments is suggestive of seondry P eoming plnt ville [4]. REFERENCES The HCl-P pool is elieved to represent soil P ssoited with primry minerls suh s ptite or C-P. The. Murphy, J. nd J.P. Riley, 96. A modified single sene of ler pttern upon fertiliztion is in line with solution method for the determintion of phosphte results y Selles et l [3] who found no effet of P in nturl wters. Anl. Chim. At., 6:

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