Phosphorus is an essential nutrient for plant growth. Million of tones of P are applied to the soils annually. However, only a small fraction of the P applied with fertilizers is taken up by crops in the year of application, and the effectiveness of any residual P fertilizer declines with time. To improve our understanding of the mechanisms underlying this response to P in the field, we have studied the mobility of P from 3 different fertilizes: monoammonium phosphate (MAP), polymer coated monoammonium phosphate (MAPp) and Organomineral phosphate (OMP) applied on high weathered soil samples in a Petri dish experiment. Total Reflection X-Ray Fluorescence (TXRF) was used to determine the P diffusive flux at different distances (0 - 7.5, 7.5 ? 13.5, 13.5 ? 25.5 and 25.5 ? 43 mm) from granular fertilizer. TXRF analyses were performed at the X-Ray Fluorescence Beamline D09B at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, São Paulo, using a polychromatic beam with maximum energy of 20 keV for the excitation and an Ultra-LEGe detector with resolution of 148 eV at 5.9 keV. Besides that, the detections were performed in a high vacuum chamber (2.5 x 10-5 mbar) to avoid air absorption. After a period of five weeks, the total P concentration increased in the soil sampled 7.5 to 13.5 mm from the fertilizer showing a diffusive flux of P. About 20% (considering MAP and MAPp) of the total P applied diffused out of the central soil ring. Different sources showed differences in diffusive flux of P. Soil pH also influenced diffusive flux of P showing higher flux on lower pH soils

ANJOS, M. J. dos

BENITES, V. de M.

CASTRO, R. C. de

OLIVEIRA, D. F. de

OLIVEIRA, L. F. de

TEIXEIRA, P. C.

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2013 International Nuclear Atlantic Conference - INAC 2013Recife, PE, Brazil, November 24-29, 2013ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABENISBN: 978-85-99141-05-2ANALYZING THE MOBILITY IN GRANULAR FORMS OF P FERTILIZER IN BRAZILIANS SOILS UNDER LABORATORY CONDITIONSRobson C. de Castro1, Paulo César Teixeira2, Vinícius Melo Benites2, Davi Ferreira de Oliveira1, Luis Fernando de Oliveira1 e Marcelino José dos Anjos11Instituto de Física Armando Dias TavaresUniversidade do Estado do Rio de JaneiroRua São Francisco Xavier, 524 – 3º andar 20559-900 Rio de Janeiro, RJprof.robinho@gmail.com2 Embrapa solosRua Jardim Botânico, 102422460-000 Rio de Janeiro, RJpaulo.c.teixeira@embrapa.br ABSTRACTPhosphorus is an essential nutrient for plant growth. Million of tones of P are applied to the soils annually.  However, only a small fraction of the P applied with fertilizers is taken up by crops in the year of application,  and the effectiveness  of  any residual  P fertilizer  declines  with time.  To improve our understanding  of  the mechanisms underlying this response to P in the field,  we have studied the mobility of P from 3 different  fertilizes:  monoammonium  phosphate  (MAP),  polymer  coated  monoammonium  phosphate  (MAPp)  and Organomineral phosphate (OMP)  applied on high weathered soil samples in a Petri dish experiment. Total Reflection X-Ray Fluorescence (TXRF) was used to determine the P diffusive flux at different distances (0 -  7.5, 7.5 – 13.5, 13.5 – 25.5 and 25.5 – 43 mm) from granular fertilizer. TXRF analyses were performed at the  X-Ray Fluorescence Beamline D09B at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, São Paulo, using a polychromatic beam with maximum energy of 20 keV for the excitation and an Ultra-LEGe  detector with resolution of 148 eV at 5.9 keV. Besides that, the detections were performed in a high vacuum chamber (2.5 x 10-5 mbar)  to  avoid air  absorption.  After  a  period of  five weeks,  the total  P concentration increased in the soil sampled 7.5 to 13.5 mm from the fertilizer showing a diffusive flux of P. About 20% (considering MAP and MAPp) of the total P applied diffused out of the central soil ring. Different sources  showed differences in diffusive flux of P. Soil pH also influenced diffusive flux of P showing higher flux on  lower pH soils.1. INTRODUCTIONThe major reason that supply of phosphorus (P) to cultivated plants is a common limiting factor for crop production is the low availability of P to plant roots rather than low P content in soils. Although farmers have used large amounts of P fertilizers to improve crop growth over many decades, only a small fraction of the applied P as fertilizers are taken up by plants in the year of application (McLaughlin et al.,  1988) while the residual effectiveness of P fertilizer for subsequent crops declines with time (Barrow, 1973). The importance of phosphorus for plant survival has promoted the development of adaptation mechanisms of the plant to improve its access to stocks of P. The concentration of P in soil is usually low (Lombi et al. 2004a; 2004b) because it is readily adsorbed on the surfaces of soil colloids and precipitated as  phosphates or calcium (Ca),  magnesium  (Mg),  iron (Fe) and aluminum (Al).Moreover, there are studies showing decreases in crop yield due to some physical problems in the subsurface well as in the form of cultivation, preventing access to the phosphorus and other nutrients and water. Lombi et al (2004a) found that phosphorus concentrations in some treatments (using types of fertilizer:  MAP granular,  MAP powder and TG-MAP)  decreases with increasing distance from the central point where the fertilizer was added. Thus, studying the concentration of phosphorus in radial distances from the point of application of fertilizer becomes a relevant parameter for soil cultivation and performance evaluation of the fertilizer.In  this  work,  we  have  studied  the  mobility  of  P  from  3  different  fertilizer  in  forms monoammonium phosphate (MAP), polymer coated monoammonium phosphate (MAPp) and Organomineral phosphate (OMP) applied on a High Weathered Brazilian soil samples in the laboratory. Total Reflection X-Ray Fluorescence (TXRF) was used to determine the mobility of P at different distances (0 - 7.5, 7.5 – 13.5, 13.5 – 25.5 and 25.5 – 43 mm) from granular fertilizer.  TXRF analyses  were performed at  the  X-Ray Fluorescence  Beamline  D09B at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, São Paulo, using a polychromatic beam with maximum energy of 20 keV for the excitation and an Ultra-LEGe detector with resolution of 148 eV at 5.9 keV. Besides that, the experiments were performed in a high vacuum chamber (2.5 x 10-5 mbar) to avoid air absorption.2. MATERIALS AND METHODSIn our analysis we used an agricultural surface layer (0-20 cm) of a Red Oxisol sampled in Rio Verde / Goiás. This soil was dried and sieved to 2 mm. Three doses of lime (0, 3 and 12 t/ha) were applied to the soil to obtain different pH values, identified as treatments A, B and C. The chemical characteristics of these soil samples are shown in Table 1.Table 1:  Chemical characteristic of the soils used in the experimentTreatments pH (watera)Total P(mg/kg)bA 5.2 297B 5.7 314C 7.0 330a. Results obtained by LASP/EMBRAPA SOLOS.b. Results obtained by LNSL/TXRF.After  incubation  of  soil  samples  for  30  days,  we  started  the  experimental  setup.  The experimental setup was similar to that described by Lombi et al. (2004) and Silva (2013). Plastic Petri dishes (8.7 cm in diameter, 1.1 cm high) were filled with 76 g of dry soil per dish, in the case of the three treatments, to obtain a soil density of 1.2 g cm3. The soil was then wetted to 60% of field capacity by dripping deionized water onto the soil.  The Petri dishes were closed, sealed with parafilm and left to equilibrate overnight. The following day, the Petri dishes were opened and  granules of fertilizer were placed in petri dishes. Table 2 shows the concentrations of phosphorus in each fertilizer. INAC 2013, Recife, PE, Brazil.Table 2:  Concentrations of phosphorus total in the fertilisersFertilisers P2O5 (%) – total (a.)MAP 56.5MAPp 52.5OMP 24.6a.  Analyzes were done according to MAPA (2007).After the treatments were prepared the Petri dishes were closed, sealed with parafilm and incubated using a BOD incubator at  28oC for five weeks in the dark . A relatively short equilibration period (five weeks) was chosen because P uptake by cereal crops occurs mainly in the initial stages of plant growth (Williams, 1948). After equilibration, the Petri dishes were opened and four concentric rings of soil, centered around the granule, were removed using a series of plastic cylinders. These cylinders were driven into the soil one at a time, starting with the smallest one, and all soil inside the cylinder was removed. This procedure was adopted by Lombi et al. (2004) and it is similar to the method used by Kouboura et al.  (1995) to sample soil at different distances from fertiliser bands (Figure 1). Samples of soil were collected between 0–7.5, 7.5–13.5, 13.5–25.5 and 25.5–43 mm radius from the granule.Figure 1: Four concentric rings of soil. Silva (2013)A subsample  of  each  soil  section  was  digested  using  extractor  Mehlich-1 and  the  total phosphorus measured. TXRF analyses were performed at the X-Ray Fluorescence Beamline D09B at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, São Paulo, using a polychromatic beam with maximum energy of 20 keV for the excitation and an Ultra-LEGe detector  with resolution of 148 eV at 5.9 keV. Besides that,  the experiments were performed in a high vacuum chamber (2.5 x 10-5 mbar) to avoid air absorption.A mass balance was calculated to determine the amount of P added to each Petri dish. The amount of P present in each section of the Petri dishes was calculated by subtracting the native P concentration from the total P concentration measured at the end of the experiment in the soil digests, and multiplying this value by the soil weight of the respective section. INAC 2013, Recife, PE, Brazil.The distribution of the added fertilizer P in the different sections of soil collected form the Petri  dishes was calculated using the measured total  P concentration and the background concentration. The percentage of P from fertilizer in each section (%Pf S1−4) was calculated as follows: Lombi et al (2004-b)∑−==41)]([)]([%iiifiifif xWSPxWSPSP                                                   (1)where, i is the soil section (1 to 4), [Pf]Si and Wi are the concentration of fertilizer P and the soil weight of each section respectively. [Pf]Si is calculated by subtracting the P concentration of the untreated soil from the concentration of the fertilized soil. 3. PRESENTATION AND ANALYSIS OF RESULTSConcentration of P varies with the pH of the soil, as well as the type of fertilizer (Figure 2). Figure 2 (a) we observe the mobility of P contained in the MAP can be observed a minor variation in the region close fertilizer application, the order 4.5% (0-7.5), 0.7% (7.5-13.5) when comparing the soil A and B. For soil C, we obtained a low mobility of phosphorus, it is  not possible to detect in the range of 25.5-43.In Figure 2 (b) analyzing the mobility of P fertilizer that is more efficient in the soil C. In the range (0-7.5), the concentration of P in soil C was greater than 24% in soil and 30% in soil than B. The values in the range (25.5-43) for soil A and C were below the detection limit. In Figure 2 (c), we conclude that the mobility of phosphorus in the soil B has developed more smoothly than in soil A. In all tracks, the values of C P to the soil were below the detection limit. 07001400210028000 - 7.5 7.5 - 13.5 13.5 - 25.5 25.5 - 43Distances (mm)Total P(mg/kg)Soil ASoil BSoil CINAC 2013, Recife, PE, Brazil.(a) 070014002100280035000 - 7.5 7.5 - 13.5 13.5 - 25.5 25.5 - 43Distances (mm)Total P (mg/kg)Soil ASoil BSoil C 07001400210028000 - 7.5 7.5 - 13.5 13.5 - 25.5 25.5 - 43Distances (mm)Total P (mg/kg)Soil ASoil BFigure 2: Concentration of P – (a) (MAP), (b) (MAPp) and (c) OMPThe results, expressed as a percentage of the P added in the fertilizers are reportes in figure 3. In the MAP treatment, as expect, the distribution of P from the fertilizer closely matched the weight distribution of the soil among the different sections as reported in figure 3(a). When MAP was applied in the centre of the Petri dish, most of the P from the fertilizer (80%) remained within 0 to 7.5 mm of the point of application and only 12% diffused to the 7.5 to 13.5 mm section, analyzing the soil A. For soils B and C, have respectively 77% in the range of 0 to 7.5 mm and 11% in the range of 7.5 to 13.5 mm and 75% in the range of 0 to 7.5 mm and 14% in the range of 7.5 to 13.5 mm. This indicated that neither the initial compaction nor the coating of the granules (to suppress dust during transport) affected the diffusion of P from the fertilizer.INAC 2013, Recife, PE, Brazil.(b)(c) 0204060801000 - 7.5 7.5 - 13.5 13.5 - 25.5 25.5 - 43Distances (mm)P(% of P added)Soil ASoil BSoil C 0204060801000 - 7.5 7.5 - 13.5 13.5 - 25.5 25.5 - 43Distances (mm)P(% of P added)Soil ASoil BSoil C 0204060801000 - 7.5 7.5 - 13.5 13.5 - 25.5 25.5 - 43Distances (mm)P(% of P added)Soil ASoil BFigure 3: P migration– (a) (MAP), (b) (MAPp) and (c) OMPThe diffusion of P from MAP granules was detectable in the first three sections of the Petri dishes indicating a migration of P up to 25.5mm in 35 d with soil C. This result is comparable INAC 2013, Recife, PE, Brazil.(a)(b)(c)with those of  Blanchard and Caldwell (1966) reported diffusion of P to 20 to 30 mm from monocalcium phosphate pellets over 2 wk in a clay loam soil.  Similarly, Lombi (2004-a) reported diffusion of P to 13.5 to 25.5 mm from monocalcium phosphate in a Calcareous Soil.Even though the maximum distance to which P diffused from MAP and MAPp (Figure 3(b)) was not significantly different, the pattern of P distribution was. Most of the P from MAP and MAPp  remained  near  the  point  of  application  whereas  more  P  from  Organomineral  phosphate spread evenly over the soil B (Figure 3(c)).3. CONCLUSIONS The TXRF with synchrotron radiation (low Z and conventional) proved to be very efficient in determining concentration multielement in soil samples. The elements detected were: Mg, Al, Si, Cl, Ti, V and Mn. The results of our study provide an insight into some of the physical processes occurring when three products that contain the same form of P are applied to a Brazilian soil. In particular diffusion of P from OMP and MAPp appeared to be enhanced in comparison with conventional MAP. These differences may reflect the difference in reaction products in the zone immediately surrounding the point of fertilizer application.ACKNOWLEDGMENTSThe authors  thank the  Brazilian  National  Synchrotron Light  Laboratory (project  XAFS1-14453),  the  Laboratory  of Electronic  Instrumentation and Analytical Measurement Techniques (LIETA). REFERENCESMcLaughlin,  M.J.,  A.M. Alston,  and J.K.  Martin., “Phosphorus  cycling  in  wheat  pasture rotations. 1. The source of phosphorus taken up by wheat”, Aust. J. Soil Res., 26 pp.323–331. (1988). Barrow, N.J.,  “Relationship  between a soils  ability  to  absorb phosphate  and the  residual effectiveness of superphosphate”, Aust. J. Agric. Res., 11 pp.57–63. (1973).Lombi E, McLaughlin M J, Johnston C, Armstrong R D and Holloway R E., “Mobility and lability  of  phosphorus  from  granular  and  fluid  monoammonium  phosphate  differs  in  a calcareous soil”. Soil Sci. Soc. Am. J., 68 pp.682–689. (2004-a).Lombi E., McLaughlin M. J., Johnston C., Armstrong R. D. and Holloway R. E., “Mobility, solubility  and  lability  of  fluid  and  granular  forms  of  P  fertiliser  in  calcareous  and  non-calcareous soils under laboratory conditions”. Plant and Soil, 269 pp.25–34. (2004-b).Williams R. F., “The effects of phosphorus supply on the rates of intake of phosphorus and nitrogen and upon certain aspects of phosphorus metabolism in gramineous plants”. Aust. J. Sci. Res., 1 pp. 333–341. (1948).INAC 2013, Recife, PE, Brazil.Kouboura  A.  D.,  Pierzynski  G.  M.  and  Havlin  J.,“Phosphorus  and micronutrients  availability  from  dual  application  of  nitrogen  and phosphorus using liquid fertilizers”. Soil Sci. 159, pp. 49–58. (1995).Ministério da Agricultura, Pecuária e Abastecimento (MAPA), Manual de métodos analíticos  oficiais para fertilizantes minerais, orgânicos, organominerais e corretivos, Brasília/Brazil (2007).Silva, Rodrigo Coqui da, Eficiência Agronômica de fertilizantes fosfatados com solubilidade  variada, Tese de Doutorado/USP/ESAL, Piracicaba/Brazil (2013).Blanchard,  R.W.,  and  A.C.  Caldwell.,  “Phosphate-ammonium  moisture relationships  in  soils:  I.  Ion  concentration  in  static  fertilizer  zones  and effects on plants”. Soil Sci. Soc. Am. Proc. 30, pp.39–43. (1966).INAC 2013, Recife, PE, Brazil.

Analyzing the mobility in granular forms of P fertilizer in brazilians soils under laboratory conditions.

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Analyzing the mobility in granular forms of P fertilizer in brazilians soils under laboratory conditions.

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