ANDRE Erika Mangili, MARCHIORI JR. Milton, NASCIMENTO JR. Alfredo, FERREIRA Manoel Evaristo, CRUZ, Mara Cristina Pessôa

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1 Enregistrement scientifique n :1155 Symposium n : 13B Présentation : poster Zinc availability to rice plants. Effects of liming and phosphorus fertilization Disponibilité du zinc pour le riz. Effet du chaulage et d une fertilisation phosphatée ANDRE Erika Mangili, MARCHIORI JR. Milton, NASCIMENTO JR. Alfredo, FERREIRA Manoel Evaristo, CRUZ, Mara Cristina Pessôa Faculdade de Ciências Agrárias e Veterinárias / UNESP, Rodovia Carlos Tonanni, km 05, , Jaboticabal, São Paulo State, Brazil. INTRODUCTION Soils from cerrado vegetation are normally acids and deficient in phosphorus and zinc. When these soils are cultivated with rice plants it is usual the application of high quantities of lime and P inducing zinc deficiency (Tagwira et al., 1993). Sharma et al. (1968) observed that when phosphorus was applied the zinc uptake in maize leaves decreased while it remained constant in the roots. In conditions of high zinc supply, phosphorus can immobilize zinc into the roots of diferent plants, by the formation of zinc phytate (Loneragan & Webb, 1993). Zinc can be removed from soil by some diferent extractants. Ferreira & Cruz (1992) verified that salts solutions removed low quantities of Zn while H 2 SO 4 0,025 mol L -1 solution removed Zn such as DTPA and Na 2 EDTA. Bataglia et al. (1989) compared the extractants Mehlich 1, HCl 0,1 mol L -1, DTPA and Na 2 EDTA, concluding that all solutions were appropriate to estimate zinc availability to sunflower and sorghum plants, but only DTPA discrimined the ph effect on zinc availability. The objective of this work was evaluate the effects of liming and phosphorus fertilization on zinc availability to rice plants. MATERIALS AND METHODS The experiment was carried out using Neubauer-Schneider tecnique. The soil sample of a Dark-Red Latosol (Typic Haplorthox) was collected from surface (0-20 cm). Some chemical properties of the soil evaluated using routine analysis (Raij et al., 1987) are: P (resin) = 4 mg dm -3 ; OM = 22 g dm -3 ; ph (0,01 mol L -1 CaCl 2 solution) = 3.9; K = 0.1 mmol c dm -3 ; Ca = 2 mmol c dm -3 ; Mg = 1 mmol c dm -3 ; H+Al = 52 mmol c dm -3 ; CTC = 56 mmol c dm -3 and degree of base saturation = 7%. The treatments were composed by five levels of liming (to increase the degree of base saturation to 10, 20, 30, 40 and 50%), obtained by adition of CaCO 3 p.a. and MgCO 3 p.a. in 1

2 the proportion of 4:1 and five levels of phosphorus fertilization: 0, 30, 60, 90 and 120 mg dm -3 of P using NH 4 H 2 PO 4 p.a.. The incubation were done in 0,8 L capacity polyethylene pots each one filled with 0,5 L soil sample after being mixed with the treatments and watered with deionized water to reach ~60% field capacity. Potassium, S, B, Cu, Mn and Mo were supplied by water solution in doses of 150, 30, 0.5, 1.25, 3 and 0.02 mg dm -3, respectively. The amount of N was added to reach 150 mg dm -3 per pot. The soil was kept at this moisture content for 21 days. After this incubation period, the soil samples were taked from all pots, air-dried, sieved to 2 mm, mixed to routine analysis (Raij et al, 1987) and availiability Zn extracted by DTPA (Lindsay & Norvell, 1978), Mehlich 1 (Mehlich, 1953), Mehlich 3 (Mehlich, 1984) and HCl 0,1 mol L -1 (Nelson, 1959). The Neubauer trial was carried out in 250 ml polyethylene pots, arranged according to a randomized factorial design (5 x 5) with three replications All pots received 50 ml of soil mixed with 50 ml of washed sand and 25 ml of deionized water. On this mixture were placed 100 ml of washed sand and 25 ml of deionized water. Fifty-four seeds of rice (Oriza sativa L.) were sown in each pot and covered by 20 ml of washed sand. The moisture was kept during the experiment by adittion of deionized water. Twenty days after the germination, the plants were harvested, tops and roots, washed with 1 ml L -1 detergent solution, deionized water, HCl 20 ml L -1 solution and deionized water (2 times). The plants were dried in a oven at ~60ºC to a constant weight. Each of these plants were grounded and subjected to HNO 3 -HClO 4 digestion. Phosphorus and zinc concentrations were determined in the resulting digest. Phosphorus was determined colorimetrically by the methavanadate method and Zn by atomic absorption spectrophotometry. Data of dry matter production, Zn and P concentrations in plants were subjected to analysis of variance. Linear regressions were calculated between soil available zinc and the parameters ph, P resin, dry matter production and absorbed zinc by rice plants. RESULTS AND DISCUSSION The soil chemical characteristics after the incubation period are described in Table 1. The results shown in Table 2 indicate that there are no significant changes in dry matter production by liming and phosphorus application. The absence of the liming and P fertilization effects on dry matter production, in soil with ph = 3.9 and P (resin) = 4 mg dm -3, is unusual. It could be mentioned that Neubauer-Schneider technique did not be adjusted for this kind of study. However, it was not possible to establish any prediction before analyse the relationship between available zinc and absorbed zinc by rice plants (Table 2). The quantity of absorbed zinc decreased significantly after the application of lime and P fertilization, while the quantity of P absorbed increased significantly after phosphorus fertilization. The absence of significative results in the interaction liming x P fertilization on P uptake showed that dry matter production was affected by Zn levels, and these ones by liming and P fertilization. DTPA extractant discrimined the ph effect on Zn availability, with consequences in Zn absorbed by plants (Table 2). This result was also reported by Bataglia & Raij (1989) and Abreu & Raij (1996). As can be seen from Table 3, the relationship between Zn content extracted by HCl 0,1 mol L -1, Mehlich 1, Mehlich 3 and DTPA, and dry matter production had low correlation coefficients (r = 0.11, -0.03, 0.04 and -0.02, respectively). Similar results were obtained by 2

3 Sedberry Jr. et al. (1979) for the extractants HCL 0,1 mol L -1, DTPA and EDTA mixed with CH 3 COONH 4 or (NH 4 )CO 3. This poor relationship is probably due to the small soil volume explored by plants and/or to the reduced time of the trial, causing no growth differences among the plants. The linear correlation between soil availability zinc and zinc uptake showed correlation coefficients (r) for HCl 0,1 mol L -1, Mehlich 1, Mehlich 3 and DTPA equal to 0.20, 0.20, 0.08 and The r value for DTPA was significant at 5% probability level. The results indicate that, in soils submited to ph variations, DTPA is the best extractant to represent soil avalilable zinc in relation with zinc uptake. Table 1. Soil chemical characteristics after the incubation period. Treatments (1) P resin ph K Ca Mg H+Al V% Zn (2) CaCl mmol c dm mg dm -3 C 1 P C 1 P C 1 P C 1 P C 1 P C 2 P C 2 P C 2 P C 2 P C 2 P C 3 P C 3 P C 3 P C 3 P C 3 P C 4 P C 4 P C 4 P C 4 P C 4 P C 5 P C 5 P C 5 P C 5 P C 5 P (1) C 1... C 5 are levels of liming and P 0... P 5 are levels of phosphorus fertilization (2) extracted with DTPA solution 3

4 Correlations between four extractants to soil zinc availability and soil ph are shown in Table 4. The correlation coefficients (r) for DTPA and Mehlich 1 extractants were high and significants, indicating that these solutions discrimined the ph effect on Zn availability. This fact was also mentioned by some authors, however, only for DTPA (Camargo et al, 1982; Abreu & Raij, 1996). By other hand, there was a poor linear correlation between zinc and phosphorus quantities extracted from soil (r = 0.13 for HCl 0,1 mol L -1, for Mehlich 1, for Mehlich 3 and for DTPA). These results indicate that zinc available in soil had no dependence from the P fertilization. Table 2. Dry matter production, P and Zn concentration and uptake in rice plants submited to different doses of lime and phosphorus. Treatments (1) Dry matter P conc. P uptake Zn conc. Zn uptake g/pot mg kg -1 mg/pot mg kg -1 µg/pot C 1 P C 1 P C 1 P C 1 P C 1 P C 2 P C 2 P C 2 P C 2 P C 2 P C 3 P C 3 P C 3 P C 3 P C 3 P C 4 P C 4 P C 4 P C 4 P C 4 P C 5 P C 5 P C 5 P C 5 P C 5 P C 0.15 ns ns ** P 1.44 ns ** * C x P 0.82 ns ns ns (1) C 1... C 5 are levels of liming and P 0... P 5 are levels of phosphorus fertilization * P<0,05; ** P<0,01; ns = no significant 4

5 Table 3. Zinc extracted from soil by HCl 0,01 mol L -1, Mehlich 1, Mehlich 3 and DTPA extractants. Treatments (1) HCl Mehlich 1 Mehlich 3 DTPA mg dm C 1 P C 1 P C 1 P C 1 P C 1 P C 2 P C 2 P C 2 P C 2 P C 2 P C 3 P C 3 P C 3 P C 3 P C 3 P C 4 P C 4 P C 4 P C 4 P C 4 P C 5 P C 5 P C 5 P C 5 P C 5 P (1) C 1... C 5 are levels of liming and P 0... P 5 are levels of phosphorus fertilization Table 4. Linear correlation between soil available zinc and soil ph. Soil ph Equation (y = ax + b) r HCl 0,1 mol L -1 y = x ns Mehlich 1 y = x ** Mehlich 3 y = x ns DTPA y = x ** * P<0,05; ** P<0,01; ns = no significant CONCLUSIONS 1. Phosphorus fertilization and mainly liming affect zinc availability to rice plants. 5

6 2. The Neubauer-Schneider technique can be used to evaluate zinc availability to rice plants since that the correlation between soil extracted zinc and zinc absorbed by plant has been done. 3. In soils with different conditions of ph, DTPA was more efficient than Mehlich 1 for estimate zinc availability to plants. 4. HCl 0,1 mol L -1 and Mehlich 3 solutions did not discrimined the ph effect on availability zinc. DTPA was the extractant that represented the influency of ph on zinc availability better than the others. REFERENCES 1. Abreu, C.A., Raij, B.van Efeito da reação do solo no zinco extraído pelas soluções de DTPA e Mehlich-1. Bragantia. 55(2): Bataglia, O.C., Raij, B.van Eficiência de extratores de micronutrientes na análise de solo. R. Bras.Ci. Solo. 13: Camargo, O.A., Valadares, J.M.A.S., Dechen, A.R Effeitos do ph e da incubação na extração do manganês, zinco, cobre e ferro do solo. R. Bras.Ci. Solo. 6: Ferreira, M.E., Cruz, M.C.P Seleção de extratores químicos para avaliação da disponibilidade de zinco em solos do Estado de São Paulo. Pesq. Agrop. Bras. 27: Lindsay, W.L. and Norvell, W.A Development of a DTPA soil test for zinc, iron, manganese and copper. Soil Sci. Soc. Am. J. 42: Loneragan, J.F., Webb, M.J Interactions between zinc and other nutrients affecting the growth of plants. In: Robinson, A.D. Zinc in soil and plants. Kluwer Academic Publishers, Dordrecht, p Mehlich, A Determination of P, Ca, Mg, K, Na, and NH 4 by North Carolina Soil Testing Laboratories. (mimeo). University of North Carolina, Raleigh, NC. 8. Mehlich, A Mehlich 3 soil test extractant: A modification of Mehlich 2 extractant. Commun. Soil Sci. Plant Anal. 15: Nelson, J.L., Boawn, C., Viets, F.G A method for assesssing zinc status of soil using acid extractable and Titratable Alkalinity values. Soil Sci. 88: Raij, B.van, Quaggio, J.A., Cantarella, H., Ferreira, M.E., Lopes, A.S., Bataglia, O.C Análise química do solo para fins de fertilidade. Fundação Cargill, Campinas, 170p. 11. Sedberry Jr, J.E., Miller, B.J., Said, M.B An evaluation of chemical methods for extracting zinc from soils. Commun. Soil Sci. Pl. Anal. 10: Sharma, K.C., Krantz, B.A., Brown, A.L., Quick, J Interaction of Zn and P in top and root of corn and tomato. Agron. J. 60: Key-words: zinc availability, liming, phosphorus fertilizer, rice Mots clés : disponibilité du zinc, chaulage, fertilisation phosphatée, riz 6