Disponibilidade de ferro, manganês, zinco e cobre no solo por Mehlich-1, Mehlich-3 e DTPA
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2019-03-27
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Universidade Federal de Viçosa
Resumo
Estudos de correlação e calibração são necessários para determinar a eficiência de um extrator em estimar a disponibilidade dos nutrientes no solo. Nos primeiros estudos são testados diferentes extratores, sendo selecionados aqueles que melhor se correlacionam com o método padrão, que é a quantidade absorvida pelas plantas. Posteriormente são definidas as doses recomendáveis do nutriente a serem adicionadas ao solo e os níveis críticos. Os objetivos deste trabalho foram: avaliar os extratores DTPA, Mehlich-1 e Mehlich-3 com relação ao potencial de avaliação da disponibilidade de Fe, Mn, Zn e Cu; determinar os níveis críticos e as taxas de recuperação desses micronutrientes pelas plantas e por cada extrator. Para isso foram realizados três experimentos. No primeiro utilizou-se o fatorial: 3 × 6, correspondendo a três Latossolos Vermelho-amarelo do Estado de Minas Gerais e seis doses dos micronutrientes em mg/dm 3 : Fe (0,0; 20,0; 40,0; 80,0; 120,0 e 200,0); Mn (0,0; 15,0; 30,0; 60,0; 90,0 e 120,0); Zn (0,0; 5,0; 10,0; 20,0; 30,0 e 50,0) e de Cu (0,0; 2,0; 4,0; 8,0; 12,0 e 20,0) que foram aplicadas nos três solos. Para o segundo experimento foi utilizado o fatorial 3 × 4 × 6, correspondendo a três solos, quatro micronutrientes e seis doses dos micronutrientes Fe, Mn, Zn e Cu que se derivaram da matriz baconiana 6 + 6 + 6 + 6. Foram utilizados os mesmos três solos e as mesmas doses do experimento um. Utilizou-se as seguintes doses de referência: 40 mg/dm 3 para o Fe; 30 mg/dm 3 para o Mn, 10 mg/dm 3 para o Zn e 4 mg/dm 3 para o Cu. O fatorial do terceiro experimento foi 12 × 6, correspondendo a 12 solos e seis doses dos micronutrientes em mg/dm 3 : Fe (0,0; 8,0; 16,0; 32,0; 48 e 80); Mn (0,0; 5,0; 10,0; 20,0; 30,0 e 50,0); Zn (0,0; 2,0; 4,0; 8,0; 12,0 e 20,0) e de Cu (0,0; 1,5; 3,0; 6,0; 9,0 e 15,0) que foram aplicadas em cada solo. As fontes utilizadas foram FeCl 3 .6H 2 O, MnCl 2 .4H 2 O, Zn(NO 3 ) 2 .6H 2 O e Cu(NO 3 ) 2 .3H 2 O. Os experimentos foram realizados em blocos casualizados com quatro repetições. A unidade experimental foi de um vaso plástico contendo 2,0 dm 3 de solo, onde cultivou-se quatro plantas de milho. A calagem foi realizada nos solos que dela necessitou. O solos ficaram incubados por um período de 15 d com o calcário. Após o período de incubação, as amostras de solo receberam as doses dos quatro micronutrientes, ficando incubadas por 7 d. Após esse período, coletaram-se subamostras para a determinação dos teores de Fe, Mn, Zn e Cu por Mehlich-1, Mehlich- 3 e DTPA. Em cada experimento as plantas foram colhidas com 33 d de cultivo. As análises estatísticas consistiram de análises de variância, regressão e correlação. Os extratores com maior acidez, Mehlich-1 e Mehlich-3, conseguiram extrair maiores teores dos quatro micronutrientes do que o DTPA. No experimento um e dois os maiores níveis críticos dos quatro micronutrientes no solo foram obtidos com o Mehlich-1. No terceiro experimento, os maiores níveis críticos dos quatro micronutrientes no solo foram obtidos com o Mehlich-3. Os teores dos micronutrientes Mn, Zn e Cu recuperados pelos extratores foram altamente correlacionados entre si. As correlaçoes mais elevadas dos teroes de Fe recuperados ocorreram entre Mehlich-1 e Mehlich-3. Nos três experimentos, o DTPA foi mais eficiente em predizer a disponibildiade de Fe para as plantas de milho. Os três extratores apresentaram capacidade de avaliar a disponibilidade de Mn, Zn e de Cu bem próximas, tendo uma ligeira vantagem o Mehlich-3. O extrator Mehlich-3 apresenta potencial para ser utilizado em análises de rotina de micronutrientes, uma vez que indicou boa correlação entre os conteúdos dos micronutrientes com os teores recuperados por ele. Entretanto, há necessidade de mais estudos com relação ao Fe.
Correlation and calibration studies are required to determine the efficiency of an extractor in estimating the availability of nutrients in the soil. In the first studies different extractors are tested, being selected those that better correlate with the standard method, that is the amount absorbed by the plants. Subsequently, the recommended doses of the nutrient to be added to the soil and critical levels are defined. The objectives of this work was to evaluate DTPA, Mehlich-1 and Mehlich-3 extractors in relation to the Fe, Mn, Zn and Cu availability potential; determine the critical levels and rates of recovery of these micronutrients by plants and by each extractor. Three experiments were carried out. In the first one the factorial was used: 3 × 6, corresponding to three Red-yellow Oxisols of the State of Minas Gerais and six doses of micronutrients in mg/dm 3 : Fe (0,0; 20,0; 40,0; 80.0, 120.0 and 200.0); Mn (0.0, 15.0, 30.0, 60.0, 90.0 and 120.0); Zn (0.0, 5.0, 10.0, 20.0, 30.0 and 50.0) and Cu (0.0, 2.0, 4.0, 8.0, 12.0 and 20.0) that were applied in the three soils. For the second experiment, 3 × 4 × 6 factorial was used, corresponding to three soils, four micronutrients and six doses of the micronutrients Fe, Mn, Zn and Cu that were derived from the baconiana matrix 6 + 6 + 6 + 6. The same three soils and the same doses of experiment one were used. The following reference doses were used: 40 mg/dm 3 for Fe; 30 mg/dm 3 for Mn, 10 mg/dm 3 for Zn and 4 mg/dm 3 for Cu. The factorial of the third experiment was 12 × 6, corresponding to 12 soils and six doses of micronutrients in mg/dm 3 : Fe (0.0, 8.0, 16.0, 32.0, 48.0 and 80.0); Mn (0.0, 5.0, 10.0, 20.0, 30.0 and 50.0); Zn (0.0, 2.0, 4.0, 8.0, 12.0 and 20.0) and Cu (0.0, 1.5, 3.0, 6.0, 9.0 and 15.0) that were applied to each soil. The sources used were FeCl 3 .6H 2 O, MnCl 2 .4H 2 O, Zn (NO 3 ) 2 .6H 2 O and Cu(NO 3 ) 2 .3H 2 O. The experiments were performed in randomized blocks with four replicates. The experimental unit was from a plastic vessel containing 2.0 dm 3 of soil, where four corn plants were grown. The liming was done in the soils that needed it. The soils were incubated for 15 d with limestone. After the incubation period, the soil samples received the doses of the four micronutrients, being incubated for 7 d. After this period, subsamples were collected for the determination of the Fe, Mn, Zn and Cu contents by Mehlich-1, Mehlich-3 and DTPA. In each experiment the plants were harvested with 33 d of culture. Statistical analyzes consisted of analysis of variance, regression and correlation. The extractors with higher acidity, Mehlich-1 and Mehlich-3, were able to extract higher levels of the four micronutrients than the DTPA. In the experiment one and two the highest critical levels of the four micronutrients in the soil were obtained with the Mehlich-1. In the third experiment, the highest critical levels of the four micronutrients in the soil were obtained with Mehlich-3. Micronutrient contents Mn, Zn and Cu recovered by the extractors were highly correlated with each other. The highest correlations of recovered Fe contents occurred between Mehlich-1 and Mehlich-3. In all three experiments, DTPA was more efficient in predicting the availability of Fe to maize plants. The three extractors were able to evaluate the availability of Mn, Zn and Cu very closely, with a slight advantage of Mehlich-3. The extractor Mehlich-3 presents potential to be used in routine analyzes of micronutrients, since it indicated a good correlation between the contents of the micronutrients with the contents recovered by it. However, there is a need for further studies regarding Fe.
Correlation and calibration studies are required to determine the efficiency of an extractor in estimating the availability of nutrients in the soil. In the first studies different extractors are tested, being selected those that better correlate with the standard method, that is the amount absorbed by the plants. Subsequently, the recommended doses of the nutrient to be added to the soil and critical levels are defined. The objectives of this work was to evaluate DTPA, Mehlich-1 and Mehlich-3 extractors in relation to the Fe, Mn, Zn and Cu availability potential; determine the critical levels and rates of recovery of these micronutrients by plants and by each extractor. Three experiments were carried out. In the first one the factorial was used: 3 × 6, corresponding to three Red-yellow Oxisols of the State of Minas Gerais and six doses of micronutrients in mg/dm 3 : Fe (0,0; 20,0; 40,0; 80.0, 120.0 and 200.0); Mn (0.0, 15.0, 30.0, 60.0, 90.0 and 120.0); Zn (0.0, 5.0, 10.0, 20.0, 30.0 and 50.0) and Cu (0.0, 2.0, 4.0, 8.0, 12.0 and 20.0) that were applied in the three soils. For the second experiment, 3 × 4 × 6 factorial was used, corresponding to three soils, four micronutrients and six doses of the micronutrients Fe, Mn, Zn and Cu that were derived from the baconiana matrix 6 + 6 + 6 + 6. The same three soils and the same doses of experiment one were used. The following reference doses were used: 40 mg/dm 3 for Fe; 30 mg/dm 3 for Mn, 10 mg/dm 3 for Zn and 4 mg/dm 3 for Cu. The factorial of the third experiment was 12 × 6, corresponding to 12 soils and six doses of micronutrients in mg/dm 3 : Fe (0.0, 8.0, 16.0, 32.0, 48.0 and 80.0); Mn (0.0, 5.0, 10.0, 20.0, 30.0 and 50.0); Zn (0.0, 2.0, 4.0, 8.0, 12.0 and 20.0) and Cu (0.0, 1.5, 3.0, 6.0, 9.0 and 15.0) that were applied to each soil. The sources used were FeCl 3 .6H 2 O, MnCl 2 .4H 2 O, Zn (NO 3 ) 2 .6H 2 O and Cu(NO 3 ) 2 .3H 2 O. The experiments were performed in randomized blocks with four replicates. The experimental unit was from a plastic vessel containing 2.0 dm 3 of soil, where four corn plants were grown. The liming was done in the soils that needed it. The soils were incubated for 15 d with limestone. After the incubation period, the soil samples received the doses of the four micronutrients, being incubated for 7 d. After this period, subsamples were collected for the determination of the Fe, Mn, Zn and Cu contents by Mehlich-1, Mehlich-3 and DTPA. In each experiment the plants were harvested with 33 d of culture. Statistical analyzes consisted of analysis of variance, regression and correlation. The extractors with higher acidity, Mehlich-1 and Mehlich-3, were able to extract higher levels of the four micronutrients than the DTPA. In the experiment one and two the highest critical levels of the four micronutrients in the soil were obtained with the Mehlich-1. In the third experiment, the highest critical levels of the four micronutrients in the soil were obtained with Mehlich-3. Micronutrient contents Mn, Zn and Cu recovered by the extractors were highly correlated with each other. The highest correlations of recovered Fe contents occurred between Mehlich-1 and Mehlich-3. In all three experiments, DTPA was more efficient in predicting the availability of Fe to maize plants. The three extractors were able to evaluate the availability of Mn, Zn and Cu very closely, with a slight advantage of Mehlich-3. The extractor Mehlich-3 presents potential to be used in routine analyzes of micronutrients, since it indicated a good correlation between the contents of the micronutrients with the contents recovered by it. However, there is a need for further studies regarding Fe.
Descrição
Palavras-chave
Química do solo, Ácido dietilenotriaminopentacético, Micronutrientes, Extração (Química)
Citação
FARIA, Arlindo Ferreira de. Disponibilidade de ferro, manganês, zinco e cobre no solo por Mehlich-1, Mehlich- 3 e DTPA. 2019. 148 f. Tese (Doutorado em Solos e Nutrição de Plantas) - Universidade Federal de Viçosa, Viçosa. 2019.