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Doctoral Thesis
DOI
https://doi.org/10.11606/T.11.1983.tde-20210104-190239
Document
Author
Full name
Nelson José Novaes
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1983
Supervisor
Title in Portuguese
Efeito de fontes e doses de fósforo na cultura do capim gamba (Andropogon gayanus Kunth variedade bisquamulatus)
Keywords in Portuguese
CAPIM GAMBA
FERTILIZANTES FOSFATADOS
FÓSFORO
Abstract in Portuguese
Foram conduzidos em vasos com terra em casa de vegetação, ensaios com fontes e doses crescentes de fósforo (0, 100,200 e 300 kg/ha de P2O5 ) em capim Gamba (Andropogon gayanus Kunth Var. Bisquamulatus),visando verificar o comportamento do fosfato de Araxá parcialmente solubilizado (FAPS), quanto à sua capacidade de fornecer fósforo (P) e cálcio (Ca) às plantas, em comparação com o superfosfato simples e fosfato natural de Araxá, em um solo ácido de vegetação de cerrado do Município de São Carlos-SP. Aos 75 dias após a semeadura, determinou-se o peso de matéria seca da parte aérea, raiz e total em cada tratamento; os teores na parte aérea e as quantidades absorvidas de P, Ca e enxofre (S); as relações entre os macronutrientes aniônicos (N/P, P/S e N/S) na parte aérea; o teor de proteína bruta e a digestibilidade “in vitro” da matéria seca. Foram retiradas amostras de solo no final do ciclo e procedeu-se à determinação dos teores de P (extração em H2SO4 0,05N e NH4F 0,03N + HCI 0,025N), de Ca (KCl 1,0N) e S-S04 (NH40Ac 0,5N). Os dados obtidos permitiram concluir que: - Houve efeito da adubação fosfatada na produção de matéria seca do capim Andropogon. - A eficiência do FAPS na produção de matéria seca, é ligeiramente inferior quando comparada ao superfosfato simples, mas superior ao fosfato de Araxá. - O superfosfato, seguido pelo FAPS, foram superiores ao fosfato de Araxá como fornecedores de P e Ca. - A produção de matéria seca correlacionou-se positivamente com as quantidades absorvidas de Ca e S, sendo que entretanto, o efeito do P não foi possível de ser separado do de Ca, pois ambos tiveram alta correlação entre si. - As quantidades absorvidas de fósforo (mg/vaso) foram: 0,55; 7,34; 6,63; 10,62 e 5,99, respectivamente para Testemunha, FAPS (1-2 mm), FAPS (2-4mm), superfosfato simples e fosfato de Araxá. - Os teores de P no solo (Bray-1), Ca(KCl, 1,0N) e S-S04(NH40AC, 0,5N) correlacionaram-se com doses e fontes de P2O5 utilizadas. - As relações N/P, P/S e N/S na parte aérea aos 75 dias ápos o plantio variaram respectivamente de 10 a 16; 0,57 a 1,51 e 9 a 14. - Os teores de proteína variaram de 4,6 a 5,7% decrescendo das fontes menos para mais solúveis, bem como o aumento das doses P2O5. - Os valores máximos da digestibilidade “in vitro”, da matéria seca estimados em torno de 42%, responderam à aplicação do FAPS e do superfosfato.
Title in English
Effect of sources ano levels of phosphorus in the gambagrass (Andropogon gayanus Kunth var. Bisquamulatus) culture.
Keywords in English

Abstract in English
Trials with different sources and increasing levels of phosphorus (0-100-200 and 300 kg/ha of P2O5) were carried out in pots in a green house, with the Gamba Grass (Andropogon gayanus Kunth var. Bisquamulatus), to evaluate the compatibility of the phosphate of Araxá partially soluble (FAPS) to supply phosphorus and calcium to the plants, as compared to the superphosfate (20% P2O5) and natural phosphate, in an acid soil of the “cerrado” region of São Carlos, São Paulo, Brazil. Seventy-five days after seeding, the dry matter weights of the aerial part, the root and total, the content of P , Ca and S in the aerial part and the absorbed amount, the relations among the anionic macronutrients (N/P, P/S and N/S) in the aerial part, the content of crude protein and the “in vitro” digestibility were determined in each treatement. Samples of soil at the end of the cycle were collected, and the content of P (extracted in H2SO4 0.05N and NH4F 0.03N + HCl 0.025N), of Ca(KCl 1.0N) and of S-S04(NH4OAc 0.5N) were determined. The results suggest the following conclusions: - There was an effect of the phosphorus fertilization in the production of dry matter. - The efficiency of the FAPS, producing dry matter, is slightly lower than the superphosphate but is better than the phosphate of Araxá. -The superphosphate, followed by the FAPS, were superior to the phosphate of Araxá as P an Ca suppliers. - The production of dry matter was correlated with the amounts of Ca and S absorbed. lt was not possible to evaluate the effects of the P, due to its high correlation with Ca. - The amounts of absorbed P(mg/pots) were 0.55, 7.34, 6.63, 10.62 and 5.99 for the control, FAPS (l-2 mm), FAPS (2-4 mm) superphosfate and natural phosfate, respectivily. - The contents of P (Bray-1), Ca (KCl 1.0N) and S-S04 (NH4OAc 0.5N) in the soil, were correlated with levels and sources of P205 utilized. - The relations N/P, P/S and N/S in the aerial part, seventy-five days after seeding, ranged from 10 to 16, 0.57 to 1.51 and 9 to 14 respectively. - The contents of crude protein ranged from 4.6 to 5.7% de decreasing from the sources less to the more soluble, and with increasing leveis of P205. -The values of the “in vitro” digestibility, estimated to be around 42%, had response to the amount of FAPS and superphosphate utilized.
 
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