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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.1978.tde-20220207-155355
Document
Author
Full name
José Carlos Chitolina
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1978
Supervisor
Title in Portuguese
Perdas de nitrogênio por lixiviação: efeitos da uréia coberta com enxofre
Keywords in Portuguese
LIXIVIAÇÃO DO SOLO
PERDAS DE NITROGÊNIO
Abstract in Portuguese
O presente trabalho teve por objetivos comparar as perdas por lixiviação do nitrogênio (N-NH+4 + N-NO-3) proveniente de uréia coberta com enxofre (SCU) e uréia não coberta e verificar o efeito do pH nessas perdas, em solos Latossol Roxo (LR), Latossol Vermelho Escuro, fase arenosa (LVE) e Latosol Vermelho Amarelo, fase arenosa (LVA), que ocorrem sob vegetação de cerrado no Estado de São Paulo. Para tal os solos foram colocados em colunas de tubos plásticos, protegidos na parte inferior por uma tela de náilon, até atingir a altura de 40 cm, sendo a uréia adicionada nos 10 cm do topo da coluna. Cada solo recebeu duas doses de uréia (60 e 120 kg N/ha), superfosfato triplo e cloreto de potássio, sendo mantidos em dois valores de pH, ou sejam, pH original do solo, tal como foi colhido no campo, e pH corrigido para o valor 6,5 através da adição de CaCO3. Empregou-se o delineamento em blocos, esquema fatorial. A amostragem foi feita mensalmente, durante seis meses, através da colocação de água suficiente para que os solos atingissem a capacidade de campo e fossem coletadas as amostras de lixiviado, nas quais determinou-se o N(NH+4 + N-NO-3). As seguintes conclusões puderam ser obtidas: a) A uréia coberta com enxofre (SCU) reduziu as perdas de nitrogênio, através do processo de lixiviação, em comparação à uréia não coberta, para os três tipos de solos estudados. b) A uréia coberta com enxofre (SCU) apresentou tendência de lenta liberação de nitrogênio, para os três tipos de solos estudados. c) A influência do pH foi variável, dependendo do tipo de solo. d) O pH não influiu nas perdas de nitrogênio quando se utilizou a uréia coberta com enxofre (SCU) isoladamente, razão pela qual se conclui que não houve influência do mesmo na liberação do nitrogênio retido no grânulo de SCU, para os três tipos de solos estudados. e) Há necessidade de que nos estudos com uréia coberta com enxofre sejam devidamente considerados e as épocas de maior necessidade do nitrogênio no ciclo da cultura e o efeito residual deste nos ciclos ou culturas posteriores.
Title in English
Not available
Abstract in English
This research aimed to compare the losses of nitrogen by lixiviation from sulphur coated urea (SCU) and uncoated urea and to verify the effect of pH on those losses. The experiment was conducted in the following types of cerrado soils of Brazil: Latosolic B Terra Roxa, Dark Red Latosol sandy phase e Red-Yellow Latosol sandy phase. The soils were placed in plastic tubes closed at the bottom with a nylon screen up to the height of 40 cm. The urea was spread in the upper 10 cm of the soil column. Each soil had received two doses of urea (60 and 120 kg N/ha), triple superphosphate, and potassium chloride and two pH values were used: the original soil pH and at the value of obtained through the addition of CaCO3. The experiment was set on randomized blocks design with a factorial scheme. The samples were obtained every 30 days during six months. Enough water was added in the soil to reach field capacity when the samples of the lixiviated were collected. Nitrogen (N-NH+4 + N-NO-3) was determined in the samples. The following conclusions were drawn: a) For the three types of soils, the sulphur coated urea (SCU) decreased the losses of nitrogen through the lixiviation process in comparison with the uncoated urea. b) For the three types of soils, the sulphur coated urea (SCU) presented evidence of slow release of nitrogen. c) The influence of pH varied depending on the type of soil. d) For the three types of soils, there was no influence of the pH on the losses of nitrogen, when sulphur coated urea (SCU) was used alone. This may lead to the conclusion that there is no influence of pH on the release of nitrogen retained in the granules of SCU. e) In the studies with sulphur coated urea it should be considerated the periods of greater demand of nitrogen by the plant and the residual effect of these on the cycle and subsequent cultures.
 
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Publishing Date
2022-02-07
 
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