Nitrogênio no sistema solo-planta após a aplicação de calcário e gesso em sistema de produção
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Data
2022-02-02
Autores
Souza, Murilo de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O milho tem sido cultivado em segunda safra no sistema de semeadura direta (SSD), após a soja, mas ainda não há informações precisas sobre sua resposta ao nitrogênio (N) nesse sistema de cultivo, principalmente quando consorciado com gramíneas forrageiras, bem como sobre as consequências na próxima cultura da soja, e processos do ciclo do carbono (C) no solo. O objetivo do trabalho foi avaliar a eficiência do uso de N pela cultura do milho em consórcio com o capim colonião cv. Tanzânia (Megathyrsus maximus) na segunda safra, crescimento radicular das culturas em SSD, produtividade das culturas e eficiência de uso do carbono (EUC) em função da correção da acidez do solo utilizando calcário e gesso. Foi conduzido um experimento com a cultura da soja e subsequente à soja, foi cultivado o milho em consórcio com capim cv. Tanzânia, nos anos agrícolas de 2017, 2018 e 2019. Os tratamentos constaram da aplicação de calcário, calcário + gesso e controle (sem aplicação de corretivos) na cultura da soja, e quatro doses de N (0, 80, 160 e 240 kg ha-1) aplicadas na cultura do milho. No tratamento com 160 kg ha-1 N foi realizada aplicação de sulfato de amônio enriquecido em 15N, para avaliação do aproveitamento do N fertilizante. A aplicação dos corretivos de acidez do solo foi eficiente em promover maior crescimento radicular, sendo mais evidente com a aplicação de calcário associado ao gesso. A correção do solo também promoveu maior absorção do N pelas plantas de milho consorciado com capim cv. Tanzânia, consequentemente, resultou em maior eficiência de uso do fertilizante nitrogenado. Além disso, há evidências que a adição de N e P pode aumentar a eficiência do uso de carbono adicionado em solos com acidez corrigida, sugerindo que a comunidade microbiana do solo é limitada pelas restrições de nutrientes minerais.
Maize has been cultivated as a relay crop in the no tillage system (NTS), after soybean, but there is still no accurate information about its response to nitrogen (N) in this cultivation system, especially when intercropped with forage grasses, as well as about the consequences on the next soybean crop, and carbon (C) cycle processes in the soil. The objective of this work was to evaluate the fertilizer N use efficiency (NUE) by maize as a relay crop intercropped with Guinea grass (Megathyrsus maximus), root growth of crops in NTS, crop yield and carbon use efficiency (CUE) as a function of soil acidity alleviation using lime and gypsum. An experiment was carried out with soybean crop and subsequent to soybean, maize was cultivated intercropped with Guinea grass, in the 2017, 2018 and 2019 seasons. The treatments consisted of the application of lime, lime + gypsum and control (without amendments application) in the soybean crop, and four N doses (0, 80, 160 and 240 kg ha-1 ) applied to maize. In the treatment with 160 kg N ha-1 , ammonium sulfate enriched with 15N was applied, to evaluate the N-fertilizer recovery. The amendments application was efficient in promoting greater root growth, being more evident with the lime associated with gypsum application. Acidity soil correction also promoted greater N uptake by maize plants intercropped with Guinea grass, consequently, resulted in greater fertilizer NUE. Furthermore, there is evidence that the addition of N and phosphorus (P) can increase the use efficiency of the added carbon in acid-corrected soils, suggesting that the soil microbial community is limited by mineral nutrient restrictions.
Maize has been cultivated as a relay crop in the no tillage system (NTS), after soybean, but there is still no accurate information about its response to nitrogen (N) in this cultivation system, especially when intercropped with forage grasses, as well as about the consequences on the next soybean crop, and carbon (C) cycle processes in the soil. The objective of this work was to evaluate the fertilizer N use efficiency (NUE) by maize as a relay crop intercropped with Guinea grass (Megathyrsus maximus), root growth of crops in NTS, crop yield and carbon use efficiency (CUE) as a function of soil acidity alleviation using lime and gypsum. An experiment was carried out with soybean crop and subsequent to soybean, maize was cultivated intercropped with Guinea grass, in the 2017, 2018 and 2019 seasons. The treatments consisted of the application of lime, lime + gypsum and control (without amendments application) in the soybean crop, and four N doses (0, 80, 160 and 240 kg ha-1 ) applied to maize. In the treatment with 160 kg N ha-1 , ammonium sulfate enriched with 15N was applied, to evaluate the N-fertilizer recovery. The amendments application was efficient in promoting greater root growth, being more evident with the lime associated with gypsum application. Acidity soil correction also promoted greater N uptake by maize plants intercropped with Guinea grass, consequently, resulted in greater fertilizer NUE. Furthermore, there is evidence that the addition of N and phosphorus (P) can increase the use efficiency of the added carbon in acid-corrected soils, suggesting that the soil microbial community is limited by mineral nutrient restrictions.
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Palavras-chave
Corretivos de solo, Soja, Milho segunda safra, Sistemas de consórcio, Carbono microbiano, Soil amendments, Soybean, Maize as a relay crop, Intercropped system, Microbial carbon