Agregação e carbono orgânico de um Latossolo cultivado por quatorze anos nos sistemas convencional e plantio direto
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Data
2017-06-16
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Universidade Federal de Viçosa
Resumo
Os sistemas de cultivo interferem no conteúdo de carbono e na agregação do solo. A estrutura é uma das propriedades que mais interfere na qualidade do solo e, deste modo, há expectativa de aumento de produtividade com a adoção de sistemas de cultivo que favoreçam a agregação. Objetivou-se, em experimento de longa duração, avaliar os índices de agregação e o teor de carbono orgânico nas classes de agregados de um Latossolo em sistemas convencional e plantio direto com cultivo de plantas de cobertura em pré-safra. O experimento foi instalado em LATOSSOLO VERMELHO Distrófico típico, textura argilosa, em delineamento em blocos ao acaso com quatro repetições, um tratamento em sistema convencional e mais seis tratamentos em plantio direto, com as seguintes plantas de cobertura em pré-safra de milho: mucuna-cinza, lablab, feijão-de- porco, guandu-anão, milheto e vegetação espontânea (VE). A coleta das amostras de solo foi realizada nas camadas de 0-5 cm e 5-10 cm para a avaliação da estabilidade dos agregados, com separação nas seguintes classes de tamanho: macroagregados (diâmetro > 2,00 mm), mesoagregados (diâmetro entre 2,00 e 0,25 mm) e microagregados (diâmetro entre 0,25 e 0,05 mm). Além das parcelas do experimento foi amostrada também uma área de mata adjacente para determinação do índice de sensibilidade. A determinação do C orgânico foi feita nas amostras que ficaram retidas nas peneiras. No sistema plantio direto ocorreu predominância de macroagregados, na camada de 0-5 cm, e de mesoagregados, na camada de 5-10 cm. Os índices de agregação no plantio direto com plantas de cobertura foram maiores do que no sistema convencional, na camada de 0-5 cm, e o índice de sensibilidade demonstrou que o uso do sistema plantio direto por quatorze anos melhorou a estabilidade dos agregados do solo. No plantio direto, o cultivo de plantas de cobertura e a VE resultaram em índices de agregação semelhantes, quatorze anos após a implantação do sistema, e a mucuna-cinza foi a espécie menos eficiente na agregação do solo, na camada de 0-5 cm. O teor de C orgânico decresceu com a diminuição do tamanho dos agregados em todos os sistemas de cultivo
Cultivation systems interfere with soil carbon content and aggregation. Structure is one of the properties that most influence soil quality and hence productivity is expected to increase with the adoption of cultivation systems that favor aggregation. The present thesis had the objective of evaluating aggregation indexes and organic carbon content in classes of aggregates from soil samples in conventional and no-till systems with cultivation of cover crops in the pre-cropping period, in long-term experiment. The experiment was installed in typical dystrophic Hapludox, with clayey texture, in a randomized block design with four replications, exhibiting one conventional and six no- till treatments with the following pre-cropping cover crops: velvet bean gray, lablab, jack bean, pigeon pea, millet and spontaneous vegetation. Soil samples were collected from layers 0-5 cm and 5-10 cm depth to evaluate the stability of the aggregates, with separation of material according to the following size categories: macroaggregates (diameter > 2.00 mm), mesoaggregates (diameter between 2.00 and 0.25 mm) and microaggregates (diameter between 0.25 and 0.05 mm). In addition to the experiment samples, an area of adjacent forest was also analyzed to assess the sensivity index. Determination of organic carbon was carried out in the samples retained in sieves. In no-till samples, macroaggregates prevailed in the 0-5 cm layer and mesoaggregates predominated in the 5-10 cm layer. Aggregation indexes for no-till treatment with cover crops were larger than the values obtained for the conventional system and the sensitivity index revealed that using a no-till treatment for fourteen years increased the stability of soil aggregates. In this system, the cultivation of cover crops and spontaneous vegetation for fourteen years resulted in aggregation indexes similar to the ones recorded before the implementation of this cultivation method and velvet bean gray was the least efficient species to cause soil aggregation in the 0-5 cm layer. The content of organic carbon decreased as the aggregate size reduced in both cultivation systems
Cultivation systems interfere with soil carbon content and aggregation. Structure is one of the properties that most influence soil quality and hence productivity is expected to increase with the adoption of cultivation systems that favor aggregation. The present thesis had the objective of evaluating aggregation indexes and organic carbon content in classes of aggregates from soil samples in conventional and no-till systems with cultivation of cover crops in the pre-cropping period, in long-term experiment. The experiment was installed in typical dystrophic Hapludox, with clayey texture, in a randomized block design with four replications, exhibiting one conventional and six no- till treatments with the following pre-cropping cover crops: velvet bean gray, lablab, jack bean, pigeon pea, millet and spontaneous vegetation. Soil samples were collected from layers 0-5 cm and 5-10 cm depth to evaluate the stability of the aggregates, with separation of material according to the following size categories: macroaggregates (diameter > 2.00 mm), mesoaggregates (diameter between 2.00 and 0.25 mm) and microaggregates (diameter between 0.25 and 0.05 mm). In addition to the experiment samples, an area of adjacent forest was also analyzed to assess the sensivity index. Determination of organic carbon was carried out in the samples retained in sieves. In no-till samples, macroaggregates prevailed in the 0-5 cm layer and mesoaggregates predominated in the 5-10 cm layer. Aggregation indexes for no-till treatment with cover crops were larger than the values obtained for the conventional system and the sensitivity index revealed that using a no-till treatment for fourteen years increased the stability of soil aggregates. In this system, the cultivation of cover crops and spontaneous vegetation for fourteen years resulted in aggregation indexes similar to the ones recorded before the implementation of this cultivation method and velvet bean gray was the least efficient species to cause soil aggregation in the 0-5 cm layer. The content of organic carbon decreased as the aggregate size reduced in both cultivation systems
Descrição
Palavras-chave
Plantas de cobertura, Classes de agregados, Sistemas conservacionistas
Citação
MARUYAMA, Fabrícia Flávia Andrioli. Agregação e carbono orgânico de um Latossolo cultivado por quatorze anos nos sistemas convencional e plantio direto. 2017. 30f. Dissertação (Mestrado em Agronomia - Produção Vegetal) - Universidade Federal de Viçosa, Rio Paranaíba. 2017.