Balanço de carbono no sistema solo-planta-atmosfera com aplicação superficial de calcário e gesso em sistema de semeadura direta
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Data
2020-03-30
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Universidade Estadual Paulista (Unesp)
Resumo
A calagem é uma pratica agrícola indispensável para a correção da acidez em solos tropicais contribuindo para o aumento da produção de grãos e biomassa. A aplicação superficial de calcário e gesso em sistema de semeadura direta (SSD) tem sido uma estratégia usada para melhorar as propriedades químicas do solo em subsuperficie, todavia, existem poucas informações sobre os efeitos dessa prática no balanço de carbono no sistema solo-planta-atmosfera. Dessa forma, o trabalho teve como objetivo avaliar a emissão acumulada anual de C-CO2, o estoque de C e N no solo, a qualidade da matéria orgânica do solo (MOS) e a atividade biológica, bem como a deposição de C e N pela biomassa do sistema radicular e pelos resíduos produzidos no final do ciclo das culturas na superfície do solo, em função da aplicação superficial de calcário e gesso em um SSD de longa duração. O experimento foi instalado em 2002 em um delineamento experimental em blocos casualizados no esquema de parcelas subdivididas e 4 repetições. A aplicação de calcário e gesso ocorreu nos anos de 2002, 2004, 2010 e por último em 2016 quando foi dado início a condução do presente trabalho. As parcelas foram constituídas por quatro níveis de calcário (ausência de aplicação, 3260, 6520 e 13040 kg ha-1) e as subparcelas por dois níveis de gesso agrícola (ausência de aplicação e 10000 kg ha-1). Ao final dos dois anos agrícolas a aplicação de calcário promoveu um aporte médio de 2,70 Mg ha-1 de C e 150 kg ha-1 de N pelo sistema radicular da soja, milho e U. ruziziensis em relação ao tratamento controle, respectivamente. A calagem promoveu um aporte médio de 14,00 Mg ha-1 de C e 400 kg ha-1 de N pela massa de matéria seca da parte aérea da soja, milho e U. ruziziensis em relação ao tratamento controle, respectivamente. A aplicação superficial de calcário e gesso não influenciaram os estoques de C e N no solo. A calagem superficial influenciou as frações da MOS, como também, os atributos biológicos do solo indicando uma possível condição de desequilíbrio. Os dados mostram que o calcário influenciou na emissão acumulada de C-CO2, e a dose de 3260 kg ha-1 de calcário apresentou emissão acumulada cerca de 10, 8 e 12% superior ao tratamento controle, dose de 6520 e 13040 kg ha-1 de calcário, respectivamente. A aplicação de calcário e gesso resultou em uma produtividade média de grãos cerca de 38 e 10% superior ao tratamento controle nas safras da soja, e 60 e 17% nas safras do milho, respectivamente. Os resultados sugerem que apesar da calagem influenciar na emissão de C-CO2, sua utilização em combinação com o gesso refletiu em maiores entradas de C via resíduos vegetais, compensando as saídas, promovendo um balanço de C mais favorável para o sistema, principalmente quando a dose de 13040 kg ha-1 de calcário foi empregada.
Liming is an indispensable agricultural practice for the correction of acidity in tropical soils contributing to the increase in the production of grains and biomass. The superficial application of lime and gypsum in a direct seeding system (NT) has been a strategy used to improve the chemical properties of the soil in subsurface, however, there is little information about the effects of this practice on the carbon balance in the soil-plant-atmosphere system. Thus, the work aimed to evaluate the accumulated annual emission of C-CO2, the stock of C and N in the soil, the quality of soil organic matter (SOM) and the biological activity, as well as the deposition of C and N by the biomass of the root system and by the residues produced at the end of the crop cycle on the soil surface, due to the superficial application of lime and gypsum in a long-term NT. The experiment was installed in 2002 in a randomized block design in a split plot and 4 replications scheme. The application of lime and gypsum occurred in the years 2002, 2004, 2010 and lastly in 2016 when the conduction of the present work began. The plots consisted of four levels of lime (no application, 3260, 6520 and 13040 kg ha-1) and the subplots by two levels of agricultural gypsum (no application and 10,000 kg ha-1). At the end of the two agricultural years, the application of lime promoted an average supply of 2.70 Mg ha-1 of C and 150 kg ha-1 of N by the root system of the soybean, corn and U. ruziziensis in relation to the control treatment, respectively. Liming promoted an average supply of 14.00 Mg ha-1 of C and 400 kg ha-1 of N by the dry matter mass of the aerial part of the soybean, corn and U. ruziziensis in relation to the control treatment, respectively. The superficial application of lime and gypsum did not influence the C and N stocks in the soil. The superficial lime influences the SOM fractions, as well as the biological attributes of the soil, indicating a possible imbalance condition. The data show that liming influenced the accumulated emission of C-CO2, and the dose of 3260 kg ha-1 of lime showed an accumulated emission about 10, 8 and 12% higher than the control treatment, dose of 6520 and 13040 kg ha-1 of lime, respectively. The application of liming and gypsum resulted in an average grain yield of about 38 and 10% higher than the control treatment in soybean crops, and 60 and 17% in corn crops, respectively. The results suggest that although liming influences the emission of C-CO2, its use in combination with gypsum reflected in higher C inputs via plant residues, offsetting the outputs, promoting a more favorable C balance for the system, especially when the a dose of 13040 kg ha-1 of lime was used.
Liming is an indispensable agricultural practice for the correction of acidity in tropical soils contributing to the increase in the production of grains and biomass. The superficial application of lime and gypsum in a direct seeding system (NT) has been a strategy used to improve the chemical properties of the soil in subsurface, however, there is little information about the effects of this practice on the carbon balance in the soil-plant-atmosphere system. Thus, the work aimed to evaluate the accumulated annual emission of C-CO2, the stock of C and N in the soil, the quality of soil organic matter (SOM) and the biological activity, as well as the deposition of C and N by the biomass of the root system and by the residues produced at the end of the crop cycle on the soil surface, due to the superficial application of lime and gypsum in a long-term NT. The experiment was installed in 2002 in a randomized block design in a split plot and 4 replications scheme. The application of lime and gypsum occurred in the years 2002, 2004, 2010 and lastly in 2016 when the conduction of the present work began. The plots consisted of four levels of lime (no application, 3260, 6520 and 13040 kg ha-1) and the subplots by two levels of agricultural gypsum (no application and 10,000 kg ha-1). At the end of the two agricultural years, the application of lime promoted an average supply of 2.70 Mg ha-1 of C and 150 kg ha-1 of N by the root system of the soybean, corn and U. ruziziensis in relation to the control treatment, respectively. Liming promoted an average supply of 14.00 Mg ha-1 of C and 400 kg ha-1 of N by the dry matter mass of the aerial part of the soybean, corn and U. ruziziensis in relation to the control treatment, respectively. The superficial application of lime and gypsum did not influence the C and N stocks in the soil. The superficial lime influences the SOM fractions, as well as the biological attributes of the soil, indicating a possible imbalance condition. The data show that liming influenced the accumulated emission of C-CO2, and the dose of 3260 kg ha-1 of lime showed an accumulated emission about 10, 8 and 12% higher than the control treatment, dose of 6520 and 13040 kg ha-1 of lime, respectively. The application of liming and gypsum resulted in an average grain yield of about 38 and 10% higher than the control treatment in soybean crops, and 60 and 17% in corn crops, respectively. The results suggest that although liming influences the emission of C-CO2, its use in combination with gypsum reflected in higher C inputs via plant residues, offsetting the outputs, promoting a more favorable C balance for the system, especially when the a dose of 13040 kg ha-1 of lime was used.
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Palavras-chave
Sequestro de carbono, Solos ácidos, Gesso, Humus, Dióxido de carbono, Carbon sequestration, Greenhouse effect, Carbon balance, CO2 flow, Soil concealers