Equações estruturais aplicadas ao entendimento da dinâmica do carbono do solo em sistemas agroflorestais no cerrado brasileiro
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Data
2019-11-01
Autores
Carvalho, Jaqueline Bonfim de
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Universidade Estadual Paulista (Unesp)
Resumo
O bioma Cerrado tem sofrido modificações nas últimas décadas, perdendo parte de sua cobertura original para culturas anuais, pastagens e florestas plantadas, tendo diferentes usos da terra. Neste trabalho, foram estudadas as interações entre os diferentes usos da terra em áreas do bioma Cerrado, bem como da dinâmica de carbono no solo e os fatores latentes formados pelos atributos físicos e químicos do solo, por meio de modelos de análise de equações estruturais, com auxílio das técnicas estatísticas multivariadas. Ensaios experimentais foram conduzidos na Fazenda de Ensino, Pesquisa e Extensão (FEPE/UNESP), localizada em Selvíria-MS: Floresta plantada de Eucalipto - Eucalyptus camaldulensis (EU); Floresta plantada de Pinus - Pinus caribaea var. hondurensis (PI); Sistema silvipastoril (SI) com uma área contendo floresta plantada de Aroeira (Myracrodruon urundeuva) e capim Braquiária (Brachiaria decumbens, e Mata Nativa (MN). Foi estudado os efeitos dos atributos físicos: densidade do solo (Ds), macroporosidade (Ma), microporosidade (Mi) e químicos com ênfase especial nas propriedades relacionadas à dinâmica do carbono no solo: matéria orgânica do solo (MO), estoque de carbono do solo (EstC), estoque de nitrogênio do solo (EstN), relação carbono e nitrogênio (C/N) e o grau de humificação da matéria orgânica do solo (HLIFS). A emissão de CO2 do solo (FCO2), umidade e temperatura do solo foram avaliados nas áreas durante três períodos distintos (definidos a partir do regime hídrico observado nas áreas) denominados de P1, P2 e P3, período de chuva, período de seca e transição, respectivamente, entre os meses de março e outubro do ano 2017. Diferenças significativas entre as médias (P <0,05) foram observadas em que no período de chuva houve maior emissão de CO2 nas áreas agrícolas, com maior média de FCO2 na MN com 5,89 μmol m-2 s-1. A análise de equação estrutural indicou que o HLIFS, MO e Ds, influenciaram negativamente a emissão de CO2 no P1 e P3. Para Ca2+, Mg2+ e P houve significância positiva para todos os períodos estudados. O uso da terra que apresentou os melhores resultados foi o SI, pois apresentou EstC semelhante a área de MN, com 21,35 Mg ha-1 e 21,57 Mg ha-1 respectivamente, porém menor FCO2 que a MN, se mostrando um sistema agroflorestal viável para manutenção de carbono no solo e menor emissão de FCO2 para atmosfera.
The Cerrado biome has undergone modifications in recent decades, losing part of its original cover to annual crops, pastures and planted forests, having different land uses. In this work, the interactions between the different land uses in areas of the Cerrado biome, as well as the soil carbon dynamics and the latent factors formed by the physical and chemical attributes of the soil through structural equation analysis models were studied. with the aid of multivariate statistical techniques. Experimental tests were performed at the Teaching, Research and Extension Farm (FEPE / UNESP), located in Selvíria-MS: Eucalyptus planted forest Eucalyptus camaldulensis (EU); Planted Pine Forest - Pinus caribaea var. hondurensis (PI); Silvipastoral system (SI) with an area containing Aroeira (Myracrodruon urundeuva) and native grass (Brachiaria decumbens), and Mata Nativa (MN). The effects of physical attributes: soil density (Ds), macroporosity (Ma), microporosity (Mi) and chemicals attributes were studied with special emphasis on properties related to soil carbon dynamics: soil organic matter (MO), soil carbon stock (EstC), soil nitrogen stock (EstN), carbon and nitrogen ratio (C / N), and the degree of soil organic matter (HLIFS). Soil CO2 emission (FCO2), soil moisture and temperature were evaluated in the areas during three distinct periods (defined from the water regime observed in the areas) called P1, P2 and P3, season rainfall, drought and transition, respectively, between March and October of 2017. Significant differences between the averages (P <0.05) were observed in that during the rainy season there was higher CO2 emission in the agricultural areas, with higher FCO2 average in the MN with 5.89 μmol m-2 s-1. Structural equation analysis indicated that HLIFS, MO and Ds negatively influenced CO2 emissions in P1 and P3. For Ca2 +, Mg2 + and P there was positive significance for all periods studied. The land use that presented the best results was the SI, since it presented an EstC similar to the MN area, with 21.35 Mg ha-1 and 21.57 Mg ha-1 respectively, but lower FCO2 than MN, showing a viable agroforestry system for soil carbon maintenance and lower FCO2 emission to atmosphere.
The Cerrado biome has undergone modifications in recent decades, losing part of its original cover to annual crops, pastures and planted forests, having different land uses. In this work, the interactions between the different land uses in areas of the Cerrado biome, as well as the soil carbon dynamics and the latent factors formed by the physical and chemical attributes of the soil through structural equation analysis models were studied. with the aid of multivariate statistical techniques. Experimental tests were performed at the Teaching, Research and Extension Farm (FEPE / UNESP), located in Selvíria-MS: Eucalyptus planted forest Eucalyptus camaldulensis (EU); Planted Pine Forest - Pinus caribaea var. hondurensis (PI); Silvipastoral system (SI) with an area containing Aroeira (Myracrodruon urundeuva) and native grass (Brachiaria decumbens), and Mata Nativa (MN). The effects of physical attributes: soil density (Ds), macroporosity (Ma), microporosity (Mi) and chemicals attributes were studied with special emphasis on properties related to soil carbon dynamics: soil organic matter (MO), soil carbon stock (EstC), soil nitrogen stock (EstN), carbon and nitrogen ratio (C / N), and the degree of soil organic matter (HLIFS). Soil CO2 emission (FCO2), soil moisture and temperature were evaluated in the areas during three distinct periods (defined from the water regime observed in the areas) called P1, P2 and P3, season rainfall, drought and transition, respectively, between March and October of 2017. Significant differences between the averages (P <0.05) were observed in that during the rainy season there was higher CO2 emission in the agricultural areas, with higher FCO2 average in the MN with 5.89 μmol m-2 s-1. Structural equation analysis indicated that HLIFS, MO and Ds negatively influenced CO2 emissions in P1 and P3. For Ca2 +, Mg2 + and P there was positive significance for all periods studied. The land use that presented the best results was the SI, since it presented an EstC similar to the MN area, with 21.35 Mg ha-1 and 21.57 Mg ha-1 respectively, but lower FCO2 than MN, showing a viable agroforestry system for soil carbon maintenance and lower FCO2 emission to atmosphere.
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Palavras-chave
AEE, Estoque de carbono, Modelagem, Sistemas agrícolas complexos, PLS-SEM, Carbon stock, EAA, Complex agricultural systems, Modeling