Balanço de Energia, Emissão Foliar e Eficiência do Uso da Radiação pela Cana-de-Açúcar em Cultivo sem e com Palhada

Abstract

ResumoNas últimas décadas houve mudança no sistema de colheita e manejo da palhada em canaviais de todo o Brasil, visando atender a legislação vigente e reduzir custos. A deposição de resíduos culturais sobre o solo, contudo, modifica as características micrometeorológicas do ambiente. Este trabalho reporta um estudo conduzido em Juazeiro-BA, para avaliar o efeito da manutenção da palhada no balanço de energia, emissão foliar e eficiência do uso da radiação da cana-deaçúcar. Medidas micrometeorológicas e da cultura foram feitas entre setembro de 2015 e julho de 2016. A magnitude e sazonalidade dos fluxos de calor latente, sensível e no solo foram afetadas pela presença da palhada (p<0,0001) com alteração na partição do LE/Rn de 84% para 64%, do H/Rn de 12% para 35% e do G/Rn de 4% para 2%, nessa ordem, para o cultivo sem e com palhada. A temperatura do ar foi maior no cultivo com palhada após o fechamento do dossel, enquanto, a umidade relativa do ar foi acrescida apenas nos primeiros meses. A modificação do microclima por causa da manutenção da palhada em campo alterou a velocidade de emissão foliar da cana-de-açúcar, mas, pouco afetou a eficiência do uso da radiação (2,51 g MJ -1 ).Palavras-chave: fluxo de calor sensível e latente, filocrono, uso da radiação. AbstractIn recent decades there has been a change in the system of harvesting and management of straw in sugarcane fields all over Brazil, aiming to comply with current legislation and reduce costs. The crop residues deposition on the soil, however, modifies the micrometeorological characteristics of the crop environment. This work reports a study conducted in Juazeiro-BA to evaluate the effect of field straw maintenance on the energy balance, development and radiation use efficiency by sugarcane. Micrometeorological and crop measurements were made between September 2015 and July 2016. The magnitude and seasonality of the latent, sensible and soil heat fluxes were affected by the presence of straw Autor de Correspondência: Thieres George Freire da Silva, thieres_freire@yahoo.com.br.Revista Brasileira de Meteorologia, v. 34, n. 1, 69À 78, 201969À 78, rbmet.org.br DOI: http://dx.doi.org/10.1590 (p < 0.0001) with a change in the LE/Rn from 84% to 64%, H/Rn from 12% to 35% and G/Rn from 4% to 2%, in that order, for the cultivation without and with straw. The air temperature was higher in the straw crop after the canopy closure, while the air relative humidity was increased only in the first months. The modification of the microclimate due to the maintenance of the straw altered the leaf emission speed of the sugarcane, but little affected the radiation use efficiency by crop (2.51 g MJ -1 ).

Soil properties and microclimate of two predominant landscapes in the Brazilian semiarid region: Comparison between a seasonally dry tropical forest and a deforested area

“…It is stated that more than 50% of the Caatinga vegetation cover has already been deforested (Althoff et al, 2018), which may justify the reduction in precipitation. Under this condition, there is a significant decrease in actual evapotranspiration in the dry season and a small increase in the wet season, impacting on the precipitation (Silva et al, 2019a(Silva et al, ,2019b. These results confirm the importance of the ecosystem services provided by the forest on the precipitation regime, and consequently for food production, greenhouse gas mitigation and climate regulation, as well as ensuring the economic stability of a region (Strand et al 2018).…”

“…The slight decrease in T MAX in the DEFA site when compared with the CAA can be justified by increases in the surface albedo and wind speed during the diurnal period, reducing the radiation balance above the soil surface. In contrast, the significant rise in T N is associated with the energy stored in the soil profile during the diurnal period, which is dissipated at night, warming up the air by irradiation (Silva et al, 2019a(Silva et al, , 2019bTeixeira et al, 2008). Domain deforestation causes T AVE to rise but depends on the type of vegetation removed, location and time of year, affecting the leaf area index seasonality, and consequently, solar energy penetration into the soil (Salazar et al, 2016).…”

“…In addition, there are small farms which consist of subsistence crops such as beans, corn, sorghum and forage cactus, as well as grassland. Therefore, conservation units share space with native areas that have suffered some kind of anthropic impact (Akhzari et al, 2015;Silva et al, 2019aSilva et al, , 2017Souza et al, 2011;Teixeira et al, 2008). Moreover, landscapes with a predominance of herbaceous plants combined with bare soil are observed in areas with failure of rainfed agricultural activity, which then became abandoned farmlands.…”

Microclimate and Irrigation Affect the Growth Dynamics of Sugarcane in a Semiarid Environment

“…The Brazil is one of the main global producers of this crop, the region north-east of Brazil also plays an important contribution, especially the coastal region of the states of Alagoas, Paraíba and Pernambuco (CONAB, 2019). Another important area of production in the region is the Lower-Middle São Francisco Valley, particularly the district of Juazeiro, Bahia, in the semi-arid region of Brazil, which, due to the use of irrigation linked to soil and climate conditions and to crop management, has excellent sugarcane production indicators (Silva et al, 2019).…”

Straw management effects on sugarcane growth, nutrient cycling and water use in the Brazilian semiarid region

“…The presence of straw, commonly referred to as green cane trash blanketing, on sugarcane fields reduces the need for irrigation, erosion risk, weed emergence, and carbon emission (Hu et al 2018;Sousa Junior et al 2018); it improves microbiota and soil physical properties (Souza et al 2005), releases nutrients (as nitrogen) into the soil (Sousa Junior et al 2018;Vitti et al 2008;Costa et al 2014), and modifies the microclimate (Sandhu et al 2013;Silva et al 2019), besides increasing the crop water productivity (Olivier and Singels 2012;Vianna et al 2020). On the other hand, excess straw changes crop growth and development (Olivier and Singels 2012; by increasing the risk of fire and infestation of pests and diseases and impairing sprouting (Awe et al 2015).…”