Although energy analysis is a way to evaluate the sustainability of production systems, this practice is not often used in the agribusiness. In this context, the castor bean (Ricinus communis L) is an agricultural crop not yet well studied despite its great potential in the Brazilian energetic scenario. This article aimed to evaluate the productive potential of the castor bean oil, using an energetic view applied to two management systems: low (System 1) and medium (System 2) technologies. The quantification of the used material fluxes was made converting these factors in energy units. The input energy fluxes were 3,170.6 MJ ha -1 and 10,366.0 MJ ha -1 for Systems 1 and 2, respectively. The energy balance of System 1 was 11,938.2 MJ ha -1 and that of System 2 16,296.5 MJ ha -1 . The net energetic gain or the energy gain over the invested energy (EROI) of System 1 was 3.8 and of System 2, 2.6. Although presenting a greater energy demand and a lower EROI, System 2 had a greater energy balance, demonstrating a better viability of this cultivation system for the production of castor bean oil. Key words: Energetic balance, oil crops, production technology, cultivation systems Fluxos de energia em sistemas de produção de mamona (Ricinus communis L.)RESUMO: A análise energética é uma forma de se avaliar a sustentabilidade de um sistema produtivo, apesar de ainda pouco utilizada no setor agropecuário. Inserida neste setor encontra-se a produção da mamoneira (Ricinus communis L.), cultura ainda pouco estudada e que apresenta grande importância para o agronegócio brasileiro. Avaliou-se sob a ótica energética a produção potencial de óleo de mamona em dois sistemas de cultivo: com baixa (Sistema 1) e média (Sistema 2) tecnologias. Foi realizada a quantificação dos fluxos de materiais empregados nos dois sistemas de produção e conversão destes fatores em unidades de energia. Os fluxos de energia de entrada foram de 3.170,6 MJ ha -1 e 10.366 MJ ha -1 para os sistemas 1 e 2, respectivamente. O balanço de energia foi de 11.938,2 MJ ha -1 no sistema 1 e 16.296,5 MJ ha -1 no sistema 2. A lucratividade energética, retorno em energia sobre energia investida (EROI) do sistema 1 foi de 3,8 e no sistema 2 de 2,6. Apesar de apresentar uma maior demanda energética e menor EROI, o sistema 2 obteve maior balanço energético, demonstrando a maior viabilidade deste tipo de cultivo para a cultura da mamoneira. Palavras-chave: Balanço energético, oleaginosas, tecnologia da produção, sistemas de cultivo
RESUMO Lixiviação de nitrato por meio do balanço hídrico climatológico na cultura de café fertirrigadaAs perdas de nitrato no perfil do solo por lixiviação devem ser monitoradas preferencialmente em ocasiões de altas precipitações pluviométricas e irrigações quando o uso de insumos nitrogenados é elevado. Foi utilizado o balanço hídrico climatológico empregando os modelos de Thornthwaite e Penman Monteith na obtenção da estimativa de evapotranspiração potencial para calcular os fluxos de drenagem de água abaixo da zona de raiz em lavoura de café fertirrigada. A extração da solução do solo a uma profundidade de 1 m permitiu o cálculo do nitrato lixiviado. A concentração de nitrato na solução do solo nas parcelas que receberam 400 kg ha Nitrate losses from soil profiles by leaching should preferentially be monitored during high rainfall events and during irrigation when fertilizer nitrogen applications are elevated. Using a climatologic water balance, based on the models of Thornthwaite and Penman Monteith for potential evapotranspiration, drainage soil water fluxes below the root zone were estimated in a fertigated coffee crop. Soil solution extraction at the depth of 1 m allowed the calculation of nitrate leaching. The average nitrate concentration in soil solution for plots that received nitrogen by fertigation at a rate of 400 kg ha , surpassing the limit of the Brazilian legislation of 10.0 mg L -1 , only during one month. For plots receiving 800 kg ha -1 of nitrogen, the average was 25.01 mg L -1 , 2.5 times higher than the abovementioned limit. This information indicates that nitrogen rates higher than 400 kg ha -1 are potentially polluting the ground water. Yearly nitrate amounts of leaching were 24.2 and 153.0 kg ha -1 for the nitrogen rates of 400 and 800 kg ha -1 , respectively. The six times higher loss indicates a cost/benefit problem for coffee fertigations above 400 kg ha -1 .
<p>The main factors determining plant growth and productivity are decisive to be understood since they<strong> </strong>contribute to maximize plant nitrogen use efficiency. Thus, more reviews related to the correlation between the real content of chlorophyll and real carotenoids with the values obtained by chlorophyll (SPAD) in the early development stages of the maize are important to be obtained. The relation between the maize crop responses to the nitrogen fertilization at different development stages is of fundamental importance as well. The primary objective of this study was to investigate the responses of maize to the nitrogen application, urea fertilizer (<sup>15</sup>N), in side-dress at different development stages. The secondary objective was verifying the correlation between chlorophylls and carotenoids with SPAD index and these with total biomass (BM), harvest index (HI), grain yield (GY) and grain N content in response to the nitrogen side-dress at different development stages. The nitrogen fertilization was carried out in plots, with the application of 30 kg ha<sup>-1</sup> of N at planting and 140 kg ha<sup>-1</sup> N as side-dress at vegetative stages V4, V6, V8, V10, and V12, without incorporation into the soil, and control treatment consisted of non-nitrogen side-dress application was also utilized. The 2011/2012 season presented higher precipitation than 2012/2013. Maize crop responded similarly for GY to the nitrogen application in side-dress in both seasons, however, the nitrogen application in the early stages caused higher values for leaf variables, leaf pigments, and SPAD. Higher amount of nitrogen in all parts of the plants was observed in the 2011/2012 season than in 2012/2013, influenced by the adequate weather conditions at the nitrogen application moment. Grain N content from <sup>15</sup>N fertilizer and N uptake and efficiency were greater for early N applications. SPAD values correlated positively with most pigment variables at V16 in both seasons, thus proving that SPAD was an efficient instrument of indirect evaluation of chlorophylls and carotenoids in maize leaves at early stages. Chlorophyll b at V16 was positively correlated (P < 0.05) with grain N content, GY, and BM, and total chlorophyll at V16 was positively correlated with GY and grain N content. However the chlorophylls a and total, evaluated at V14, were negatively correlated with GY. So, measurement of real chlorophyll and carotenoid pigment contents should be done after V14 stage when studies aim to evaluate crop nutritional conditions and prescribe future grain production practices.</p>
RESUMO Drenagem interna em cultura de cafeeiro fertirrigada por pivô centralA cultura de cafeeiro, conduzida via fertirrigação por pivô-central, pode provocar perdas por drenagem profunda nas áreas irrigadas. Este trabalho analisa estas perdas para o caso de cultura de cafeeiro, conduzida em alto padrão tecnológico de fertirrigação por pivô central, estabelecida no oeste baiano, sobre planície de solo arenoso. Este estudo é uma tentativa de estimar, por meio do balanço hídrico climatológico (BHC), obtido a partir de dados meteorológicos e medidas físicas das características do solo, a perda por drenagem profunda (Q), com uso de pivô central em cultura de cafeeiro fertirrigada. O estudo visa a contribuir para o conhecimento do regime hídrico destas culturas manejadas por irrigação com pivô central, utilizando-se para isso três cenários (Sc) distintos de regime hídrico, durante o período de um ano do ciclo da cultura de cafeeiro: i) apenas precipitação; ii) precipitação + irrigação no ano inteiro; e iii) precipitação + irrigação apenas na estação seca. Os valores estimados de Q foram: Sc i = 811,5 mm; Sc ii = 1010,5 mm; e Sc iii = 873,1 mm, sendo que o corte da irrigação no período chuvoso (Sc iii ) reduziu Q em 15,7% e não afetou o aparecimento de períodos de défices. Por meio do BHC, com a utilização de parâmetros climatológicos e medidas físicas da característica do solo, foi possível fazer a estimativa da drenagem profunda do solo em estudo. Coffee cultivation via central-pivot fertigation can lead to fertilizer losses by soil profile internal drainage when water application is excessive and soils have low water retention and cation adsorption capacities. This study analyses the deep water losses from the top 1 m sandy soil layer of east Bahia, Brazil, cultivated with coffee at a high technology level (central-pivot fertigation), using above normal N fertilizer rates. The deep drainage (Q) estimation is made through the application of a climatologic water balance (CWB) program having as input direct measures of irrigation and rainfall, climatological data from weather stations, and measured soil water retention characteristics. The aim of the study is to contribute to the understanding of the hydric regime of coffee crops managed by central-pivot irrigation, analyzing three scenarios (Sc): i) rainfall only, ii) rainfall and irrigation full year, and iii) rainfall and irrigation dry season only. Annual Q values for the 2008/2009 agricultural year were: Sc i = 811.5 mm; Sc ii = 1010.5 mm; and Sc iii = 873.1 mm, so that the irrigation interruption in the wet season reduced Q by 15.7%, without the appearance of water deficit periods. Results show that the use of the CWB program is a convenient tool for the evaluation of Q under the cited conditions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.