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Nitrogen (N) is the most extracted and exported element by the soybean crop. In high yield tropical environments with irrigation, little is known about N accumulation in different soybean plant organs as well as the N balance. The objective of this study was to characterize soybean growth, N accumulation in plant organs, N balance, and N gap in a high yield tropical environment. This study was performed in a homogeneous field, in a soil with low organic matter, with 20 kg ha-1 of N, under furrow fertilization. Evaluations were performed ten times, temporally distributed from emergence to senescence. The soybean cultivar used was 'RK7518 IPRO' and was sown with row spacing of 0.45 m and a seeding rate of 300,000 plants ha-1. Plant N partition, N from the biological N fixation (BNF), grain yield, crop harvest index (HI), N harvest index (NHI) with and without root contribution were evaluated. Also, at the grain filling stage the N gap was evaluated from the soil by difference between whole plant accumulated N and the amount of N from BNF. The average grain yield was 6,470 kg ha-1 and leads to a negative partial balance of N of -33.4 and -42.8 kg[N] ha-1 with and without roots, respectively. The N gap from the soil was 231.7 kg[N] ha-1. It is recommended to adopt techniques that increase the efficiency of BNF and the soil N accumulation to balance these production systems in the medium to long term.

RESUMO

The objective of the study was to evaluate the growth and production efficiency of forage-grain dual-purpose wheat in two arrangements and four agroforestry systems (Intercrop-I and Intercrop-II), as well as to evaluate crop management for the wheat crops in two planting seasons (Crop Season I-2014 and Crop Season II-2015. The experiment was conducted in a randomized complete block design, factorial scheme 7x2x2, with seven cultivation systems Eucalyptus urophylla x Eucalyptus grandis Intercrop-II and Intercrop-I; Peltophorum dubium Intercrop-II and Intercrop-I; P. rigida Intercrop-I; S. parahyba Intercrop-I; a wheat monoculture with no tree species present; and two harvest management techniques (with and without harvesting of the forage species). Agroforestry systems generated shading for wheat plants, with a higher phyllochron and lower values of leaf area index of those individuals kept under trees with higher crown shading (non-deciduous trees) due to the lower transmissivity of solar radiation. The systems composed with Schizolobium parahyba in Intercrop-I and Parapiptadenia rigida in Intercrop-I provide a minor phyllochron to the wheat, resulting in a higher leaf area index and dry matter yield. Thus, the cultivation of tree species and dual-skilled agricultural crops, such as wheat, provides promising alternatives for the future use of land in tropical countries.

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Despite its economic importance, the microclimate in soybean canopies has not yet been studied in detail. Such a study can yield valuable information regarding the interaction of a crop with its environment. In this context, the aim of this study was to evaluate the solar radiation dynamic and yield responses for each canopy strata for two soybean cultivars with determined and undetermined growth habits. A field study was conducted during the 2013/2014 and 2014/2015 growing seasons in the city of Frederico Westphalen, Rio Grande do Sul, Brazil. The cultivar NA6411, with a determinate growth habit, presented a greater interception of radiation in the middle and lower canopies strata which results in higher soybean yield when compared to the cultivar TEC6029, and thus, can be recommended for cultivation in crop production systems. The contribution of the middle and upper canopy strata to the total yield formation was greater than that observed in the lower canopy strata due to the greater interception of solar radiation by these strata. To increase soybean yields, new studies regarding the microclimatic conditions of the soybean canopy should be developed to improve the maximum potential yield of the new soybean cultivars.

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The purpose of this study is to determine the growth, the solar radiation use efficiency, and the gross protein of sorghum forage under different cutting management. A unifactorial design in random blocks (cutting management) was used, varying from no-cut treatment to four cuts. The first cut occurred 44 days after sowing, the second one after 23 days of regrowth, the third one after 25 days of regrowth, and the last one after 40 days of regrowth. The efficiency of the sorghum forage's solar radiation use reduces as the number of cuts increases. The sorghum forage's gross protein increases with cutting management. Therefore, for a sorghum forage crop, it is recommended to restrain the cutting management up to three times during the crop cycle, since it has the biomass potential production, and the cuts should be made at every 25 days, depending on the increase of dry mass. After that, the cutting management should not be done, mainly due to the low radiation use efficiency, reduced dry mass accumulation, and low material quality.(AU)

O objetivo deste trabalho foi determinar o crescimento, a eficiência do uso da radiação solar e a proteína bruta do sorgo forrageiro submetido a diferentes manejos de cortes. Foi utilizado um esquema unifatorial em delineamento de blocos casualizados (manejo de cortes), que variou do tratamento sem corte até quatro cortes. O primeiro corte ocorreu 44 dias após a semeadura, o segundo 23 dias após o rebrote, o terceiro 25 dias após o rebrote e o último após 40 dias do rebrote. A eficiência do uso da radiação solar do sorgo forrageiro reduziu com o aumento do número de cortes. A proteína bruta das plantas de sorgo aumentou com o manejo de cortes. Portanto, para a cultura do sorgo forrageiro, recomenda-se restringir o manejo de cortes para até três vezes durante o ciclo, desde que exista potencial produtivo de biomassa, e esses cortes devem ocorrer a cada 25 dias, dependendo do acréscimo de matéria seca. Não se recomenda a realização de mais do que três cortes, devido à baixa eficiência na utilização da radiação solar, à reduzida acumulação de matéria seca e à baixa qualidade desse material.(AU)

Assuntos

RESUMO

The purpose of this study is to determine the growth, the solar radiation use efficiency, and the gross protein of sorghum forage under different cutting management. A unifactorial design in random blocks (cutting management) was used, varying from no-cut treatment to four cuts. The first cut occurred 44 days after sowing, the second one after 23 days of regrowth, the third one after 25 days of regrowth, and the last one after 40 days of regrowth. The efficiency of the sorghum forage's solar radiation use reduces as the number of cuts increases. The sorghum forage's gross protein increases with cutting management. Therefore, for a sorghum forage crop, it is recommended to restrain the cutting management up to three times during the crop cycle, since it has the biomass potential production, and the cuts should be made at every 25 days, depending on the increase of dry mass. After that, the cutting management should not be done, mainly due to the low radiation use efficiency, reduced dry mass accumulation, and low material quality.

O objetivo deste trabalho foi determinar o crescimento, a eficiência do uso da radiação solar e a proteína bruta do sorgo forrageiro submetido a diferentes manejos de cortes. Foi utilizado um esquema unifatorial em delineamento de blocos casualizados (manejo de cortes), que variou do tratamento sem corte até quatro cortes. O primeiro corte ocorreu 44 dias após a semeadura, o segundo 23 dias após o rebrote, o terceiro 25 dias após o rebrote e o último após 40 dias do rebrote. A eficiência do uso da radiação solar do sorgo forrageiro reduziu com o aumento do número de cortes. A proteína bruta das plantas de sorgo aumentou com o manejo de cortes. Portanto, para a cultura do sorgo forrageiro, recomenda-se restringir o manejo de cortes para até três vezes durante o ciclo, desde que exista potencial produtivo de biomassa, e esses cortes devem ocorrer a cada 25 dias, dependendo do acréscimo de matéria seca. Não se recomenda a realização de mais do que três cortes, devido à baixa eficiência na utilização da radiação solar, à reduzida acumulação de matéria seca e à baixa qualidade desse material.

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Sugarcane (Sacharum officinarum L.) monocropping has had a great socio-economic and environmental impact in Brazil, and agroforestry systems have been considered as an alternative for more sustainable production; however, there is a lack of field research under such conditions. The aim of this study was to evaluate the growth rates, radiation use efficiency and yield traits in sugarcane cultivated in the understory of Aleurites fordii, in two agroforestry arrangements and monocropping systems. A field experiment was conducted from July 2015 to June 2016 in the city of Frederico Westphalen, Rio Grande do Sul, Brazil. The radiation use efficiency, assimilate partitioning, leaf area index, absolute growth rate, net assimilation rate, number of tillers, plant height, % of intercepted solar radiation, extinction coefficient, and yield in each system was evaluated. In agroforestry systems, the dynamic interactions between multiple plant species change with the time and can result in unique microclimates. The use of agroforestry systems in 12 x 12m arrangements should be prioritized because it enables greater yields and radiation availability in the understory. This study sought to provide new sustainable alternatives for farmers in order to increase the diversification of the rural property and maintain the preservation of existing agroecosystems.

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Soybean (Glycine max L.) monocropping have had a great socio-economic and environmental impact on the world and agroforestry systems has been considered an alternative for more sustainable production. The aim of this study was to evaluate the effect of different arrangements of agroforestry systems of the species E. urophylla x E. grandis and P. dubium and the pruning of the trees on the dynamics of solar radiation and soybean yield. A field experiment was conducted in Southern Brazil. In order to achieve the objective of the study, the solar radiation transmissivity and the productive performance of the soybean were evaluated. In this study, the soybean yield was determined by the arrangement of the agroforestry system and forest species utilized. The soybean crop cultivated in the understory of the P. dubium trees showed the highest yield response. The use of silvicultural practices for the management of forest species should be considered to generate the balance of the productive system. In this context, tree pruning is a viable side for agroforestry systems, as it promotes an increase in the incidence of solar radiation in the understory, resulting in an increase in soybean yield, especially when integrated with P. dubium.

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The use of wood for energy purposes is common in Brazil, motivated mainly by the diversity of species that present a potential for energy production. The objective of this study was to determine the effects of tree age and spacing on the energy properties of different components of the biomass: wood, bark, and branch of the species Ateleia glazioviana Baill, distributed at different spacings: 2.0 × 1.0m, 2.0 × 1.5m, 3.0 × 1.0m, and 3.0 × 1.5m in the 1st, 3rd, and 5th year after the planting. The experiment was carried out in a randomized complete block design with three replications. The following variables were determined: biomass (BIO), gross calorific power (GCV), basic density (BD), energy productivity (EP), energy density (ED), fixed carbon content (FCC), volatile material content (VMC), and ash content (AC). Different tree ages significantly affected all analyzed variables, increasing the distribution of BIO, EP, AC, BD, and ED with no tendency to stabilize over time. The four tree spacings induced different levels of BIO and EP, with a trend toward lower values with increasing tree spacing for all assessed periods. The four components of the trees had a significant effect on the variables BIO, EP, GCV, FCC, VMC, and AC.(AU)

A utilização da madeira para fins energéticos é elevada no país, motivada principalmente pela diversidade de espécies que apresentam potencialidade de geração de energia. Esse trabalho teve como objetivo determinar o efeito da idade e do espaçamento de plantio nas propriedades energéticas em diferentes compartimentos da biomassa: madeira, casca e galho da espécie Ateleia glazioviana Baill, distribuída em diferentes espaçamentos: 2,0x1,0m, 2,0x1,5m, 3,0x1,0m e 3,0x1,5m, no 1º, 3º e 5º ano após o plantio. O presente trabalho foi realizado em um experimento instalado em delineamento experimental de blocos completos casualizados em três repetições. Foram determinadas as variáveis biomassa (BIO), poder calorífico superior (PCS), massa específica básica (ME), produtividade energética (PE), densidade energética (DE), teor de carbono fixo (CF), teor de material volátil (MV) e teor de cinzas (CZ). Concluiu-se que as diferentes idades das árvores influenciam significativamente todas as variáveis analisadas, proporcionando uma distribuição crescente da BIO, PE, CF, ME e DE, sem tendência a estabilização ao longo do tempo. Os quatro espaçamentos de plantio induzem a diferentes produções de BIO e PE, com uma tendência de redução dos seus valores com o aumento do espaçamento, em todos os períodos avaliados. Os quatro compartimentos das árvores induzem a um efeito significativo das variáveis BIO, PE, PCS, CF, MV e CZ.(AU)

Assuntos

RESUMO

The use of wood for energy purposes is common in Brazil, motivated mainly by the diversity of species that present a potential for energy production. The objective of this study was to determine the effects of tree age and spacing on the energy properties of different components of the biomass: wood, bark, and branch of the species Ateleia glazioviana Baill, distributed at different spacings: 2.0 × 1.0m, 2.0 × 1.5m, 3.0 × 1.0m, and 3.0 × 1.5m in the 1st, 3rd, and 5th year after the planting. The experiment was carried out in a randomized complete block design with three replications. The following variables were determined: biomass (BIO), gross calorific power (GCV), basic density (BD), energy productivity (EP), energy density (ED), fixed carbon content (FCC), volatile material content (VMC), and ash content (AC). Different tree ages significantly affected all analyzed variables, increasing the distribution of BIO, EP, AC, BD, and ED with no tendency to stabilize over time. The four tree spacings induced different levels of BIO and EP, with a trend toward lower values with increasing tree spacing for all assessed periods. The four components of the trees had a significant effect on the variables BIO, EP, GCV, FCC, VMC, and AC.

A utilização da madeira para fins energéticos é elevada no país, motivada principalmente pela diversidade de espécies que apresentam potencialidade de geração de energia. Esse trabalho teve como objetivo determinar o efeito da idade e do espaçamento de plantio nas propriedades energéticas em diferentes compartimentos da biomassa: madeira, casca e galho da espécie Ateleia glazioviana Baill, distribuída em diferentes espaçamentos: 2,0x1,0m, 2,0x1,5m, 3,0x1,0m e 3,0x1,5m, no 1º, 3º e 5º ano após o plantio. O presente trabalho foi realizado em um experimento instalado em delineamento experimental de blocos completos casualizados em três repetições. Foram determinadas as variáveis biomassa (BIO), poder calorífico superior (PCS), massa específica básica (ME), produtividade energética (PE), densidade energética (DE), teor de carbono fixo (CF), teor de material volátil (MV) e teor de cinzas (CZ). Concluiu-se que as diferentes idades das árvores influenciam significativamente todas as variáveis analisadas, proporcionando uma distribuição crescente da BIO, PE, CF, ME e DE, sem tendência a estabilização ao longo do tempo. Os quatro espaçamentos de plantio induzem a diferentes produções de BIO e PE, com uma tendência de redução dos seus valores com o aumento do espaçamento, em todos os períodos avaliados. Os quatro compartimentos das árvores induzem a um efeito significativo das variáveis BIO, PE, PCS, CF, MV e CZ.

Assuntos

RESUMO

ABSTRACT: The use of wood for energy purposes is common in Brazil, motivated mainly by the diversity of species that present a potential for energy production. The objective of this study was to determine the effects of tree age and spacing on the energy properties of different components of the biomass: wood, bark, and branch of the species Ateleia glazioviana Baill, distributed at different spacings: 2.0 × 1.0m, 2.0 × 1.5m, 3.0 × 1.0m, and 3.0 × 1.5m in the 1st, 3rd, and 5th year after the planting. The experiment was carried out in a randomized complete block design with three replications. The following variables were determined: biomass (BIO), gross calorific power (GCV), basic density (BD), energy productivity (EP), energy density (ED), fixed carbon content (FCC), volatile material content (VMC), and ash content (AC). Different tree ages significantly affected all analyzed variables, increasing the distribution of BIO, EP, AC, BD, and ED with no tendency to stabilize over time. The four tree spacings induced different levels of BIO and EP, with a trend toward lower values with increasing tree spacing for all assessed periods. The four components of the trees had a significant effect on the variables BIO, EP, GCV, FCC, VMC, and AC.

RESUMO: A utilização da madeira para fins energéticos é elevada no país, motivada principalmente pela diversidade de espécies que apresentam potencialidade de geração de energia. Esse trabalho teve como objetivo determinar o efeito da idade e do espaçamento de plantio nas propriedades energéticas em diferentes compartimentos da biomassa: madeira, casca e galho da espécie Ateleia glazioviana Baill, distribuída em diferentes espaçamentos: 2,0x1,0m, 2,0x1,5m, 3,0x1,0m e 3,0x1,5m, no 1º, 3º e 5º ano após o plantio. O presente trabalho foi realizado em um experimento instalado em delineamento experimental de blocos completos casualizados em três repetições. Foram determinadas as variáveis biomassa (BIO), poder calorífico superior (PCS), massa específica básica (ME), produtividade energética (PE), densidade energética (DE), teor de carbono fixo (CF), teor de material volátil (MV) e teor de cinzas (CZ). Concluiu-se que as diferentes idades das árvores influenciam significativamente todas as variáveis analisadas, proporcionando uma distribuição crescente da BIO, PE, CF, ME e DE, sem tendência a estabilização ao longo do tempo. Os quatro espaçamentos de plantio induzem a diferentes produções de BIO e PE, com uma tendência de redução dos seus valores com o aumento do espaçamento, em todos os períodos avaliados. Os quatro compartimentos das árvores induzem a um efeito significativo das variáveis BIO, PE, PCS, CF, MV e CZ.