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We proposed and evaluated a new approach (“Farm-school project”) to develop children's awareness about the role of people in agricultural production and environmental quality. The materialization of the “Farm-school” project was performed by a theoretical-practical 4-hour visit at an experimental farm. 240 Elementary school students were evaluated through concept maps and drawings, before and after the visit. There was a conceptual evolution in concept maps of 41 and 82%, and an increased number of categories per drawing of 23% and 37%. In concept maps, students did not relate people to the different spheres of agricultural production before the farm visit, but after, people became the main element. After the visit, students began to portray not only productive aspects in their drawings but also processes involving production, such as soil conservation practices and maintenance of mulch for soil cover. With the population concentrated in urban areas, there is a lack of contact with the rural landscape, generating a distorted view of food systems and rural land use, which affects social drivers and pro-environmental behavior. This imposes an educational task on governments to bring about information on agricultural production to elementary school students. We have proven the effectiveness of the “Farm-School” project as a low-cost educational policy alternative and a tool to increase children’s awareness about the role of people in agricultural production and environmental quality since students come to a better understanding of where food comes from and how it is produced.

Temperament often depends on the animals’ reaction to people, social and environmental conditions. However, little is known about the influence of changes in the pasture environment on cattle temperament. Thus, this study was designed to evaluate if an animals’ temperament changes in response to being kept in a silvopastoral system. This study evaluated the effect of the tree components in a pasture environment on the temperament of any grazing cattle in integrated crop-livestock systems. A total of thirty-two Angus steers were allocated to either a livestock (L) or livestock-forest (LF) system and observed from December 2019 to February 2020. Each animal was evaluated for their reactivity score, flight speed, and number of vocalizations. The statistical model established that the animals were random effects and that the treatments and periods were fixed effects using the MIXED procedure, and the means were compared using LSMeans. The flight speed and number of vocalizations were similar in both production systems, while the reactivity score was lower for animals kept in the LF system when compared to those in the L system. This suggested that the LF system interferes positively with the animal’s temperament in relation to the L production system. However, additional research is needed to understand the influence of the production system on animal temperament. RESUMO: As divergências no temperamento dependem da reação dos animais às pessoas e à diferentes situações sociais e ambientais. Contudo, pouco se sabe acerca da influência de alterações no ambiente pastoril sobre o temperamento dos bovinos. Com isso, a hipótese de trabalho é de que o temperamento dos animais pode ser alterado se mantidos em sistemas pastoris arborizados. Para tanto, objetivou-se avaliar o efeito do componente arbóreo em ambiente pastoril sobre o temperamento de bovinos em pastejo em sistemas integrados de produção agropecuária. Foram avaliados 32 novilhos da raça Angus alocados em dois sistemas pecuária (PEC) e pecuária-floresta (PF) durante o período de dezembro de 2019 a fevereiro de 2020, no qual foi mensurado: o escore de reatividade dos animais; a velocidade de fuga e o número de vocalizações. O modelo estatístico utilizado considerou como efeito fixo de tratamentos e períodos e efeitos aleatórios dos animais, utilizando o procedimento MIXED, as médias foram comparadas pelo recurso lsmeans. A velocidade de saída e número de vocalizações foram similares entre os sistemas de produção. O escore de reatividade foi menor para os animais mantidos no sistema PF quando comparados aos do tratamento PEC. O sistema PF interfere positivamente no temperamento animal em relação ao sistema de produção PEC, observado pelo menor escore de reatividade nos animais mantidos neste sistema. Contudo, o estudo sobre a influência da integração de sistemas sobre o temperamento animal exige mais pesquisas para revelar o potencial deste modelo de produção sobre o comportamento animal.

Aims This study evaluated the optimal herbage level from both plant and animal perspectives, through the adjustment of instantaneous herbage accumulation rate as estimed by the Gompertz curve model and short-term intake rate of sheep. Schedonorus arundinaceus (tall fescue) was used as an experimental model. Methods Weekly tall fescue herbage accumulation was measured during seven growth periods initiated on monthly intervals (October, November, and December 2015, and March, April, August and September 2016) with the initiation dates arranged in a randomized complete block design with four replicates. Total herbage mass, leaf lamina mass, pseudo-stem + sheath mass, senescent mass, and sward surface height were measured each week. Results We demonstrated that a pre-grazing sward surface height of 22.3 cm of tall fescue promoted concomitantly the maximum short-term intake rate of sheep and the instantaneous herbage accumulation rate in the spring and autumn periods. In general, the convergent point occurred after the maximum instantaneous leaf lamina accumulation rate and before the maximum instantaneous accumulation rate of pseudo-stem + sheath and senescent material. Conclusions We suggest the existence of a convergent point in which both primary and secondary production of pastoral ecosystems could be fostered, potentially reconciling the fundamental ecological dilemma of grazing systems.

The study of factors influencing animal intake can provide a better understanding of the dynamics of the pasture ecosystem and serve as a basis for managing livestock in a more efficient way. We measured different sward surface heights of tall fescue in the process of short-term intake rate of sheep. There was a significant effect of sward surface height on herbage mass (P P P = 0.02), bite mass (P = 0.01) and short-term intake rate (P = 0.03) of sheep. There was a quadratic fit between time per bite and bite mass (P = 0.006). Multivariate analysis showed that the short-term intake rate and bite mass were positively correlated (r = 0.97), bite rate and total jaw movement rate were positively correlated but both were negatively correlated with time per bite. The sward surface height of tall fescue corresponding to the maximum short-term herbage intake rate was 22.3 cm. The underlying processes were driven by the bite mass, which was influenced by the leaf lamina bulk density and its consequences upon time per bite. This sward surface height can be adopted as a pre-grazing target for rotational stocking systems to optimize sheep nutrition on pastures.

Effective integrated weed management in agricultural landscapes depends on the ability to identify and manage processes that drive weed dynamics. The current study reports the effects of grazing management and crop rotation strategies on the seedbank and emerged weed flora in an integrated crop-livestock system (ICLS) experiment during a 12-year period under no-tillage in sub-tropical southern Brazil. During winter, Italian ryegrass cover crops were grazed by sheep: grazing management treatments included two stocking methods (continuous and rotational) and two forage allowances (10 and 20 kg of herbage dry matter available per 100 kg animal live weight). During summer, the crop rotation treatments involved either soybean-maize or soybean-soybean in succession with winter-grazed cover crops. The treatments were part of a factorial randomized complete block design. Treatment effects were evaluated on the weed seedbank and emerged weed flora populations during winter-grazed cover crop and summer crop growth as well as during the harvest phase. The current results demonstrate that crop rotation and grazing management exhibited interactive effects on the determination of weed outcomes in an ICLS. However, overall, compared with moderate forage allowance, high forage allowance during the winter-grazed cover crop caused lower emerged weed flora in subsequent crops (20% reduction during crop growth and 90% reduction at crop harvest) and 48% reduction in seedbank size. High forage allowance promoted more residue from winter-grazed cover crop biomass, which remained during the summer crop phases and probably resulted in a physical barrier to weed emergence.

The objective of this work was to evaluate the effect of tree pruning on the incidence and intensity of the damages caused by cattle to 26-month-old Eucalyptus benthamii, in a silvopastoral system, in the municipality of Pinhais, in the state Paraná, Brazil. The experiment was performed in a randomized complete block design, with two treatments - livestock and forest with pruned eucalyptus (WP), and livestock and forest with unpruned eucalyptus (UP) - and three replicates, characterizing six types of damages and five damage intensities. There were significant differences between the WP and UP treatments for the different types of damages. Cattle entry in the silvopastoral system at 26 months after the planting of eucalyptus causes low-intensity damages to the trees, in the treatment with pruning, and medium-intensity damages to the trees in the treatment without pruning. Damages of stronger intensities were detected in the UP treatment, in which class-two damages (d2 = average damage) were verified in approximately 91% of the trees. The silvicultural practice of pruning E. benthamii trees does not affect the diameter at breast height or the total height of trees. Pruning can be recommended, as it does not affect tree development; moreover, this practice enables the production of knot-free, better-quality wood. Resumo: O objetivo deste trabalho foi avaliar o efeito da desrama sobre a incidência e intensidade de danos causados por bovinos a Eucalyptus benthamii aos 26 meses de idade, no município de Pinhais, no estado do Paraná, Brasil. O experimento foi feito em um delineamento de blocos ao acaso, com dois tratamentos - pecuária-floresta com eucaliptos desramados (WP) e pecuária-floresta com eucaliptos sem desrama (UP) - e três repetições, que caracterizaram seis tipos de danos e cinco intensidades. Houve diferenças significativas entre os tratamentos WP e UP para os diferentes tipos de danos. A entrada de bovinos no sistema silvipastoril, 26 meses após o plantio de eucalipto, causa danos de baixa intensidade às árvores, no tratamento com desrama, e danos de média intensidade às árvores no tratamento sem desrama. Danos de maiores intensidades foram registrados no tratamento UP, em que o dano de classe dois (d2 = dano médio) foi verificado em aproximadamente 91% das árvores. A prática silvicultural de desrama das árvores de E. benthamii não afeta o diâmetro à altura do peito nem a altura total das árvores. A desrama pode ser recomendada, já que não influencia o desenvolvimento das árvores; além disso, essa prática possibilita a produção de madeira sem nós, de melhor qualidade.

Sunflower is an important crop for Integrated Crop-livestock Systems (ILCS), and one of the main management difficulties identified in this crop is weed control, especially under no-till conditions when chemical weed control is not allowed. Therefore, the aim of this research was to evaluate the effect of greater sunflower population density on weed control, and its impact on sunflower yield, in an ILCS with eucalyptus in an Environmental Protection Area. Two population densities were tested (45 and 90 thousand pl. ha-1) in two crop systems (sunflower monoculture and sunflower-eucalyptus integration). An additional treatment was provided in the sunflower-eucalyptus integration, and 5 positions (2,4; 4,8; 7,2; 9,6; and 12 m) between the tree rows were evaluated. In a randomized block design, with eight repetitions, weed density and weed dry matter were determined at 40, 70 and 100 days after crop emergence. Also, phytosociological indices were calculated. The following yield components were evaluated: head diameter, number of achenes per head, and 1000-achene weight. There was lower weed infestation on the high density treatment in both systems. There was no difference of weed occurrence in the 5 positions between the tree rows. Sunflower yield was higher in the greatest population density in both systems. Increasing population density in sunflower crop is a practicable management to control weeds and to gain higher yield under free-herbicide conditions. RESUMO: O girassol é uma cultura importante para os sistemas integrados de produção agropecuária (SIPA), e uma das principais dificuldades de manejo nessa cultura consiste no controle de plantas daninhas, especialmente em condições em que o controle químico não é permitido. Portanto, o objetivo desta pesquisa foi verificar o efeito do adensamento populacional do girassol no controle de plantas daninhas e seu impacto na produtividade da cultura, em SIPA integrado com eucalipto de um ano, em uma Área de Proteção Ambiental. Foram testadas duas populações (45 e 90 mil pl. ha-1) em dois sistemas de produção (monocultivo de girassol e integração girassol-eucalipto). Ainda, nas áreas de integração girassol-eucalipto, as avaliações ocorreram em cinco posições (2,4; 4,8; 7,2; 9,6; e 12 m) entre os renques de árvores. Em um delineamento em blocos ao acaso, com oito repetições, determinou-se a densidade e a matéria seca de plantas daninhas por espécie, aos 40, 70 e 100 dias após a emergência da cultura. Também foram calculados índices fitossociológicos. Os componentes de rendimento do girassol analisados foram: diâmetro do capítulo, número de aquênios por capítulo e peso de mil aquênios. Nas áreas com população adensada houve menor infestação de plantas daninhas, em ambos os sistemas. Não houve diferença na ocorrência de plantas daninhas nas posições entre os renques de árvores. A produtividade de girassol foi superior na população mais adensada em ambos os sistemas. O adensamento populacional na cultura do girassol mostrou-se uma prática de manejo viável, tanto do ponto de vista de controle de plantas daninhas como de produtividade de aquênios em condições de livre convivência com plantas daninhas.

Weeds are a concern to farmers mainly by reducing crop yield, especially in organic farming where herbicides are not an option. Additionally, reducing reliance on herbicides is among the goals to achieve sustainable crop production. By investigating alternatives for weed control, several studies have shown that grassland is more competitive with weeds than cash crops and adopting diversified crop rotations reduces overall weed infestation. However, in many of those studies the effect of the rotation is confounded with herbicide use. Moreover, there is a gap in understanding how diversified rotations influence the weed community and how changes in that weed community impact yield of the subsequent cash crop. Here, using a 4-year herbicide-free experiment in southern Brazil, we compared a grassland-cropping rotation (i.e., 3-year perennial tropical grassland before maize cultivation) vs. a crop-based rotation (i.e., sunflower-maize) to clearly characterize how a more diversified crop rotation changed weed patterns and weed interference in maize. We demonstrate the higher suppressive effect on weeds of a grassland-cropping rotation compared with a crop-based rotation, clearly evidenced in the early season of maize growth, in which the crop-based rotation had about twice as many number of weeds as the grassland-cropping rotation. However, there was no difference in seedbank size between both rotations. Weed community composition was not affected (i.e. rotations had 98% similarity in species composition), but weed assemblage was drastically changed with different rates of species-specific infestation in each rotation. The crop-based rotation selected weeds with rapid light acquisition ability (higher specific leaf area) that added to higher early season weed infestation and higher competitive pressure of weeds resulted in maize grain yield losses, whereas there was no significant weed interference on maize grain yield in the grassland-cropping rotation. The strategy of including a tropical grassland in rotation with cash crops as a herbicide-free weed management tool reduces overall weed infestation and prevents selection of weeds that cause a significant yield reduction in maize and represents an economically viable alternative.

International audience; AbstractWeeds are a major constraint on food and feed production, and the excessive use of herbicides to control them is a global concern for food security, human health, and environmental sustainability. Under no-tillage systems, cover crop residues provide a physical barrier to weed emergence that reduce weed infestations and reliance on herbicides. In integrated crop-livestock systems, cover crops provide fodder to grazing animals, adding an additional source of revenue for farmers; however, grazing can cause a trade-off because it reduces biomass during the cover crop season and residues left on the soil surface in the next cash crop, which may increase weed infestation. In the current study, it was hypothesized that there is an optimal cover crop forage allowance during the grazing period that maximizes beef production while retaining enough cover crop biomass and residue to minimize weed infestations and maintain grain yield of the subsequent cash crop. Therefore, the effects of cover crop (mixed black oat + Italian ryegrass) forage allowances (based on sward height) during the winter grazing period on weed infestations, beef production, and soybean grain yield during the next summer season were evaluated. The experiment was conducted in several commercial fields involving two experimental protocols (one short-term and one long-term experiment) in Southern Brazil, and the results demonstrated that a moderate forage allowance in winter cover crops (i.e., maintaining 17.8 cm of winter grazed cover crop sward height) reduced weed infestations and increased soybean and beef production when compared with a lower forage allowance (i.e., 17.8 cm of winter grazed cover crop sward height). Therefore, the current study provides evidence that it is possible to optimize forage allowance to sustainably intensify arable cropping systems using winter cover crops for direct grazing.

While global demand for food increases, agricultural expansion faces more stringent environmental preservation demands and sustainability laws aimed to prevent deforestation (Nascente and Crusciol, 2012). Integrated crop-livestock systems (ICLS) are diversified agroecosystems that can contribute to sustainable intensification, increasing food production while maintaining or improving environmental quality and preserving natural biodiversity. A conceptual representation of ICLS can be drawn from the description of how crop and livestock activities interact. From a field- to territorial-level scale (e.g., landscape, watershed, or region), crop and livestock production can be structurally independent or interact in time and space dimensions (Moraine et al., 2016). ICLS are designed to achieve synergy and emergent properties resulting from the spatial and temporal interactions among the components soil, plant, animal, and atmosphere (Moraes et al., 2014a,b).

Objetivou-se com esta pesquisa avaliar a competicao interespecifica do Panicum maximum cv. Aries no periodo de estabelecimento, sendo os fatores estudados os niveis de sombreamento e de nitrogenio. Os niveis de sombreamento provocados pelas plantas daninhas foram de 0%, ate 40%, ate 70% e 60%, na ausencia e na presenca de nitrogenio. Foram analisados: altura de planta, dinâmica de perfilhamento, indice de area foliar (IAF), materia seca, material senescente de folha e intensidade de competicao relativa (ICR) de P. maximum cv. Aries com as plantas daninhas. Os dados foram submetidos a testes de homogeneidade de variâncias e normalidade de residuos, e entao realizados analises de variância (ANOVA), teste de media (Tukey) ao nivel de 5% de probabilidade e regressao. As caracteristicas morfologicas e produtividade do P. maximum cv. Aries apresentaram melhores respostas em condicao de nao interferencia das plantas daninhas. O nitrogenio contribuiu para um melhor desenvolvimento de P. maximum cv. Aries, contudo no tratamento de convivio com as plantas daninhas sem corte houve o dominio sobre o P. maximum cv. Aries. O corte realizado nas plantas daninhas promoveu a diminuicao da intensidade de competicao interespecifica. A condicao variavel de sombreamento no tempo exprime diferentes respostas morfologicas em comparacao com uma condicao homogenea, interferindo principalmente na velocidade de estabelecimento do P. maximum cv. Aries.

This study aimed to evaluate the impact of different grazing intensities and nitrogen fertilization applied on oats and its effect upon maize cultivated in succession in a no tillage system. The experiment was carried out at Abelardo Luz municipality during the winter and summer seasons of 2004/2005. The experimental design was a completely randomized block in a split-plot arrangement with four replicates. Treatments were five different grazing intensities, represented by utilization periods in an oat culture grazed for 0, 3, 6, 9 and 12 weeks, and at sub-plot level nitrogen doses were applied at 0 and 150 kg/ ha. The availability and residual dry matter of oat was evaluated each three weeks after the beginning of grazing until the drying of the pasture. Was also evaluated the yield of maize after oat under different intensities of grazing and nitrogen fertilization. Results indicated the existence of interaction between grazing and winter nitrogen fertilization, which affected maize nutrition and yield. Moreover, the oat residual dry matter availability was positively influenced by applied nitrogen. The nitrogen in the pasture, besides favoring the production of residual dry matter of oats, determines the greatest potential productivity of corn in sequence. In the absence of nitrogen fertilization on winter pastures, the grazing intensity should be reduced so as not to affect the productivity of maize.Este trabalho objetivou verificar o impacto da aplicação de diferentes intensidades de pastejo e da adubação nitrogenada na cultura da aveia, e sua influência na cultura do milho em sucessão, em sistema de plantio direto. O experimento foi implantado no município de Abelardo Luz – SC, durante o período de inverno e verão de 2004/2005. O delineamento foi o de blocos ao acaso com parcelas subdivididas e quatro repetições. Os tratamentos constituíram-se em cinco diferentes intensidades de pastejo na parcela, representadas por períodos de utilização de uma cobertura de aveia sob pastejo por 0, 3, 6, 9 e 12 semanas, e nas subparcelas trabalhou-se com doses de nitrogênio de 0 e 150 kg ha-1. A massa seca disponível de aveia foi avaliada a cada três semanas após o inicio do pastejo até o momento da dessecação da pastagem. Foi avaliada também a produtividade da cultura do milho após aveia submetida a diferentes intensidades de pastejo e adubação nitrogenada. Os resultados indicaram a existência de interação entre pastejo e adubação nitrogenada no inverno, a qual afetou a nutrição e a produtividade da cultura do milho. Além disso, a disponibilidade de massa seca residual na pastagem de aveia foi influenciada positivamente pelo nitrogênio aplicado. A adubação nitrogenada na pastagem, além de favorecer a produção de massa seca residual de aveia, determina maior potencial de produtividade de milho em sequencia. Na ausência da adubação nitrogenada na pastagem de inverno, a intensidade de pastejo deve ser reduzida, para não afetar a produtividade do milho.

O objetivo deste trabalho foi avaliar a rentabilidade do sistema de integração lavoura‑pecuária (ILP), em comparação ao cultivo de cereais de inverno e de plantas de cobertura para o plantio direto de soja e milho no verão. Foram comparados dados simulados de sistema agrícola tradicional com produção de grãos de milho e soja, no verão, e cultivo de trigo e plantas de cobertura do solo, no inverno; e dados de um trabalho publicado em que foram avaliadas combinações de pastagens (diversificadas ou puras) e categorias de animais (leves ou pesados), com produção de grãos de milho e soja, no verão, e pastejo no inverno. A análise econômica foi realizada com base nos resultados experimentais e simulada para uma propriedade de 100 ha. A ILP com recria de novilhas leiteiras em pastagens anuais de inverno, em substituição ao sistema convencional com cultivo de cereais de inverno e plantas de cobertura de solo para o plantio direto, é a alternativa mais rentável aos produtores. The objective of this work was to evaluate the profitability of the integrated crop‑livestock (ICL) system in comparison to the cultivation of winter cereals and cover crops for soybean and maize cropped under no‑tillage in the summer. The following were compared: simulated data from a conventional agricultural system with production of maize and soybean grains in the summer and cultivation of wheat and ground cover plants in the winter; and data from a published work in which combinations of pastures (diversified or pure) and animal categories (light or heavy) were evaluated in a system with the production of maize and soybean in the summer and grazing during the winter. Economic analysis was carried out based on previous experimental results and simulated for a 100‑ha property. ICL with rearing of dairy heifers in winter annual grazing, as a replacement to winter cereal crops and ground cover crops for no‑tillage, is the most profitable alternative for producers.

Com o objetivo de estudar alternativas de extensificação, avaliou-se o efeito da redução da oferta de suplemento (níveis de 100, 65, 45 e 20% das exigências totais para produção) e de sua substituição por pastagens de capim-quicuio sobre a produção e composição de leite. O experimento foi realizado em delineamento de blocos completos casualizados, com três repetições, pelo método de pastejo com lotação contínua e taxa de lotação variável, tendo como meta a manutenção do pasto a 20 cm de altura. A produção de leite individual e por área apresentou resposta linear positiva com o nível de suplementação. Os componentes qualitativos do leite não foram alterados pela redução do uso de suplementos, contudo, as produções diárias de proteína bruta e gordura por vaca variaram com os níveis de suplementação. Vacas pastejando capim-quicuio não mantêm a produção de leite quando se reduz a oferta de suplemento. Aiming to study alternatives to extensification, it was evaluated the effect of supplement supply reduction (levels of 100, 65, 45 and 20% of the total requirements for production) and the possibility of its substitution by kikuyu grass on milk production and composition. The trial was performed using a completely randomized block design with three replicates, using the continuous and variable stocking rate grazing method aiming to keep the sward height at 20 cm. Individual and per hectare milk production presented positive linear response with the supplementation level. The qualitative milk components were not modified by reducing the use of supplements, however, daily productions of crude protein and fat by the animal varied with the supplementation levels. Cows grazing kikuyu grass do not maintain their milk production when supplement offer is reduced.

Resumen Los estudios de la composicion isotopica del nitrogeno en el suelo y las plantas son importantes para identificar las diferencias en los procesos biogeoquimicos de reciclage de este elemento en los ecosistemas. Para evaluar la contribucion de BNF, asi como las diferencias en la capacidad de fijar y transferir N entre las especies de legumbres perennes y gramineas existen varias tecnicas que se han utilizado, como la reduccion de acetileno, dilucion isotopica 15N y abundancia natural de 15N. Sin embargo, las caracteristicas responsables por estas variaciones tienen que ser, en gran parte identificadas. Esta revision tuvo como objetivo comparar la dinamica de la transferencia y la fijacion de N de gramineas y leguminosas forrajeras.

RESUMO - Objetivou-se nesse trabalho avaliar o efeito da aplicacao de doses de nitrogenio em tres epocas: em cobertura na pastagem de inverno; em pre-semeadura e em cobertura no milho, sobre a produtividade de graos e componentes de rendimento do milho, em um Sistema Integrado de Producao Agropecuaria. O experimento foi realizado em Guarapuava, Parana, em delineamento de blocos casualizados com parcelas sub-subdivididas. A parcela principal consistiu dos tratamentos 0; 75; 150 e 225 kg ha-1 de N, aplicados na pastagem de aveia + azevem. Por sua vez, na subparcela foram aplicados 0 e 75 kg ha-1 de N em pre-semeadura do milho e na sub-subparcela foram utilizados 0; 75; 150; 225 e 300 kg ha-1 de N no milho, correspondendo aos fatores Inverno (I), Pre-semeadura (PS) e Verao (V), respectivamente. A produtividade foi afetada pela interacao de todos os tratamentos. A menor produtividade foi de 4.176 kg ha-1 de graos, sem aplicacao de N. Com 75 kg ha-1 de N em PS, a produtividade de graos de milho foi de 7.148 kg ha-1. Com aplicacao de 75 kg ha-1 de N em PS, mais 150 ou 225 kg ha-1 de N no I, nao se faz necessaria a aplicacao de N no Verao. Palavras-chave: produtividade, componentes de rendimento, teor de N foliar, clorofila. NITROGEN FERTILIZATION STRATEGIES IN CORN UNDER INTEGRATED CROP-LIVESTOCK SYSTEM ABSTRACT - The objective of this study was to evaluate the effect of applying N rates at three different times: in coverage in winter pasture ; in pre-sowing and coverage corn on corn yield, on grain yield and corn yield components in an Integrated Crop-Livestock System. The experiment was conducted in Guarapuava, Parana, Brazil, in a randomized block design with split plots. The main plot treatments consisted of 0; 75; 150 and 225 kg ha-1 N applied in the pasture of oat + ryegrass; in the subplot treatments 0 and 75 kg ha-1 N were applied in the pasture in pre-sowing corn and sub-subplot treatments 0; 75; 150; 225 and 300 kg ha-1 of N in corn, corresponding to factors Winter (I), Pre-sowing (PS) and Summer (V), respectively. Productivity was significant for the triple interaction. The lowest observed productivity was 4.176 kg ha-1of grain without the application of N with 75 kg ha-1 N in PS, productivity of corn grains was 7.148 kg ha-1. With application of 75 kg ha-1 N in PS, with 150 or 225 kg N ha-1 in I, the application of N in Summer is not necessary. Keywords: productivity, yield components, leaf nitrogen content, chlorophyll.

Os sistemas integrados de produção agrícola e pecuária são caracterizados como sistemas planejados para explorar sinergismos e propriedades emergentes, resultado de interações entre os diferentes compartimentos solo-plantaanimal- atmosfera, que se integram em diferentes escalas espaço-temporais. Nesta revisão é apresentado um panorama da evolução das pesquisas embasadas em uma produção integrada entre os diferentes compartimentos. Considerou-se o período até 2013 e palavras-chave como fator de busca, sendo construída uma base de dados, partindo de um universo de 450 artigos em 93 periódicos nacionais e internacionais. Estes artigos foram classificados de acordo com a região de origem do Brasil: subtropical ou tropical; e categorizados quanto aos componentes: solo, planta, animal e outros. Dentro desses componentes foram elencados grupos de variáveis que caracterizassem diferentes linhas temáticas. As publicações no mundo têm aumentado e o Brasil está entre os principais provedores de trabalhos científicos nessa área. Embora seja crescente o número de trabalhos científicos no Brasil, que buscam melhor compreensão dos sistemas integrados de produção agrícola e pecuária, as pesquisas com visão sistêmica e de maior escala temporal e espacial ainda necessitam de mais estudos, para que possam detectar interações entre os diversos fatores bióticos e abióticos e novas propriedades que emergem destes sistemas. Integrated crop-livestock systems (ICLS) are designed to exploit synergisms and emergent properties resulting from interactions between different soil-plant-animal-atmosphere compartments that integrate themselves at different spatial-temporal scales. In this review, a panorama of the evolution of studies based on ICLS is presented. Specific keywords were used as search terms to construct a database of 450 articles from 93 national and international journals published up to and including 2013. These articles were classified according to the region of origin within Brazil (subtropical or tropical) and categorized regarding the studied components: soil, plant, animal and ‘others’. Within these components, groups of variables that could characterize the different thematic lines were listed. The number of publications worldwide has been increasing, and Brazil is one of the main suppliers of scientific work within this area. Although the number of scientific studies seeking better understanding of ICLS may have increased in Brazil, further studies with a systematic view and with larger temporal and spatial scales are still required to help identify interactions between diverse biotic and abiotic factors that define new properties that emerge from these systems.

O presente estudo objetivou avaliar a decomposicao da materia seca inicial e a liberacao de nitrogenio (N) das diferentes coberturas invernais para a subsequente cultura do milho. O trabalho foi realizado em uma fazenda no municipio de Major Vieira-SC. O delineamento experimental foi o de blocos ao acaso, com cinco tratamentos (alternativas de cobertura do solo) e tres repeticoes. As alternativas de cobertura do solo constituiram de: a) Pastagem de aveia preta ( Avena strigosa ) + azevem ( Lolium multiflorum ) + ervilhaca ( Vicia spp.)+ trevo vesiculoso ( Trifolium vesiculosum ), com pastejo e com adubacao nitrogenada (100 kg de N); b) Pastagem de aveia preta + azevem + ervilhaca + trevo vesiculoso, com pastejo e sem adubacao nitrogenada; c) cobertura (aveia + azevem + ervilhaca + trevo vesiculoso), sem pastejo e sem adubacao nitrogenada d) nabo forrageiro ( Raphanus sativus ) em pastejo e sem adubacao nitrogenada, e e) pousio (testemunha). O tratamento nabo forrageiro apresentou as caracteristicas quimicas mais limitantes a uma rapida decomposicao e fornecimento de N para a cultura em sucessao. O tratamento consorcio cobertura por apresentar rapida liberacao inicial de N foi considerado o mais adequado para a utilizacao na sucessao com a cultura do milho. O pastejo teve influencia sobre a liberacao de N, principalmente pela menor quantidade de massa seca total produzida. A produtividade de graos de milho nao foi influenciada pelas coberturas do solo. ABSTRACT This study aimed to evaluate the decomposition of the residual dry mass and the initial release of nitrogen from different coverages winter for the subsequent cultivation of maize. The work was conducted in Major Vieira, SC, on a family property. The experimental design was a randomized block, with five treatments (alternative soil cover) and three replications. The treatments: a) consortium of oat ( Avena strigosa ) + ryegrass ( Lolium multiflorum ) + vetch ( Vicia spp.) + vesiculoso clover ( Trifolium vesiculosum ),, with grazing and nitrogen fertilization (100 kg of N); b) Grassland of black oat + ryegrass + vetch + clover vesiculoso, with grazing and without nitrogen fertilization; c) coverage (oat + ryegrass + vetch + vesiculoso clover), without grazing and without nitrogen fertilization; d) forage turnip ( Raphanus sativus ), without grazing and without nitrogen fertilization, and e) fallow (control). The rate of decay was measured through pockets of decomposition (litter bags), collected in seven seasons during the corn crop. The turnip forage was the treatment that was more difficult to decompose according to their chemical characteristics. This limited the supply of nitrogen for the corn crop. Treatment coverage consortium made rapid initial release of N and thus was considered the most appropriate for use in succession with the corn crop. The grazing influenced the release of nitrogen, mainly by the lower amount of total dry mass produced. The grain yield of maize was not influenced by soil cover.

O aumento da eficiência de produção para a cultura do milho (Zea mays) tem levado os produtores a buscaremalternativas sustentáveis através de sistemas integrados. O objetivo deste trabalho foi determinar o efeito do nitrogênio na produtividade do milho e seus componentes de rendimento, em um sistema de integração lavoura-pecuária. O experimento foi conduzido na fazenda experimental Capão da Onça da Universidade Estadual de Ponta Grossa, Brasil, durante a safra agrícola de 2002/2003. O delineamento experimental foi de blocos completos casualizados com parcelas subdivididas e quatro repetições. Os tratamentos foram duas doses de N (0 e 150 kg ha-1) com e sem pastejo aplicados no inverno sobre aveia preta mais azevém estabelecidas em abril de 2002 e dessecadas para o plantio do milho em outubro do mesmo ano. Sequencialmente, os tratamentos aplicados no milho foram doses de N (0, 75, 150, 225 kg ha-1). O milho apresentou uma resposta de produtividade crescente para o aumento das doses de nitrogênio nas áreas sem pastejo e sem adubação nitrogenada no inverno, no entanto quando há o pastejo é possível alcançar maiores produtividades de milho com menores doses de nitrogênio. ABSTRACT Producers seeking higher corn (Zea mays) production efficiency have pursued more sustainable, integrated systems. The objective of this investigation was to determine the effect of nitrogen fertilization on corn yield and yield components in an integrated crop-livestock production system. The experiment was conducted on the experimental farm Fazenda Capão da Onça of the Universidade Estadual de Ponta Grossa, Brazil during the 2002/2003 harvest. Treatments were replicated four times in a split-plot randomization of a randomized complete block design. Whole plot treatments were two N rates (0, 150 kg ha-1) with and without grazing applied to a winter cover crop of black oat and Italian ryegrass established in April 2002 and desiccated prior to planting the corn in October 2002. Sequentially, treatments were four N rates (0, 75, 150, 225 kg ha-1) applied to the corn. The corn presented an increasing yield in relation to increasing N rates in plots without neither grazing nor N fertilization during winter; however, grazing allows for higher corn yields with lower N rates.

Crop-livestock systems are regaining their importance as an alternative to unsustainable intensive farming systems. Loss of biodiversity, nutrient pollution and habitat fragmentation are a few of many concerns recently reported with modern agriculture. Integrating crops and pastures in no-till systems can result in better environmental services, since conservation agriculture is improved by system diversity, paths of nutrient flux, and other processes common in nature. The presence of large herbivores can positively modify nutrient pathways and soil aggregation, increasing soil quality. Despite the low diversity involved, the integration of crops and pastures enhances nature’s biomimicry and allows attainment of a higher system organization level. This paper illustrates these benefits focusing on the use of grazing animals integrated with crops under no-tillage systems characteristic of southern Brazil.

Producers in southern Brazil are seeking to diversify farm income and increase production efficiency by integrating livestock grazing of winter annual forages within rotations of summer grain crops. Our objective was to determine grazing and nitrogen fertilization effects on decomposition of winter annual forage residues in corn. A winter cover of oat (Avena strigosa Shreb) and annual ryegrass (Lolium multiflorum L.) was no-till seeded in April 2002 near Ponta Grossa, PR in southern Brazil. Treatment combinations of N fertilizer (0 or 150 kg ha-1) and grazing (grazed or not grazed) were imposed on the winter forage cover. The grazing period was from June to early October 2002. The winter forage was desiccated on 11 October and corn was no-till planted 20 d later with two N treatments (0 and 150 kg N ha-1). Above ground forage biomass residue was hand-clipped, placed in small nylon bags that were scattered on the soil immediately after corn planting, and recovered after five periods of three weeks each for determination of residual dry matter. Results were submitted to analysis of variance. The loss of residual dry matter followed a quadratic function on time. Decomposition of winter annual forage residue was affected by winter treatment (P

O trabalho foi conduzido na área experimental da Fundação ABC, Fazenda Capão do Cipó, no município de Castro/PR. No período de 13/05/1998 à 30/01/1999 com objetivo de avaliar a dinâmica da decomposição e liberação de nutrientes (N, P, K, Ca e Mg) da palhada das coberturas de inverno, envolvendo as culturas de aveia preta (Avena strigosa Schreb) e nabo forrageiro (Raphanus sativus L.). O delineamento experimental empregado foi de blocos ao acaso em fatorial. Os tratamentos testados foram resultantes das combinações das duas coberturas de solo (aveia preta e nabo forrageiro), cortadas em três estádios de desenvolvimento: vegetativo (94 dias), florescimento (103 dias) e pleno florescimento (116 dias) e com cinco épocas de coleta dos materiais para avaliação da liberação de nutrientes. Os resultados das avaliações foram submetidos a análise de variância e regressão, sendo feito o ajuste a um modelo matemático que descreve a perda de massa no tempo, segundo (BADRE et al, 1998). Este modelo exponencial relaciona a taxa de decomposição da massa bem como da liberação de nutrientes como uma função quadrática do tempo (t). O modelo matemático usado foi: M(t) = M(o) Exp.t(at + b). A produção de massa seca não diferiu entre as espécies sendo maior nas condições de florescimento e pleno florescimento em relação ao estádio vegetativo, tanto para aveia como para o nabo forrageiro (p < 0,01). O modelo exponencial se ajustou perfeitamente à taxa de mineralização da massa seca (MS) com o tempo (p < 0,01) para ambas espécies e os estádios avaliados, cujos coeficientes variaram em função das diferenças quanto à relação carbono/fósforo (C/P), celulose e hemicelulose (FDN), para as espécies (p < 0,01) e não entre os estádios (p > 0,05). A relação carbono/nitrogênio (C/N) e lignina, sílica e cutina (FDA) foram diferentes entre os estádios (p < 0,05), mas não para as espécies (p > 0,05). Para a liberação de nutrientes o modelo exponencial indicou ser altamente significativo (p < 0,01) para todos os nutrientes avaliados independente das espécies e dos estádios de desenvolvimento.