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ABSTRACT The objective of this work was to determine Paspalum notatum genotypes appropriate for the establishment of mixtures with temperate legumes and compare the productivity of mixtures with mineral-fertilized systems along two years. Four hybrids of P. notatum, ecotype Bagual and cv. Pensacola, were either subjected to mixtures with white clover (Trifolium repens) and birdsfoot trefoil (Lotus corniculatus) or fertilized with 0, 60, 120, 240, and 480 kg N ha−1 year−1. P. notatum leaf blades and stems and herbage accumulation denoted a management × year interaction. Herbage accumulation varied between the mixtures and fertilized systems in first year, while in the second year, herbage accumulation of mixed systems employing the B26, B43, C22, C9, and Bagual genotypes were similar to that of systems fertilized with 120 and 240 kg N ha−1. Hybrids B26 and C9 and ecotype Bagual, once made available to producers, could be indicated for mixtures with temperate legumes because they are superior to cv. Pensacola. Herbage accumulation in mixtures involving white clover plus birdsfoot trefoil and P. notatum genotypes is similar to that of mineral nitrogen-fertilized systems with 240 kg N ha−1, emphasizing the viability of mixed between these species.

Background: Nitrogen (N) plays an important role in dairy systems, both in production costs and as an indicator of environmental impact. Objective: The objective was to investigate the effects on milk production and nitrogen excretion by dairy cows fed cut pastures either of perennial ryegrass-red clover (PRG-RCL) or annual ryegrass-white clover (ARG-WCL), complemented with ground maize straw and of commercial concentrate. Methodology: Six dairy cows were used in a double cross-over on-farm experiment with 14-day experimental periods. Milk yield and composition, live weight, body condition score, chemical composition of feeds and N content in faeces, urine, milk and blood were recorded over the last four days of each experimental period. Results: No differences were found (P > 0.05) for milk yield nor composition. Cows on ARG-WCL had a higher N intake and N balance than those on PRG-RCL (P < 0.05); also, there were higher levels of blood urea nitrogen (BUN) and urine urea nitrogen (UUN) when cows were fed ARG-WCL than PRG-RCL (P < 0.05). Implications: This work allows us to know the amount of nitrogen excreted in milk production in small-scale dairy systems. Conclusions: It is concluded that PRG-RCL may be a feeding strategy to reduce N excretion and achieve higher efficiency in N use for small-scale dairy systems.

ABSTRACT: Imazapyr+imazapic ready mix is the main herbicide used to weed control in Clearfield® Rice System. The continuous use of high doses may increase their residual activity in the soil. The aim of this research was determine the sensitivity of cover crops and soybean in rotation with flooded rice to different levels of imazapyr+imazapic residues in the soil and its effect on soil microbiology. A field experiment was performed during the 2014/15 and 2015/16 seasons. In the first crop season, flooded rice was cultivated using herbicide rates in order to have levels of residue in the soil: 0, 140 (label dosage, equivalent to 73.5+24.5 g a.i. ha-1), 280, 560, 840 and 1,120 g ha-1. After crop harvest, during fall-winter, it was sown ryegrass, white clover and fallow (no soil cover); and in the followed season it was sown soybean in the same area (simulating rotation crop). At that occasion, soil samples were collected to perform soil microbiology analyses of acid phosphatase, β-glucosidase, fluorescein diacetate and urease activity. Growth characteristics on cover crops related to residue levels, and soybean development related to soil residue and cover crops used was evaluated. The results showed that the increase of imazapyr+imazapic doses caused a negative effect on the cover crops evaluated at 75 and 140 days after sowing, mainly at doses greater than twice the label dosage that also reduced the growth and yield of soybean. In general, the enzymes activity in soil decreased as the dose of the imazapyr+imazapic residue increased, showing lower microbiota activity to herbicides degradation.

The Brazilian state of Rio Grande do Sul has approximately 5.4 million hectares of lowland. The introduction of winter forage legumes, such as white clover, can increase the productivity of these lowland areas through biological nitrogen fixation (BNF). However, this benefit can only occur if the legume is associated with rhizobia that can efficiently fix nitrogen under available soil conditions. The objective of this study was to select rhizobia of Rio Grande do Sul soils, which are efficient in BNF when in symbiosis with white clover, and evaluate the tolerance of this symbiosis under flooded soil conditions. The experiment was conducted in a greenhouse, in soil-filled pots, where 14 isolates were evaluated for nitrogen fixation ability under flooded soil conditions. Each treatment was tested under two soil moisture conditions (flooded and field simulated). Flooding significantly reduced the number and nodule weight as well as the production of dry matter and nitrogen accumulation in the shoots of plants inoculated with rhizobia. The effect of soil flooding on BNF varied according the isolate evaluated. The strains CVII, P3 4, T4 and VP16 exhibited high nitrogen fixation efficiency under flooding conditions, surpassing the nitrogen-added control treatment, on nitrogen accumulation in shoots.

Neste trabalho objetivou-se avaliar a influência de espécies em consórcio com azevém sobre a composição botânica e estrutural e o valor nutritivo dos pastos em um sistema de transição agroecológica. Foi avaliada a cultura do azevém (Lolium multiflorum Lam.) consorciada com aveia-preta (Avena strigosa Schreb.), trevo-branco (Trifolium repens L.) e amendoim-forrageiro (Arachis pintoi Krapov. & Gregory). O delineamento experimental foi o inteiramente casualizado, com três tratamentos e três repetições. O primeiro pastejo foi realizado 21 dias após a emergência das plantas nas pastagens de azevém + aveia-preta e azevém + amendoim-forrageiro e 28 dias após a emergência na pastagem de azevém + trevo-branco. O segundo pastejo na pastagem de azevém + aveia-preta ocorreu 30 dias após o primeiro pastejo, enquanto nas demais pastagens ocorreu 37 dias depois. As taxas de acúmulo de matéria seca (MS) do início do período de exclusão até o pico de produção de MS foram de 77,7; 75,0 e 71,3 kg/ha/dia de MS para as pastagens consorciadas com trevo-branco, amendoim-forrageiro e aveia-preta, respectivamente. A razão folha/colmo até o segundo pastejo foi elevada em todas as pastagens. A redução dos teores de PB conforme os dias de exclusão no pasto de azevém + aveia-preta é menor que nos pastos de azevém consorciado com trevo-branco ou amendoim-forrageiro.The objective of this work was to evaluate the influence of species intercropped with ryegrass on the botanical and structural composition and the nutritional values of pastures in an agroecological transition system. It was evaluated ryegrass (Lolium multiflorum Lam.) intercropped with black oats (Avena strigosa Schreb.), white clover (Trifolium repens L.) and forage peanut (Arachis pintoi Krapov. & Gregory). It was used a complete random design with three treatments and three repetitions. The first grazing was done 21 days after emergence of the plants on the pastures with ryegrass and black oats and ryegrass and forage peanuts and 28 days after emergence on the pasture of ryegrass + white clover. The second grazing, on the pasture with ryegras + black oats, occurred 30 days after the first one, whereas on the other pastures, grazing occurred 37 days later. The rates of dry matter (DM) accumulation, from the beginning of period of exclusion until maximal production of dry matter were: 77.7; 75.0 and 71.3 kg/ha/day of DM for the pastures intercropped with white clover, forage peanut and black cover, respectively. Leaf/culm ratio until second grazing, was high on all pastures. Reduction on contents of crude protein according to exclusion days on ryegrass + black oat pasture is lower than on pastures of ryegrass intercropped with white clover or forage peanut.

Sheep and cattle farmers need pastoral systems that are more productive and environmentally sustainable. The role that high feeding value herb and legume forage species can play in the farms of the future is highlighted. It is shown that species such as chicory (Cichorium intybus), plantain (Plantago lanceolata), red clover (Trifolium pratense) and white clover (T.repens) can provide live weight gains in lambs that are 70% greater than those from perennial ryegrass (Lolium perenne) based pastures. A case for replicated experiments that examine the value of whole technology packages based on herb and legume species, rather than component research, is made.Produtores de ovinos e bovinos necessitam de sistemas pastoris mais produtivos e ambientalmente sustentáveis. As espécies forrageiras herbáceas e leguminosas de alto valor nutricional podem ter um papel destacado no futuro desses produtores. Foi demonstrado que espécies tais como a chicória (Cichorium intybus), plantago (Plantago lanceolata), trevo vermelho (Trifolium pratense) e trevo-branco (T. repens) podem fornecer um ganho de peso 70% maior em carneiros quando comparado com pastagens de azevém (Lolium perenne). Mais que um componente de pesquisa, este é um caso para repetidos experimentos que examinem o valor de todos os pacotes tecnológicos baseados em espécies herbáceas e leguminosas.

O objetivo neste trabalho foi avaliar o valor nutritivo de dois sistemas forrageiros (SF): capim-elefante (CE) + azevém + trevo-branco + espécies de crescimento espontâneo (SF1); e capim-elefante + azevém + amendoim forrageiro + espécies de crescimento espontâneo (SF2). O delineamento experimental utilizado foi de blocos ao acaso com duas repetições (piquetes), totalizando quatro piquetes de 0,25 ha. O capim-elefante foi estabelecido em linhas espaçadas a cada 4 m e as pastagens foram adubadas com 50-40-40 kg/ha do formulado NPK. Durante o período experimental, foram realizados nove pastejos (326 dias no SF1 e 336 dias no SF2). Para avaliação, foram usadas vacas em lactação da raça Holandesa, recebendo suplementação alimentar de concentrado (3,5 kg/dia). Avaliaram-se a massa de forragem inicial, a composição botânica e os componentes estruturais do capim-elefante. Amostras de simulação de pastejo foram coletadas para análises dos teores de fibra em detergente neutro (FDN) e proteína bruta (PB), da digestibilidade in vitro da matéria seca (DIVMS) e matéria orgânica (DIVMO) e da composição em nutrientes digestíveis totais (NDT). No sistema forrageiro com trevo-branco, os valores médios de FDN foram de 47,71%; os de PB, 15,69%; a DIVMS, 77,28%; a DIVMO, 75,92%; e o teor de NDT, 65,00%, enquanto, no sistema com amendoim forrageiro, foram de 51,84; 14,62; 73,7; 72,27; e 63,06%, respectivamente. Os resultados de PB, DIVMS e DIVMO na pastagem total foram melhores no sistema forrageiro com trevo-branco, enquanto os de FDN foram melhores no sistema com amendoim forrageiro. O valor nutritivo das duas pastagens é melhor no período hibernal. Considerando a adubação, o manejo e o tempo de utilização da pastagem, pode-se afirmar que os valores qualitativos de ambos os sistemas são elevados.The objective of this study was to evaluate the nutritive value of two pasture-based systems (PS), with elephant grass (EG) + ryegrass (RG) + white clover (WC) + spontaneous growing species (SGS), for PS1; and EG + RG + forage peanut (FP) + SGS, for PS2. Four paddocks, each one with 0.25 ha, were used in the assessment. A complete randomized block design was used with two replications (paddocks). The EG was established in rows with 4 m spacing. Pastures were fertilized with 50-40-40 kg/ha NPK formulated, respectively. Nine grazings were performed during the experimental period (326 days in PS1 and 336 in PS2). Holstein cows receiving 3.5 kg/daily complementary concentrate feed were used in the evaluation. The initial forage mass, botanical composition and structural components of EG were evaluated. Samples were collected by the hand-plucking method to analyze neutral detergent fiber (NDF), crude protein (CP), in vitro dry matter digestibility (IVDMD), in vitro organic matter digestibility (IVOMD) and total nutrient digestibility (TND). The mean values for NDF, CP, IVDMD, IVOMD and TDN were 47.71; 15.69; 77.28; 75.92; 65.00% in PS1; and 51.84; 14.62; 73.72; 72.27 and 63.06% in PS2, respectively. Superior results were detected for CP, IVDMD, IVOMD and TDN forage total in PS1 while superior NDF values were detected in PS2. In two pastures, the best nutritive value results were observed in the winter period. Both systems showed high qualitative values considering fertilization, management and use time.

Estudou-se o comportamento alimentar de vacas da raça Holandesa em lactação mantidas em pastagem de misturas de espécies de capim-elefante (Pennisetum purpureum Schum.), azevém (Lolium multiflorum Lam.) e outras de crescimento espontâneo. Como diferencial destas pastagens, introduziu-se trevo-branco (Trifolium repens L.) ou amendoim forrageiro (Arachis pintoi Krapov. & Greg.). Nos meses de julho, agosto e outubro de 2005, foram feitas avaliações em pastejo utilizando-se em cada uma seis vacas entre o segundo e o quinto mês de lactação, observadas nos períodos de 18 às 6 h e de 8 às 16 h, a cada 10 minutos, por dois observadores. Foram observados o tempo de pastejo nas linhas constituídas por capim-elefante (CE), o tempo de pastejo nas espécies estabelecidas na entrelinha e os tempos de pastejo total (pastejo de CE + entrelinha), ruminação e ócio. Também foram avaliados a massa de forragem inicial, o valor nutritivo da forragem ingerida e as condições climáticas do período. O tempo médio de pastejo na entrelinha foi de 4 horas e 9 minutos para o trevo-branco e de 3 horas e 6 minutos para o amendoim forrageiro. O tempo médio de pastejo do capim-elefante não diferiu entre as misturas com trevo-branco (4 horas e 27 minutos) e com amendoim forrageiro (5 horas e 51 minutos), assim como os tempos de ruminação e ócio, que também não diferiram entre as espécies associadas. A presença de forrageiras de inverno está associada ao maior tempo de consumo de forragem. A presença de espécies de ciclos diferentes possibilitou que os animais equilibrassem a dieta volumosa.The objetive of this research was to study the eating behavior of lactating Holstein cows grazing mixed species of elephant grass (Pennisetum purpureum Schum.), ryegrass (Lolium multiflorum Lam.) and others spontaneous growth species. As differential of these pastures, was introduced white clover (Trifolium repens L.) or peanut forage (Arachis pintoi Krapov. & Greg.). Grazing eating behavior evaluations were taken on July, August and October of 2005. In each grazing eating behavior evaluation, six cows, between the second and fifth month of lactation, were observed in the periods from 18 to 6 h and 8 to 16 hours, every 10 minutes, by two observers. Grazing time of elephant grass (EG) in lines, grazing time of introduced species, established in interlines, and time of total grazing (EG grazing + interlines), rumination and idle were evaluated. Also, were evaluated the initial herbage mass, nutritional value of ingested forage and climatic conditions in the period. Grazing mean time in interline was 4 hours and 9 minutes for white clover and 3 hours and 6 minutes for peanut forage. Grazing mean time for elephant grass did not differ among the mix with white clover (4 hours and 27 minutes) and with peanut forage (5 hours and 51 minutes) as for rumination time and idle, which also did not differ among introduced species. The presence of winter forage is associated to the higher time of forage intake. The presence of species of different cycles enabled the animals to balance the forage diet.

Este trabalho foi desenvolvido com o objetivo de analisar aspectos fenológicos e produtivos de leguminosas nativas (Adesmia latifolia, A. tristis) e exóticas (Lotus corniculatus, L. uliginosus, Trifolium repens), em função do estádio fenológico no primeiro corte: vegetativo (CEV) e florescimento (CEF). As plantas foram estabelecidas em monocultura, no campo, e avaliadas entre maio/2000 e setembro/2001, em Passo Fundo, Rio Grande do Sul. Após o primeiro corte, as plantas foram desfolhadas em intervalos de 45 dias. Foram realizadas nove desfolhações no manejo CEV e sete no CEF. O estádio fenológico no primeiro corte influenciou a produção de massa seca (MS) de T. repens (CEV= 9.000 kg/ha de MS, CEF = 7.000 kg/ha de MS) e A. tristis (CEV = 4.000 kg/ha de MS, CEF = 8.000 kg/ha de MS). O L. corniculatus produziu cerca de 15.000 kg/ha de MS e A. latifolia, de 2.000 a 3.000 kg/ha de MS, independentemente do manejo. O L. uliginosus não floresceu, produzindo 7.000 kg/ha de MS no manejo CEV. As espécies nativas mostraram baixa persistência, com morte de plantas (A. tristis) e estolões (A. latifolia) no final da estação de crescimento. A maior produção de T. repens foi na primavera e a das espécies de Lotus, no verão.This work had the objective to evaluate phenological and productive aspects of native (Adesmia latifolia, A. tristis) and exotics legumes (Lotus corniculatus, L. uliginosus, Trifolium repens) as for the phenological stage on first-cutting: vegetative (CEV) and flowering (CEF). The plants were established as monoculture in the field and evaluated between May/2000 and September/2001, in Passo Fundo, Rio Grande do Sul. After the first cutting the plants were defoliated in 45 days intervals. There were nine cuttings in CEV-management and seven in the CEF-management. The phenological stage on first-cutting modified significantly (P

As espécies forrageiras de inverno: aveia preta (Avena strigosa Schreb cv. Comum), azevém anual (Lolium multiflorum Lam. cv. Comum) e trevo branco (Trifolium repens L. cv. Zapicán) foram sobre-semeadas em uma pastagem de capim-aruana (Panicum maximum Jacq. cv. Aruana), utilizada com ovinos em sistema intensivo de produção (irrigação, adubação e lotação rotacionada), com o objetivo de suprir o déficit de forragem no período crítico. Nos dois anos (14/04/00 a 18/01/01 e 07/06/01 a 22/02/02), foram avaliados: massa total de forragem pré-pastejo, composição botânica, porcentagem de lâminas foliares, acúmulo de forragem (AF) e taxa diária de acúmulo de forragem (TDAF), em seis períodos de rebrotação. O delineamento experimental foi o de blocos completos casualizados, com repetição dentro do bloco e dois tratamentos: 1) capim-aruana exclusivo (AE) e 2) sobre-semeadura da mistura das espécies forrageiras de inverno (MFI). No primeiro ano, a pastagem MFI apresentou maior massa total de forragem que a pastagem AE, na média dos seis períodos e no segundo período. A aveia apresentou a maior contribuição no segundo período e o azevém, no terceiro. As pastagens com MFI apresentaram maiores AF que as AE, na média dos seis períodos de rebrotação e no segundo e quinto períodos. No segundo ano, a massa total de forragem apresentou quantidades semelhantes entre as duas pastagens, nos seis períodos de pastejo. A aveia esteve mais presente no primeiro período e o azevém, no terceiro. Não houve diferença entre tipos de pastagem para AF, nos seis períodos de rebrotação. Pastos de capim-aruana adubados e irrigados, com sobre-semeadura de espécies forrageiras de inverno, produzem mais forragem no período crítico que pastos não sobre-semeados.Three winter forage species: black oat (Avena strigosa Schreb. cv. Common), italian ryegrass (Lolium multiflorum Lam. cv. Common) and white clover (Trifolium repens L. cv. Zapican) were introduced in a pasture of aruanagrass (Panicum maximum Jacq. cv. Aruana), grazed by sheep in an intensive production system (irrigation, fertilization and rotational stocking) with the objective of increasing the forage supply during the dry winter period. From 04-14-00 to 01-18-01 and 06-07-01 to 02-22-02, in six grazing periods, the pre-grazing forage mass, botanical composition and leaf blades percentage were evaluated in the six regrowth periods, as well as forage accumulation (FA). A completely randomized block design with replication within blocks was used. The treatments were: 1) grass alone and 2) the grass oversown with the mixture of winter forages. The oversown pasture had a greater total forage mass than the control in the second period as well as in the overall mean of the six periods of first year. The black oat made higher contribution in the second period while italian ryegrass contribution was higher in the third period. Higher FA was observed in the oversown pasture compared to the pure aruanagrass pasture, in the second, fifth and in the mean of the six regrowth periods. Total forage mass did not differ between treatments in the second year. The black oat contribution was higher in the first period while that of italian ryegrass was higher in the third period. The FA was similar in the two pasture systems. Fertilized and irrigated aruanagrass pasture, oversown with winter annual forages, out-yielded pure aruanagrass pasture during the dry winter period.