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Changes in grazing intensity affect forage production and performance of animal on C4 grass pastures; however, these relationships are not well defined for cattle grazing on limpograss (Hemarthria altissima (Poir) Stapf & C.E. Hubb. cv. Flórida) under continuous stocking. The objective of this study was to quantify plant and animal production from Flórida limpograss pastures, managed at different grazing intensities by beef heifers (i.e. different sward heights) in order to define pasture management outcomes that maximise plant and animal responses. For a 3-year period, the influence exerted by the sward height (10, 20, 30 and 40 cm) was assessed. Greater total herbage accumulation and herbage accumulation rate were observed for the more lenient grazing heights (30 and 40 cm). The 20-, 30- and 40-cm heights revealed similar heifer average daily gain of 0.49 kg liveweight (LW) animal–1 day–1, reducing at the rate of 0.04 kg LW animal–1 day–1, for each cm decrease below 19 cm, according to a segmented equation. LW gain per area showed a quadratic response to the sward height, with optimum values (i.e. 2.1 kg LW ha–1 day–1) achieved at a pasture height of around 21 cm. Therefore, to optimise cattle performance on continuously stocked Flórida limpograss pastures, a sward height of ~20 cm should be maintained.

We evaluated the effect of different grazing intensities by steers on animal performance, herbage intake and CH4 emissions in the stocking period of a soybean-beef cattle integrated system in southern Brazil. Treatments consisted of different grazing intensities, defined by target sward heights (10, 20, 30 and 40 cm) of mixed black-oat (Avena strigosa Schreb.) and Italian ryegrass (Lolium multiflorum Lam.) pastures under continuous stocking. Grazing management affected herbage utilization and, consequently, animal performance and CH4 emission. At the individual level, CH4 emission and animal performance had optimal values when pasture height was managed within a range of 23–30 cm. At the farm level, we found a positive linear effect of grazing intensity on animal live weight gain per hectare and the associated environmental costs of land use. Liveweight gain increased by 90 g ha−1 day−1 and CH4 emissions increased by 500 g CO2eq ha−1 day−1 for each cm of target sward height reduction. Given that most producers graze pastures to very short heights, large-scale adoption of target heights within 23–30 cm in southern Brazil has the potential to achieve 13–14% of the mitigation target for GHG emissions from the whole agricultural sector and 22–25% of the target for enteric fermentation from the livestock sector pledged by the Brazilian Government in the Paris Agreement. We conclude that adequate grazing management is the key strategy to improve animal production and reduce the environmental impact from livestock in ICLS.

Climate models project greater weather variability over the coming decades. High yielding systems that can maintain stable crop yields under variable environmental scenarios are critical to enhance food security. However, the effect of adding a trophic level (i.e. herbivores) on the long-term stability of agricultural systems is not well understood. We used a 16-year dataset from an integrated soybean-beef cattle experiment to measure the impacts of grazing on the stability of key crop, pasture, animal and whole-system outcomes. Treatments consisted of four grazing intensities (10, 20, 30 and 40 cm sward height) on mixed black oat (Avena strigosa) and Italian ryegrass (Lolium multiflorum) pastures and an ungrazed control. Stability of both human-digestible protein production and profitability increased at moderate to light grazing intensities, while over-intensification or absence of grazing decreased system stability. Grazing did not affect subsequent soybean yields but reduced the chance of crop failure and financial loss in unfavorable years. At both lighter and heavier grazing intensities, tradeoffs occurred between the stability of herbage production and animal live weight gains. We show that ecological intensification of specialized soybean systems using livestock integration can increase system stability and profitability, but the probability of win–win outcomes depends on management.

In the last decades, population growth worldwide boosts agricultural demand for food production. This huge driver rendered global food production more and more specialized, so agricultural landscapes became uniform and monotonic. The loss of diversity is a strong evidence of how modern agricultural landscapes have been disconnecting from nature. Evidence of environmental side-effects from this pathway are abundant in literature. Now, society is pressing towards changing practices aiming for healthy diets and sustainable food production systems. This raises the question: how to reconnect nature and agriculture in the context of future food production? In this review we propose a reconnection process based on the principles of ecological intensification or sustainable intensification. The integrated crop-livestock systems (ICLS) are the most consolidated technological pathway for reconciling crop production with natural processes. These systems are diverse and can partially mimic natural ecosystems exploring the synergies of natural biological processes, while achieving high levels of food production. ICLS promote soil improvements and mitigate greenhouse gas (GHG) emissions, reducing the agricultural share of global warming and climate change. Besides, these systems are more efficient in the use of nutrients and can optimize the use of other inputs such as pesticides. We present evidence of soil health and biogeochemical cycle restoration in addition to system stability improvement, and assume those symptoms as evidence of mixing crops and livestock fostering reconnection with natural processes.

International audience; Worldwide supply of water and nitrogen (N) are critical to crop yield with multiple interactions that need to be untangled. We used an allometric framework to quantify the dynamic relationships between crop growth, transpiration and N uptake in maize (Zea mays L.) and sorghum (Sorghum bicolor L.) using published data from experiments in France, New Zealand and United States. Our analysis highlighted a two-fold effect of drought on crop growth: a direct effect whereby crop growth is reduced proportionally to the reduction in transpiration, and an indirect effect mediated by a drought-induced crop N deficit, quantified as N nutrition index (NNI), the ratio between actual and critical plant N concentration (the minimum plant N concentration for achieving maximum crop mass). Under drought, sorghum maintained NNI and transpiration efficiency (biomass per unit of transpiration) whereas both NNI and transpiration efficiency declined in drought-stressed maize in comparison to well-watered crops. Nitrogen uptake per unit of transpiration (N/T) is a valuable trait for analyzing the combined effect of water and N deficit on water use efficiency (biomass per unit of evapotranspiration). However, both N/T and crop N concentration decline allometrically with biomass, hence comparisons of genotypes, environments and management practices would be biased unless they are scaled by crop biomass.

The objective of this work was to evaluate the impact of grazing intensities after 11 years of an integrated crop-livestock system, under no-tillage, on soil moisture and soybean physiological parameters during a summer season affected by drought. The experiment was established in 2001 on a Rhodic Hapludox. Treatments consisted in the succession of soybean (summer) and a mixed pasture of black oat + Italian ryegrass (winter), under different beef-cattle grazing intensities: intensive grazing, with 0.10-m pasture height; moderate grazing, with 0.20-m pasture height; and no grazing. During the soybean cycle, in the 2011/2012 crop season, rainfall was 40% of the climatological normal. The soil moisture was within the limits of available water both under moderate grazing and no grazing, at 0.00-0.50-m soil depth, but, under intensive grazing, it was below the permanent wilting point, especially up to the grazing height of 0.20 m. Intensive grazing affected negatively the plant physiology parameters, reaching peaks of -2.5 MPa and +6°C for leaf water potential and leaf-air temperature difference, respectively. Moderate grazing or the absence of grazing, during the winter season, results in similar physiological responses, contributing to soybean plant homeostasis. Resumo: O objetivo deste trabalho foi avaliar o impacto de intensidades de pastejo após 11 anos de um sistema de integração lavoura-pecuária, em plantio direto, na umidade do solo e em parâmetros fisiológicos da soja durante uma safra de verão afetada por seca. O experimento foi iniciado em 2001, em um Latossolo Vermelho. Os tratamentos consistiram na sucessão de soja (verão) e pastagem mista de aveia-preta + azevém (inverno), com diferentes intensidades de pastejo por bovino de corte: pastejo intensivo, com altura de pastejo de 0,10 m; pastejo moderado, com altura de pastejo de 0,20 m; e sem pastejo. No ciclo da soja, na safra 2011/2012, a precipitação foi de 40% da normal climatológica. A umidade do solo ficou dentro dos limites de água disponível, tanto em pastejo moderado quanto sem pastejo, na camada de 0,00-0,50 m, mas, em pastejo intensivo, a umidade do solo foi menor que o ponto de murcha permanente, especialmente até 0,20 m de altura de pastejo. O pastejo intensivo afetou negativamente os parâmetros fisiológicos da soja, que atingiu picos de -2.5 MPa e +6°C para potencial de água na folha e diferença entre temperatura do ar e da folha, respectivamente. O pastejo moderado ou a ausência de pastejo, durante o inverno, acarreta respostas fisiológicas similares, o que contribui para a homeostase da soja.

Crop-livestock integrated systems possess some uniqueness in soil and plant hydro-physical properties and processes. To obtain a better understanding of these systems, it is necessary to evaluate them with indices that take into account several attributes. Our study aimed to evaluate the efficiency of the least limiting water range in determining the influence of grazing intensities on soybean yield in an Oxisol managed in a long no-till, integrated soybean-beef cattle system. We evaluated an 11 year trial located in southern Brazil, with soybean summer cropping and black oat + Italian ryegrass winter grazing and different winter grazing intensities, namely intensive, moderate and no grazing. Intensive grazing only results in the most superficial soil layer compaction. Long-term moderate grazing, on the other hand, leads to intermediate compaction, not negatively affecting surface or subsurface soil physical properties. The least limiting water range is an inadequate indicator of soil physical quality in integrated soybean-beef cattle system, provided no direct relations with soybean yields. Under normal rainfall conditions, soybean yield depend mainly on rainfall amount and distribution, rather than on soil quality.

The objective of this work was to evaluate the effect of grazing intensity on the decomposition of cover crop pasture, dung, and soybean residues, as well as the C and N release rates from these residues in a long-term integrated soybean-beef cattle system under no-tillage. The experiment was initiated in 2001, with soybean cultivated in summer and black oat + Italian ryegrass in winter. The treatments consisted of four sward heights (10, 20, 30, and 40 cm), plus an ungrazed area, as the control. In 2009-2011, residues from pasture, dung, and soybean stems and leaves were placed in nylon-mesh litter bags and allowed to decompose for up to 258 days. With increasing grazing intensity, residual dry matter of the pasture decreased and that of dung increased. Pasture and dung lignin concentrations and C release rates were lower with moderate grazing intensity. C and N release rates from soybean residues are not affected by grazing intensity. The moderate grazing intensity produces higher quality residues, both for pasture and dung. Total C and N release is influenced by the greater residual dry matter produced when pastures were either lightly grazed or ungrazed. Resumo:O objetivo deste trabalho foi avaliar o efeito da intensidade de pastejo na decomposição dos resíduos da pastagem utilizada como cultura de cobertura, do esterco e da soja, bem como a liberação de C e N desses resíduos, em um sistema integrado de produção de soja e bovinos de corte, em plantio direto e em longo-prazo. O experimento foi iniciado em 2001, com soja cultivada no verão e aveia-preta + azevém no inverno. Os tratamentos consistiram de quatro alturas de pasto (10, 20, 30 e 40 cm), além de uma área sem pastejo, como controle. Em 2009-2011, resíduos da pastagem, do esterco, e do caule e das folhas de soja foram alocados em sacos de decomposição feitos com malha de nylon e decompostos até 258 dias. Com o aumento da intensidade de pastejo, a matéria seca residual da pastagem diminuiu e a do esterco aumentou. A concentração de lignina e as taxas de liberação de C da pastagem e do esterco foram menores com a intensidade de pastejo moderada. A liberação de C e N do resíduo de soja não é afetada pela intensidade de pastejo. A intensidade moderada de pastejo produz resíduos de maior qualidade, tanto para a pastagem quanto para o esterco. Já a quantidade total de C e N liberada é influenciada pela maior quantidade de matéria seca residual produzida quando a pastagem foi submetida ao pastejo leve ou não foi pastejada.

To improve our knowledge on the effects of different grazing intensities on integrated crop-livestock systems (ICLS) and thus define solid management goals to maximize plant and animal responses in these systems, we analyzed 16 years of data regarding to herbage mass, daily herbage accumulation, total herbage production, stocking rate, individual average daily gain and live weight gain per hectare from a long-term ICLS in southern Brazil. Treatments consisted of different grazing intensities (defined by the sward heights of 10, 20, 30 and 40 cm) by steers on mixed black oat (Avena strigosa Schreb.) and Italian ryegrass (Lolium multiflorum Lam.) pastures under continuous stocking. Herbage mass was consistently correlated to sward height, increasing by 88.7 kg DM ha−1 for each centimeter of sward height. The sward management heights of 20, 30 and 40 cm were similar with an average of 1.08 kg LW-1 animal-1 day−1, decreasing at a rate of 0.03 kg LW animal-1 day−1 for each cm decrease under 19 cm following a segmented equation. Stocking rate and live weight gain per area responded linearly decreasing by 35.8 kg LW ha−1 and 12.1 kg LW ha−1 for each cm increase in sward height, respectively. The long-term pasture and animal production presented a consistent pattern over the 16 experimental years, showing that swards managed under 19 cm are detrimental to animal individual performance despite of increases in the live weight gain per area. We conclude that managing the sward heights between 20 and 30 cm (moderate grazing intensities) maximize both plant and animal production and should be adopted as the management goal for mixed black oat and Italian ryegrass pastures within an ICLS meeting the global demand for increased food production and sustainability of the agroecosystems.

International audience; Interactions between nitrogen and water may vary between N-2 fixing species and species that rely only mineral soil nitrogen. Here we compared above ground biomass accumulation (W), nitrogen uptake (N), evapo-transpiration (ET) of alfalfa (Medicago sativa L.) and tall fescue (Festuca arundinacea Schreb.) during regrowth periods under contrasting supply of water (irrigated vs non-irrigated) and N (for non-fixing species). Using previously published data, we estimated the dynamics of the two components of ET, evaporation from soil (E) and transpiration (T), in order to analyse the impact of E/T, of the transpiration efficiency (TE = W/T) and the role of crop N nutrition on water use efficiency (WUE = W/ET). In tall fescue, limiting N supply reduced WUE by both increasing E/T ratio and decreasing TE. Water limitation in both alfalfa and tall fescue led to crop nitrogen deficit. This drought-induced N deficiency resulted in a proportional reduction in TE irrespective of the source of N for the plant. We propose that the ratio N/T, representing the apparent N concentration of water transpired by the crop, is relevant for analysing N-water interactions. Comparisons of dynamics of N/T ratio must be done at similar biomass or similar transpiration because N and T are related allometrically.

This paper aims to discuss the impact of the introduction of pastures and grazing animals in agricultural systems. For the purposes of this manuscript, we focus on within-farm integrated crop-livestock systems (ICLS), typical of Southern Brazil. These ICLS are designed to create and enhance the synergisms and emergent properties have arisen from agricultural areas where livestock activities are integrated with crops. We show that the introduction of the crop component will affect less the preceding condition than the introduction of the livestock component. While the introduction of crops in pastoral systems represents increasing diversity of the plant component, the introduction of animals would represent the entry of new flows and interactions within the system. Thus, given the new complexity levels achieved from the introduction of grazing, the probability of arising emergent properties is theoretically much higher. However, grazing management is vital in determining the success or failure of such initiative. The grazing intensity practiced during the pasture phase would affect the canopy structure and the forage availability to animals. In adequate and moderate grazing intensities, it is possible to affirm that livestock combined with crops (ICLS) has a potential positive impact. As important as the improvements that grazing animals can generate to the soil-plant components, the economic resilience remarkably increases when pasture rotations are introduced compared with purely agriculture systems, particularly in climate-risk situations. Thus, the integration of the pastoral component can enhance the sustainable intensification of food production, but it modifies simple, pure agricultural systems into more complex and knowledge-demanding production systems.

International audience; Nitrogen is essential to improving agricultural production systems, explaining why the contamination of groundwater by this nutrient is widespread. The aim of this paper was to describe data collected over 9 years on estimated leaching levels using a simple computation procedure and measurements of soil water content and water balance, nitrate concentrations in drainage water and meteorological data, and to assess the impacts of the duration of the grassland phase and the level of nitrogen fertilization on grassland on the drainage water quality. The study was carried out at a site of the Long-term Environmental Research Observation and Experimentation facility (SOERE) for Environmental Research-Agro-ecosystems, Biogeochemical Cycles and Biodiversity, run by the INRA experimental unit of Lusignan. The experimental treatments were sequences of maize, wheat and barley with different grassland rotational periods (a pure arable crop rotation; three or six years of grassland receiving high-level nitrogen applications; six years of grassland with a low N application rate and long-term grassland with nitrogen application). The study covered the period from April 2005 to June 2013, during which most drainage occurred in the autumn and early winter. Treatments with the longest duration of grassland exhibited less drainage than those containing a higher proportion of arable crops. The average nitrate concentration was 52.7 +/- 38.63 mg NO3 L-1 under a pure crop rotation, compared to 14.9 +/- 14.76 mgNO(3) L-1 under a petmanent grassland treatment. There were significant differences (P

Under integrated crop–livestock production system (ICLS), the animal acts as a catalyzer, modifying and accelerating fluxes by ingesting forage nutrients (grazing) and returning them to the soil as urine and dung in a continuous process whose magnitude and direction depend on grazing intensity. Thus, ICLS may change soil acidification processes and rates. The objective of this research was to verify the influence of grazing intensities on soil acidification through measurements of the soil chemical attributes in the soil profile and the efficiency of basic cation use in a soybean–beef cattle integration system nine years after surface liming under long-term no-till conditions in southern Brazil. An experiment established in 2001 in a Rhodic Hapludox with soybean (summer) and a mix of black oat + Italian ryegrass (winter) succession was used. Treatments consisted of different grazing intensities during the winter season: intensive grazing (IG), moderate grazing (MG), and no-grazing (NG). The experiment was set up in a randomized complete blocks design with three replicates. To evaluate soil chemical attributes, soil was sampled up to 40 cm, in May 2010, nine years after lime application. To quantify basic cations budgets and efficiencies, the inputs and outputs of calcium, magnesium, and potassium, as well as their initial and final exchangeable soil stocks were evaluated. Areas under grazed treatments, regardless of the intensity (IG or MG), presented lower soil acidification. Calcium and magnesium budgets were negative under NG and positive under MG. Potassium budgets were always negative, regardless of the management system, due to soybean grain harvest exportation and non-productive outputs. The soybean–beef cattle integrated system, with either IG or MG, was more efficient in calcium and magnesium utilization to produce protein; however, grazing does not affect potassium use efficiency.

Grazing livestock in integrated crop-livestock systems can cause impacts in the subsequent crop cycle. Aiming to investigate how grazing could affect soybean, the 9th crop cycle of a pasture/soybean rotation was assessed. Treatments were grazing intensities (10, 20, 30 and 40 cm of sward height) applied since 2001 in a mixed of oat and annual ryegrass; and an additional no grazing area as control. Treatments were arranged in a completely randomized block design with three replicates. Grazing affected soybean population and the mass of individual nodules (P0.05). Soybean yield showed differences among treatments, but no difference was found between grazed and non-grazed areas. Grazing intensities impact the coverage and frequency of weeds (P>0.05). In conclusion, grazing intensity impacts different parameters of soybean yield and development, but only the grazing intensity of 10 cm can jeopardize the succeeding soybean crop. RESUMOEm Sistemas Integrados de Produção Agropecuária, a presença dos animais em pastejo pode provocar alterações na produção das culturas subsequentes. Com o objetivo de verificar como diferentes manejos do pasto poderiam afetar o cultivo de soja, a 9ª fase de lavoura em rotação pecuária/lavoura foi avaliada. Os tratamentos foram intensidades de pastejo (10; 20; 30; 40 cm de altura do pasto), aplicados desde 2001, em pasto misto de aveia e azevém anual, além de área sem pastejo utilizada como testemunha. O delineamento experimental foi de blocos ao acaso, com três repetições. Houve diferença na população inicial de plantas e na massa do nódulo (P0,05). O rendimento de soja foi diferente entre os tratamentos, porém, não houve diferença entre áreas pastejadas e não pastejadas. Houve diferença para cobertura e frequência de espécies indesejáveis entre tratamentos (P>0,05). Em conclusão, diferentes intensidades de pastejo afetam os parâmetros de rendimento e desenvolvimento da soja, mas apenas a intensidade de pastejo de 10 cm pode comprometer a safra de soja subsequente.

Feeding livestock with cover crops can improve the efficiency and sustainability of integrated crop–livestock systems under no-till. However, no-till systems are based on permanent soil cover by organic material, so grazing livestock can compete for soil cover. Hence, managing stocking rates during the grazing period of the cultivated forage species is a key factor to assure enough herbage mass for maintaining long-term sustainable no-till systems. In this context, the objective of this study was to determine sward management targets for a continuously stocked mixed oat ( Avena strigosa ) × annual ryegrass ( Lolium multiflorum ) pasture in rotation with soybean in a no-till integrated crop–livestock system to determine the optimum balance between animal production and herbage mass for soil cover. The effects of sward height management on animal performance and herbage mass covers were evaluated. Treatments corresponded to four sward heights: 10, 20, 30 and 40 cm, maintained throughout the experimental period through continuous stocking and variable stocking rate, plus a no-grazing control area. Treatments were arranged in a randomized complete block design with three replications. Herbage mass and animal performance increased linearly with sward height, but weight gain per hectare decreased. Grazing efficiency fitted to a quadratic regression and conversion efficiency a logarithmic model. Equilibrium between grazing and conversion efficiencies was reached on swards managed at 20 cm, indicating that this sward height provided enough herbage mass to allow both animal performance and no-till crop demand for soil cover.

In the subtropical region of Brazil, integrated crop–livestock systems (ICLSs) are characterized by the annual rotation of pastures and crops in a no-till system where the pasture component is used to produce either meat or milk. These systems focus on integration within the farm rather than between farms, being characterized by alternating cropping and pasturing in the same area. Independent of the crop rotations possible in a subtropical environment, the main integrated farming system found was rotation or succession of summer crops ( Glycine max , Zea mays , Phaseolus vulgaris or Oryza sativa ) with winter annual grazing grasses (mixed or solely Avena strigosa and Lolium multiflorum ) or successive natural pastures. The high variability of crop yield in the Brazilian subtropics (due to climate extremes) as well as associated high costs and low prices has encouraged farmers to integrate livestock into their enterprises as a low-risk diversification option. Long-term experiments have demonstrated the benefits of crop–livestock integration with respect to many aspects of the soil–plant–animal system. There is evidence that such a system is not only a livestock–agriculture combination but also a unique system reaching a new complexity threshold, resulting in emergent properties with novel functionalities, some of which have yet to be investigated. In addition to greater environmental gains with less vulnerability, there are higher yields and more financial gain by the farmer, compared to that in the use of monocultures or non-integrated livestock farming. We conclude that ICLSs in Subtropical Brazil provide the opportunity for intensification with sustainability.

Biophysical and socio-economic improvements of farming systems have been obtained with integrated crop–livestock systems (ICLS). Grazing in ICLS under no-tillage conditions may alter soil phosphorus (P) dynamics, because of changes in P budgets and distribution of P forms. The need to understand impacts on P dynamics is important because they can modify soil quality and, consequently, have implications for agriculture sustainability. The objective of this work was to compare the geochemical and biological forms of P (P-geo and P-bio) under long-term grazing, as well as to assess the mobility and lability of these nutrient forms in the soil profile. The experiment was established in 2001 in an Oxisol and consisted of soybean ( Glycine max L.) rotated to a winter cover crop of black oat ( Avena strigosa Schreb.) and Italian ryegrass ( Lolium multiflorum Lam.) under no-tillage management. Treatments were two grazing heights (target of 20 and 40 cm) with young cattle and a non-grazed (NG) treatment. The experimental design was set up in completely randomized blocks with three replicates. Soil was sampled at the beginning of the experiment (May 2001) and again after six years (May of 2007) to study P fractionation at depths of 0 to 2.5, 2.5 to 5.0, 5.0 to 7.5, 7.5 to 10, 10 to 15 and 15 to 20 cm. After six years of ICLS, total P increased in the top 20 cm soil layer in both the grazed and non-grazed treatments. The P-geo and P-bio concentrations also increased in all treatments in the 0 to 2.5-cm layer. Despite the greater P accumulation in the non-grazed no-till treatment, grazing maintained the P lability (labile + moderately labile) at the same level as in the long-term no-till treatment. The ICLS also promoted increases in labile P stocks, both in organic and inorganic forms. In spite of the higher P-geo stocks in the non-grazed treatment, P cycling was enhanced by grazing, such that soybean yields were similar in all treatments. Furthermore, the grazing treatment led to higher P budgets (surpluses) and more efficient P use, as represented by meat production in addition to the soybean production.

In Brazil, as well as globally, land use has been increasingly addressed for environmental impacts and economic improvements. Integrated crop–livestock systems (ICLSs) are a potential strategy to optimize use of land, increase total production and reduce economic risk through diversification. We compared production and economic outcomes of a soybean-only system with ICLS differing in sward management. The study area was managed since 2001 using no-till in southern Brazil. Soybean [Glycine max (L.) Merr.] was rotated with a mixture of black oat (Avena strigosa Schreb) and ryegrass (Lolium multiflorum Lam) either for: (i) grazing (ICLS) or (ii) cover crops as cropping system only (CS) with no livestock grazing. Four sward height management methods (10, 20, 30 or 40 cm) were evaluated under put-and-take stocking. Across years, soybean yield (2516±103 kg ha−1) was not affected by treatment, but was affected by year (PP<0.001). Average daily gain was lower when pasture was managed at 10 cm than between 20 and 40 cm. With increasing sward height, a gradual reduction in cattle GPH was observed (P

Sustainable intensification of land-use practices has never been more important to ensure food security for a growing world population. When combined under thoughtful management, cover cropping and crop-livestock integration under no-till systems can benefit from unexpected synergies due to their unique features of plant-animal diversification and complex agroecosystem functions. Mimicking the nutrient coupling/decoupling processes of natural ecosystems by diversifying plant and animal components of no-till integrated crop-livestock operations is an essential feature of the design of agroecological systems that support self-regulating feedbacks and lend resilience while increasing productivity and ecosystem service provision. Focusing on grazing animals as drivers of agroecosystem change, we highlight the benefits of grazed cover crops in rotation with cash crops for primary and secondary production and for soil physical, chemical, and biological parameters. However, careful management of grazing intensity is imperative; overgrazing drives soil deterioration, while light to moderate grazing enhances overall system functioning and allows for the generation of emergent properties.

Com o objetivo de avaliar o efeito da estrutura de uma pastagem nativa nos parâmetros que compõem o processo de ingestão de forragem de ovelhas e bezerras em pastejo, foram estabelecidas quatro alturas de pasto (4, 8, 12 e 16 cm), em delineamento estatístico inteiramente casualizado, com quatro tratamentos e duas repetições no tempo e no espaço. A massa do bocado e a taxa de ingestão foram estimados por diferença de peso vivo corrigido para a perda de peso metabólico, durante 45 minutos. Os movimentos mandibulares de apreensão e mastigação foram registrados pelo aparelho IGER Behaviour Recorder. A profundidade do bocado foi obtida em 40 perfilhos marcados por unidade experimental, em medições realizadas antes e após o pastejo. Observou-se correlação positiva entre a altura do pasto e a massa de forragem, e negativa com a densidade de forragem. A profundidade de bocados apresentou relação linear e positiva com o aumento da altura do pasto e não diferiu entre espécies animais. Acima de 9,5 cm de altura do pasto, a profundidade do bocado das ovelhas não compensou a pouca densidade de forragem nos estratos mais superiores, o que reduziu a massa do bocado. A mesma resposta foi observada a partir da altura do pasto de 11,4 cm para as bezerras. Com o aumento da massa do bocado, houve diminuição na taxa de bocados e aumento na taxa de mastigação. A taxa de ingestão foi maior nas alturas em que a massa de bocados foi também superior, o que evidencia a correlação positiva entre as duas variáveis. Nessas condições, para aumentar o consumo de ovelhas e bezerras em campo nativo, a estrutura ideal de manejo requer manutenção de altura do pasto entre 9,5 e 11,4 cm, respectivamente. Aiming to evaluate the influence of native pasture structure in the intake process of grazing ewes and calves, four sward heights (4, 8, 12 and 16 cm) were established. A completely randomized design with four treatments and two replicates in time and space was used. Bite mass and forage intake were estimated by the short-term weight changes technique, corrected for the rate of insensible weight loss, during a 45 minutes test. The grazing and mastication jaw movements were registered by the IGER Behaviour Recorder device. Bite depth was obtained through 40 tillers marked in each experimental unit, by measurements carried before and after grazing. A positive correlation was observed between sward height and herbage mass, and negative between sward height and herbage bulk density. Bite depth fitted positively and linearly with increasing sward height, being not different between animal species. Ewe bite mass increased with increasing sward height up to 9.5 cm, then decreasing due to the low bulk density in the superior stratum. The same response was observed with calves, but bite mass reached a plateau only at 11.4 cm sward height. Bite rate decreased and mastication rate increased with increasing bite mass. Intake rate was greater at the sward height in which bite mass was also superior, indicating the positive correlation between these two variables. Under those conditions, to optimize the intake of sheep and calves, in native pasture, the ideal structure for management requires the maintenance of sward heights between 9.5 and 11.4 cm.

Avaliou-se o desempenho de cordeiros em pastagem de azevém anual (Lolium multiflorum Lam.) manejada em duas intensidades (moderada e baixa, 2,5 ou 5,0 vezes o potencial de consumo) e dois métodos de pastejo (lotação rotacionada ou contínua) durante 113 dias. O delineamento experimental foi o de blocos casualizados, em esquema fatorial 2 × 2 × 4 com quatro repetições. Não houve interação métodos × intensidades de pastejo e, portanto, seus efeitos foram analisados de forma independente. A intensidade de pastejo moderada resultou em menor oferta de forragem, menor massa média e menor altura da pastagem. As características qualitativas da forragem também foram afetadas positivamente pela intensidade moderada. A altura e a massa de forragem foram maiores no pastejo sob lotação rotacionada, mas a qualidade da forragem foi melhor nos piquetes de lotação contínua. As ofertas de forragem não diferiram entre os métodos de pastejo e proporcionaram condições necessárias para a comparação de todas as variáveis. O ganho médio diário e a carga animal foram afetados tanto pelo método quanto pela intensidade de pastejo. O ganho por área foi maior para a intensidade de pastejo moderada, no entanto, não foi influenciado pelo método de pastejo. A quantidade de forragem ofertada para o animal é o principal determinante da produtividade do sistema, independentemente do método de pastejo. A intensidade de pastejo baixa foi mais adequada para o manejo, pois refletiu em melhor ganho por animal. This work measured lamb performance in a ryegrass pasture (Lolium multiflorum Lam.) under different grazing intensities and methods. The pasture was used from July 12th to November 1st of 2003 (total of 113 days). The treatments were two grazing intensities (moderate and low) in rotational and continuous stocking. The moderate and low grazing intensities were represented, respectively, by forage allowance of 2.5 and 5 fold the intake potential. It was used a factorial arrangement (2 intensities × 2 methods × 4 replicates) in a complete randomized block design. There was no interaction among grazing methods and grazing intensities and they were analyzed separately. The moderate grazing intensity provided the lower forage allowance, lower herbage mass and lower pasture height. This intensity affected positively the qualitative characteristics of pasture as well. Regarding the grazing methods, the height and the herbage mass were larger under rotational stocking, while the forage quality was higher under continuous stocking. There was no difference of forage allowance between methods, and the necessary conditions to compare all the variables measured were reached. There were significant differences between average daily gain and stocking rates on both, grazing methods and intensities. The gain/hectare was better under moderate grazing intensity, but no difference was identified under grazing methods for this intensity. The amount of forage available for the animal is the central key for the productivity, despite the grazing method used. Low grazing intensity was considered more appropriate for pasture management because it allows better gain per animal.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:07:55Z No. of bitstreams: 1 S1516-35982012000600007.pdf: 69662 bytes, checksum: 153fdb7db7324b6d5185a4bac22983c8 (MD5) Made available in DSpace on 2013-08-22T19:07:55Z (GMT). No. of bitstreams: 1 S1516-35982012000600007.pdf: 69662 bytes, checksum: 153fdb7db7324b6d5185a4bac22983c8 (MD5) Previous issue date: 2012-06-01 Made available in DSpace on 2013-09-30T20:12:41Z (GMT). No. of bitstreams: 2 S1516-35982012000600007.pdf: 69662 bytes, checksum: 153fdb7db7324b6d5185a4bac22983c8 (MD5) S1516-35982012000600007.pdf.txt: 50874 bytes, checksum: b2e78764a875c091e60e8d7d2eee6c92 (MD5) Previous issue date: 2012-06-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:18:23Z No. of bitstreams: 2 S1516-35982012000600007.pdf: 69662 bytes, checksum: 153fdb7db7324b6d5185a4bac22983c8 (MD5) S1516-35982012000600007.pdf.txt: 50874 bytes, checksum: b2e78764a875c091e60e8d7d2eee6c92 (MD5) Made available in DSpace on 2014-05-20T15:18:23Z (GMT). No. of bitstreams: 2 S1516-35982012000600007.pdf: 69662 bytes, checksum: 153fdb7db7324b6d5185a4bac22983c8 (MD5) S1516-35982012000600007.pdf.txt: 50874 bytes, checksum: b2e78764a875c091e60e8d7d2eee6c92 (MD5) Previous issue date: 2012-06-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The objective of this study was to evaluate the chemical composition of the forage apparently consumed by steers in a natural grassland on region of Campanha, in Rio Grande do Sul, Brazil, subjected or not to different inputs: NP - natural pasture without inputs; FNP - fertilized natural pasture and INP - improved natural grassland with fertilization and over-seeded with cultivated winter species. Three Angus steers testers and a variable number of regulator animals per experimental unit were utilized in order to maintain 13 kg of DM/100 kg of live weight (LW) as forage allowance. One time at each season, hand plucking samples were performed along the daily grazing time simulating forage harvested by the animals. The collected samples after drying and grind were submitted to chemical analysis to determine the forage quality. Except in winter and spring, the values of neutral detergent fiber were higher than the critical value of 550 g/kg of DM, which could limit forage intake, demonstrating that the values of forage on offer provided (15.6; 13.7; 13.5; 15.8 kg of DM/100 kg of LW/day in summer, autumn, winter and spring, respectively) were not restrictive to intake. The oversowing of winter cultivated species or fertilization positively alter the degradable fiber content. The seasons had marked influence on the chemical composition of forage apparently consumed; positively increasing some fractions of forage chemical composition in the seasons in which native or cultivated winter species increased their participation. The forage chemical composition is the determining factor in animal performance in natural pasture. Universidade Federal do Rio Grande do Sul (UFRGS) Faculdade de Agronomia Programa de Pós-Graduação em Zootecnia Universidad de La República Del Uruguay Faculdad de Agronomía Universidade Estadual de São Paulo Programa de Pós-Graduação em Zootecnia Universidade Federal do Rio Grande do Sul (UFRGS)

Monitoraram-se variáveis relacionadas à produção e à estrutura de pastos de aveia-preta (Avena strigosa, Schreb) e azevém (Lolium multiflorum, Lam) manejados em quatro alturas (10, 20, 30 e 40 cm), em pastejo contínuo com lotação variável (put and take). Utilizaram-se novilhos de corte mestiços de aproximadamente 10 meses de idade com peso médio inicial de 190 kg, em delineamento de blocos completos casualizados com três repetições. Investigou-se o tipo de distribuição das frequências de altura em seis datas, bem como o potencial de predição da massa seca de forragem por meio da altura do pasto. A massa de forragem aumentou de forma linear de acordo com a altura do pasto: cada 1 cm de aumento na altura acima de 10 cm correspondeu a um acréscimo de cerca de 107 kg de MS/ha na massa de forragem. Não houve efeito da altura do pasto na taxa de acúmulo (55,8 kg de MS/ha.dia) nem na produção total de matéria seca (8.210 kg de MS/ha). A distribuição das frequências ajustou ao modelo normal em apenas uma das 96 séries analisadas. A distribuição tipo Gamma foi a que mais frequentemente se ajustou aos dados de altura do pasto, porém, uma vez iniciado o pastejo, a heterogeneidade no pasto foi tão alta que a distribuição das alturas não se ajustou a nenhum dos modelos estudados. É possível estimar a massa seca de forragem existente no pasto por meio de sua altura média, assim, sugere-se estabelecer alturas variáveis ao longo do ciclo de pastejo, com o intuito de se administrar a heterogeneidade causada pelo animal. It was monitored variables related to production and structure of oat (Avena strigosa Schreb) and ryegrass (Lolium multiflorum Lam) pastures managed at four sward heights (10, 20, 30, and 40 cm) on continuous grazing with variable stocking (put and take). It was used crossbred beef steers at approximately 10 months of age and an average initial weight 190 kg in a complete random block design with three replicates. The type of sward height distribution in six different sample dates as well as the forage dry mass prediction through sward heights were investigated. Forage mass linearly increased according to the sward height: for each 1-cm increase of the height above 10 cm, there was an approximately 107 kg DM/ha addition in the forage mass. There was no effect of sward height on the accumulation rate (55.8 kg DM/ha) neither on the dry matter total production (8,210 kg of DM/ha). Frequency distributions fitted to the normal model in only one out of the 96 analyzed data series. Gamma type distribution was the one that was the most frequently adjusted to sward height data, however, once grazing was started, pasture heterogeneity was so high that height distribution did not fit any of the investigated models. It is possible to estimate forage dry mass on the pasture by its average height so it is suggested to establish variable heights over the grazing cycle aiming to manage the heterogeneity caused by the animal.

The overseeding of ryegrass (Lolium multiflorum Lam) on sub-tropical native pastures increases the availability and quality of forage in the cold season. However, soil chemical amendment and nitrogen use can affect the floristic composition, with consequences to the primary and secondary production. In a randomized complete block design with three replications, the effect of nitrogen fertilization (40, 90 and 140 kg/ha of nitrogen) on native pasture overseeded with ryegrass in two consecutive years was assessed regarding production and composition of pasture and performance of beef calves. In both years, the forage accumulation rate and forage production responded linearly to the increase in nitrogen rates as a result of increased participation of ryegrass. The lower efficiency of responses in 2008 was due to the increased participation of dead material and the reduction of ryegrass in the forage sward. In 2007 there was an increasing substitution of the participation of native grasses by ryegrass with increasing nitrogen rates. Native legumes and other species were almost not affected by nitrogen fertilization. The average daily weight gain of the animals responded linearly to nitrogen rates in 2007, and quadratically in 2008. The stocking rate and gain per hectare increased linearly in both years, with greater responses in 2007. The production and composition of forage and livestock production are improved by the use of nitrogen, but the efficiency of responses can be affected by sowing date and nitrogen fertilization.

National audience

Plant residues removal (PRR) of cleaning cuts in seed crops of signalgrass (Brachiaria decumbens Stapf) can increase pure seed yield (PSY), but on the other hand, can reduce the plant nitrogen concentration (PNC), nitrogen (N) uptake, and affect the efficiency of N fertilization and the balance of N. There are still uncertainties, however, related to the interaction with no removal of plant residues (RNPR) of closing cleaning cuts and N fertilizer rates. This study conducted with signalgrass seed crops aimed to: i) evaluate the effects of plant residues management practices (PRMP) of cleaning cuts (plant residues removed or retained) in the initial october (in preparation for january harvest) and post-harvest january (in preparation for may harvest) and N fertilizer rates (0, 50, 100 and 150 kg ha-1) on PSY, in PNC, N uptake, and the balance presumed of N remaining after harvest (BPNRAH); ii) determine the nitrogen uptake efficiency (NUpE), nitrogen utilization efficiency (NUtE), nitrogen use efficiency (NUE), as well as other N efficiencies commonly used in the literature, and iii) determine if there was correlation between PNC, N uptake, NUpE, NUtE and NUE with PSY. The study was conducted in Umuarama, northwestern Paraná, Brazil, during the growing seasons of 2010-2011 and 2011-2012. The experiment was arranged in a randomized blocks design in a split-plot scheme, with three replications. The PNC and N uptake was significantly higher when plant residues were retained in the soil only in may 2011 harvest, but in other seed harvest these variables did not differ significantly in response to MPR evaluated. PNC and N uptake increased curvilinearly with increased N fertilizer rates in 2011 and 2012 harvests. In january and may harvests 2011 and may harvest 2012, PNC among N rates ranged from 0.9 to 1.3 g N kg dry matter-1 (DM), while N uptake ranged from 90 to 200 kg N ha-1. The results showed that in all harvests when the plant residues were removed the presumed balance of N remaining after harvest was curvilinear and negative. Conversely, when the plant residues were retained and the N fertilizer rate increased, this variable increased and then leveled. There were differences in the responses to N between harvest for NUpE, NUtE, NUE, nitrogen recovery efficiency (NRE) and nitrogen agronomic efficiency (NAgE). In general, NUpE and NUE from the 50 kg N ha-1 rate applied had better values. Physiologic N-efficiency (PNE) was affected by N fertilizer rate only on cycle of seed production of may 2012. Biomass plant efficiency (BPE) was not affected by N fertilizer rate in all harvest evaluated. Significant positive correlations, which were consistent in all seed harvest, were observed between the PNC, N uptake and NUtE with PSY, with exception of NUtE at May 2012 harvest, which the coefficient of correlation was not significant. A remoção de resíduos de plantas (RRP) de rebaixamentos em culturas do capim-braquiária (Brachiaria decumbens Stapf) para a produção de sementes pode incrementar o rendimento de sementes puras (RSP), mas, em contrapartida, pode reduzir a concentração de nitrogênio nas plantas (CNP), absorção de nitrogênio (N), o balanço de N e a eficiência da adubação nitrogenada. Entretanto, existem incertezas sobre a interação entre a RRP ou a não remoção de resíduos de plantas (NRRP) de cortes de rebaixamento e taxa de aplicação de N. Este estudo conduzido em uma cultura de capim-braquiária para a produção de sementes objetivou: 1) avaliar os efeitos de práticas de manejo de resíduos de plantas (PMRP) de cortes de rebaixamento (RRP ou a NRRP) realizados no início de outubro (em preparação a colheita de janeiro) e pós-colheita de janeiro (em preparação a colheita de maio) e de doses de N (0, 50, 100 e 150 kg ha-1) no RSP, na CNP, absorção de N e no balanço presumido de nitrogênio remanescente após a colheita (BPNRAC); 2) determinar a eficiência de absorção de N (EAN), eficiência de utilização de N (EUtN) e a eficiência de uso de N (EUN), bem como outras eficiências de N comumente usadas na literatura; e 3) determinar correlação entre a CNP, absorção de N, EAN, EUtN e a EUN com o RSP. O estudo foi conduzido em Umuarama, Noroeste do Paraná, Brasil, nas estações de crescimento de 2010-2011 e 2011-2012. O delineamento experimental usado foi blocos ao acaso em esquema de parcela subdividida, com três repetições. A CNP e a absorção de N foram significativamente maiores com a NRRP somente na colheita de maio de 2011, nas demais colheitas não diferiram em resposta as PMRP. A CNP e a absorção de N aumentaram de maneira quadrática com o aumento na dose de N em todas as colheitas. Nas colheitas de janeiro e maio de 2011, a variação na CNP foi de 0,9 a 1,3 g de N kg de matéria seca ha-1 (MS), enquanto que na absorção de N foi de 90 a 200 kg ha-1 de N. Os resultados mostram que, em todas as colheitas, quando houve a RRP, o BPNRAC teve comportamento curvilinear negativo. Contrariamente, com a NRRP e com a dose de N incrementada, o BPNRAC aumentou e então atingiu o platô. Em geral, na dose de N de 50 kg ha-1, a EAN e a EUN tiveram valores melhores. A eficiência fisiológica de N (EFN) foi afetada pelo N somente no ciclo de produção de sementes de maio de 2012. A eficiência de produção de biomassa (EPB) não foi afetada pela adubação de N em nenhuma x colheita. Correlações significativas e positivas, consistentes em todas as colheitas, foram observadas entre a CNP, absorção de N e EUtN com o RSP, com exceção da EUtN na colheita de maio de 2012, na qual o coeficiente de correlação não foi significativo. xvii, 54 f