IMPACTOS TÉCNICO-ECONÔMICOS DA ADUBAÇÃO DE PASTOS

A criação de bovinos no Brasil ocorre, prioritariamente, em pastagens e, neste contexto, a adubação do pasto é uma importante estratégia de aumento na eficiência produtiva. Diante disso, objetivou-se, com esta revisão, descrever os impactos técnicos da adubação no desenvolvimento de gramíneas tropicais. A calagem é uma prática importante na disponibilidade dos nutrientes e, novos estudos visam demonstrar que o intervalo entre a incorporação do calcário e a semeadura tem maior dependência da umidade do solo e que é possível reduzir este período que tradicionalmente é de 60 a 90 dias. A adubação fosfatada tem maior impacto sobre a implantação do que a manutenção do pasto, e quando negligenciada na formação do pasto, observa-se um efeito residual sobre a rebrota. O nitrogênio e o potássio são os nutrientes mais extraídos na manutenção dos pastos, o que se torna importante o estudo da relação entre estes nutrientes, bem como a adoção da adubação potássica em sistemas em que a adubação nitrogenada é uma prática rotineira. A varredura, que consiste na mistura de sobras de fertilizantes em galpões, embora tenha baixo custo por quilo de produto, o uso pode ser antieconômico, o que depende da composição do insumo adquirido. Palavras-chave: calagem; fertilização de pastos; formação de pastagens. Technical and economic impacts of pasture fertilization ABSTRACT: Cattle production on Brazil priority occurs in grasslands, in this context, pasture fertilization is an important strategy to improve production efficiency. Therefore, the aim with this review is to describe the technical impacts of fertilization on tropical grass development. Liming is an important practice in nutrient availability and new studies aim to demonstrate that the interval between limestone incorporation and seeding has more dependence on soil moisture, and that is possible to reduce this period, which traditionally is from 60 to 90 days. Phosphate fertilization has a greater impact on pasture implantation than maintenance, and when neglected in pasture formation, there is a residual effect on regrowth. Nitrogen and potassium are the nutrients extracted on pasture maintenance, which makes it important to study the relationship between these nutrients, as well as the adoption of potassium fertilization in systems where nitrogen fertilization is a routine practice. Mixing leftover fertilizers in warehouses, although it has a low cost per kilo of product, the use can be uneconomical, which depends on the input composition purchased. Keywords: liming; pasture fertilization; pasture implantation.

Production, morphology and chemical-bromatological characteristics of Urochloa brizantha cv. Marandu under doses of compost from dairy cows

Confinement of dairy cows in Brazil is significant, with the compost badded pack barn being the most used model, generating a large amount of good quality organic compost that can be used as a fertilizer in the pastures of the farms, reducing the use of industrialized fertilizers and mitigating the environmental impacts of dairy activity. An experiment was carried out in pots under greenhouse conditions to evaluate the effect of compost doses on the production, morphology and chemical-bromatological characteristics of Urochloa brizantha cv. Marandu A completely randomized design with 3 replications and 6 treatments consisting of 6 doses of the compost: 0; 50; 10; 20; 40 and 80 g.vaso-1. Increasing compost doses resulted in higher dry matter yield, higher tillers density and higher potassium and phosphorus contents in the forage. Dairy cow compost can be used for pasture fertilization, partially replacing industrialized fertilizers.

Improve Pasture or Feed Grain? Greenhouse Gas Emissions, Profitability, and Resource Use for Nelore Beef Cattle in Brazil’s Cerrado and Amazon Biomes

Economic development, international food and feed demand, and government policies have converted Brazil’s natural ecosystems into agricultural land. The Integrated Farm System Model (IFSM) was evaluated using production, economic, and weather data collected on two cooperating farms in the Legal Amazon and Cerrado biomes in the Midwest state of Mato Grosso, Brazil. Three sustainable agricultural intensification strategies, namely grain supplementation, pasture re-seeding, and pasture fertilization were simulated in IFSM with double the beef cattle stocking density compared to extensive grazing. Livestock dry matter consumption simulated in IFSM was similar for pasture grazing estimates and actual feed consumed by beef cattle on the two collaborating farms. Grain supplementation best balanced beef production and profitability with lower carbon footprint compared to extensive grazing, followed by pasture fertilization and pasture re-seeding. However, pasture re-seeding and fertilization had greater use of water and energy and more nitrogen losses. Human edible livestock feed use was greatest for grain supplementation compared to other modeled systems. While grain supplementation appears more favorable economically and environmentally, greater use of human edible livestock feed may compete with future human food needs. Pasture intensification had greater human edible feed conversion efficiency, but its greater natural resource use may be challenging.

Financial transition and costs of sustainable agricultural intensification practices on a beef cattle and crop farm in Brazil's Amazon

The intensification of Brazil's beef cattle production system can involve different strategies to increase beef production while reducing deforestation in the Amazon biome and mitigating climate change. This study economically evaluates a cooperating beef farm in the state of Mato Grosso, Brazil's Amazon biome over three crop years (2015–16 to 2017–18), transitioning from an extensive grazing system to a semi-intensive system using five sustainable agricultural intensification (SAI) practices. These five practices include (1) grain supplementation for cattle, (2) pasture fertilization, (3) pasture re-seeding, (4) crop–livestock integration (CLI) and (5) irrigated and fertilized pasture that is rotationally grazed. The relative costs of these five SAI strategies used on this cooperating farm are compared. The adoption of SAI strategies increased beef productivity 5.7% (228–241 kg live-weight sold per hectare) and gradually improved net farm income by ~130% over the 3 years of transition (−US$94.79 to $29.80 ha−1). Grain supplementation (US$188 ha−1) had the cheapest cost per hectare, followed by pasture fertilization (US$477 ha−1) and pasture reseeding (US$650 ha−1). The most costly practice was in-ground irrigation of fenced rotationally grazed pasture (US$1600 ha−1) with the second most costly being CLI (US$672 ha−1). Despite adoption challenges of these SAI practices, past research confirm these five practices can increase beef productivity and profitability while reducing carbon footprint. Regardless of the cost per hectare of each practice, farmer adoption can be improved through education, support and incentives from both the public and private sectors.

Costo de criar una ternera lechera de reemplazo desde el nacimiento al parto

Dairy heifers are the future of any dairy farm; however, before they begin to produce milk, they represent a very significant cost unknown by an important number of producers. The objective of the present study was to determine the economic cost associated with the rearing of dairy replacements. The study was carried out at the dairy cattle Alfredo Volio Mata Experiment Station of the University of Costa Rica, during the year 2016. A total of forty Jersey heifers were reared from birth to calving (twenty-five months) grouped into three age categories: 0-3 months, 3 to 16 months and 16 to 25 months. In order to determine the total costs within each category, detailed records of all the expenses incurred each day for each animal were kept in an electronic spreadsheet, considering all the activities involved and related to feeding, cleaning and disinfection, veterinary treatments, pasture fertilization, workforce, health management and maintenance, among others. It was determined that the total cost for raising a replacement heifer from birth to calving was ¢818 360.95 ($1473.62); representing a 25.17; 53.27 and 21.56% for the stage of birth to three months, three months to service, and service to calving, respectively. Of the total costs, 78.72% corresponded to feed and 6.82% to labor. Depending on milk production and net economic return from each liter of milk produced, the investment would be recovered beyond the second lactation.

Chemical Characteristics of the Use of Gelatine Sludge in Soil Cultivated as Fertilizer

Various types of industrial wastes have been tested as a source of pasture fertilization. However, little is known about the sludge of the gelatine industry. This study aimed at testing gelatine sludge as a soil amendment by assessing the chemical modifications caused in the soil profile. The experiment was conducted in Araguaina, Tocantins, using a typical Quartzipsamment soil (Entisols) from February to November 2013. Four doses were tested in experimental plots: 0, 50, 150 and 300 m3 ha-1. Soil sampling was performed at four depths: 0-5, 5-10, 10-20 and 20-30 cm with collection at the beginning and the end of the experimental period. Five grazing simulations of 21 days of rest of Piatã grass were testes. The gelatine sludge was able to raise the contents of calcium, phosphorus, and sum of bases only in the superficial layer (0-5 cm) and did not alter the pH, potential acidity and saturation by base, indicating that there was no use restriction due to salinization or acidification. Therefore, it was concluded that the maximum tested dose (300 m3 ha-1) improved the chemical characteristics of the soil, especially in the 0-5-cm layer.

Mombaça Grass Responds to Partial Replacement of K+ by Na+ with Supplemental Ca2+ Addition in Low Fertility Soil

Partial replacement of potassium by sodium may be an alternative to reduce the cost of pasture fertilization and reduce the dependence on imported potassium sources. The objective of this study was to evaluate different sources and doses of calcium as enhancers of sodium effect on the partial replacement of potassium by sodium. Here, Mombaça grass (Megathyrsus maximus) was grown on low fertility soil. The experiment was conducted in a factorial (3 × 5) based on a completely randomized design with 4 replications as follow: three sources of Ca2+ (dolomitic limestone, agricultural gypsum and calcium chloride), five doses of Ca2+ (0, 10, 20, 30 and 40 mg dm-3) and two additional treatments (fertilization with 100% of K+ without application of Ca2+ and one control without any fertilization). Potassium was partially replaced (25%) by Na+ prior to Ca2+ additions. Plant height, growth rate, dry weight, Na+, K+, K+/Na+ and shoot proline contents were evaluated as well as Na+ levels and the electrical conductivity of the soil. The results show that the addition of Ca2+ provided better plant development when K+ was partially replaced by Na+ and that the supply of Ca2+ reduced the absorption of sodium by plants. The partial replacement of K+ by Na+ did not increase soil salinity or caused stress to the plants.

Phosphorus bioavailability in soybean grown after pasture under different fertility regimes

The aim of this study was to evaluate the residual effect of phosphorus (P) fertilizer applied to an Urochloa decumbens cv. Basilisk pasture on the P bioavailability to the following soybean crop. Low-productivity pasture, planted on an Oxisol in an experimental field at Embrapa Cerrados, was divided into three strips, each of 1.5 ha and fertilized by broadcasting annual applications of 0, 20 and 40 kg ha-1 of P2O5 for four years. After the pasture was desiccate with herbicide, soybeans were sown and fertilized with 0, 50 and 100 kg ha-1 of P2O5 applied within each strip, making a total of nine (3x3) P treatments. Residual available P content (Mehlich-1 and resin) from the pasture fertilization was lower than from soybean fertilization. However, the bioavailable residual P from the pasture, determined by P accumulated in plants, production of dry matter and grain yield, had similar availability to inorganic P applied to the soybean. Early P fertilization applied to pasture is technically feasible and can be used to maintain the pasture: it is recommended to replace corrective fertilization for following soybean crops.

Species Diversity and Botanical Composition of Permanent Grassland as a Response to Different Grazing Management Practices

The effects of different levels of grazing utilization (two, three and four grazing cycles per year) and mineral fertilization (nil-fertilization; N100P30K60) on the botanical composition of permanent grasslands were studied in the locality of Rapotín (Czech Republic, 332 m a.s.l.) from 2003–2010. The vegetation of the experimental pasture was classified as Cynosurion. It was found that moderate treatment (three grazing cycles per year) without mineral fertilization showed the highest value of diversity index (DI = 6.08), and maximum dominance of legumes (Dmax = 9.1%), particularly Trifolium repens. The highest dominance of grasses (Dmax = 77.7%), mainly Dactylis glomerata and Elytrigia repens, was achieved with the fertilized treatment utilized in two grazing cycles per year. Based on RDA results, tested management treatments explained 26% of species composition variability, where effect of number of grazing cycles per year was five-times higher than effect of fertilization. We recommend grassland utilization in three grazing cycles per year as the most suitable way from the objective of both species diversity and botanical composition of pastures in similar site conditions. Pasture fertilization should be more controlled by careful consideration of individual pasture goals, actual nutrient status of the soil and possible environmental risks.

Phosphorus Management and Water Quality Problems in Grazingland Ecosystems

Phosphorus management in grazingland ecosystems represents a major challenge of agronomic and environmental importance. Because of the extensive acreage occupied by grazinglands, decisions concerning pasture fertilization and nutrient management in forage-based livestock systems are crucial to both farmers and regulatory agencies. The purpose of this paper is to provide an overview of the literature relevant to pasture P fertilization and the potential impacts on water quality. There continue to be uncertainties regarding interrelationships between pasture management and water quality issues. Despite the extensive body of literature on nutrient transport from grazinglands, limited information is available on the relationships between land use, transport potential, water management, and climatic conditions affecting nutrient losses at a watershed scale. As agriculture continues to modernize and intensify, public concerns about the impacts of plant nutrients on environmental quality will likely increase. Managing water quality protection and profitable agriculture will be a major challenge for the next generations.