The dynamics of N losses in fertilizer by ammonia volatilization is affected by several factors, making investigation of these dynamics more complex. Moreover, some features of the behavior of the variable can lead to deviation from normal distribution, making the main commonly adopted statistical strategies inadequate for data analysis. Thus, the purpose of this study was to evaluate the patterns of cumulative N losses from urea through ammonia volatilization in order to find a more adequate and detailed way of assessing the behavior of the variable. For that reason, changes in patterns of ammonia volatilization losses as a result of applying different combinations of two soil classes [Planossolo and Chernossolo (Typic Albaqualf and Vertic Argiaquolls)] and different rates of urea (50, 100 and 150 kg ha-1 N), in the presence or absence of a urease inhibitor, were evaluated, adopting a 2 × 3 × 2 factorial design with four replications. Univariate and multivariate analysis of variance were performed using the adjusted parameter values of a logistic function as a response variable. The results obtained from multivariate analysis indicated a prominent effect of the soil class factor on the set of parameters, indicating greater relevance of soil adsorption potential on ammonia volatilization losses. Univariate analysis showed that the parameters related to total N losses and rate of volatilization were more affected by soil class and the rate of urea applied. The urease inhibitor affected only the rate and inflection point parameters, decreasing the rate of losses and delaying the beginning of the process, but had no effect on total ammonia losses. Patterns of ammonia volatilization losses provide details on behavior of the variable, details which can be used to develop and adopt more accurate techniques for more efficient use of urea.

Objetivou-se caracterizar o potencial produtivo, a distribuição mensal, a composição morfológica e botânica da forragem de aveia preta e de azevém anual submetidos a estratégias de manejo de corte no estado de São Paulo. O delineamento experimental foi inteiramente casualizado, com tratamentos correspondendo a combinações entre formas de cultivo (aveia e azevém exclusivos ou combinados) e estratégias de colheita (cortes com 95% de interceptação de luz (IL) ou intervalo FIXO de 30 dias de rebrotação), em arranjo fatorial com três repetições. Os estandes colhidos por IL acumularam 1580kg MS ha-1 corte-1, e os por FIXO 2020kg de MS ha-1 corte-1. A proporção de folhas foi maior no azevém (70%), seguido do cultivo combinado (64%) e depois pela aveia (52%). Entre os manejos, a IL resultou em maiores proporções de folha e menor proporção de colmos que o FIXO. A proporção de azevém foi de 64%, sob o manejo por IL, e 70% no manejo por descanso FIXO. Ao longo do tempo, ocorreu a substituição da aveia pelo azevém na composição do dossel combinado. Ambas as estratégias de manejo podem ser adotadas para essas forrageiras de inverno em sistemas de integração agricultura e pecuária, com vantagem para o azevém.

In Brazilian sugarcane plantations, fertilization with vinasse, supplemented or not with mineral fertilizer, is a common practice. But little is known about the effects of this application on N losses, especially those forms of N which give rise to greenhouse gas emissions. The aim of this study was to quantify N2O and NH3 emissions from soil after vinasse application and urea fertilizer addition and to examine the possible impact adding vinasse before or after urea. Two experiments were conducted under greenhouse conditions and one in the field with treatments of vinasse and urea fertilizer, either alone, or in sequence. The highest proportions of N emitted as N2O were registered in the vinasse treatment, which amounted to 15 % of the N applied in the first greenhouse experiment, and 2.5 % in the field experiment. With respect to the losses by NH3 volatilization, urea was the only treatment where this process was significant. N2O emission from vinasse was 2.5 %, somewhat above the default emission factor of 1 % of the IPCC. N2O emissions from urea were also variable, but emission factors registered were still well below the default IPCC factor for organic residues. The order of addition of urea and vinasse had little effect on NH3 volatilization in the field, but there were evidences it was important for N2O.

O estado do Paraná localiza-se em uma região de transição climática, abrangendo regimes térmicos
diferentes e variações no risco de geadas. O abacaxizeiro (Ananas comosus L.) é uma cultura sensível
às condições climáticas e o conhecimento dos riscos a que a cultura estará exposta é importante para
o seu sucesso. O objetivo deste trabalho foi efetuar o zoneamento agroclimático para o cultivo do
abacaxizeiro no estado do Paraná. Foram veri¿cados os limites adequados das variáveis climáticas e
avaliadas a temperatura média anual, a temperatura do mês mais frio, o risco anual de geadas, o risco de
de¿ciência hídrica, o número de horas de insolação anual e o fotoperíodo no Estado. O Paraná possui
áreas com baixo risco climático para a cultura do abacaxizeiro. A temperatura média anual acima de
19°C, a temperatura média do mês mais frio superior a 15,5°C e a altitude inferior a 600 m permitiram
delimitar áreas aptas ao cultivo do abacaxizeiro no Paraná. A de¿ciência hídrica anual não é limitante ao
cultivo do abacaxi no Estado. A temperatura média anual e o fotoperíodo podem induzir naturalmente o
Àorescimento do abacaxi no Estado. Destacam-se as regiões Oeste, Noroeste e Norte, com temperatura
média anual superior a 22°C, que são as mais recomendadas ao cultivo. Nas regiões com temperatura
média anual entre 19 e 22°C, a escolha do local de cultivo deve ser criteriosa, levando-se em conta o
risco de geada local. As regiões Centro, Sul e Leste não são recomendadas, por apresentarem faixas de
temperatura abaixo do mínimo exigido.

The aim of this study was to evaluate the forage yield during the growing season of 2003/2004 as well as the ruminal dry matter degradability, neutral detergent fiber and acid detergent fiber concentration in the forage of five Panicum grasses (Mombaça, Tanzânia, Massai, Tobiatã and Atlas) in Piracicaba, SP. Rest period was fixed on 28 days for Atlas, Massai and Mombaça and 35 days for Tanzânia and Tobiatã, according to their morphologic and structural characteristics. The samples were incubated for 96; 48; 24; 12; 6; 3 and 0 hours. Mombaça (15500 kg DM ha-1) and Massai (20400 kg DM ha-1) were the highest yielding genotypes. Ruminal degradability showed that, although chemical composition is similar across genotypes, some parameters such as potential degradability, lag time and effective degradability are variable, suggesting contrasts in animal production potential.

Os citros encontram-se entre as espécies mais estudadas no mundo. Há
várias décadas, são conduzidos programas de melhoramento genético de cultivares
porta-enxerto e copa, principalmente na África do Sul, Austrália, Brasil, China, Espanha,
Estados Unidos, França, Israel, Itália e Japão. Das estratégias clássicas, e mais
recentemente as ferramentas da biotecnologia utilizadas no melhoramento genético
de citros, destacam-se a hibridação sexual controlada, a seleção de mutantes espontâneos
ou induzidos e de híbridos naturais, a hibridação somática via fusão de protoplastos,
o mapeamento genético, o sequenciamento de genoma e a transformação
de plantas que têm sido usados na obtenção de novas cultivares cítricas. Ressalta-se
a importância de aspectos relacionados a diversidade genética, taxonomia e biologia
reprodutiva de Citrus (L.) e gêneros afins, tais como a heterozigosidade, apomixia,
poliembrionia, ploidia, juvenilidade, partenocarpia, autoincompatibilidade, esterilidade
gamética e zigótica. Estes são apontados para as perspectivas futuras na área de
melhoramento genético de plantas cítricas.

The effects of land-use change (LUC) on soil carbon (C) balance has to be taken into account in calculating the CO2 savings attributed to bioenergy crops1, 2, 3. There have been few direct field measurements that quantify the effects of LUC on soil C for the most common land-use transitions into sugar cane in Brazil, the world’s largest producer 1, 2, 3. We quantified the C balance for LUC as a net loss (carbon debt) or net gain (carbon credit) in soil C for sugar-cane expansion in Brazil. We sampled 135 field sites to 1 m depth, representing three major LUC scenarios. Our results demonstrate that soil C stocks decrease following LUC from native vegetation and pastures, and increase where cropland is converted to sugar cane. The payback time for the soil C debt was eight years for native vegetation and two to three years for pastures. With an increasing need for biofuels and the potential for Brazil to help meet global demand4, our results will be invaluable for guiding expansion policies of sugar-cane production towards greater sustainability.

Phosphorus (P) and zinc (Zn) are important determinants of plant productivity, particularly in the tropical grasslands of Brazil. Nutrient deficiency is one of the most important factors limiting plant productivity, decreasing photosynthesis efficiency and plant development. The present study investigates in Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. cv. ‘Marandu’: 1) the gas exchange measurements; 2) the total leaf area development; and 3) the dry matter production due to P and Zn nutrition. Plants of B. brizantha cv. ‘Marandu’ were grown in nutrient solution under five rates of P (0.1, 0.6, 1.1, 1.6, and 2.1 mmol L⁻¹) and five rates of Zn (0.00, 0.75, 1.5, 2.25, and 3.00 μmol L⁻¹), in a fractioned factorial. Plants were harvested two times. Phosphorus supply increased carbon dioxide (CO₂) assimilation and stomatal conductance, and decreased intercellular CO₂. The interaction P rates x Zn rates were significant for the total leaf area variables and shoot dry matter in the second growth period. The nutrition of P and Zn interfered in the B. brizantha productivity by changing the grass photosynthesis and leaf area.

Phosphorus (P) and zinc (Zn) availabilities are important to the nutrition of tropical forage grasses. In this manner, this study aimed to identify and quantify changes in metabolism, tillering, and root system of Brachiaria brizantha cv. ‘Marandu’ related to P and Zn availabilities. Plants of B. brizantha cv. ‘Marandu’ were grown in nutrient solution under five rates of P (0.1, 0.6, 1.1, 1.6, and 2.1 mmol L−1) and five rates of Zn (0.00, 0.75, 1.5, 2.25, and 3.00 μmol L−1), in a fractionated factorial. The interaction P x Zn rates and the Zn supply were not significant for the activity of acid phosphatase enzyme, P-use index, number of tillers, and root parameters. P-use index and enzyme activity decreased as P availability increased. The high efficiency in P use was a result of high acid phosphatase activity and P supply was essential to the development of ‘Marandu’ palisadegrass root system.

Cattle ranching is one of the most important agricultural activities in Brazil. The impact of livestock on soil N2O emissions in Brazil has only been assessed using a Tier 1 approach of the IPCC guidelines, as there are no data available from field studies. Apart from the need for accumulating data for the development of proper direct N2O emission factors, we tested for possible differences between urine and dung as N2O sources and the difference in emissions between the dry and wet season. An area of Brachiaria brizantha at the Embrapa Rice and Bean Centre in the Cerrado (central savannah) region (Goiás state) was subdivided into plots where fresh cattle urine and dung were monitored for three consecutive periods (two in the rainy and one in the dry season) for N losses, principally N2O emissions and NH3 volatilization. 15N-labelled urine N was used in the first monitoring period for an N balance study which indicated that denitrification and NH3 volatilization were the most important processes for N loss. Percentages of N lost as N2O and as volatilized NH3 were greater for urine than for dung. In addition, N losses as N2O in the rainy season were much greater than during the dry season. Representing the Cerrado region and the extensive pasture systems common in this region, direct emission 0.007 g N2O–N g−1 (0.7%) excreta N, well below the EF3PRP of 0.020 g N g−1 (2%) used by IPCC for cattle N in excreta. The fraction of excreta N lost as NH3 of ∼15% was in line with the IPCC guidelines. Disaggregation of emission factors for excreta type is recommended.

The presence of some inorganic elements in biodiesel can compromise the fuel quality and
enhance the emission of pollutants. In this context, a new procedure for biodiesel sample preparation
using a high pressure asher (HPA) is presented, aiming the determination of Al, Ca, Cu, Fe, K, Mg,
Mn, Na, Ni, P, Sr, and Zn, in soybean, sunflower, animal fat, cotton and castor oil, by inductively
coupled plasma optical emission spectrometry (ICP OES). The digestion conditions of the HPA
were optimize to digest 1.5 g of biodiesel, with HNO3 and H2O2, at a temperature of 300 °C and
pressure of 435 psi, which considered the sample dilution factor, the total solids in solution and the
acidity for ICP OES determinations. Analytes concentrations in these biodiesels were calculated
using standard addition method. Detection limits from 0.05 to 0.7 mg kg–1 were suitable to attend
biodiesel quality parameters, government policy and legislations worldwide. Therefore, the
proposed procedure proved to be efficient to eliminate the major organic interferences typically
present in oil based samples allowing a fast, precise, interference-free and robust analytical
condition for biodiesel characterization.

Poor-quality roughages are widely used as fiber sources in concentrate-based diets for ruminants. Because roughage quality is associated with the efficiency of energy use in forage-based diets, the objective of this study was to determine whether differing the roughage source in concentrate-based diets could change the energy requirements of growing lambs. Eighty-four 1/2 Dorper × 1/2 Santa Inês ram lambs (18.0 ± 3.3 kg BW) were individually penned and divided into 2 groups according to primary source of dietary roughage: low-quality roughage (LQR; sugarcane bagasse) or medium-quality roughage (MQR; coastcross hay). Diets were formulated to be isonitrogenous (2.6% N) and to meet 20% of physically effective NDF. After a 10-d ad libitum adaptation period, 7 lambs from each group were randomly selected and slaughtered (baseline). Twenty-one lambs in each diet group were fed ad libitum and slaughtered at 25, 35, or 45 kg BW. The remaining 28 lambs (14 from each diet group) were submitted to 1 of 2 levels of feed restriction: 70% or 50% of the ad libitum intake. Retentions of body fat, N, and energy were determined. Additionally, 6 ram lambs (44.3 ± 5.6 kg BW) were kept in metabolic cages and used in a 6 × 6 Latin square experiment designed to establish the ME content of the 2 diets at the 3 levels of DM intake. There was no effect of intake level on diet ME content, but it was greater in the diet with LQR than in the diet with MQR (3.18 vs. 2.94 Mcal/kg, respectively; P < 0.01). Lambs fed the diet with LQR had greater body fat (g/kg of empty BW) and energy concentrations (kcal/kg of empty BW) because of a larger visceral fat deposition (P < 0.05). Using a low-quality roughage as a primary source of forage in a concentrate-based diet for growing lambs did not change NEm and the efficiency of ME use for maintenance, which averaged 71.6 kcal/kg0.75 of shrunk BW and 0.63, respectively. On the other hand, the greater nonfibrous carbohydrate content of the diet with LQR resulted in a 17% better efficiency of ME use for gain (P < 0.01), which was associated with a greater partial efficiency of energy retention as fat (P < 0.01). This increased nutritional efficiency, however, should be viewed with caution because it is related to visceral fat deposition, a nonedible tissue.