Compostagem de misturas de capim-elefante e torta de mamona com diferentes relações C:N

A viabilidade econômica da compostagem está relacionada à utilização de matérias-primas abundantes, de custo competitivo e com níveis reduzidos de contaminação química e biológica. Seguindo esses critérios identifica-se a biomassa de capim-elefante e a torta de mamona como materiais bastante promissores. Objetivou-se, neste trabalho, determinar as características dos produtos finais e os índices de eficiência do processo de compostagem em três formulações da mistura de capim-elefante (Pennisetum purpureum) e torta de mamona com diferentes relações C:N, além de um tratamento de referência com a mistura de capim-elefante e biomassa de Crotalaria juncea. A compostagem da mistura de capim-elefante com torta de mamona possibilitou a obtenção de material orgânico estabilizado com elevado teor de N, sem a necessidade de utilização de qualquer inoculante ou aditivo. Os compostos se estabilizaram aproximadamente aos 60 dias após o início da compostagem e apresentaram reduções de cerca de 50% de sua massa e 65% de seu volume, após 90 dias de compostagem. Compostos com os menores valores iniciais de relação C:N apresentaram as maiores perdas proporcionais de N durante a compostagem

A simple and easy method to measure ammonia volatilization: Accuracy under field conditions

Field studies on soil ammonia (NH3) volatilization are restricted in many countries owing to the high costs commonly demanded for accurate quantification. We assessed the accuracy of a simple, open chamber design to capture NH3 under field conditions, as affected by different chamber placement schemes. Urea-15N was surface applied to lysimeters installed in the spaces between maize rows. Open chambers made from plastic bottles were installed on each lysimeter with variations in i) N rates (3, 8, 13, and 18 g m–2), ii) the height of the chamber above the soil surface (0, 5, and 10 mm), and iii) chamber relocation (static vs. dynamic). Reference lysimeters without chambers were used to measure NH3 losses by 15N-balance. Losses of NH3 -N accounted for more than 50% of the applied N. Relocation of the chambers had no impact on their NH3-trapping efficiencies, proving to be an unnecessary procedure. Variation in the height of the chambers above the soil surface affected the capture of NH3, but the results still maintained high linearity with the NH3 losses quantified by the reference method (R2 > 0.98). When the same placement scheme used in the introductory study describing the chamber was utilized (static and touching the soil surface), we found a trapping efficiency of 60%, which was very similar to that (57%) obtained in the previous study. Our results show that this simple, open chamber design can be used with satisfactory accuracy under field conditions, provided that simple, standardized procedures are warranted

Optimizing the use of open chambers to measure ammonia volatilization in field plots amended with urea

Measuring ammonia (NH3) volatilization from urea-fertilized soils is crucial for evaluation of practices that reduce gaseous nitrogen (N) losses in agriculture. The small area of chambers used for NH3 volatilization measurements compared with the size of field plots may cause significant errors if inadequate sampling strategies are adopted. Our aims were: i) to investigate the effect of using multiple open chambers on the variability in the measurement of NH3 volatilization in urea-amended field plots and ii) to define the critical period of NH3-N losses during which the concentration of sampling effort is capable of reducing uncertainty. The use of only one chamber covering 0.015% of the plot (51.84 m2) generates a value of NH3-N loss within an expected margin of error of 30% around the true mean. To reduce the error margin by half (15%), 3–7 chambers were required with a mean of 5 chambers per plot. Concentrating the sampling efforts in the first two weeks after urea application, which is usually the most critical period of N losses and associated errors, represents an efficient strategy to lessen uncertainty in the measurements of NH3 volatilization. This strategy enhances the power of detection of NH3-N loss abatement in field experiments using chambers

Recuperação no sistema solo-planta de nitrogênio derivado da adubação verde aplicada à cultura do repolho

O objetivo deste trabalho foi determinar a eficiência de recuperação, no sistema solo-planta, do nitrogênio derivado da adubação verde aplicada à cultura de repolho (Brassica oleracea). O experimento foi dividido em duas etapas: a primeira consistiu da produção de palhada de feijão-de-porco (Canavalia ensiformis), mucuna-cinza (Mucuna cinereum), e sorgo (Sorghum bicolor), em substrato enriquecido com 15N. A segunda etapa consistiu da aplicação das palhadas marcadas com 15N, em cobertura nos canteiros com repolho. Os tratamentos consistiram de: palha fresca de feijão-de-porco; palha fresca de mucuna-cinza; palha fresca de sorgo; mistura das palhas de mucuna, feijão-de-porco e sorgo a 1:1:1; e controle sem adubação verde. A recuperação de N no sistema solo-planta foi influenciada pelo tipo de palhada utilizado, e a eficiência de recuperação do N derivado da palhada de leguminosa variou de 9 a 16%. O tratamento com palha de feijão-de-porco é o que apresenta maior eficiência de recuperação e, portanto, a melhor sincronia da oferta de nitrogênio pela decomposição da palhada com a demanda pela cultura do repolho

NEOTROPICAL CARNIVORES: a data set on carnivore distribution in the Neotropics

Mammalian carnivores are considered a key group in maintaining ecological health and can indicate potential ecological integrity in landscapes where they occur. Carnivores also hold high conservation value and their habitat requirements can guide management and conservation plans. The order Carnivora has 84 species from 8 families in the Neotropical region: Canidae; Felidae; Mephitidae; Mustelidae; Otariidae; Phocidae; Procyonidae; and Ursidae. Herein, we include published and unpublished data on native terrestrial Neotropical carnivores (Canidae; Felidae; Mephitidae; Mustelidae; Procyonidae; and Ursidae). NEOTROPICAL CARNIVORES is a publicly available data set that includes 99,605 data entries from 35,511 unique georeferenced coordinates. Detection/non-detection and quantitative data were obtained from 1818 to 2018 by researchers, governmental agencies, non-governmental organizations, and private consultants. Data were collected using several methods including camera trapping, museum collections, roadkill, line transect, and opportunistic records. Literature (peer-reviewed and grey literature) from Portuguese, Spanish and English were incorporated in this compilation. Most of the data set consists of detection data entries (n = 79,343; 79.7%) but also includes non-detection data (n = 20,262; 20.3%). Of those, 43.3% also include count data (n = 43,151). The information available in NEOTROPICAL CARNIVORES will contribute to macroecological, ecological, and conservation questions in multiple spatio-temporal perspectives. As carnivores play key roles in trophic interactions, a better understanding of their distribution and habitat requirements are essential to establish conservation management plans and safeguard the future ecological health of Neotropical ecosystems. Our data paper, combined with other large-scale data sets, has great potential to clarify species distribution and related ecological processes within the Neotropics. There are no copyright restrictions and no restriction for using data from this data paper, as long as the data paper is cited as the source of the information used. We also request that users inform us of how they intend to use the data