RESUMO A quantificação das emissões destes gases do solo é onerosa, uma vez que requer metodologias e equipamentos específicos. O objetivo deste foi avaliar a modelagem utilizando regressão não linear e redes neurais artificiais para estimar a emissão de CO2 em função do manejo do solo, e de suas propriedades físicas e químicas. A emissão de CO2 foi avaliada em dois diferentes manejos do solo, o plantio direto e o cultivo mínimo. As leituras de fluxo CO2 foram realizadas por meio de uma câmara de sistema fechado automático, determinou-se ainda a temperatura e teor de água do solo, densidade do solo e carbono orgânico total. O modelo de regressão e os modelos de redes neurais artificiais foram ajustados a partir da correlação entre as variáveis medidas nas áreas em que o solo foi manejado com plantio direto e cultivo mínimo, com os dados de emissão de CO2. As redes neurais artificiais são mais precisas na determinação das relações entre a emissão de CO2 e a temperatura, teor de água no solo, densidade do solo e carbono orgânico, quando comparado com os resultados de regressão linear.
ABSTRACT Quantifying soil gas emissions is costly, since it requires specific methodologies and equipment. The objective of this study was to evaluate modeling by nonlinear regression and artificial neural networks (ANN) to estimate CO2 emissions caused by soil managements. CO2 emissions were evaluated in two different soil management systems: no-tillage and minimum tillage. Readings of CO2 flow were carried out by an automated closed system chamber; soil temperature, water content, density, and total organic carbon were also determined. The regression model and the ANN models were adjusted based on the correlation of the variables measured in the areas where the soil was managed with no-tillage and minimum tillage with data of CO2 emission. Artificial neural networks are more accurate to determine correlations between CO2 emissions and soil temperature, water content, density, and organic carbon content than linear regression.
ABSTRACT Brazilian soil scientists have increased the use of the term “soil quality” in their scientific publications in the last decade. However, it remains unclear if those publications only mention “soil quality” in a broad context, or the studies are focused on soil quality assessments, integrating soil chemical, physical and biological indicators. The objective of this systematic review was to carry out a critical analysis of the conception in using the term “soil quality” in recent publications derived from studies performed in Brazil. For this purpose, the terms [(“soil health” or “soil quality” or “qualidade do solo”) and (“Brazil*” or “Brasil*”)] were searched in databases of Web of Science, Scopus, and Scielo from 2014 to 2021. Initially, 1,284 peer-reviewed papers were found, subsequently selected according to the criteria established in two filters: (i) First filter - studies carried out in Brazil, which mentioned at least one of the terms of interest (“soil health” or “soil quality” or “qualidade do solo”) and that evaluated soil biological, physical or chemical indicators, assessing at least one of them; (ii) Second filter - studies in which all three groups of soil indicators were assessed and integrated, and presented a specific discussion about soil quality. According to the results, 36 % of the papers met the first criteria (n = 464), and only 2 % (n = 30) attended the second filter. The terms “soil health” or “soil quality” or “qualidade do solo” were mentioned 7 and 37 times per paper for those papers selected in the first and second filter, respectively. We evidenced in our study that the term soil quality in agricultural science papers has been predominantly used in a broad context, mostly to refer to the suitable soil conditions for plant growth. Thus, we concluded that even if the use of soil quality term is increasing in Brazilian literature, there are still very few researchers working specifically with soil quality assessments, in its full conception (i.e., integrating chemical, physical and biological indicators). Therefore, there is a promising research field to be explored to promote scientific advances in the soil quality area (e.g., new concepts, assessment frameworks, on-farm monitoring protocols), as well as disseminate the soil quality assessment among the Brazilian farmers, environmentalists, and other stakeholders.
Avaliou-se o efeito do fornecimento de monensina sódica no desempenho de vacas leiteiras em fase inicial de lactação, cuja alimentação, em sua dieta total no cocho, compôs-se em 81,4% de silagem de milho e 18,6% de concentrado, em que se fez uso de maior proporção de silagem de milho de que concentrado. Foram utilizadas 14 vacas multíparas 7/8 Holandês, aos 20±10 dias pós-parto aproximadamente, com média de 22±0,5kg vaca-1 dia-1 de leite, em delineamento de blocos casualizados, adotando-se o esquema de parcelas subdivididas no tempo, em modelo de medidas repetidas. Os tratamentos nas parcelas foram diferenciados pela presença (200mg animal-1dia-1) ou ausência da monensina na ração e, nas subparcelas, pelos diferentes períodos de avaliação. Não se observaram diferenças no consumo em matéria seca da dieta, conversão alimentar, produção de leite in natura e corrigida e peso vivo nas médias diárias de cada período. No entanto, a produção de sólidos totais foi superior para os tratamentos com o ionóforo, sinalizando que a administração da monensina sódica para vacas no início de lactação modifica o rendimento em produção de leite.
The effect on the performance of early lactation cows when supplying them with sodium monensin was evaluated, whose power in their overall diet in the trough, was composed of 81.4% of corn silage and 18.6% of concentrate in which use was made of a higher proportion of corn silage to concentrate. Fourteen multiparous 7/8 Dutch cows were used, approximately 20±10 days post-labor, with the average weight of 22±0.5kg cow-1 day-1 of lactation, in randomized blocks, adopting the scheme of subdivided portions in time and repetitive measurement model. The treatments in portions were differentiated by the presence (200mg.animal-1day-1) or absence of monensin in the food and, in the sub-portions, different evaluation periods were used. The animals were fed with their total diet in the feeder composed of 81.4% of corn silage and 18.6% of concentrate. No difference was found in the consumption of diet dry matter, alimentary conversion, in natural and corrected production of milk and live weight in the daily averages of each period. However, the production of total solids was superior for treatments with ionophore, signalizing that the administration of sodium monensin in early lactation cows changes the milk production performance.