Plantas daninhas em área de reforma de cana crua com diferentes manejos do solo e adubos verdes em sucessão

Abstract

Resumo -A renovação dos canaviais é importante para manter elevada a produtividade agrícola da cultura e é realizada em média após cinco cortes, com o objetivo de comparar o efeito residual das culturas de sucessão nos diferentes sistemas plantio sobre a ocorrência espontânea de plantas daninhas em área de reforma de cana crua, instalou-se o experimento sobre ARGISSOLO VERMELHO-AMARELO Eutroférrico, localizado no município de Novais-SP, em canavial colhido sem queima prévia nos últimos cinco cortes. Utilizou-se delineamento experimental blocos casualizados, com os tratamentos arranjados em parcelas sub-divididas, com quatro repetições. Os tratamentos principais consistiram dos três sistemas de cultivo; convencional, cultivo mínimo e plantio direto. Os tratamentos secundários foram constituídos de duas opções de adubos verdes (crotalária e mucuna) e uma parcela em pousio. Após 180 dias da colheita da cana-de-açúcar contou-se o número de plantas daninhas m -2 e determinou-se a massa seca da parte aérea, calculando seus índices fitossociológicos. Dentre os sistemas de manejo do solo o plantio direto mostrou um efeito supressor das plantas daninhas, resultando em menor número de plantas, menor massa seca de plantas e menor variedade de espécies, suprimindo espécies consideradas importantes na cultura da cana-de-açúcar, sendo o cultivo mínimo o tratamento intermediário e o plantio convencional o mais afetado pela comunidade infestante. Entre os adubos verdes plantados em sucessão a mucuna se destacou, sendo seu efeito supressor das plantas infestantes mais importante em áreas cultivadas com manejo de solo convencional. Palavras-chave -Crotalaria juncea. Cultivo mínimo. Mucuna aterrima. Plantio direto.Abstract -The renewal of plantations is important to maintain high agricultural productivity of the culture of sugar cane and is performed after 5 cuts. In order to compare the residual effects of crop succession in different planting systems on the spontaneous occurrence of weeds in the area of reform of sugarcane, the experiment was done on Acrisol eutrophic soil, located in the city of Novais, São Paulo, in sugar cane harvested without prior burning in the last five cuts. The randomized block design with treatments arranged in split plot and arranged in four replications was used. The main treatments consisted of three cropping systems, conventional tillage, minimum tillage, and no tillage. Secondary treatments consisted of two choices of green manure (sunnhemp and velvet bean) and a fallow plot. After 180 days of harvest of sugar cane was counted the number of weeds.m -2 and determined the dry mass of shoots, calculating their phytosociological index. Among the management systems of soil, the no tillage system showed a suppressive effect of weeds, resulting in fewer plants, less dry mass of plants and less variety of species, suppressing species that are considered important in the culture of sugar cane. The minimum tillage method revealed intermediate results and conventional tillage was most affected by weeds. Amon...

Weed Community in a Raw Sugarcane Renovation Area Submitted to Different Soil Managements

“…Soares et al (2012) have found similar results in work comparing soil management and crop rotation with green manures. The decrease of the nutsedge importance when peanuts are grown in succession to sugarcane may be due both to the dampening provided by the vegetation cover as the residual effect of imazapic applied in peanut crops, for the transposition of imazapic through sugarcane straw is highly significant (Ferreira et al, 2010).…”

“…However, while raw sugarcane harvest presents agronomic benefits, a lot of waste left on the surface and the intense mechanization of the area may reduce the sugarcane plantation longevity (Soares et al, 2012). Sugarcane fields renovation is performed on average after five sugarcane crops, and in most cases these areas remain in fallow during the period between the sugarcane harvest and the implementation of the new sugarcane field.…”

Interference periods of velvet bean in sugarcane

“…One of the most commonly used legumes was velvet bean (Mucuna aterrima), mostly due to its green manure properties (AMBROSANO et al, 2013) and high vigor, being able to suppress the establishment of some weed species (SOARES et al, 2012).…”

Which spatial arrangement of green manure is able to reduce herbivory and invasion of exotic grasses in native species?

“…This result is mainly owing to the physical effect of joint smothering and reduction of light availability by the green manure species (Soares et al. ). Greater light availability for the soil favors the spread of invasive grasses because they are highly intolerant to shading (Meschede et al.…”

“…The arrangement with green manure and native species mixed favors greater vegetation cover, and thus reduces the presence and establishment of invasive grasses. This result is mainly owing to the physical effect of joint smothering and reduction of light availability by the green manure species (Soares et al 2012). Greater light availability for the soil favors the spread of invasive grasses because they are highly intolerant to shading (Meschede et al 2007, Pereira et al 2012).…”