Plantas espontâneas de pastagens naturais: aspectos fitossociológicos, dispersão e métodos de controle

Abstract

Weeds are a major problem for agricultural crops around the world, as they cause countless losses such as increased production costs and losses in the productivity of the crop of interest. One of the ways of introducing weeds in the planting areas is the use of cattle manure in the fertilization of crops, as the partially humified organic matter can contain viable seeds of weeds. In this sense, studies dealing with this theme are of great importance, especially in regions with a semi-arid and dry sub-humid climate in the Northeast region of Brazil, where agriculture plays an important economic and social role. This work aimed to analyze the weed species transported from the municipalities of Caturité and Boqueirão to Lagoa Seca through the trade of cattle manure between these localities. For this, phytosociological studies were carried out in two rural properties located in the cities of Caturité and Boqueirão in order to identify the weeds inserted in the grazing areas. The occupied square method was used, where the parameters frequency, density, abundance, relative importance index and similarity index were analyzed. After the "in loco" study, the cattle manure that is sold to the region of Lagoa Seca was collected in these same properties in order to identify the harmful species that are taken from one location to another by this way of dissemination. The manure was taken to a greenhouse environment at the Center for Agricultural Sciences, campus II of the State University of Paraíba, located in the municipality of Lagoa Seca, PB. Through an adaptation of the occupied square method, a phytosociological survey of weeds identified in cattle manure was carried out. The same parameters observed for the properties were also analyzed. Finally, questionnaires were applied to farmers in the municipality of Lagoa Seca who purchase cattle manure from the municipalities of Caturite and Boqueirão for use in agricultural crops in order to understand the knowledge of farmers about this issue. At the end of the research, it was possible to conclude that the trade of cattle manure for agricultural use between the municipalities of Caturité, Boqueirão and Lagoa Seca is responsible for the dispersion of at least 23 species of weeds between these locations. Among the species identified, the most important in this way of dissemination were Amaranthus spinosus L. and Amaranthus retroflexus L. The spread of weeds in agricultural crops via cattle manure causes countless losses to farmers in the municipality of Lagoa seca, mainly related to the increase in costs with hiring labor to contain the infestations. To mitigate the problem, it is necessary for farmers to adopt new management practices within rural properties, such as the treatment of cattle manure through composting and vermicomposting processes before introducing this fertilizer to agricultural crops.