Utilização de pseudocaule de bananeira como cobertura morta de solos cultivados com laranjeira lima (Citrus sinensis Osbeck) e mamoeiro (Carica papaya L.) sob manejo orgânico de produção

Abstract

The present work was developed at the Integrated System of Agroecological Production (Agroecological Small Farm of the Km 49), which is conducted through partnership among three institutions: Embrapa, UFRRJ and PESAGRO-RIO. Two experiments were done, one of them installed at orange tree orchard files and the other in an area cultivated with papaya trees Baixinho de Santa Amália . The objectives of the first experiment were to evaluate the effects of the dead cover banana tree pseudo-stem application in some chemical, physical and biological soil variables as: temperature, humidity, available contents of some essential elements and soil macro and mesofauna communities. Moreover, it was done an evaluation of the nutrient contents of the orange leaf tissues. In the second experiment at the papaya orchad, the effects of dead cover application were observed on the plants development, the nutrient contents of the leaf tissues and on the spontaneous plants population. The experimental design was of random blocks, with three treatments: an area maintained without covering, another with dead cover formed with the straw of Paspalum notatum grass (in the case of orange) or triturated Pennisetum purpureum cv. Napier grass (in the case of papaya); and the last formed with fragments of pseudo-stem of banana trees. For the humidity determination two methods were used, one through the gravimetric humidity (area with orange tree files) being collected in the depths of: 0-0,05; 0,05-0,10; 0,10-0,20; 0,20-0,40 m and other for tensiometry (area with papaya trees) in the depths of 0-0,10 and 0,10-0,20 m. The temperature was taken jointly with the humidity, with aid of the digital geothermometer in the layer of 0-0,05 m of the soil. For characterization of the edaphic fauna two methodologies were used: for collection of the mesofauna (Berlesse-Tüllgren) and macrofauna (TSBF), being the samplings accomplished in the beginning and at the end (macrofauna) and in the beginning, middle and at the end (mesofauna) of the experiment. In the papaya tree plants, it was evaluated the height, diameter of the stem; the radius of the leaf blade; the petiole length; height at the beginning of the flowering and fructification. In relation to the spontaneous vegetation, collections were done for evaluation by the application of some phytossociological indexes. The results indicate that the pseudo-stem use increased the soil K+ content in the orange tree files and increased the P and K in the leaf tissues of both fruit bowls, and reduced the temperature and the hydric deficit in the first layers of the soil (up to 0,10 m) of the two areas. As for the edaphic fauna, was verified that the banana tree pseudo-stem reduced the individuals' medium density, differently of the effect of the covering of Paspalum notatum grass, when compared to the soil without dead cover. It was observed that the group Oligochaeta was expressive and negatively affected by the pseudo-stem cover. In the experiment with papaya trees, it was verified that the use of the pseudo-stem as dead cover provided a decrease in the incidence of the spontaneous vegetation, especially of the mad, beyond to contribute to the plants larger vegetative development in the juvenile phase. Like this, it was evidenced that the use of dead cover with fragments of banana tree pseudo-stem provided important impacts in some chemical, physical and biological characteristics of the soil, as well as in the phytossociology of spontaneous herbs and initial development of papaya trees.