Plantas úteis para revestimento do solo: II - Gramíneas de porte médio e grande

Preliminary results have been obtained on the development of 11 types of grasses with average height varying from 0.70 to 1.15 m and from 11 other types with average height from 1.30 to 5.00 m. From plots with an area of 25 m², from the collection of useful plants of the Soil Conservation Department of the Instituto Agronômico de Campinas, one sample of the plants was taken for each plot the sampled area being of 0,50 and 1.00 m², for the grasses of medium and large size, respectively. The above-ground parts of the plants were cut at the heights of 80, 26, 8, 2 and 0 cm (ground level) respectively and determinations were made of the weight and volume of each portion of the plants under investigation. The results obtained are presented in tables 1 to 3. The underground parts of the grasses were studied in the same areas where the aerial parts were cut. Blocks of soil were taken with depths of 2, 8, 26 and 80 cm. The underground portions of the plants in each block were separated by the dry method, using wire screen, their weight and volume being determined (table 1 to 3). The soil particles holding capacity of each species of grass was determined by adding to the weight of the above-ground part at the lowest cut (block Aa) the weight of the underground portion found at the first block (block Ba, table 2 and 3). It has been observed that among the medium sized grasses the capim chorão (Eragrostis curvula Nees var. valida Stapf), capim de boi (Setaria poiretiana Kunth), capim Araguai (Paspalum fasdculatum Willd.) and capim de planta (Panicum purpurascens Raddi) and among the taller grasses the capim sempre-verde (Panicum maximum Jacq. var. gongylodes), capim elefante Merker, Napier and AxB (Pennisetum purpureum Schum.) as well as capim vetiver (Vetiveria zizanioides Nash), seem to be more promissing for holding the soil particles and more useful for soil conservation purposes.