Nutrientes limitantes em pastagens nativas de Panicum zizanoides H.B.K. e Axonopus affinis em um Plintossolo da ilha de Marajó, Pará.

Abstract

The missing element technique was used to determine nutrient deficiencies of the native grasses taboquinha (Panicum zizanoides H. B. K.) and pancuã (Axonopus affinis) grown in greenhouse conditions on a plinthic soil of the Marajó island in 1996. The experimental design was a randomized experiment, with 13 treatments (complete: complete plus liming; control and others obtained by subtracting N, P, K, Ca, Mg, S, Cu, Zn, B, Mo from the complete formula) and three replicates for each grass. Fertilizers application increased (a < 0,01) the top and root production of the two grass species. P was the principal nutrient which limited top growth (a < 0.01) of all grasses, followed by N (a < 0.01) and K (a <0.05) to taboquinha and by K, Zn (a < 0.01) and S (a < 0.05) to pancuã. The omission of P decreased (a < 0.01) root growth of taboquinha and the omission of N increased (a < 0.01) root growth of pancuã. The relative growth of the grasses were in the order taboquinha > pancuã. These results showed that there is the possibility to increase growth and productivity of native grasslands of the Marajó island with soil management.