PRODUCTIVITY AND QUALITY OF TROPICAL GRASSES UNDER NITROGEN APPLICATION AT THE END OF THE RAINY-SEASON

The present study was carried out at the Department of Animal Husbandr y of the Escola Superior de Agricultura de Lavras, Minas Gerais State, Brazil, in a Dark-Red Latosol. The experiment started on February 1, 1991 and was accomplished on May 29, 1991. The objective was to evalua te the dry matter yield, crude protein yield and fibre (neutral deterg ente) content in transvala grass (Digitaria decumbens Stent cv. Transv ala), swazi grass (Digitaria swazilandensis Stent) and coast-cross (Cy nodon dactylon L. Pers. Cv. Coastal x C. nlemfuensis Vanderyst var. ro bustus) under four different levels of N application (0, 100, 200 and 400 kg/ha N as ammonium sulphate). The N fertilizer increased dry matt er production, crude protein and fibre of the grasses although the con centration of fibre was more affected by the time of harvest than by t he N level. For all parameters studied, application of 100 kg/ha N sho wed the highest utilization efficiency and apparent recovery of the ap plied N. Coast-cross also proved to be the best grass concerning dry m atter, protein yield and fibre and in response to N applied, while swa zi grass was slightly superior than transvala-grass.