EVALUATION AND EXPERIMENTAL DEVELOPMENT OF A DRIP TAPE IRRIGATION SYSTEM FOR TAIWAN GRASS Pennisetum purpureum Schum

Abstract

A drip tape irrigation system for Taiwan grass (Pennisetum purpureum Schum) was evaluated, in order to know the efficiency of its operation; besides, the response of this grass to four nitrogen fertilizer levels (100, 350, 600 and 850 kg ha-1 year-1) and four soil moisture tensions (0.30, 1.32, 2.33 and 3.34 bar) in the irrigation water, were tested, in order to recommend practices which improve the system operation. This study was conducted at El Principio ranch, Medellín, Veracruz State, from October 1995 to March 1996. Seven treatments were defined by the San Cristóbal matrix with two factors in a randomized block design with four replications. Response variables were root density and biomass produced by Taiwan grass. The irrigation system showed low efficiency operation because a uniformity coefficient of 50 % was obtained in the most critical case; this coefficient improved by 33.5 % when changes were made after checking the original design of the hydraulic system. Root density varied with an inverse relationship to the nitrogen fertilizer dose, without a significant effect of soil moisture tension. The results for biomass defined optimal economic levels of 587 kg ha-1 year-1 of nitrogen fertilizer, and 0.64 bar for soil moisture tension. These levels may be recommended since they may improve the economic productivity of Taiwan grass.