Adubação nitrogenada de capim-braquiária sob sombreamento

Abstract

This study aimed to evaluate the effect of nitrogen on morphogenetic, structural and productive characteristics of Brachiaria grass under shading. The experiment was conducted at Experimental Farm of Agricultural Research Company of Minas Gerais (EPAMIG), located in the municipality of Felixlândia, center west of Minas Gerais. The experimental design was in randomized blocks with five treatments (100, 200, 300 and 400 kg ha-1 ) and four blocks. There was no significant effect (P>0.05) of N levels in leaf appearance rate, number of green leaves per tiller and culm length. For the production of green matter, nitrogen fertilization provided increase of 41.77; 37.35; 94.23 and 10.,98 %, respectively for 100, 200, 300, and 400 kg N ha-1 , with an increase of 22 kg of green matter for each unit of N applied. With the use of fertilizer it was produced 1.19 ton of dry matter more than the control. Nitrogen fertilization provided lower ratios of leaf blade : stem compared to the control. Linear decrease (P<0.05) of 0.0005 units per kg of N supplied was observed. Regarding the crude protein content, the highest averages were observed at doses of 300 and 400 kg N ha-1 . For each kg of N applied, there was an increase of 0.006 % in the crude protein content. The nitrogen fertilization did not affect the neutral detergent fiber (P>0.05) in relation to the control, observing an average of 61.38 %. As for the contents of acid detergent fiber, it was found that for every unit of N applied there was a reduction of 0,008 percentage units of ADF. Based on these results, the doses of up to 400 kg N ha-1 are recommended.