Tifton 85 grass responses to different nitrogen levels and cutting intervals

Abstract

The objective of this study was to evaluate the influence of five levels of N and two regrowth intervals on the structural, productive, and nutritional characteristics of Tifton 85 grass (Cynodon spp). The experiment was conducted in a hay production field at the State University of West Paraná, planted in 2004 with Cynodon spp. cv. Tifton 85. The experiment was established in a randomized block design with factorial treatments of five N fertilization amounts (0, 25, 50, 75 and 100 kg ha-1 cut-1) applied as urea after each cut, and two regrowth intervals (28 and 35 d), with four replicates. N application promoted changes in plant structure, such as increased canopy height, stem length, leaf elongation rate, and dry mass (DM) production. The greatest N use efficiency, considering the four harvests, occurred in the plot with 25 kg N ha-1 cut-1 at the 35-d interval, with a production of 13.79 kg DM kg-1 of N applied. A nutritional analysis indicated that 100 kg ha-1 of N cut-1 promoted higher crude protein (CP) at 28 d, with the highest concentration observed in the fourth cut (208.2 g kg-1 DM) and the lowest in the second cut (140.12 g kg-1 DM). The content average in the four cuts for CP and LIG at 28 days of regrowth was 175.85 and 104.33 kg-1 g MS and at 35 days of regrowth interval was of 164.45 and 118.65 g kg-1 DM, respectively. No differences were found between regrowth intervals in the contents of mineral matter and acid detergent fiber (ADF). Environmental factors including the wide variation in precipitation (greater than 200 mm between the peak in December 2010 and the lowest in March 2011) greatly influenced Tifton 85 grass production, affecting DM and the nutritional value of the forage in each cut.