Response of Guinea, Pangola, and Coastal Bermuda Grasses To Different Nitrogen Fertilization Levels Under Irrigation in The Lajas Valley of Puerto Rico

Abstract

An experiment was established at the Lajas Substation to measure the response of Guinea, which is the prevailing grass of the Valley, Pangola, and Coastal Bermuda grasses to fertilization with nitrogen at the levels of 200, 400, 800, and 1,200 pounds of nitrogen in six equal applications per year for two consecutive years under irrigation. A split-plot design was followed with four replications, grasses being tested in the large plots and nitrogen in the subplots. The grasses were cut every 60 days and the following classes of data were taken for comparisons: 1, Yields of green and dry matter per acre per year; 2, hay yields per acre, using an all-crop dryer and adjusting yields to 20- percent moisture for uniformity; 3, gross-energy values as affected by treatment; 4, percentage of protein and total protein per acre as affected by treatment; 5, leaf-to-stem ratio; 6, observations on palatability of the hays produced; 7, other observations. Generally speaking, and with few exceptions, highly significant differences were found in yield per acre of green forage, dry matter, hay, and total protein for all three grasses between the high and lower nitrogen treatments. No differences were found between the two high-nitrogen treatments. Seasonal variation was measured. There was an increase in yield for the three grasses, starting in April with a peak in September, and a reduction starting in late October with the lowest yield in January no matter how much water and fertilizer was applied. Tentative recommendations are made. Further work is being carried on, however.