Effect of Frequency of Application on Response of Guinea Grass to Nitrogen Fertilization

Abstract

The effect of frequency of application on the response of Guinea grass to nitrogen fertilization with cutting and simulated grazing management was studied in the humid coastal region of Puerto Rico. Guinea grass responded strongly in yield and protein content to nitrogen applications up to 800 pounds per acre yearly, regardless of frequency of application or harvest procedure. When cut every 60 days, Guinea grass produced its highest yields and recovered more of the fertilizer nitrogen when it was applied immediately after cutting. Its lowest yields occurred when nitrogen was applied 25 days after cutting. Splitting the applications resulted in yields intermediate between these two. Under grazing management annual yields and protein content of the forage were similar whether the nitrogen was used in eight, four, or two applications yearly. However, seasonal yields and protein and potassium content of the forage varied more widely when there were two applications only of fertilizer yearly. It appears best to apply nitrogen to Guinea grass immediately after each cutting and to make about four applications a year to Guinea grass pastures.