Coastal bermudagrass and Renner lovegrass fertilization responses in a subtropical climate

Abstract

Forage production in subtropical regions usually requires fertilization to meet plant nutrient needs. This study was conducted to determine the influence of N and P application on yield response, nutrient uptake, and apparent fertilizer and water use efficiency of 2 grasses on a subtropical coastal prairie. Treatments consisting of factoral combinations of 0, 112, and 224 kg N/ha and 0, 15, and 29 kg P/ha were annually applied to coastal bermudagrass (Cynodon dactylon (L.) Pers.) and Renner lovegrass (Eragrostis curvula (Schard.) Ness) on a Sarita fine sand (grossarenic paleustalf) in South Texas. Cuttings were made 2 to 4 times per year for 4 years. Soil samples taken annually and plant samples from each cutting were analyzed for N and P concentration. Forage yields by both grasses improved dramatically with N application, but to a much lesser degree with P application. While yields were also strongly dependent on rainfall level, N substantially improved forage yield per unit of rainfall received. Forage concentration of both N and P increased with increasing application rates of each nutrient. Apparent fertilizer recovery fluctuated between years, reflecting stand age and rainfall; however, fertilizer rate had no effect. None of the fertilizer N not removed in the forage could be found as inorganic N at the 0 to .3-m soil depth, while up to 20% of the P applied remained available in the soil. Between 65 and 80% of the fertilizer applied was not used by the forage grasses. Improvements in forage yield and quality with N and P fertilization justify their use, even though inefficiency of fertilizer recovery and use is substantial.