Bahiagrass Response to N, K, and Langbeinite Fertilization of Different Soils.

Bahiagrass (Paspalum notatum Flügge) is a popular warm-season subtropical perennial grass grown in the southern U.S.A.  Since it can survive neglect, balanced fertilization practices are often substituted with no fertilization, or single to multiple nitrogen (N) only applications, particularly during economically challenging times.  There are few reports on the effect of other nutrient elements alone or in combination, on multi-year bahiagrass production. Langbeinite (KMag or sulpomag) is a water-soluble natural mineral mined in New Mexico, U.S.A. It provides an analysis of 0-0-22-22-11 (N-P-K-S-Mg), and is used in certified organic, as well as conventional agriculture.  Due to its high solubility, it is an attractive choice for studying potassium (K), sulfur (S) and magnesium (Mg) forage uptake and plant-soil nutrient interactions in situ. The objectives of this 3-year study were to field-test, using three different soils (a Typic Quartzipsamment, an Aeric Alaquod, and a Rhodic Kandiudult), and bahiagrass fertilization without K, with K (KCl), or with K+S+Mg (KCl plus langbeinite) at two application rates, 54 or 27 kg K/ha/Mt dry yield each cutting, with or without 25% of K supplied as langbeinite.  Bahiagrass yield had a strong linear correlation with N uptake, regardless of fertilizer treatment, soil type or sampling period.  Bahiagrass appeared to benefit from K and S fertilization by the third year of the study for the Quartzipsamment and Kandiudult soils, but not with the Alaquod soil. The Quartzipsamment soil was typically K deficient even with the high K fertilization rate. Soil K applications suppressed Mg uptake to some extent, at all locations. The economics of fertilizing for bahiagrass on these different soils will be discussed.