Applied phosphorus and potassium effects on yield of dallisgrass‐bermudagrass pastures¹

Mississippi Agriculture and Forestry Experiment Station. Journal Series No. J‐7027.

Abstract

There are substantial areas of dallisgrass (Paspalum dilatatum Poir.)‐common bermudagrass (Cynodon dactylon (L). Pers.) summer‐type pastures in the Southeastern Central Plain, but little information is available on their response to P and K fertilization. The purpose of this study was to measure the response of dallisgrass‐common bermudagrass pastures to P and K fertilization with and with‐ out N. Phosphorus and K were applied to two soils in May each year for three years. Yield data were collected by clipping a swath through the length of the plots when the minimum forage height was approximately 30 cm. Responses to P and K applications were obtained when the soil test levels were low to very low, but not when they were medium as determined by the Mississippi Soil Test (MST). Forage P concentration of the control in the medium P and K soil was within the adequate range of 2.8 to 3.4 g/kg, but forage K concentration was below the critical range of 16 to 18 g/kg. Forage P and K concentrations of the controls in the low P and K soil were below critical levels. At both locations forage P and K concentrations were increased by P and K fertilization. Available soil P increased with rate of P application but soil extractable K was unaffected by K application. No yield response to P and K are likely at medium soil test levels (MST) even at high rates of N. There was no response to P and K application without N.

Notes

Mississippi Agriculture and Forestry Experiment Station. Journal Series No. J‐7027.