770-4 Bermudagrass Yield and Mehlich-3 Phosphorus Response to Phosphorus Fertilization.

See more from this Division: S08 Nutrient Management & Soil & Plant Analysis
See more from this Session: Measurement and Management of Soil Potassium and Phosphorus Availability

Wednesday, 8 October 2008: 2:00 PM
George R. Brown Convention Center, 371A

Nathan Slaton1, Russell DeLong2, Colin Massey2, Bobby Golden2 and Elliot Maschmann2, (1)Crop, Soil, and Environmental Sciences Department, Univ. of Arkansas, Fayetteville, AR
(2)Crop, Soil, and Environmental Sciences Department, University of Arkansas, Fayetteville, AR
Abstract:
The agronomic need for P fertilization of bermudagrass grown for forage has been overshadowed by environmental concerns. Our research objective was to evaluate the effect of P-fertilizer rate on bermudagrass yield, P uptake, and Mehlich-3 soil P across time. Triple superphosphorus was applied annually (2006 and 2007) at rates of 0, 22, 44, 66, 88, and 110 kg P ha-1 to a Captina soil cropped to common bermudagrass. Forage was harvested three or four times annually. The initial Mehlich-3 extractable P (0-10 cm) was 116 mg P kg-1. Individual harvest and season total yields always differed between years, but only third harvest yields were affected by P rate, averaged across years. Compared to the unfertilized control, application of >22 kg P ha-1 yr-1 increased third harvest yield by 13-22%. Harvested forage P removal increased linearly from 2.49 to 2.92 kg P Mg-1 forage as P rate increased from 0 to 110 kg P ha-1 yr-1 and average P content was greater in 2006 than in 2007 (2.60 vs 2.84 kg P Mg-1). The 2-yr net balance between P removal by harvested forage and P-fertilizer additions was negative for P rates <66 kg P ha-1 yr-1 and positive for greater P rates. After 2-years of fertilization and cropping, Mehlich-3 P decreased for P rates <44 kg P ha-1 yr-1, was unchanged for 44 and 66 kg P ha-1 yr-1, and increased for P rates >66 kg P ha-1 yr-1. Overall, the cummulative net balance showed that Mehlich-3 P changed by ±1 mg P kg-1 per ±2 kg P ha-1. Results indicate that managing forage for moderate to high yield on soil with slightly above optimum soil P (>50 mg P kg-1) can slowly reduce Mehlich-3 P across time and late-season forage yields on such soils may respond positively, albeit nominally, to P fertilization.

See more from this Division: S08 Nutrient Management & Soil & Plant Analysis
See more from this Session: Measurement and Management of Soil Potassium and Phosphorus Availability