Maintenance fertility levels for vegetable crops on heavily fertilized Tennessee soils

Tomatoes (Lycopersicon esculentum Mill), cabbage (Brassica oleracea var. capitata L.), and lima beans (Phaseolus limensis L.) were grown for three years (1975-77) with seven fertilizer treatments at the Main Experiment Station, Knoxville, and at the West Tennessee Experiment Station, Jackson, to determine maintenance levels of N, P, and K for these crops. Tomatoes, cabbage, and snap beans (Phaseolus vulgaris L.) were tested with the same treatments at the Plateau Experiment Station, Crossville (1975-77). Soil samples were collected each year at each location; tissue samples were collected from each crop each year at Knoxville. Annual application rates of 30 kg P/ha and 56 kg K/ha were sufficient for maintaining maximum yields of tomatoes, cabbage, and lima beans for three years at Knoxville and Jackson (also snap beans at Crossville). Nitrogen applications of 67 kg/ha were sufficient for maintaining maximum tomato yields; cabbage showed a positive yield response to the highest N treatment (134 kg/ha) for two years at Knoxville and Crossville. Withholding P and K applications did not cause significant reductions in total marketable tomato yields at any location. Maximum or near maximum cabbage yields were maintained for three years at Knoxville without P and K applications. Lima yields were not reduced when P and K applications were withheld for two years at Knoxville and Jackson. Snap beans showed little response to N and no response to P and K applications. Soil test results from Knoxville and Jackson indicated that annual applications of 30 kg P/ha and 56 kg K/ha maintained high soil P and K levels for three years under these cropping conditions. There was a net accumulation of soil P at Knoxville (60 kg p/ha treatment). Soil K levels appeared to decline more rapidly than soil P levels when P and K applications were withheld. In some years, tissue ammonium-N and K concentrations were higher in samples from plots which received the higher N and K treatments. Phosphorus concentrations in tissue samples appeared to be unaffected by P application rates.