16 



In Florida, iiigh riianagement vegetable crops such as tomato and 

 pepper ( Capsicum annuum L. ) are double cropped with either low or hi^ 

 management vegetables and field crops (Zl, 33? ^3< 52, 35, 93 )• The 

 objective is to utilize applied fertilizer more efficiently and increase 

 productivity by eliminating added costs. Kretschmer et al. (95) suggested 

 that field corn is a good crop to follow fall tomato and other heavily 

 fertilized vegetable crops on sandy soils in Florida. Wheni corn was 

 planted following these crops, additional applications of P, K, and 

 micronutrients, were net necessary. Yields of carrot ( Paucus carota L.), 

 green onion, lettuce, and radish were significantly higher in plots 

 where no additional fertilizers were applied than in plots applied with 

 fertilizers after a fall tomato (33)- The low yield of vegetables in 

 the fertilized plots was the result of high total soluble salts that 

 inhibited germination and reduced seedling sur'/ival. 



As cropping intensity increases, high levels of added cnemical 

 fertilizers may cause rapid shifts in soil properties sucii as pH (12, 

 5Z, 35. 98, 135, ^^O), total soluble salts (3^, 53, 73, 103, 161), 

 organic matter (l, 2, 10, ?!, 98, 111, 11^, 1^7, Ifl, 166). H (33, 39, 

 135. 1^2, 146), ? (139, 141), and K (14, I35, I37) . Consequently, 

 shifts in soil properx-ies may create a soil environment that caJi 

 restrict crop grovrch ajid limit cropping potential of soils. For 

 example, shifts in pK may result in excesses and deficiencies of both 

 micro and macronutrients (85). 



.'^ji example of the effect of intensive sequential cropping on 

 soil properties was studied by Nair et al. (114). Rice, wheat, and 

 mungbean or potato were grown sequentially per year. In spite of high 



