13 



During winter, a single crop such as sweet potato or edible-podded pea 

 ( Pi sum sativam L. Macrocarpon Group) and many green leafy vegetables 

 can be relay interplanted before rice harvest to increase total 

 production id.thin the 100-day period (I69) . 



In North Florida, relay interplanting of sweet potato and pigeon 

 pea in corn did not reduce com grain yield (3). Higher yields of sweet 

 potato and pigeon pea were obtained with early maturing corn at low 

 populations than at high populations. 



Relay intercropping vegetable crops has some limitations because 

 of management constraints. For instance, the Taiwan method of planting 

 sweet potato into puddled rice imposed difficulty in seedbed preparation 

 particularly in fine textured soils (^7) . This method is also expensive 

 since construction of ridges takes 400 to 500 hours/ha. Managemenx. of 

 these ridges is extremely difficult in terms of vreed control (4?), 



Soil and Fertilizer Management in Vegetable Cropping Systems 

 Soil and fertilizer management studies in vegetable multiple 

 cropping systems are limited. As fertilizer costs increase every year 

 because of high energy cost for their production, many researchers are 

 finding methods to reduce fertilizer use or to increase efficiency 

 (122, 123, 143). Oesligle et al. (122) stated that high analysis ferti- 

 lizers, if available at any price, frequently constitute a direct input 

 cost that is beyond the means of the marginal farmer. High fertilizer 

 prices in developing countries imply that this input be used efficiently. 

 Thus, consideration of the economics of management practices simul- 

 taneously with their biological potential is Lmportant when developing 



