59 

 previous bulb onion and pole bean significantly contributed to higher 

 soil N. These results agree with Rao and Sharma (135) who reported 

 that soil N decreased at low fertilizer levels after each crop in six 

 cropping patterns, whereas soil N increased at high fertilizer levels. 



Soil potassium . A consistent increase in double -acid extractable 

 soil K was observed with successive cropping in HM-HM-HM but not with 

 the other three cropping patterns (Fig. ?) ■ For each cropping pattern, 

 high fertilizer levels increased soil K except the third crop in the 

 HM cropping pattern (Fig. 7)' However, residual soil K remained almost 

 constant with successive crops in all cropping patterns except the HM 

 cropping pattern (Fig. 7) . 



In general, residual K was higher than applied K for the LM 

 cropping pattern, whereas HM and MM vegetable crops required supplemen- 

 tal applications of about 40 to 80 kg/ha K. Results from this study 

 do not agree with Biswas et al. (14), and Rao and Sharma (135) who 

 reported that soil K remained low after two cycles and after harvest 

 of different crops at various fertilizer levels. 



Effects of Crop and Fertilizer Management Levels on Marketable Yields 



Cropping pattern HM-HM-HM . Marketable yield of bulb onion was 

 generally high because of eaxly planting date (Table lo). Onion ferti- 

 lized with the medium level of fertilizer (120 kg/ha N, and 160 kg/ha K) 

 yielded significantly higher than onion fertilized with low level 

 (Table lO). Application of a high fertilizer level resulted in no sig- 

 nificant yield increase (Table lo). Marketable yield of pole bean was 

 generally low because of late spring planting which subjected the crop 



