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returns but also on farmer's motives, studies should emphasize improve- 

 ment of farmer's traditional cropping systems before recommending alter- 

 native cropping patterns. Cropping systems of small-scale farmers are 

 usually characterized by diversity, stability, and low productivity 

 (70). To improve income, productivity should be increased without 

 sacrificing diversity and stability. 



Improving crop management practices attempts to increase productiv- 

 ity. Researchers develop improved production technologies for each 

 stage of crop production from tillage to harvesting by varying levels 

 of production inputs or introducing a new techjiique. These studies 

 generally focus on one crop vrLth yield majcimization as the main objective, 

 but exclude economic considerations (16, 2^). For some crops, a signi- 

 ficant increase in agronomic yield may not be economically acceptable 

 to farmers (24) . Although economic evaluation of different crop manage- 

 ment practices is common, similar studies for year-round cropping 

 patterns are limited. Most studies compare costs and returns from 

 various types of cropping patterns using standard cultural practices 

 which are in some situations higher than the farmer's management level 

 (25, 85). For example, in Chiang Mai , Thailand, Calkins (25) reported 

 that the cropping pattern peanut-tomato-rice had higher economic potential 

 than tomato-mungbean-rice because a heat-tolerant tomato cultivar was 

 planted in the first pattern resulting in yields with high market price. 

 In the Philippines, the cropping pattern rice-watermelon was the most 

 profitable, whereas the cropping patterns rice-mungbean auid rice-sweet 

 potato resulted in equal net returns as the rice-rice or rice-sorghum 

 (127). Economic evaluation of the cropping pattern rice-sweet potato 

 using three power sources was studied by Banta (9). Costs and returns 



