22 



intercropped with mango, lower levels of fertilizer application reduce 

 input costs without significant yield loss (24) . 



Some Taiwan farmers plant sweet potato stem cuttings near rice 

 stubble with no tj.llage and minimum input requirement. Others use 

 complete tillage before planting or intercropping with corn and edible 

 sugarcane. The tillage method requires higher inputs, whereas the inter- 

 crop method involves the least inputs. Survey data showed that yields 

 were increased with increased net returns, but the correlation value 

 between yield and net return was low with tillage method suggesting 

 that added costs did not result in higher yields (24) . There was no 

 significant relationship between capital inputs notably fertilizer and 

 yield. Farmers may be applying excessive capital inputs to sweet 

 potato but returns to fertilizer and material costs were lower than 

 returns from tomato. The highest net return and farm return were not 

 associated with high yield but with low cost (24) . Although the inter- 

 crop method produced intermediate yields, production costs were lowest, 

 and therefore, farm returns, net retiom, and rsvenue-cost ratio were 

 highest (24) . 



Charreau (2S) reported that improved cropping patterns consisting 

 of high tillage and fertilizer levels were more profitable in the central. 

 zone of West Africa where rainfall was higher than in the northern zone. 

 This was a situation where potential of improved technology to increase 

 productivity and profitability was limited by climatic factors. 



The goal of most cropping systems research has been to improve 

 productivity and income among small farms (8, 31, 69, 70, 118, 1??) . 

 Since adoption of cropping patterns not only depends on economic 



