15 

 Jones (91) reported that when corn followed cotton ( Gossypi^oji hirsutum L.), 

 the response ^o N vias maximum at 8^ kg/ha, whereas com following sorghum, 

 peanut ( Arachis hypogaea L.). and cowpea required 168 kg/ha to achieve 

 maximum yield. Experiments in Sudan Gezira (22) have shown that sorghum 

 and wheat (Triticum aestivum L.) were responsive to fertilizer N and 

 were affected by residual N, whereas hyacinth bean ( Polichos lablab L.) 

 did not respond to residual N but yield consistently increased by increas- 

 ing residual F, 



Residual N from previous crops had a greater influence on tomato 

 yield than fertilizer applied specifically to the tomato crop (123,! ■ 

 For example, Osterli and I'leyer (123> found that tomato yields responded 

 favorably to 33^ kg/na N applied to the previous sugar beet ( Beta 

 vulgaris L.). When additional N was applied directly to tomato there 

 T.'as no significant increase in fruit 3i::e and quality, 



Hayami (72) stated that optimum elemental concentrations for 

 most vegetable crops axe about 5 '^c IC times ti^ose required for rice. 

 Under lowland paddled soil conditions in tropical Asia, Hayami (72) found 

 that frjiting vegetables such as tomato and cucumbers accumulated 

 nitrate N preferentially from the initial grovrth stage. Since this 

 fonn of M vouli be found only before the soil is puddled, growers can 

 benefit if they plant tomato and cucumber before rice. However, with 

 proper soil, fertilizer, and water management, growers may also benefit 

 by growing these vegetables after rice. Leafy and heading cabbages 

 absorb ammonium N and required an increasing amount thjroughout the 

 growing period. These crops are suited for production in post rice 

 soils (72). 



