Nitrogen and potassium interactions
Various investigations have reported that without adequate K supply, cassava does not respond to N fertilizers or it only responds poorly to N at very low rates of K application. These two major mineral nutrients interact with each other in cassava production, with N playing a dominant role in vegetative growth, including leaf development, and K being important in tuber initiation and bulking as described above. Optimal rates of N and P application were studied in a systematic trial in Colombia, where maximum yield was obtained by using 130 kg ha-1 N and 160 kg ha-1 K, indicating that relatively high rates of both these nutrients are essential to achieve high root yield for cassava (Howeler and Spain, 1978).