
Urea is very high nitrogen, which will promote vegetative growth but not flowering. It's best to use a complete organic fertilizer that has a balance of all essential plant nutrients,with plenty of Phosphorus. In the US I'd use a product of 5-7-2 with the following ingredients:
Nutrient-rich Cottonseed Meal, Wild-caught Alaskan Fish Bone Meal, Wild-caught Alaskan Fish Meal, Valley Grown Alfalfa Meal, Cold Water Kelp Meal, Naturally Mined Potassium Sulfate, Mined and Micro-nutrient dense Colloidal Soft Rock Phosphate, Micro-active Micro-nutrient-rich Seaweed Extract.
Here in Thailand I make my own blend with bat guano, bone meal, sulfate of potash, magnesium sulfate and other ingredients for primary, secondary and trace mineral nutrients.
I'm sorry I don't know what is available in Zambia. Check with a local garden center or online sources like Amazon.com or whichever source will deliver to your area.
EM or compost tea is a good addition to your soil fertility program, but will not furnish complete nutrition by itself.
Can you get hydrolysed fish fertilizer and kelp meal?