Fertilisers are used to replace nutrients lost from the soil profile. The suitability of a fertiliser to maximise yield for a particular soil and crop combination is governed by its proportion of nutrients. Plants contain 100 or more natural chemical elements, less than 20 of these elements are essential for plant growth. If a grower used 100 kg of urea per hectare they would be applying 46 kg of nitrogen to the crop. If a grower used 100 kg of superphosphate per hectare they would be applying 9 kg of phosphorus and 11 kg of sulphur to the crop.
Many growers use fowl manure to provide nutrients to their crops.
Too much fowl manure added could lead to an excessive amount of phosphorus and potassium in the soil. Applying fertilisers with the wrong nutrient ratio or applying the wrong amount of fertiliser will cost the grower money and sometimes damage crops. Selecting a fertiliser with the right nutrient ratio for your soil and crop is best determined from reliable soil sampling and soil analysis programs which should be carried out well before planting. Contact your local agriculture department for further information. Flowers are yellow, 6-8 cm in diameter.