Proximate and Mineral Composition of Celosia argentea (L.) Leaves as Influenced by Fertiliser Application

Celosia argentea (L.) is an important indigenous leafy vegetable widely consumed in Nigeria and                valued for its protein, fibre, vitamins and mineral nutrients. However, its nutritional composition can be influenced by soil fertility, fertiliser source and nutrient availability, while limited information exists on how different fertiliser types affect the proximate and mineral composition of the crop under the environmental conditions of Igboora, Oyo State. This study therefore evaluated the effects of NPK fertiliser, single superphosphate (SSP), biochar and compost on the proximate and mineral composition of Celosia argentea leaves. The experiment was conducted at the Teaching and Research Farm of Oyo State College of Agriculture and Technology, Igboora, while laboratory analyses were carried out at the institution’s Central Laboratory. Five treatments comprising NPK (10 g), SSP (10 g), biochar (100 g), compost (200 g) and an unfertilised control were evaluated. Mature leaves were harvested and analysed for moisture, crude protein, crude fat, crude fibre, ash, carbohydrate and selected minerals including nitrogen, phosphorus, potassium, calcium, magnesium, iron and zinc. Data obtained were subjected to analysis of variance, and treatment means were separated using the Least Significant Difference (LSD). Fertiliser application improved most of the measured nutritional parameters compared with the control. Compost recorded the highest crude protein (27.70%), crude fat (3.52%), moisture (84.90%), ash (14.80%), nitrogen (4.53%), phosphorus (0.68%), potassium (3.54%), calcium (2.06%), magnesium (0.83%) and zinc (6.88 mg/100 g). Biochar recorded the highest crude fibre (12.00%) and iron (26.53 mg/100 g), while carbohydrate was highest in the control (53.58%). The study concludes that fertiliser application, particularly compost and biochar, can enhance the nutritional quality of Celosia argentea leaves under the study conditions. Compost at 200 g produced the most favourable overall proximate and mineral composition and is therefore recommended as a suitable amendment for improving the nutritional quality of Celosia argentea in Igboora and similar production environments.