Effects of mineral fertilizers on the performances of selected vegetables grown in soils from different land use types in southwestern Nigeria

Abstract

Vegetables are rich in several mineral nutrients, vitamins, anti-oxidants and dietary fibre. However, poor soil fertility may limit their  production. Furthermore, their growth responses to external fertilizer input may be dependent on the type of soil on which they are  grown. An experiment was, therefore, conducted between March and July, 2021, at the Teaching and Research Farm, Ladoke Akintola  University of Technology, Ogbomoso, Oyo State, Nigeria, to determine the effects of nitrogen (For Amaranthus, Celosia and Corchorus)  and NPK (For Okra) fertilizers on the performances of the aforementioned vegetables grown in soils from three previous land use types.  The land use types, namely Arable field (S1), Cocoa plantation (S2), and Abandoned local soap production site (S3) were the main plot  treatments while 0 (control), 30 and 60 kg N/ha (For Amaranthus, Celosia and Corchorus); and 0 (control), 45 and 90 kg NPK/ha (For Okra)  formed the sub plot treatments arranged as 3 x 3 factorial in completely randomized design replicated three times. Data were  collected on leaf production, plant height, fresh shoot and fruit weights. The data were subjected to analysis of variance and where F was  significant; treatment means were separated using LSD at 5% probability level. Generally, soil from the cocoa plantation significantly  influenced the best vegetative growth, fresh shoot and fruit weights of the selected vegetables compared with the other two land use  types. Soil from the abandoned local soap production site had adverse effects on the performances of the selected vegetables. Irrespective of the land use types, application of mineral fertilizers enhanced the performances of the selected vegetables compared with  the control. However, the optimum rate of the fertilizer required to enhance performances of the vegetables was dependent on the  type of vegetable and land use type. Furthermore, for Amaranthus, 30 kg N/ha was sufficient to improve fresh shoot weight in land use  types S1 (29.43 g/plant, 274.4% higher than the control) and S3 (25.37 g/plant, 130.2% higher than the control); further increase in fresh  shoot weight at application of 60 kg N/ha was observed in land use type S2 (57.48 g/plant, 83.3% higher than the control). Vegetables should not be cultivated in abandoned local soap making sites while there is the need to select adaptable vegetables and appropriate  external nutrient levels in either arable fields or cocoa plantations for sustainable vegetable cultivation.