EFFECTS OF AMENDMENTS ON SOIL PROPERTIES, GROWTH, YIELD AND NUTRIENT COMPOSITION OF WHITE SEED MELON (CUCUMEROPSIS MANNII NAUDIN)

Abstract

Field experiments were conducted between 2018 and 2019 growing seasons at Kabba and Ile- Oluji, Kogi and Ondo States of Nigeria respectively. The experiments were to investigate direct and residual effects of plant residues alone or combined with NPK 15:15:15 fertilizer (NPKF) on soil properties, growth, yield and nutrient composition of white seed melon (Cucumeropsis mannii, Naudin.). The soil amendments treatments involved application of milled cocoa bean husk (CBH), cocoa pod husk (CPH), cocoa pod waste (CPW), kola pod husk (KPH), weed mulch (WM) and NPKF. Treatments involved a control (no treatment), 300 kg/ha NPKF, three cocoa plants residues, kola pod waste, weed much and ten combined application of plants residues with NPKF at different rates, given a total of seventeen treatments. The soils were low in OM, marginal in N, P and acidic. The application of 300 kg/ha NPKF improved soil pH, organic matter (OM), available P, exchangeable K, Ca, Mg, Na, H, Al, ECEC and bulk density but reduced the total porosity. The sole application of CPH, CPW and WM increased the number of leaves and the 6 t/ha CPH gave the highest number of leaves at Ile-Oluji and Kabba. The 200 kg/ha NPKF in combination with 4 t/ha plant residue had effect on leaf production than 100 kg/ha NPKF in combination with 4 t/ha plant residue while 100 kg/ha NPKF in combination with 4 t/ha residue was more effective than 2 t/ha residue combined with 200 and 100 kg/ha NPKF. Throughout the 28 weeks of observation, number of leaves was significantly increased by combined application of 2 or 4 t/ha residues with NPKF at 100 or 200 kg/ha. All the treatments increased number of branches. The 4 t/ha CBH + 200 kg/ha NPKF, 4 t/ha CBH + 200 kg/ha NPKF, 4 t/ha CPH + 200 kg/ha NPKF, 4 t/ha CPW + 200 kg/ha NPKF had highest value of branches at Kabba, All plants residues and NPKF significantly increased number of branches between 2 to 28 week after treatment application (WATA) at Kabba and Ile-Oluji. The 300 kg/ha NPKF most significantly increased leaf and vine length among seventeen (17) treatments. The plant residues alone or combined with NPKF also increased vine length significantly relative to control. Combinations of residues with fertilizer were superior to fertilizer alone with respect to crop nutrient contents. The CPW increased seed weight by 303 % at Kabba and 292 % at Ile-Oluji while NPKF and CPW increased number of seeds by 576 and 507 % respectively at Kabba. At Ile-Oluji, The increases were 567 and 553 % respectively. The use of sole and combined amendments ensured better soil physical and chemical properties compared to chemical fertilizer alone and the control. The combined approach ensured a more balanced soil nutrients status, increased organic matter and improved growth, yield and nutrient composition of white seed melon. It is recommended that 6 t/ha. CBH and CPW and 4 t/ha CBH in combination with 200 kg/ha NPK 15:15:15 Fertilizer be used as soil amendments for the production of white seed melon in the study area.