Influence of Poultry Manure Rates and Spacing on Growth, Yield, Nutrient Concentration , Uptake and Proximate Composition of Onion (Allium cepa L.)

Plant spacing determines to a greater extent crop performance in terms of growth and yield. The production of crop with organic fertilizer also plays a vital role in organic agriculture. Field studies were conducted to evaluate the effects of spacing and poultry manure on the growth, yield and quality of onion. Three spacing regimes were carried out consisting of (15cm x 15 cm , 20 cm x 20 cm and 25 cm x 25 cm) and four levels of poultry manure at ( 0, 5, 10 and 15 t /ha ). The effects of spacing and poultry manure were evaluated for 2 years based on plant growth, yield, nutrient concentration, uptake and proximate composition of onion plant. Leaf thickness, bulb and shoot fresh weights were significantly increased by the wider spacing of 20 cm x 20 cm and 25 cm x 25 cm, compared with the narrower spacing of 15cm x 15 cm in both seasons. However, highest total dry yield (1.82 and 1.58) t /ha, shoot yield (2.31 and 1.32) t /ha and total fresh yield (13.69 and 12.55) t/ha were obtained with the spacing of 20cm x 20 cm in both years. Similarly, application of poultry manure increased leaf thickness, bulb and shoot fresh weights and yields compared with the control. Generally, using 10 t/ha poultry manure has a superior effect on proximate composition and most of growth parameters and yield components achieved the highest nutrient concentrations and uptake on most of the macro and micronutrients in leaves and bulbs as compared with the control in both years

COMPARISON OF YIELD PERFORMANCE AND PROFITABILITY OF Dioscorea rotundata UNDER DIFFERENT NPK FERTILIZER REGIME IN HUMID FOREST ULTISOLS

Studies were conducted to determine the appropriate level of NPK 15:15:15 fertilizer application that will produce the most profitable yield in a humid forest ultisol. This study involved the use of Dioscorea rotundata Poir fertilized with NPK (15:15:15) at rates of 0 (0 kg N + 0 kg P + 0 kg K), 100 (15 kg + 6.79 kg P + 12.45 kg K), 200 (30 kg N + 13.58 kg P + 24.90 kg K), 300 (45 kg N + 20.37 kg P + 37.35 kg K) and 400 kg ha-1 (60 kg N + 27.16 kg P + 49.80kg K) using a randomized complete block design. Results from the trial showed that leaf area index values ranged from 1.24 to 2.88 at 16 weeks after planting (WAP) and 2.20 to 3.10 at 24 WAP respectively for the unfertilized and 400 kg NPK ha-1. The corresponding values for dry matter accumulation were 1.29 to 3.70 t ha-1 and 2.97 to 5.67 t ha-1 at 16 and 24 WAP respectively. These parameters were responsible for higher tuber yield and relative yields for plants fertilized. The greatest yield (19.16 tonnes hectare) was produced from plots treated with 300kg ha‑1 fertilizer. The production cost increased from  N 390440.00 - N 417920.00, revenue from N 1036000 - N 1155000.00, gross margin from N 680000.00 - N 773200.00, net income from N 645560.00 - N 732080.00 and benefit-cost ratio from 1.65 - 3.73 as fertilizer application rate increased from zero to 400 t/ha. The optimum fertilizer application rate was 200kg ha-1 based on the fact that it had the greatest gross margin (N 1547600.00), net income (N 1507720.00) and benefit-cost ratio (3.73)