The integrated effect of DAP fertilizers and rhizobium inoculation on the growth and yield of common beans (Phaselous vulgaris l.)
Abstract
Agricultural production in Uganda is a key factor in the contribution of Uganda’s economy and also an important source of dietary protein for most households. For a balanced diet to be attained, common beans as plant proteins contributes largely to the countries proteins source. Production of beans in Uganda is still below the potential productivity level and this is mainly as a result of nutrient deficiency most especially phosphorus and nitrogen in many soils of Uganda and also as a result of inefficient rhizobial inoculation hence poor N2-fixing capacities of beans. To meet the high demand for protein, improvement in bean production plays an important role in providing the required protein through Phosphorous fertilization as diammonium phosphate (DAP, 46 % P2O5, 18 % N) and rhizobium inoculation. Field experiment was conducted in Bulima village, Bwijanga Sub County, Masindi district located in the mid-western part of Uganda to examine the combined effect of DAP fertilizers and rhizobium inoculation on the growth and yield of common beans (Phaseolus vulgaris L). Composite soil samples were collected from the identified field and taken to determine the soil physical and chemical properties. The study was conducted as randomized complete block design replicated thrice in which each experiment unit measured 1m × 1m and each block made of 10 experimental units. There were ten treatments applied that included, control, rhizobium treatment only, DAP fertilizer at rates 25 kgha-1, 50 kg ha-1, 75 kg ha-1, 100 kg ha-1 and combined treatment of rhizobium and DAP fertilizer at rates 25 kg ha-1, 50 kg ha-1, 75 kg ha- 1, 100 kg ha-1. The Phosphorus fertilizers were incorporated into the soil just before planting and the plant spacing used was 25 cm×20 cm giving a total population of 200,000 plant ha-1. Data on the number of leaves per plant, number of branches per plant, plant height, leaf area index, number of pods per plant, number of seeds per plant and weight of seeds per plant were collected at intervals of days after planting (14, 28, 42, 56 and 70 days). The processed data was subjected to Genstat software, 20th Edition for analysis of variation. The treatments indicated a significant influence (p ≤ 0.05) on growth and yield of beans with exception of the control. The maximum growth and yield was attained when treated with rhizobium + DAP fertilizers at a rate of 75 kg ha-1 and the lowest yield was experienced under the control treated experimental unit. Application of DAP fertilizers combined with rhizobium inoculation increased growth and yield of beans as compared to other treatments.