Physio-chemical characteristics of sawdust as a growth medium in hydroponics

Sawdust has been considered a cultural medium for agricultural production, but in practice, its characteristics should be considered for economic reasons. The quest for the utilization of different particle sizes of sawdust as a growth medium in place of regular soil leads to this research. The main objective of this study was to determine the hydro-physical characteristics of different particle sizes of sawdust and to contribute scientific knowledge on the utilization of sawdust as a growing medium in hydroponics. Samples of sawdust were randomly obtained from a sawmill in Omu Aran locality. Omu Aran is the closest area in Kwara State to the rainforest and the derived savanna in the North Central (middle belt) of Nigeria and, hence forming the zone with the highest rainfall in the State. The samples were air-dried at room temperature and sized by sieving using 0.425 mm and 1.70 mm sieve sizes for the purpose of determine the hydro-physical and chemical characteristics of the different particle sizes and the composite sawdust. The specimens were labeled, F/ fine (particle sizes ˂ 0.425 mm), M/ medium (particle sizes ranging from 0.425 - 1.700 mm) and C/ coarse ˃1.700 mm (the composite sawdust/ whole feed-stock) to analyze some of the hydro-physical and chemical properties, which include bulk density, particle density, porosity, moisture content, water retention, pH, EC, total nitrogen, carbon content, and other ionic compositions of the samples. The data obtained were subjected to one-way analysis of variance, at 5% level of significance using Tukey’s method of comparison. The mean values of the moisture contents and porosity at the different particle sizes of sawdust fine, medium and coarse were 42.46, 36.14, 39.17 for moisture content, and 29.76, 26.53, 28.06 for the porosity, respectively. The differences in the means obtained were statistically insignificant (P > 0.05). The unique hydro-physical properties such as aeration, drainage and water retention capacity that these particle sizes of sawdust possess will contribute to improved crop yield in soilless culture.