Effects of Zeolite and Manures Applications on Biological Properties of Light and Heavy Soils in Greenhouse Maize Culture

The objective of this study was to evaluate the effect of addition of natural zeolite and manures applications on some soil microbial population and activities in greenhouse maize culture. Two experiments were conducted, in two types of loamy sand and clay soils separately. Each experiment was conducted under a complete randomized factorial design in three replicates. The studied factors were zeolite (at three levels of 0%, 10% and 20% of zeolite), manures at a rate of 20 g/kg soil on dry weight basis (at three levels including no manure, poultry manure and cow manure) and soil sampling zone at two levels including rhizosphere and nonrhizosphere. The modified thin-slicing technique was used for soil sampling from rhizosphere zone. At the flowering stage of maize growth, soil was sampled from the rhizosphere and nonrhizosphere zone for some biological analyses. The result were revealed that the addition of zeolite and manures to both of the loamy sand and clay soils, changed the soil biological properties markedly, in which populations of the bacteria and actinomycetes and substrate induced respiration were significantly increased in the all treatments. However, the population of fungi was not significantly changed in the zeolite treated soils. The addition of zeolite increased the basal respiration, glumerales spore numbers, biomass carbon and biomass phosphorus in the loamy sand soil significantly but they were not increased in clay soil in the same treatments statistically. Therefore, the application of zeolite and manures in the loamy sand soil compared to clay soil caused marked changes in biological properties.