The Effect of Organic and Inorganic Acids on the Physiology of Reproduction and Growth of Earthworms, Soil Fauna, and Microbial Communities in Calcareous Soils

Inroduction & Organic and inorganic acids can affect the reproduction and growth of soil living organisms through the influence of some soil characteristics such as pH and electrical conductivity, or by changing the solubility of some solid soil compositions. Application of these acids as calcareous soil conditioner is common placein Iran. The purpose of this study was to investigate the effects of organic and inorganic acids on the physiology of reproduction and growth of earthworms, soil fauna, and microbial communities in calcareous soil.
This experiment was conducted in a laboratory on a calcareous soil in special containers in a completely randomized design with 10 treatments and 3 replications. Citric acid, acetic acid, oxalic acid at a concentration of 5 and 10 m M , a mixture of three organic acids, each with a concentration of 33.3 mM, sulfuric acid and phosphoric acid, each with a concentration of 5 mM was used. Containers containing 1 kg of soil were placed at room temperature for 20 days. At the end, the number of soil fauna and population of the microbial community were counted in each treatment. A separate experiment was designed to study the growth and reproduction of the earthworm. To the mixture of soil and fresh cow manure, treatments were applied and inoculated with earthworm and placed at room temperature for 56 days. At the end, the total number of juvenile worms, adult worms and cocoons and total worms were measured.
According to the results, the use of acids reduced pH and increased electrical conductivity in soils. Phosphoric acid and citric acid increased the number of earthworm cocoons, but other acids decreased the number. Citric acid increased the number of juvenile worms, but other treatments reduced the number of juvenile worms. Phosphoric acid reduced the number of adult worms but increased their weight. In other treatments, the number and weight of earthworms decreased. The use of organic and inorganic acids reduced the reproduction of nematodes, amoebae, flagellates and ciliates. The population of bacteria and fungi in all acids increased, except for sulfuric acid.
The results showed that organic and inorganic acids, affect the population of earthworms, soil fauna and microbial communities by reducing the pH of the soil and increasing the dissolution of minerals or action as a nutrient or growth inhibitor, , which is different depending on the type of acids and their concentration.