Short-term Effect of Mushroom Substrate Compost on Some Physical and Chemical Properties of Soils with Different Textures

One of the solutions to sustainable agriculture is the use of mushroom substrate compost (MSC). Mushroom substrate compost is a mixture of stable organic matter and composed of various components such as wheat straw, poultry manure and gypsum. It is rich in nutrients, such as nitrogen, ammonium nitrate, superphosphate, potassium salts and etc. MSC could be a good alternative for other fertilizers and amendments due to less cost and improving soil properties. However, its simultaneous effect in three levels of 0, 3 and 6 % on the properties of soils with different textures has not been before reported. Therefore, objective of this study was to evaluate the short-term effect of the MSC on some physical and chemical properties of soil with different textures.

In this study, three soil samples with different textures, sandy loam, loam and clay, were taken from a bayer farm of the Agricultural Research Center, Abbas Abad Farm of the Bu-Ali Sina University and a bayer farm in the Kerk Suffla Village of Nahavand County, respectively. Sampling was done with a knowledge of soil properties, from soil surface layer (0-20 cm depth). The soil samples were transferred to the Soil Physics Laboratory of the Bu-Ali Sina University for testing and after being air dried, they were passed through a 4 mm sieve. The research was conducted as a factorial experiment in a completely randomized design with three replications. The factors were included soil texture at three levels (sandy loam, loam and clay), and MSC at three levels (0, 3 and 6% W/W). The MSC sample was obtained from Alvand Mountain Company in Hamadan Industrial City. The mushroom substrate consisted of wheat straw, lime and poultry manure, which were mixed at rates of 57, 36 and 7%, respectively. MSC levels were calculated based on treatments after determining the desired soil content for each container. The treated soils were transferred into plastic containers with dimensions of 21 × 13.5 ×12.5 cm based on the field bulk density of each soil. A total of 27 plastic containers containing treatments were prepared. Soils treated in plastic containers were saturated with tap water and then dried for a 120-day incubation period.

The results showed that the order of the soil total porosity was loam > clay > sandy loam, with significant difference between them. The application of mushroom substrate compost significantly increased the porosity at 3 and 6% levels compared to the control. But there was no significant difference between total porosity at 3 and 6% levels. Also, the order of the bulk density in different textures was exactly opposite to that of total porosity. Application of 6% mushroom substrate compost significantly increased cation exchange capacity in sandy loam soil compared to that in the control and 3% level, but no significant difference was found between the cation exchange capacity of control and 3% level. The order of cation exchange capacity was clay > loam > sandy loam, with significant difference between them. Comparison of the electrical conductivity of the soils at different levels of MSC showed that at the zero level of the MSC, the order of electrical conductivity values was loamy > clay> sandy loam, with significant difference between them. The order of pH values was sandy loam > clay > loam at control. The order of pH values was sandy loam = clay > loam at the 3 and 6% levels of the MSC. The results showed that, soil cation exchange capacity, electrical conductivity and total porosity increased in the ranges from 11.8 to 36 cmolc kg-1, 0.16 to 0.69 dS m-1 and 0.52 to 0.56, respectively and bulk density and pH decreased in the ranges from 1.24 to 1.18 g cm-3 and 8.25 to 7.3, respectively, by using MSC. The greatest effect of treatments at the 6% level of MSC on the electrical conductivity, total porosity, and bulk density was obtained in the soil with loam texture, and on the pH and cation exchange capacity was obtained in soil with clay texture.

According to the results, mushroom substrate compost increased cation exchange capacity, electrical conductivity and total porosity and decreased pH and bulk density in all three soils by increasing MSC levels. Overall, the results showed that mushroom substrate compost improved soil physical and chemical properties, due to its stable organic matter and low bulk density. As this compost has a much lower price than other soil modifiers, therefore, mushroom substrate compost can be used in agricultural lands to maintain soil fertility, improve soil stability, and improve soil physical and chemical properties.