Document Type : Research Paper
Authors
- samira mohamadi 1
- Fardin Sadegh-Zadeh 2
- Mohammad AIi bahmanyar 3
- mostafa emadi 2
- mahdi ghajar- sepanlu 2
1 Ph.D. Student of Department of Soil Science, Sari University of Agricultural Sciences and Natural Resources, Mazandaran, Iran
2 Associate Professor, Department of Soil Science, Sari University of Agricultural Sciences and Natural Resources, Mazandaran, Iran
3 Profesor, Department of Soil Science, Sari University of Agricultural Sciences and Natural Resources, Mazandaran, Iran
Abstract
Introduction: Recovery of nutrients from plant residues is a sustainable and economical method in agriculture. Considering the important role of nutrients, it is essential to supply these elements in the soil and achieve the appropriate yield. The amount of nutrients in the plant residues after harvesting is very variable due to the difference between the species used. Each plant residue contains some nutrients that during the decomposition process, these nutrients can be available to the soil and crops in different amounts. In more detail, considering that the excessive use of chemical fertilizers has caused environmental problems and unused plant residues in the environment have created problems for the environment and farmers, therefore, to solve these problems, recovering important elements such as silicon from plant residues can be effective in improving the quality and quantity of many different products and plants. Rice straw, wheat straw and sugarcane bagasse are among the most common plant residues that have been studied in different studies to recover nutrients from them with different methods. In particular, rice straw is known as one of the most important plant residues that can be found in abundance in the north of Iran. Obviously, there is still a need for a better understanding of the amount of nutrients recovery from plant residues with different methods. And there is an effect of these elements on improving the condition of the soil. Considering that the excessive use of chemical fertilizers has caused environmental problems, as well as unused or underused plant residues in the environment have caused problems for the environment and farmers. The purpose of this study is to compare the residues of rice straw, wheat straw and sugarcane bagasse and the methods of recovering nutrients from these residues in order to add macro-nutrients (nitrogen, phosphorus and potassium) and micro-nutrients (iron, zinc, copper and manganese) into the soil.
Materials and Methods: This research was carried out based on a factorial experiment in the form of a completely "randomized" design with three replications during 2022-2023. The treatments of plant residues in three levels (rice straw, wheat straw and sugarcane bagasse) and the methods of recovering elements from these residues in five levels (biochar, straw, digestion, ash and ash with acid) were examined. Soil samples, from a depth of 0-25 cm and with silty loam texture were randomly taken from the forest parts of Mazandaran province, Iran, characterized by a Mediterranean climate, Csa type, with an average annual rainfall of 676 mm, and average air temperature of 14 ℃, and then were air-dried. After preparing the samples, the characteristics of the treatments, macronutrients and micronutrients, including pH, electrical conductivity, total nitrogen, phosphorus, potassium, iron, zinc, manganese, copper, and silicon were measured. Analysis of variance (ANOVA) assessed the statistical significance of the differences in the studied variables among the different treatments. Tukey test was used for the post-hoc comparisons at a p-level < 0.01. Prior to the statistical analysis, QQ-plots were used to check the normality of sample distribution, and the data were square root-transformed whenever necessary. Moreover, the principal component analysis (PCA) was used to cluster the studied variables in groups related to the studied treatments.
Results and Discussion: The results of analysis of variance showed the effect of plant residues and element recovery method on all studied characteristics including soil characteristics (pH, electrical conductivity and organic carbon), macronutrients (nitrogen, phosphorus and potassium) and micronutrients (silicon, manganese, copper, iron and zinc) were significant at the probability level of 1%. The results showed that the biochar treatment of rice straw had the maximum amount of pH (7.66), organic carbon (2.61%), nitrogen (0.24%), phosphorus (46 mg/g), potassium (781 mg/g) and silicon (261.33 mg/g) compared to other treatments. Also, the results of the compare means showed that sugarcane bagasse biochar treatment had the maximum amount of manganese (25.01 mg/kg), zinc (3.20 mg/kg), iron (48.27 mg/kg) and copper (2.20 mg/kg) compared to other treatments. The application of principal component analysis showed that three distinct groups (for rice straw/biochar, sugarcane bagasse/biochar and control treatments) were demonstrated, without clear overlap of the points related to these treatments and their element recovery methods.
Conclusions: In general, this study confirmed that the treatment of rice straw residues and the method of recovering its elements through biochar play a significant role in increasing the quality and fertility of the soil and can be recommended to farmers.
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