A Review on the Effects of Rice Straw Burning on the Rice Paddy Fields, Guilan Province Iran

Review Article

Austin Environ Sci. 2022; 7(1): 1068.

A Review on the Effects of Rice Straw Burning on the Rice Paddy Fields, Guilan Province Iran

Mohammadi Galangash M¹, Ghasemi Zolpirani R¹, Askari Tappeh F² and Forouhar Vajargah M³*

¹Department of Environmental Sciences and Engineering, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Iran

²Natural Sciences and Engineering, Faculty of Natural Resources, University of Guilan, Iran

³Department of Fisheries, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Iran

*Corresponding author: Mohammad Forouhar Vajargah, Department of Fisheries, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Iran

Received: December 20, 2021; Accepted: January 12, 2022; Published: January 19, 2022

Abstract

Agriculture, as the oldest activity in the world, has positive and negative effects on the environment. In agricultural activities, the main target is to obtain a food product that can be consumed in human nutrition or to produce raw materials for industry. Humans cannot consume some of the plant organs produced, but their existence is not avoidable. Occupancy of Fields by postharvest crop residues has often become a major problem for farmers. As a result, they burn the crop residue. Burning is one of the most commonly used methods for removing crop residue including rice straw. Guilan province is one of the most important rice productions center in Iran. In this province, farmer’s burn straw every year between August to November after harvesting rice, this causes extremely air pollution, violent respiratory problems and damage to the paddy fields soil. Straw burning cause reduces microorganisms in the surface layer of soil, loss of minerals, reduces soil permeability and increases its specific gravity. In fact, despite the awareness about the dangers of rice straw burning in paddy fields, based on a misconception, farmers continue to burn. The effects of this action can be seen in the long-time.

Keywords: Soil properties; Rice straw; Paddy field; Open burning; Crop residue

Introduction

In agriculture, burning crop residues is an activity that is done with various purposes such as converting forestlands to agriculture and changing crops, controlling pests and diseases, removing crop residues after harvest and ease of harvest. In fact, post-harvest incineration has become an important management mode [1]. Most farmers burn the residue immediately after harvest. This makes the soil easier to prepare for the next crop and releases amounts of minerals such as calcium, magnesium, phosphorus and potassium from the residue. On the other hand, burning reduces soil organic matter and reduces soil organic matter in the long-term, leading to losses of nitrogen, carbon, sulfur and other important soil elements through their sublimation.

Annually in Iran, more farmers burning crop residues due to the pest control. This method of crop residue management causes the rapid release of nutrients in the soil and the relative control of pests and weeds. As well as, increases efficiency and is economically and temporarily cost-effective. However, due to destructive effects such as increased erosion, reduced organic matter, biological deterioration, structural and permeability disorders, disturbance of the balance and population of soil microorganisms, besides environmental pollution, ultimately in long-term leads to reduced crop yields [2].

Rice (Oryza sativa) is the hugely important food crop for the world’s population, especially in East, South, Southeast Asia, the Middle East, Latin America, and the West Indies. In many countries, rice accounts for more than 70% of human caloric intake. In Asia, just over 30% of all calories come from rice [3,4]. Rice is one of the most important crops in Iran. The annual production of rice in Iran was more than 2.6 Mt in 2020. Guilan province with 35% share of total rice crop production is among the main rice production areas in Iran. Rice production share of this province was 42% (1.09 Mt) in 2020 [5].

This article reviews the survey on soil properties changes due to rice straw residues burning. One of the most important crop residues in the Iranian agricultural system is rice straw. Rice straw is a source of soil nutrients and organic materials. Decomposition releases these resources to build and maintain the soil. Soil resources, in turn, enhance crop production. Although burning returns part of the mineral elements to the soil, most of the organic material and nutritional content of straw is lost upon burning. In addition, large and repeated burning at a specific location can damage the physical and chemical properties of soil layers, especially the surface layer. Unfortunately, more than 700000 ton of rice straw annually, burned by guilanian farmers in the months of August to November each year in the Guilan paddy fields. Some legal measures in Iran for example Waste Management Act (approved in May 9, 2004), Clean Air Act (approved in July 16, 2017), and Soil Protection Act (approved in May 25, 2019) to intercept of rice straw burning in guilan could not successful. However, most farmers still despite the ban regulation prefer the burning method. Therefore, the objective of this study was to survey effects of rice straw burning on paddy fields soil in guilan province, Iran.

Location of Guilan Province

Guilan province with an area of 14711 km2 is located in the north of Iran on the south of Caspian Sea, within 36° 34' and 38° 27' north latitude and 48° 53' and 50° 34' east longitude (Figure 1). Guilan has a population of 2.5 million people. This province shares a border with the country of Azerbaijan. In addition, this province has 300km of coastline [6]. Guilan has a temperate and humid climate. The annual average rainfall of 1100mm and moisture of 80 percent. The average annual temperature is 15.8°C. This province includes the green areas of the northwest of the Alborz mountain range and the western part of the southern shores of the Caspian Sea [7,8].