# Potential Use of Paper Mill Sludge in Improving Soil Quality for Plant Growth
## 1 Introduction  
Soil quality enhancement is critical for optimizing plant growth and ensuring sustainable crop production. Organic amendments, such as soil modifiers, play a vital role in improving soil properties and providing essential nutrients for plants. Paper mill sludge (PMS), a waste product generated in significant quantities by pulp and paper mills, is one potential organic amendment that should be explored. PMS is a mixture of organic matter, inorganic matter, and water. It is generated during paper production, with approximately 40-50 kg of dry sludge produced per ton of paper [1, 2]. PMS has been shown to improve soil structure, nutrient availability, and water retention [1]. It can also help to reduce soil erosion and improve crop yields. However, there are challenges to using PMS as a soil modifier, such as its high organic content and potential for heavy metal contamination [1]. Despite these challenges, the potential benefits of using PMS as a soil modifier are significant. If PMS can be used safely and effectively, it could be a valuable tool for improving soil quality and promoting sustainable crop production. One way to address the challenges of using PMS is to compost it before applying it to soil. Composing can help to reduce the organic content of PMS and remove some of the heavy metals [3, 4, 5]. It can also help to improve the nutrient content of PMS, making it more beneficial for plant growth. Another way to use PMS as a soil modifier is to mix it with other organic materials, such as oilseed cakes. Oilseed cakes contain nutrients that are essential for plant growth,such as nitrogen, phosphorus, and potassium. Mixing PMS with oilseed cakes can help to improve the overall nutrient content of the soil, making it more productive [6; 7]. PMS can be disposed of or reused in various ways, depending on the regulations and available options in a particular region. Common methods of PMS disposal or reuse include landfilling, incineration, land reclamation, cement production, and alternative fuel sources [8; 9; 10; 11; 12; 13; 14]. In the past, landfilling and incineration were the most common methods of PMS disposal [8; 9; 10]. However, landfilling of PMS is considered less sustainable due to limited space and the potential for leachate contamination [11]. Incineration can be a more sustainable way to dispose of PMS, but it requires specialized facilities and careful emission management [12; 13]. Moreover, PMS can serve as a source of calcium, silica, and other minerals required in the cement and ceramic manufacturing process [14; 15; 16; 17]. Additionally, due to its organic content, PMS has been explored as a potential alternative fuel source [18; 19; 20; 21]. It can be co-fired with other fuels in power plants or used in the production of biofuels. Some studies have also demonstrated that PMS can be economically used as a raw feedstock for producing solid fuels when appropriately mixed with other woody biomasses in suitable proportions [21; 22]. Furthermore, some studies have shown that PMS mixed with old newspaper (ONP) can be used to create biodegradable seedling pots for replacing plastic pots [23; 24; 25]. While PMS holds potential as an essential resource, an efficient method for its large-scale utilization has not been developed yet. Ensuring the safe and effective use of PMS is crucial in order to mitigate potential risks. Therefore, further research is necessary to optimize the utilization of PMS as a soil amendment and to explore new and improved methods for managing PMS. Currently, a technology is urgently needed to treat the large amount of PMS that is generated every day. The most effective way to consume PMS in large quantities is to apply it to the soil, but this requires a pre-treatment process that does not burden the soil before direct land spreading of PMS. The primary objective of this study was to investigate the potential of PMS as a soil modifier in conjunction with oilseed cakes and peat moss to enhance soil conditions for seed germination and plant growth.