Document Type : Research Article
Authors
1
Department of Agronomy Research, Khuzestan Sugarcane Research and Training Institute, Ahvaz, Iran
2
Department of Irrigation and Drainage Research, Khuzestan Sugarcane Research and Training Institute, Ahvaz, Iran
Abstract
Introduction
One of the main challenges of agricultural soils in arid and semi-arid regions is the low amount of organic matter, which has a negative effect on the physical and chemical properties of the soil. Soil organic matter plays a role in various soil properties and processes, including soil water retention capacity, soil water distribution, soil microbial activity, water and nutrient availability to plants, and subsequently plant nutrition and yield. The application of biochar as an organic amendment is one of the strategies that has received attention in recent years for increasing soil organic matter and improving the physical and chemical attributes of the soil. Another way to improve soil organic matter is compost application to the soil as an organic amendment. The low organic matter in the soils of sugarcane fields in Khuzestan Province and also the optimal amount of biochar and compost application to improve the physical and chemical properties of these soils, have not been studied. Therefore, this study was carried out to investigate the effect of applying different levels of biochar and compost derived from sugarcane green harvest residues on the physical and chemical properties of soil and water availability for sugarcane plants under field condition.
Materials and Methods
This study was conducted under field conditions at Research Station No. 1 of the Khuzestan Sugarcane Research and Training Institute. This experiment was conducted in a randomized complete block design with seven treatments, including control, biochar application at three levels of 5 (B5), 10 (B10), and 15 (B15) t ha-1, and compost application at three levels of 15 (CO15), 30 (CO30), and 45 (CO45) t ha-1, with three replications. For the application of biochar and compost treatments prior to sugarcane planting, the required amounts of each treatment were weighed, manually distributed and incorporated into the soil to an approximately 30 cm depth. Subsequently, sugarcane setts were planted. Soil sampling was conducted at the end of the growth period in different treatments and the physical and chemical properties of the soil were determined. In this study, the effects of different treatments on the soil chemical characteristics (soil pH, EC and organic carbon), soil phosphorus and potassium availability, physical properties (soil bulk density and mean weight diameter of soil aggregates), field capacity, and permanent wilting point (PWP) were measured and water availability for the sugarcane plant was determined.
Results and Discussion
The results indicated that the application of biochar treatments (B10 and B15) and compost treatments (CO30 and CO45) decreased soil pH and bulk density, while significantly increasing mean weight diameter, soil organic carbon, available phosphorus, available potassium, and plant-available water. The mean weight diameter of soil aggregates in the CO30, CO45, B5, B10, and B15 treatments was 15.8%, 23.7%, 20.2%, 32.5%, and 36.0% higher than that of the control, respectively. The greatest increases in mean weight diameter of soil aggregates and field capacity plant water availability were observed in the B10 and B15 treatments. The amount of plant-available water in B10 and B15 was 38.9% and 37.5% higher than the control, respectively. In addition, the results also indicated a greater effect of biochar treatments on increasing plant-available water compared with compost treatments. Plant available water in B10 treatment was 21.7% higher than CO45 and 26.3% higher than CO30 treatment. The results indicated that there were no significant differences among B10, B15, and CO45 with respect to soil pH, organic carbon, and phosphorus availability. However, the biochar treatments (B10 and B15) were significantly more effective than CO45 in enhancing soil potassium availability, improving soil physical properties, and increasing plant-available water.
Conclusion
Overall, it can be concluded that biochar application at 10 t ha-1 and compost application at 45 t ha-1 represent the optimal rates for improving soil chemical properties in calcareous soils of sugarcane fields. Furthermore, biochar at 10 t ha⁻¹ was the most effective treatment for improving soil physical properties and enhancing water availability for sugarcane.
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