Utilizing rice husk biochar and selected phosphate fertilizer to increase phosphate status of ultisol and shallots (Allium ascalonicum L.) production

Department of Agrotechnology, Faculty of Agriculture, Riau University, 28293, Pekanbaru, Indonesia

^* Corresponding author: irwinmirzaumami@lecturer.unri.ac.id

Abstract

Low soil phosphorus (P) availability is an important impediment to successful shallot cultivation in ultisols, a type of soil distinguished by its low fertility. A field experiment was conducted to investigate the effects of rice husk biochar in combination with various types of phosphate fertilizers on ultisol P status, growth performance and production of shallot. The experiment followed a completely randomized design with three replications and involved the two fixed factors: the application of three different levels of rice husk biochar (0, 5, and 10 t ha^-1) and addition of three distinct phosphate fertilizer sources (90 kg ha^-1) that included triple superphosphate (TRP), rock phosphate (RP) and guano. Our experiment revealed that using rice husk biochar in conjunction with various sources of P fertilizer had a propensity to raise the pH, enhance the availability and total P content in the observed soil. Furthermore, the application of 5 t ha-¹ of rice husk biochar, along with the use of TSP resulted in the highest P availability in the soil. The use of biochar and P fertilizers has the potential to be an effective strategy for improving soil phosphorus status and increasing shallot production, as evidenced by the weight of storable bulbs.