The effect of biostimulants and red mud on the growth and yield of shallots in post-unlicensed gold mining soil

Abstract

Abstract Shallot production in West Kalimantan is still low. Land that has the potential for the development of shallots is the soil from post-unlicensed gold mining (PUGM). The soil at PUGM was exploited very extensively and can be used to develop shallots, but it is obstacled by low pH values and nutrient content. This research aims to investigate the impact of biostimulants and red mud on the growth and yield of shallots. The experiment was carried out in two stages: (1) investigated the ratio of the red mud and PUGM soil at the laboratory and (2) investigated the biostimulants and red mud effect on two varieties of shallots in a screen house. For the second experiment, there were three factors. The first factor was the biostimulant (0, 2, 3, and 4%); the second factor was the dose of red mud (0, 2, and 4 tons ha−1); and the third factor was the shallot varieties (Bima Brebes and Tajuk). The results of the first research indicated that the application of the red mud and PUGM soil in a ratio of 1:500 and 1:1,000 had a pH of 7.88 (slightly alkaline) and 7.24 (neutral), respectively. The second study found that a 2% concentration of biostimulant increased plant height and tuber count by 23.78 cm and 6.55 tubers, respectively. The Bima Brebes variety produced better fresh tubers weight clump−1 and dry tubers weight clump−1 than the Tajuk variety, with, respectively, 42.08 g (7.36 tons ha−1) and 32.60 g (5.71 tons ha−1). These findings show that the use of the biostimulants and red mud together in integrated management can help shallots grow and produce more, especially on PUGM land that has obstacles with low soil fertility. This research contributes to the identification of sustainable solutions for agricultural development in environments that have experienced severe land degradation, such as unlicensed gold mining activities.