Post-Tin-Mining Agricultural Soil Regeneration Using Local Resources, Reduces Drought Stress and Increases Crop Production on Bangka Island, Indonesia

Abstract

Mining severely affects ecosystems and threatens local food security. Remediation practices, however, are a viable way of reducing the negative impacts on post-mining lands. In this study we aim to improve crop yields and drought resistance on a post-tin-mining site located in Bangka Island, Indonesia, with locally available resources. Plots with five different soil amendments: (1) dolomite; (2) compost; (3) charcoal; combinations of (4) charcoal + compost; and (5) charcoal + sawdust; and a control were established. An intercropping system with cassava and centrosema was employed, and yields were determined. Drought resistance was evaluated by carbon isotope discrimination (∆13C) from crop parts of cassava and centrosema’s shoot. Soil physicochemical properties were determined at harvesting time. Soil amendments significantly improved cassava and centrosema yields. In particular, the compost and combined (charcoal + compost) treatments enhanced centrosema yields (1.18 and 1.99 kg·plot−1, respectively) and were related to higher nutrient availability. Similarly, compost, charcoal, and combined treatments showed positive effects on the cassava yield (0.15–0.16 kg·plant−1) and a higher drought resistance in the charcoal treatment (∆13C= 21.48‰). Increased water-holding capacity (WHC) reduced the water deficiency and boosted yields of cassava and centrosema when the soil was treated with dual amendments (charcoal + compost). Charcoal, compost, and their combination turned out to be the most sustainable amendments in degraded post-mining tropical soils.

Post-Tin-Mining Agricultural Soil Regeneration Using Local Organic Amendments Improve Nitrogen Fixation and Uptake in a Legume–Cassava Intercropping System

“…The N content of the soil amendments varied (Table 1), with dolomite having the lowest value. For a more detailed description of the experimental design, crop species, and field management, see Maftukhah et al [3].…”

“…Cassava and centrosema were harvested from each plot after each growth period [3]. Subsamples from fresh weight yield determinations were used for dry matter and isotope nitrogen analysis.…”

“…Post-mining soils have been subjected to numerous physicochemical and biological changes, resulting in a significant loss of soil organic matter (SOM), the primary source of nitrogen (N) in soil [2]. The post-tin-mining soil on Bangka Island had a low pH and nutrient content, limiting its potential for agricultural production [3].…”

“…Intercropping legumes with other plant Land 2023, 12, 1107 2 of 17 species has been widely adopted in agricultural production systems for ecological and agronomic reasons [8,9]. At this study site, local farmers grow legumes such as centrosema (Centrosema pubescens) as intercrops with cassava (Manihot esculenta Crantz) [3,10]. Centrosema and other legume species have adapted to poor soil conditions and serve as an alternative N source for non-leguminous crops [11,12].…”

“…This selection required estimating the effect of the soil amendments on the N 2 -fixation potential of the centrosema. As cassava and centrosema yields differed significantly among soil amendment treatments [3], we hypothesized that (1) compost and its combination with charcoal would lower the percentage of nitrogen derived from N 2fixation (%NDFA); (2) N 2 -fixation by centrosema in combination with organic amendments would improve N uptake in intercropping cassava-centrosema; and (3) combining charcoal and compost would result in a high N 2 -fixation input from centrosema and increase soil N stock.…”