Indonesia is likely to face a water crisis due to mismanagement of water resources, inefficient water systems, and weak institutions and regulatory organizations. In 2020, most of the fresh water in Indonesia was used for irrigation (74%) to support the agricultural sector, which occupies 30% of the total land area in Indonesia. Of all agricultural commodities, rice is one of the major and essential commodities, as it is the basic staple food for almost every Indonesian. However, in 2018, the Ministry of Public Works and Housing (MoPWH) reported that 46% of Indonesian irrigation infrastructure is moderately to heavily damaged. Looking at how irrigation can be very crucial to the welfare of Indonesian population, this study conducted an extensive literature review of the historical, current, and future management of irrigated rice production systems in Indonesia. This study has clearly shown that the irrigation systems in Indonesia have existed for thousands of years and, thus, there is a close relationship between irrigation and the socio-cultural life of the Indonesian population. Aside from how climate change influences water availability for irrigation, rice production with a constant water ponding system has been found to contribute to climate change, as it emits methane (CH₄) and other greenhouse gases from agricultural fields of Indonesia. Therefore, the required modernization of irrigation systems in Indonesia needs to consider several factors, such as food demands for the increasing population and the impact of irrigated agriculture on global warming. Multi-stakeholders, such as the government, farmers, water user associations (WUA), and local research institutions, need to work together on the modernization of irrigation systems in Indonesia to meet the increasing food demands of the growing population and to minimize the impacts of agriculture on climate change.

Purpose: The complex process of post-mining land reclamation poses a great challenge in combatting land degradation and food insecurity. In this study, a field experiment was conducted to determine the effects of different soil amendments on soil organic carbon (SOC) characteristics and plant biomass to reclaim a highly degraded soil after tin-mining. Methods: Quantity and quality of SOC, annual plant biomass, and their relationships were determined over four years in post-tin mining soil that had been treated with six different soil amendments: control, dolomite, compost, charcoal, charcoal with compost and charcoal with sawdust. Results: Charcoal-compost application led to the highest increase in SOC stocks, followed by compost application. It enhanced annual plant biomass to twice that of the control treatment. In contrast to organic soil amendments, dolomite tended to cause SOC stock losses over time. Dissolved organic carbon exhibited a highly dynamic pattern, with a tendency to decrease over time. Dolomite and charcoal application induced SOC chemical composition changes distinct from other treatments. The potential interactions between amendment materials and time as well as crop species were observed for SOC characterization. Conclusions: Charcoal-compost combination with regular compost application was recommended to reclaim the soil for promoting SOC accumulation whilst sustaining crop production.

Natural resource management is a cross-sectoral topic, as reflected by its inclusion in several of the United Nations Sustainable Development Goals (e.g., SDGs 2, 6, 12, 15). In the study area on Bangka Island, Indonesia, agriculture is a pillar of local food security and livelihoods, making restoration of degraded lands also a local issue. The present study aims at restoring degraded land after tin mining and at restoring the natural soil base rendering it more suitable for agriculture. We use co-experimentation with citizens as a tool to develop options for re-habilitation at a pilot scale. The recruitment process in this study was reversed insofar as local citizens were at the origin of the project idea. Consequently, buy-in was high among local stakeholders. This set to increase the probability of successfully scaling up effective and actionable practices that were developed during co-experimentation at both local and regional levels. Co-experimentation provided a platform for exchange between local citizens and scientists. Citizens did not need to learn new skills to be able to participate in the scientific process and could autonomously evaluate results. We see involvement of citizens in this type of scientific projects not only as feasible, but as rewarding for all involved partners and as beneficial for the project outcomes. In light of the call for partnerships to achieve the Sustainable Development Goals, we can only recommend investing in communication and relationship building to work together on better solutions to the challenges we face.

The low nitrogen content of Bangka Island’s post-tin-mining soil may limit its suitability for agricultural production. In this study, we investigated the effect of locally available organic soil amendments on nitrogen fixation (N₂–fixation) and crop nitrogen (N) uptake in a cassava–legume intercrop system. Cassava was intercropped with centrosema in post-tin-mining soils with six treatments, including a control and different soil amendments, such as dolomite, compost, charcoal, a combined treatment of charcoal and compost, and a combined treatment of compost and sawdust. The percentages of N derived from N₂-fixation (%Ndfa) with the different seasons and treatments were comparable. Nonetheless, due to the higher shoot biomass accumulation, the mass of N₂–fixation in soil amended with compost and when combined with charcoal was significantly higher than the control (50 to 73 kg ha⁻¹). Treatments with compost and its combination with charcoal exhibited higher N uptake from the cassava–centrosema intercropped system (82 and 137 kg ha⁻¹) and higher inorganic ammonium (NH₄⁺) concentrations in the soil at harvest time (5.5 and 6.7 µg g⁻¹). When combined with organic soil amendments, N₂–fixation from centrosema produces not only higher biomass, but also higher N contribution to the system. Overall, locally available organic amendments, particularly the combined application of charcoal and compost, showed promise for improving N₂–fixation of intercrop centrosema as well as for increasing N availability in the soil, which is of critical importance for crop growth in post-mining soils that have lost fertility.

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.

Surface irrigation networks in Indonesia are damaged by several factors, and sedimentation is among the most severe challenges. Sand traps play a substantial role in improving irrigation system efficiency by reducing sedimentation. There are two periods in sand trap operation: the operational and maintenance periods. Pengasih is one of the irrigation schemes implemented in the Progo Opak Serang (POS) River Basin, which has a high level of erosion. This study aimed to propose an appropriate management strategy for the Pengasih sand trap as the first barrier in irrigation network sedimentation based on mathematical modeling. The HEC-RAS simulation software was used to simulate the sand trap hydraulic behaviour. The results show that the validated Manning’s coefficient was 0.025. The optimal transport parameters were Laursen for the potential function, Exner 5 for the sorting method, and Rubey for the fall velocity method. The recommended flushing timeframe is 315 min, with a discharge of 2 m³/s. We suggest that the sand trap flushing frequency be performed twice a year, and it can be performed at the end of March and October. This coincides with the end of the first and third planting seasons of the irrigation scheme.