Source: SEAMEO BIOTROP's Research Grant | 2020
Karst terrane is a special landscape developed on carbonate rock which generally considered as a fragile and vulnerable environment (Sullivan et.al., 2014). Karst desertification is the consequences of ecosystem fail of karst related to ecological degradation characterized by loss of cultivated soil, water shortage, soil erosion, decreased biodiversity, and phyto-community degradation (Jiang et al., 2014). Mining represents a frequently overlooked threat for limestone karst ecosystem in Southeast Asia, as this region is one of the greatest exporters of limestone (Hughes, 2017). The cost of this to ecosystem degradation is not only through the direct loss of areas for mines, but also through the development of roads that further fragment the landscape (Jaffe et.al., 2016), and increase soil loss including organic matter and its fertility which lead to rocky desertification (Zhao and Hou, 2019).
Carbonate rock are widely distributed in Indonesia covering 15.4 million hectares or about 8.2% of total country area. In Indonesia, karst has an important function particularly for its economic value, such as building material, handicraft, bleach, marbles, and as mixture of cement paste (Sarwanto and Prayitno, 2015). The increase demand of limestone leads to the high land use change of forest into mining of limestone in Indonesia including in Gunung Kidul and Imogiri, Yogyakarta District. Those, lead to the soil degradation including rocky desertification of the karst become much more severe particularly since this region is in fault-karst area. It will worsen the drought condition in those areas. The soils that form atop carbonate bedrock is mostly found very shallow and highly susceptible to degradation, especially through subsurface erosion in the case of karst terrain (Wang et.al., 2014). Furthermore, soil nutrient particularly nitrogen, phosphate, potassium, and soil organic is very limited in karst area (Yang et.al., 2019). Thus, exposing the unfavorable soil condition for plant to grow. In the absence of organic matter input become a crucial factor limiting function on water storage and nutrient source. Vegetation loss is corresponded to the changes of organic carbon content in karst ecosystem which effect on organic carbon storage of the region.
In order to stop the rate of damage in the karst landscape, a comprehensive integrated restoration of rocky deserted karst area is a must. Revegetation is needed for 2 marginal soil such as ex-limestone mining soil. Revegetation is the most common method to restore degraded area. Adapted plant species with high economic value, such as Melaleuca leucadendron is still a challenge to restore degraded karst area.
The high success rate of land restoration is lower than the rate of land degradation. The high failure of land restoration is because most of restoration effort is only consider on above ground only. Ongoing increases in karst desertification pressure will only add further challenge to the already difficult task of restoring degraded karst using vegetation only. Regarding to this issue, here we focus on the contributions of selected microbial together with modified organic soil amendment to revegetate degraded rocky desertification of karst area, including assess the gas sequestration on revegetated area. In summary, current research acknowledged the connections between the aboveground vegetation, the edaphic property (soil), and the soil microbiome in karst rocky desertification.
Organic matter has an important role not only supplies plant nutrition, but also to improve soil structure, minimize erosion, and maintain soil physical, biological, and chemical properties of soil (Esmaelzadeh and Ahangar, 2014), including increase water holding capacity, water content, field capacity, wilting point, and available water capacity (Minasny and McBratney, 2018). Enterobacter sp. is a free living microorganism which may also forming endophyte to plant. It also has ability in solubilizing phosphate that playing important role on providing phosphorus (Wang et al., 2017) and fixing nitrogen (Chauhan et.al., 2017). As Phopshate solubilizing microorganism (PSM), it contributes on P solubilization in limestone (Adnan et.al., 2018). Arbuscular mycorrhizal fungi (AMF) are well-known on their ability in improving nutrient uptake particularly P and increase plant adaptation to drought stress (Bowles et al., 2018). Inoculation of AMF enhances growth of native plants from karst area (He et al., 2017). The role of mycorrhizal fungi in carbonate rock weathering of karst is observed (Thorley et al., 2015).
Application of organic matter such as pot organic together with selected beneficial microorganism into selected adapted economic plant species to restore degraded limestone in karst area of Indonesia is still very limited. Understanding and improving environmental quality by and enhancing land productivity such as Karst have always been the goals of bio-ecosystem researchers and producers. The utilization of microbial engineering strategies together with soil organic amendment pot organic to accelerate success of plantation in karst field is proposed in this study as one of the indicator on plantation success in karst area.
This research aims: (1) to perceive the connection and effect of aboveground vegetation, edaphic property, and soil microbiome in karst rocky desertification; (2) to investigate the effect of modified soil amendment on plant growth performance when growing with and without pot organic in karst field.
1. Revegetation improved the soil chemical characteristics represented by improved nutrient availability in the soil for plant growth
2. Inoculation of beneficial microorganisms improved nutrient availability in the soil, plant nutrient acquisition, plant biomass, and plant survival ability in the field
3. Utilization of soil organic amendment, the pot organic, improved plant growth and
survival rate in the field