Sorption and Environmental Risks of Phosphorus in Subtropical Forest Soils

Phosphorus (P) is one of the key limiting factors for the growth of forests and their net primary productivity in subtropical forest ecosystems. Phosphorus leaching of the forest soil to the catchment and groundwater in karst region is the main source of water eutrophication. Strong P sorption capacity of minerals is generally assumed to be a key driver of P leaching in subtropical ecosystems which varies among different soil types. Here, we estimated P adsorption capacity of the O/A and AB horizon in both limestone soil and red soil of subtropical forests by fitting the Langmuir and Freundlich isotherm to investigate the potential environmental risks of P. The maximum P sorption capacity ( Q m ), P sorption constant ( K L ), P sorption index (PSI), degree of P saturation (DPS), and maximum buffer capacity (MBC) were calculated. The results indicate that Q m of the O/A horizon in both soils were similar. Comparing these two soils, the red soil had a higher K L and MBC in the AB horizon; Q m of limestone soil was larger but K L was lower, indicating that the adsorption capacity of limestone soil was weaker and MBC was lower. There was no significant difference in PSI between the two soils. The DPS values of both soils were below 1.1%, indicating that P saturation is low in both subtropical forest soils due to the lack of marked anthropogenic disturbance. In the O/A horizon, P saturation associated with available P (DPSM3 and DPSOlsen) and that associated with P in the Fe-Al bound state (DPScitrate) were higher in the red soil than in the limestone soil. DPS did not differ significantly in the AB horizon, except for higher DPSM3 and DPScitrate in the red soil. The findings highlight the influence of the soil types on P adsorption. The P adsorption and buffering of red soils were higher than those of limestone soils, indicating a lower risk of P leaching in red subtropical forest soils.

Modelling the Organic Evolution of a Mediterranean Limestone Soil under Usual Cropping of Durum Wheat and Faba Bean

The modeling of carbon (C) and nitrogen (N) fluxes between microorganisms and plants in pure and associated cultures of durum wheat and faba bean demonstrated a close link between the C and N cycles in agroecosystems. The MOMOS (microorganisms and organic matter of soils) model integrates simplified descriptions of photosynthesis (origin of organic C in soil), N microbial exchange (soil origin for N), N fixation (atmospheric origin for N), and plant growth with an organic matter decomposition core that has the soil microbial community at its center. This work provides estimates of the exchange parameters between plant organs and microbes, which were compared to literature data when available. In a connection with photosynthesized C, the root demand for inorganic N can be adjusted by its microbial production. Our approach is a new methodology for improving plant production, by optimizing the interactions with soil microorganisms. Additionally, the coupling of plant growth and microbial processes enabled determining changes of the organic compartments of soil. In the unfertilized limestone soil of this study, sequestration was found to be located in the labile microbial metabolites for one year, then significantly transferred to stable humus during 6-year intercropping. Thus, we propose the MOMOS mathematical tool, not only for guiding ecological intensification, but also related to the management of agroecosystems for climate change mitigation.

Peanut Pods (Arachis hypogaea L.) In Ex-Mining Limestone Soil Enriched with Indigenous Bacteria

Pioneer plants are found in the former limestone mining area, and there are bacteria in their root systems. These bacteria can be used as biofertilizers. This study aims to find out the use of indigenous PGPR in ex-mining limestone land to be able to increase the yield of pea (Arachis hypogaea L.) var. Tuban. This research was an experimental study with 5 treatments applying indigenous PGPR at concentrations of 0%, 25%, 50%, 75%, and 100% and consist of 5 replications. Stages of research include planting peanuts (Arachis hypogaea L.) var. Tuban by adding indigenous PGPR with the same dose and source in an environment with sufficient sunlight. The parameters observed were biomass, pithy weight, empty pod weight, wet weight, dry weight, pH, and temperature of the planting medium for peanuts. In this study, the results showed that the concentration of PGPR 25% had a significant effect on the dry weight of peanuts and doesn’t had significant effect on biomass. Meanwhile, the provision of PGPR with different concentrations did not have a significant effect on the temperature and pH of the lime mining soil planting media

Revegetation of Critical Land with Gaharu (Aquilaria malaccensis) under Various Ameliorants Application

Rehabilitation of post-mining limestone soils is often a challenge due to a lack of nutrients and poor soil humus. The research aims to study the effect of various ameliorants on soil chemical properties, growth, and P uptake of gaharu plant (Aquilaria malaccensis) in post-mining limestone soil for revegetation of critical land. The research was conducted in a Completely Randomized Design with three replications. The treatments were P0 (Control, without ameliorant); P1 (Humic Acid, HA, 4 kg ha-1 ); P2 (Phosphate Rocks, PR, 350 kg ha-1 ); P3 (Vesicular Arbuscular Mycorrhizal Fungi, AMF, 500 spores plant-1 ); P4 (HA+AMF); P5 (PR+AMF); and P6 (HA+PR+AMF). Data were analyzed using ANOVA at 95% confidence level and continued with the LSD test. The use of various types of ameliorants (HA, RP, and AMF) significantly increased root length, root volume, wet and dry weight of roots, shoot wet and dry weight, and P uptake of gaharu tree. The best ameliorant in increasing gaharu tree growth was AMF (P3) treatment, and AMF combined with HA (P4) treatment. Thus, for revegetation of critical land, especially post-mining limestone land, using gaharu tree requires HA and AMF inoculation.

Suku Phyllanthaceae pada Rawa Bakau dan Tambak di Telang Asri, Kabupaten Bangkalan, Pulau Madura

Madura island is known as a mixed deciduous forest area with dry seasons and limestone soil. The island has unique plant species compared to the mainland Java. However, most of the mangrove forest areas have been converted into ponds and housing. One of the remaining mangrove swamps is located at Telang Asri village, Kamal Subdistrict, Bangkalan Regency. Several species of mangroves have been reported here, along with other groups of plants from the Phyllanthaceae family, found numerously at the time of observation. In 1963, CA Backer and RC Bakhuizen van den Brink Jr. have already listed 16 species of Phyllanthaceae from Madura Island. Since then, the updated information on the Phyllanthaceae of Madura has not been available. Therefore, this study aimed to collect the members of Phyllanthaceae family in the mangrove swamp areas of Telang Asri village. The field study was carried out using the exploratory method, while specimen preparation was conducted in Herbarium Bandungense (FIPIA). In this study, seven species were collected from Telang Asri, namely Glochidion littorale Blume, G. zeylanicum (Gaertn.) A. Juss., Phyllanthus amarus Schumach. and Thonn., P. debilis Klein ex Willd., P. reticulatus Poir., P. urinaria L., and P. virgatus G. Forst.

Research of Efficiency of the Horizontal Coating Depending on Intensity of Capillary Absorption

In this article, research of intensity of a capillary suction of horizontal waterproof coatings when using dry polymer plaster mixtures is described. Line charts of dependence of intensity of capillary absorption on the depth of dipping and mortars for waterproofing coatings are made based on test data. The following stage of experiment is modeling of horizontal waterproofing of shell limestone masonry in sandy and clay soils. Samples of stone were laid on waterproofing material. Material was applied according to the plan of experiment, in one, two and three layers on dry and wet surfaces of samples. Thus, during the research, it has been established that the intensity of capillary absorption is affected by porosity of shell limestone, soil conditions and types of waterproof coating.

Pengaruh Penambahan Arang Tempurung Kelapa dan Bokashi Pupuk Kandang Terhadap Pertumbuhan Semai Akasia (Acacia Mangium Willd.) di Media Bekas Tambang Kapur

Continuous mining activities of limestone operation may cause negative impact such as environmental damage and reduction of soil quality (physically, chemistry, or biological). Revegetation is the process to increasing productivity of postmining limestose land. Acacia mangium is one of fast growing species that can grow in marginal land, symbitotic with rhizobium bacteria, and high economic value. The purpose of this research are to test the response of coconut shell charcoal and cow feces (bokashi) addition to the growth of akasia (Acacia mangium) seedling on postmining limestone soil and to find out the optimum dose of coconut shell charcoal and cow feces (bokashi) addition. This research used a complete randomized design factorial with two factors, each factor have four degree. First factor is addition of coconut shell charcoal and second factors is addition of cow feces (bokashi). The result of this research showed that coconut shell charcoal and cow feces (bokashi) addition on postmining limestone soil gives positive influence towards the amount of root nodule. But not affect other parameters such as height, diameter, total wet weight, total dry weight, and root tops ratio. The interaction between addition 10 g of coconut shell charcoal and 20 g of cow feces (bokashi) is the best composition for a significant effect in improving the amount of root nodule of A. mangium seedling by 78.58%. Very high levels of Ca in the soil medium will be toxic to the acacia plant.Keywords: Acacia mangium, bokashi cow feces, coconut shell charcoal, limestone mining

Comparison of the Use of Cement, Gypsum, and Limestone on the Improvement of Clay through Unconfined Compression Test

Soil stabilization is an effort to improve soil properties by adding additives in the soil to increase the soil strength and maintain the shear strength of the soil. There are many materials which can be used as stabilizers. The materials used in this study were cement, gypsum, and limestone, then the compressive strength values were compared by using the Unconfined Compression Test (UCT). The mixture combinations used in this study were 1% to 10% of cement, gypsum, and limestone on clay by curing for 14 days. The compressive strength value resulted from the unconfined compression test on the original soil sample was 1.4 kg/cm2. The original soil was classified as moderately sensitive soil because the sensitivity value of the original soil was 2. After being stabilized with various mixtures of cement, gypsum, and limestone, soil stabilization using cement obtained the maximum unconfined compressive strength value is 3.681 kg/cm2 in the mixture of 10%. Similarly, the soil stabilization using limestone and gypsum also obtained its maximum unconfined compressive strength value in the mixture of 10% is 3.307 kg/cm2 and 2.975 kg/cm2, respectively.