The condition of chemical properties in the soil on the liquefied land in Jono Oge Village, Sigi Regency, Central Sulawesi

Liquefaction is an event in which the soil loses shear strength due to increased pore water stress by the presence of cyclic loading. As a result of this incident, a number of paddy fields and housing estates in Jono Oge village experienced liquefaction. There is mud vomiting and the movement of a number of soils, causing eroded areas and some of them experiencing hoarding Research aims to identify the chemical properties of soils affected by liquefaction. The study was conducted using the survey method, soil sampling was carried out by purposive sampling. Soil samples were taken on three categories of affected land: eroded land, landfilled land, and surrounding land that was not liquefied. The results showed that the areas affected by liquefaction in the three categories of land had a soil pH relative to the same criteria, namely neutral (pH 6.52-6.77). Then C-organic levels in both eroded and hoarding fields are moderate status (2.50-2.70%) and in non-liquefied lands is low status (1.52%), while N-Total all three have low status (0.12-0.19%). Sodium content is generally medium status (0.41-0.60 me/100g), Calcium is generally high status (11.88-13.42 me/100g) and Magnesium is generally moderately. This research was conducted after more than 2 years of liquefaction and the most affected soil chemical properties in the respected area is the increasing of C-organic content.


Introduction
The role of land for human life and livelihood is undeniable.Along with the increase in development activities, the need for land is increasing, while the existing land area remains and will not change, often causing conflicts over control and use which results in inefficient land use, increased land damage, and disruption of environmental sustainability [1].
Soil properties are very decisive in supporting plant growth and development, both chemical, physical and biological properties of the soil.The chemical properties of the soil include soil pH and the content of macro and micro nutrients.The nutrient content consists of macro nutrients and micronutrients and organic carbon.To determine the status of soil chemical properties on land that is experiencing liquefaction, research has been carried out in the form of a survey to take several soil samples and then an analysis of the chemistry of soil properties has been carried out to support the management process [2,3].
The phenomenon of liquefaction due to earthquakes is an event of loss of strength of loose sand layers due to an increase in pore water pressure due to receiving earthquake vibrations.Thus, liquefaction events will occur in large earthquake-prone areas composed of low-density water-saturated 1253 (2023) 012112 IOP Publishing doi:10.1088/1755-1315/1253/1/012112 2 sand deposits, and in areas where the movement of co-seismic surfaces exceeds their threshold values [2].Liquefaction is an event where the soil loses shear strength due to increased pore water stress as a result of a cyclic load (earthquake load) that is very fast and in a short time [1].
The liquefaction event resulted in the movement of a large area of paddy fields and housing in Jono Oge Village, accordingly, paddy fields was no longer formed because part of the land was eroded and shifted erratically.As a result of the shifting of a number of periods of soil resulted in the direction of the drainage flow not patterned, the soil surface was uneven and some parts formed a kind of hole.Uneven surface conditions and the absence of drainage directions to drain the surface flow when rain occurs are obstacles in the management of the land.Areas eroded by the soil layer are generally filled with sand and gravel.The presence of mud overflow and the movement of a large amount of soil period is alleged to affect the chemical properties of the soil, especially in the topsoil [3].
The purpose of this study is to determine the condition of soil chemical properties in the form of pH, Nitrogen, Organic Carbon, Natrium, Calcium, and Magnesium soil in relation to the criteria for the suitability of plant life needs.The usefulness of this research is expected to contribute information about some of the chemical properties of the soil as a result of liquefaction.It can also be used as a recommendation in the management of such land.

Research methods
This research was carried out from September to December 2020 in Jono Oge Village, Sigi Regency.The implementation of soil analysis was carried out at the Soil Science Laboratory of Agriculture Faculty, Tadulako University The tools used in this study are a GPS (Global Position System), machete, hoe, shovel, plastic bag, meter, camera, writing stationery, and a set of laboratory equipment.Meanwhile, the materials used in this study were soil, water, and several other chemicals used to analyze soil samples.
The method used in this study was a survey directly in the field, then continued with purposive sampling of soil samples at several points in accordance with the coordinate points determined deliberately in eroded areas, buried areas and areas that are not affected by liquefaction.After that, it is managed and analyzed the chemical properties of its soil in the laboratory.Soil samples were aired, sifted over a 2 mm sieve to further analyze the alkaline cation content with flame photometers for K and Na, and titration with EDTA for Ca and Mg.Furthermore, the data were analyzed descriptively based on the nutrient content standards.
Soil sampling at each site is carried out at a depth of 0-20 cm, and soil samples are taken using a drill, at each study site soil samples are taken as many as three points and each sample consists of composite soil.All samples are labelled according to the location of each collection location and then taken to the Soil Science laboratory of the Faculty of Agriculture which is then analyzed for the chemical properties of the soil studied.

Results and discussion
This study analyzed six soil chemical components: pH, C-organic, N total, Na, Ca, and Mg.Successively the results of the analysis were presented one by one as follows:

Soil pH
The pH results in each field of eroded land, hoarding land, and land that does not experience liquefaction are presented in Table 1 The results of the pH analysis in Table l can be seen that the soil acidification is neutral.In the liquefaction area has neutral criteria.In areas that are not affected by liquefaction, the pH criteria are also neutral.This is because the acidification measured using H20 is active acidification, while the pH of KCI measures potential acidification.KCI is able to measure the activity that exists outside the soil solution because K+ ions derived from KCI can be exchanged for H+ ions, while this does not apply to H20.Therefore, is better to use KCI instead of H20 because it is more accurate.The acidification that is exchanged at the actual pH is the H+ ion that is present in the soil solution, while the potential pH is a measured ion in addition to the soil solution as well as the soil giraffe complex.In the actual pH measurement, the pressing agent is H20 and the potential pH of the pressing agent is KCI.This KCI is able to release H+ ions in the soil giraffe into free H+.Meanwhile, H20 does not free much H + ions, so the measurement of potential pH of the number of H will be lower than the actual pH [5].
This information about soil pH is very important because it can be used as a clue that in the soil there can be certain elements needed by plants or can provide information that an element is excessively available in the soil that can poison the roots of plants [3].In addition, by knowing the pH of the soil, it can be used as a reference to determine the type of fertilizer that will be used to fertilize plants [6].

C-organic
The results of the C-organic analysis of soil in each land category, namely eroded land, stockpiling and land that does not experience liquefaction are presented in Table 2.  2 shows that the C-organic content in areas affected by liquefaction tends to be better, namely at medium levels (2.50-2.70%)and on soils that are not liquefied at low levels (1.52%).When liquefaction occurs a jet of pitch-black mud inundates the surface of the ground and then flows.This pitch-black sludge is alleged to contain high organic carbon.Organic carbon deposits in marshy soils can occur due to the accumulation of organic matter over a period of time [3,7].Black color in flooded soils such as irrigated rice fields is a contribution to the presence of organic matter derived from dead plants or vegetation [7,8].
In eroded location and hoarding has the same C-organic criterion, namely medium which content of 2.70 % for eroded land and 2.50 % for hoarding land.Meanwhile, areas that do not experience liquefaction has a low C-organic criterion content of 1.52%.It is suspected that the black sludge that was sprayed from underground during the liquefaction event of the C organic was quite high.C-Organic is a constituent of organic matter.Soil organic matter is complex organic compounds that are or have undergone a decomposition process, both in the form of humified humus and mineralized inorganic compounds [9].
The content of organic matter in C-organic form in the soil must be maintained no less than 2 percent, so that the content of organic matter in the soil does not decrease with time due to the process of decomposition of mineralization, during tillage the addition of organic matter must be given annually [6].

N-total
The results of the analysis of N total land in each land category, namely eroded land, hoarding, and land that does not experience liquefaction are presented in Table 3. Analysis in Table 3 shows that the N-Total content in the study has the same criteria, namely low which is eroded with a value of 0.12%, Hoarding with a value of 0.19%, and Control or land that is not affected by liquefaction which is 0.16%.
Nitrogen in tissues is a constituent component of various essential compounds for plants such as amino acids, proteins, and enzymes.The element N is useful in the division and enlargement of cells that occur in the apical meristem so as to allow the growth of shoots.Legume plants turned out during their growth to be able to hoard Nitrogen-bound results of free N-release symbiotically by involving certain bodies [10].

Na, Ca and Mg Levels
The results of the analysis of Na, Ca, and Mg on each land category, namely eroded land, hoarding, and land that does not experience liquefaction are presented in Table 4.In Table 4 shows that the results of the analysis of Na content in the affected and unaffected areas of liquefaction have moderate criteria (0.41 -0.60 me 100g -1 ).High concentrations of Ca are between 11.88 -13.42 me 100g -1 , and Mg in the range of 1.12 -1.53 me 100g -1 in the moderate category.The high content of Ca cations comes from the parent material, namely limestone deposits rich in Ca elements and the washing of bases is not as intensive as with areas with high rainfall, so the soil is still rich in these alkaline elements [11].Sodium in soils is most commonly found as an exchangeable cation (Na + ), soluble in groundwater but bound by the charge (electronegativity) of soil particles, especially clay minerals.Among the cations commonly found in the soil, Na is the most difficult to exchange ions [12] compared to other ions.Interchangeable cations play an important role in plant metabolism.Other forms of Na in soil are those associated with organic matter and the fractions of cations that are in the crystal structure of minerals.Sodium is particularly susceptible to leaching and the available soil sodium can be lost during the rainy season.Deeper plant rooting can aid sodium absorption into the soil layer under the plot tread.It is not possible to establish sodium reserves in the soil with repeated application throughout the year.High levels of sodium interchangeability can disperse clay particles resulting in damage or loss of soil structure.This is often seen during flood events caused by rising seawater.An unreal effect can also occur when the application of sodium is carried out on the soil so that it is tied to salt or to the fertilizer used.However, this can be addressed by the provision of lime [13].
Analysis of the ratio of sodium to Ca and Mg cations or Sodium adsorption ratio (SAR) in areas affected by liquefaction is generally still very ideal for plant growth environments [14], Based on SAR It appears that the Na content of the soil is still low and cannot be categorized as a sodic soil class (SAR > 13).The soil saltiness of the study area is still relatively low so it is safe for planting development [15].The data shows that the total Na + is still lower than the total cations of Ca + and Mg + .
During the rainy season or when irrigation water is available, dilution occurs, and dissolving part of the interchangeable Na will be washed with the water flow both horizontally and vertically.However, if the concentration of Na input is higher than the concentration that can be washed, the soil will absorb it so that there will be accumulations that increase the Na content in the soil [16].The main problem faced in the arid area is insufficient water available for washing or irrigation purposes [15].

Conclusion
-According to the data obtained, it can be drawn as follows: the areas affected by liquefaction that are eroded land and land that undergoes hoarding have a relatively stable soil pH on the same criteria as the pH of non-liquefied land soils, namely neutral.Then N-Total all three categories of land are of low status.-Specifically, organic C levels experienced slight differences with moderate status for both eroded and hoarding land compared to low status for non-liquefied lands.-The content of sodium (Na) is generally of medium status, and calcium (Ca) is generally of high status and Mg is of medium status.Sodium adsorption ratio (SAR) in areas affected by liquefaction is generally still very ideal (low).

Suggestion
Seeing that the chemical properties of soil on land affected by liquefaction do not experience chemical changes that are worrying in terms of the needs of plant growth and development, the land affected by liquefaction can be used for agricultural activities.
Annotation: S: Medium, T: High

Table 1 .
. Results of soil pH analysis at the liquefaction study site

Table 2 .
Results of soil C organic analysis at the liquefaction study site

Table 3 .
Results of soil N total analysis at the liquefaction study site

Table 4 .
Results of soil Na, Ca, and Mg analysis at the research site.