Analysis of potential soil degradation on agricultural land based on geographic information systems in Slogohimo District, Wonogiri Regency

Slogohimo District is one of the districts located in Wonogiri Regency with an area of 6.415 ha. Population growth in Slogohimo District has increased by 7,068 people from 2017 to 2022. The total population in 2022 is 53,403 people with the majority livelihood being farmers. Population increase will have an impact on increasing the demand for biomass. Land management that does not pay attention to conservation principles will cause changes in the soil’s basic properties and impact the biomass produced. About 84,91% of the land in Slogohimo District is used as agricultural land in paddy fields, moor, and plantations. The increase in population and the need for biomass, triggers more intensive processing of agricultural land which has the potential to cause soil degradation potential degradation. Based on these problems, it is important to carry out an assessment of the potential for degradation to agricultural land in Slogohimo District. The method used is overlaying thematic maps consisting of soil type maps, rainfall maps, slope maps, and land use maps through spatial data analysis based on Geographic Information Systems (GIS). The potential for soil degradation is obtained from the scoring results which refer to the standard criteria in the Technical Guidelines for Preparation of Soil Degradation Degradation Status Maps for Biomass Production. The results showed that potential degradation to the soil on agricultural land in Slogohimo District was classified into three classes by area or proportion of land, namely low class covering 1.558,08 ha, medium class covering 2.800,70 ha, and high class covering 919,93 ha.


Introduction
Slogohimo District is one of the districts located in Wonogiri Regency with an area of 6.415 ha.Population growth in Slogohimo District increased by 7,068 people from 2017 to 2022.The total population in 2022 was 53,403 people and in 2017 amounted to 46,335 people [1].Population growth will have an impact on increasing energy needs, especially biomass [2] .Land management that does not pay attention to conservation principles will result in changes in soil properties and will have an impact on the production of biomass [3].Biomass production is the result or forms of utilization of land resources to produce biomass, while the meaning of biomass is plants or their parts, namely flowers, 1314 (2024) 012108 IOP Publishing doi:10.1088/1755-1315/1314/1/012108 2 seeds, fruits, leaves, twigs, stems, and roots, including plants produced by agricultural activities, plantations, and forest plantations [4] Wonogiri Regency has the highest contribution to the agricultural sector among six surrounding regencies.[5].One of the land problems faced on agricultural land is the continuous cultivation of crops over a long period of time which will cause problems on land that is already critical [6].Slogohimo District has an area of 72.85 ha with an area of agricultural land in the form of paddy fields, moor, and plantations amounting to 52.85 ha.The percentage of agricultural land area to the area of Slogohimo District is 74.55%.Based on data from BPS Wonogiri in 2022, Slogohimo District produces food crops (rice, corn, cassava, and tubers), horticulture (shallots, chilies, cabbage, and tomatoes), and plantations (coconut, cocoa, and coffee).Various intensive soil processing and utilization can cause soil degradation in an area [7].Soil degradation is a change in the basic properties of the soil that exceeds the standard criteria for soil degradation for biomass production [8].
Some climatic factors, such as rainfall, erosion, and poor agricultural practices, such as continuous crop cultivation and excessive soil compaction along with biomass burning [9].Erosion will cause the loss of topsoil through water, wind or waterlogging [10].Land with higher slope will cause surface runoff and soil loss [11].Land use is also one of the factors that influence the occurrence of soil degradation due to erosion [12].In determining the level of soil degradation, there are several indicators in accordance with the technical guidelines for preparing soil degradation status map for biomass production issued by the Ministry of Environment in 2009 that are used to measure, including soil type, rainfall, land use, and slope [13].
Based on the description of the problems, the agricultural sector is a sector that has the potential to be developed to support the economy of the community in Slogohimo District.This research aims to identify sources of variability that have the potential to cause degradation to the soil and make recommendations for proper agricultural land management on agricultural land in Slogohimo District.The absence of studies on the analysis of potential soil degradation based on Geographic Information Systems (GIS) in Slogohimo District is a novelty in this research.

Research Site
This research was conducted from June to July 2023 in Slogohimo District, Wonogiri Regency, which consists of 15 villages and 2 urban villages, namely Padarangin Village, Watusomo Village, Sambirejo Village, Pandan Village, Made Village, Tunggur Village, Waru Village, Bulusari Village, Slogohimo Village, Gunan Village, Sedayu Village, Soco Village, Klunggen Village, Randusari Village, Karang Village, Sokoboyo Village, and Setren Village.Slogohimo District is bounded to the north by Magetan and Karanganyar Regency, to the east by Bulukerto and Purwantoro Districts, to the south by Jatiroto and Kismantoro Districts, and to the west by Jatipurno and Jatisrono Districts.The research focused on agricultural land in Slogohimo District, which includes paddy fields, moor, and plantations covering an area of 52.85 ha.

Research Method
The materials used to make the land unit map are thematic maps, namely administrative maps (Indonesian Earth Form Map scale 1: 25,000), soil type maps (Indonesian Earth Form Map scale 1 : 25,000 and Indonesian Center for Agricultural Land Resources Research and Development Soil Type Map scale 1: 25,000), land use map (Indonesian Land Shape Map 1 : 25,000 and Land Use Map of Wonogiri Regency 1: 25,000), slope map ((Digital Elevation Map EM (DEM) Map of Central Java 1 : 25,000), and rainfall map (Indonesian Landform Map 1 : 25,000 and Rainfall Map of Wonogiri Regency 1: 25.000).The method used to produce a map of potential soil degradation is overlaying thematic maps through Geographic Information System (GIS)-based spatial data analysis using ArcGIS 10.Based on the results of overlay through ArcGIS, two types of soil are andisols and inceptisols, four slope classes with a variety of slopes 1-8%, 8-15%, 15-25%, and 25-45%, rainfall 2000-2500 mm/year, land use consists of paddy fields, plantations, and moor.The four variability maps were overlaid and produced a land unit map of 18 points.The data on the land unit map was then matched and scored based on the Technical Guidelines for the Preparation of Soil Degradation Status Maps for Biomass Production 2009.The following are tables of potential soil degradation assessment criteria based on soil type, slope, rainfall, land use, and soil degradation potential class.

Potential soil degradation
Determination of the class of potential soil degradation is based on the summation of the weighting scores of each variability (soil type, slope, rainfall and land use).The potential soil degradation class was divided into five classes, from <15 to 45-50 (Table 5).The data obtained were then analyzed through the SPSS application using the 95% ANOVA (Analysis of Variance) test followed by Pearson correlation analysis (α = 0.05).Agricultural land in Slogohimo District has two types of soil, namely andisols and inceptisols (Figure 1).The andisols soil has a weighting score of 10, which is a very high potential for soil degradation and the inceptisols soil has a potential value of soil degradation that can be categorized as high with a value of 8.The soil type in the research location is dominated by inceptisols which is spread in almost all villages covering an area of 5.874.77ha, while the distribution of andisols soil is only in Setren Village covering an area of 1.413.1 ha.Land uses in the research location include paddy fields, moor, and plantations (Figure 4).The weighting score of paddy fields is 2 (low), plantations are 4 (medium), and moor has the highest score of 8 (high).The highest agricultural land use in Slogohimo District is paddy fields and the lowest is pasture covering 6.81 ha.
The slope on agricultural land in Slogohimo district are 1-8%, 8-15%, 15-25%, and 25-45% (Figure 2) which respectively have a weighting score of 3, 6, 9, 12, and 15.The slope class owned is four classes with a dominance of the 0-8% slope class which has very low potential, while the 25-45% slope class is high potential.The 0-8% slope class is spread in almost all villages, while the 25-45% slope class is mostly only spread in Setren Village, Padarangin Village, and Sambirejo Village.Rainfall on agricultural land in Slogohimo District has an average of 2000-2500 mm/year which is included in the medium class with a weighting score of 9 (Figure 3).Based on the overlay results of 4 variations map, resulting in 18 LMU (Figure 5).The results of the thematic map overlay (Figure 6), the total area of agricultural land that has the potential soil degradation is 5.278,71 ha with the PR.II (low) class of potential land degradation having an area of 1,558,08 ha which is spread in almost all villages, the PR.III (medium) class has an area of 2.800,70 ha which is partly spread in the north and south of the village, including Setren Village, Sokoboyo Village, Karang Village, Randusari Village, Karang Village, Made Village, Sambirejo Village, Pandan Village, Watusomo Village, and Padarangoin Village, and PR.IV class (high) has an area of 919,93 ha which is spread in Setren Village, Padarangin Village, Made Village, and Tunggur Village.
LMU 8 have a low soil degradation potential score 24 with the following land use of paddy fields, andisols soil type, and slope of 0-8%.Andisols has high organic matter content > 2%, dark color, and low volume weight < 0.9 gr/cm 3 [14].LMU 16 also have a low soil degradation potential score with the following land use of plantation, inceptisols soil type, and slope of 0-8%.Inceptisols have inadequate chemical properties for chili cultivation, coarse texture, and low nutrient content [15].Paddy fields and plantations have low soil degradation potential scores because they are generally located on relatively flat land.LMU 2 has a high soil degradation potential score of 39 with land use of moor, andisols, and slope of 25-45% located in Setren Village.Land with a high slope will be more easily degraded [16]  Based on the ANOVA test results, the slope is significantly affects to potential soil degradation (F-count= 10.188, P-value= 0.002).This value indicates that there is a significant difference in the potential for soil degradation in the sources of variability slope.The ANOVA test showed that land use (F-count= 2.050, P-value=0.163)and soil type (F-count= 1.011, P-value=0.387)are not significant to potential soil degradation.Pearson Correlation test results show that slope has a significant relationship (r=0.757) to the value of potential soil degradation, while land use and soil type do not have a significant relationship to potential soil degradation.Land use has a significant relationship with potential soil degradation.

Land Management Recommendations
Based on the results of the analysis that has been done, it shows that the determining factor of soil degradation is slope.Improper agricultural practices on sloping land will cause erosion, loss of soil fertility, and decreased crop yields [17].There are various kinds of land management that can be done to mitigate sloping land.Sloping land has the potential to experience a decrease in soil organic matter content along with reduced nutrient and soil water availability for plants, thus the addition of organic matter needs to be done [18].Providing organic matter in the form of compost and inorganic fertilizers in accordance with the recommendations and doses needed to improve soil fertility status [19].Organic matter has an important role in formation of soil structures and aggregates so that it will improve the physical condition of soil [20].Land management that can be done for sloping land is revegetating sloping land through agroforestry cropping patterns [21].Agroforestry is one of the culvitation systems that can prevent soil degradation [22] Mechanical soil conservation to minimize soil erosion is the creation of reverse slope beds, contour strip planting with grass or vetiver, and terracing [23].Terraces have supported conservation in intensive agriculture on land with steep slopes to reduce surface flow velocity and soil erosion [24].Land management that can be applied in the study area are revegetation on sloping land, addition of organic matter, and terracing to mitigate soil degradation.

Conclusions and Suggestions
The results show that the potential for soil degradation on agricultural land in Slogohimo District, Wonogiri Regency consists of three classes, namely PR II (Low) covering 1,558.08 ha (29.52%),PR.III (Medium) covering 2,800.70 ha (53.06%), and PR.IV (High) covering 919.93 ha (17.43%).The potential value of soil degradation is dominated by PR class III (medium) covering an area of 2,800.70 ha.Based on statisctical analysis, it shows that the determining factor of soil degradation potential is slope which is significantly related to the value of soil degradation potential (r=0.757).The more sloping or steep a land there is a difference land management so that it can be utilized as agricultural land.Land management that can be applied in the study area are revegetation on sloping land, addition of organic matter, and terracing to mitigate soil degradation.Soil sampling and laboratory analysis can be a further study in this research to present data that is appropriate to current conditions in the field.
4 and continued with scoring that refers to the standard criteria in the Technical Guidelines for the Preparation of Soil Degradation Status Maps for Biomass Production.Based on the results of overlay through 1314 (2024) 012108 IOP Publishing doi:10.1088/1755-1315/1314/1/0121083 ArcGIS, the following are soil type maps, slope maps, rainfall maps, land use maps, and land unit maps at the research location.

Table 1 .
Assessment of potential soil degradation based on soil types

Table 2 .
Assesment of potential soil degradation based on slope

Table 3 .
Assesment of potential soil degradation based on rainfall

Table 4 .
Assesment of potential soil degradation based on landuse

Table 5 .
Weighting index of potential soil degradation classification

Table 6 .
Assessment level of potential soil degradation in Slogohimo District agricultural land

Table 7 .
Potential soil degradation on Slogohimo District agricultural land

Table 8 .
ANOVA (Analysis of variance) test of potential soil degradation