Land suitability study for the development of rice production in Moruku Village, Papua Pegunungan Province to support food security

Yahukimo Regency is one of the districts in Papua Island which has high food insecurity. The staple food of the local community is generally tubers. However, changing consumption patterns from tubers to rice is one of the challenges and problems for local governments to ensure the sustainability and safety of food ingredients. The purpose of this study was to determine the chemical and physical quality of the soil in the area of food crop cultivation development, as well as engineering recommendations for the development of rice cultivation technology based on the results of soil quality analysis in the study area. The research was conducted in Dekai District, Yahukimo Regency using a descriptive qualitative research approach using an experimental method. Analysis of the physical and chemical properties of the soil was carried out at the Bogor ICBB Laboratory. The results showed that the organic C content in the soil was included in class S1, meaning it was suitable for rice cultivation. However, the level of acidity and indications of levels of Copper (Cu), Iron (Fe), and Zinc (Zn) are very high. While the results of nutrient analysis available on the parameters Total N, P2O5 and K2O are all included in class S1, meaning that the nutrients available in the soil are suitable for the development of lowland rice cultivation. For this reason, it is suggested that technological engineering be carried out, namely with a soil washing system on agricultural land, applying dolomite lime, using organic fertilizers, and selecting varieties that have a level of adaptation and tolerance to high acidity. What is novel in this study is the chemical and physical properties of the soil which can be further identified as an effort to determine the potential for new natural resources in the research area.


Introduction
Food insecurity is a condition of insufficient food experienced by a region, community or household, at a certain time to meet physiological needs standards for growth and public health [1].One of the areas in Indonesia that is included in the food insecure area is Yahukimo Regency.Based on the 2020 National Food Security Agency's annual report, Yahukimo ranks 412 out of 416 districts in Indonesia.
Yahukimo Regency, which is located in one of the regions of the Province of Papua Pegunungan, is following up on the PEN program by realizing food self-sufficiency in the mountainous areas.Yahukimo Regency is located in the La Pago region with a population of ± 181 thousand people spread across 51 districts.One of the strategic issues in development at Yahukimo is sustainable food security.With all the potential that Yahukimo Regency has, there is a strategic issue that needs to be addressed wisely, namely the issue of food insecurity.The food insecurity of the people in Yahukimo is very important because 90% of their food needs are supplied from outside the region, namely from Jayapura, Timika and Merauke with irregular access to transportation.
In response to this, the local government of Yahukimo Regency is committed to creating Yahukimo Mandiri in terms of food by establishing a program for cultivating food crops, namely rice and corn, which will be integrated with livestock and fisheries businesses.To realize this, one of the factors that must support the food crop cultivation program at Yahukimo is the suitability of the land in terms of the chemical properties of the soil considering that the growing requirements for lowland rice cultivation must be met, especially the quality of the soil so that productivity can be good.Soil and plants have a very important reciprocal relationship.Plants absorb water, nutrients, and more from the soil.Plant excretion results into the soil.Nutrients absorbed by plants are in the form of macro nutrients and micro nutrients [2].Darmawijaya (1990) in [3] explained that the nature of the soil in a field is very decisive in supporting the growth and development of plants, both the physical, biological and chemical properties of the soil.Soil physical properties include texture, structure and soil permeability.Soil chemical properties include soil pH and nutrient content.Nutrient content, consisting of nitrogen, phosphorus, potassium and organic matter.Soil biological properties include microorganisms that decompose organic matter in the soil.There needs to be an analysis of soil properties to support plant productivity and community welfare.
Based on the above empirical facts, in order to support and see the level of land suitability for food development in Yahukimo, it is necessary to conduct a land suitability study and strategy for the development of a food production center area in Moruku Village, Dekai District, Yahukimo Regency, Papua Pegunungan Province.For this reason, the aim of this study is to determine the chemical quality of the soil in the area of food crop cultivation development, as well as engineering recommendations for the development of lowland rice cultivation.

Methodology
The research was conducted in the field and laboratory.Field research was conducted in Moruku Village, Dekai District, Yahukimo Regency, South Papua Province to observe land conditions and take soil samples.Furthermore, the research was continued at the ICCB Laboratory.Based on several parameters of soil chemical properties which are the benchmarks, namely pH H2O, C-organic, Total Nitrogen, available Phosphorus (P2O5), Potassium K2O, Total Iron (Fe), and Manganese (Mn), and Cation Exchange Capacity (CEC), Saturation of base (NH 4-Acetate 1N pH 7) P2O5 (Olsen), K2O (HCl 25%) and C-organic.Materials and tools used in the field, namely, hoes, shovels, plastic bags, tape measure, label paper and stationery.The research was conducted for 2 months, from September to October 2022.

General picture of the research location
The physical and chemical properties of the soil are distinguished by the type of soil.In general, based on the parent material, the soil is classified into 2, namely mineral soil and organic soil.Mineral soils are formed from the results of the development (genesis) of the parent material which is formed from the weathering of rocks.Organic soil (peat) or Histosol is formed from organic parent material as a result of anaerobic weathering of organic matter [4].Most of the area of Yahukimo Regency, Highlands Papua Province, consists of alluvial, lithosol, podzolic and metamorphic rocks as part of the Pacific plate which is pushed by the Baltic embankments.The location for the development of the food production center area for Yahukimo Regency will be implemented in Moruku Village which is included in the valley area category.In the valley area there is an alluvial soil type, which is usually characterized by low levels of organic matter, moderate to high base saturation with absorption capacity, low permeability while the sensitivity of the soil to erosion is very small.The land system in Moruku Village, Dekai District, Yahukimo Regency, South Papua Province is predominantly classified as the Timika land type (TMK).In this land system dystropepts, entropepts, and tropofluvents are common, meaning the presence of inceptisols and entisols that form in alluvial loamy or clay-like deposits.The soil in Dekai City's land is dry (sand, onshore sand dunes) and sedimentary.There is a layer of sirtu (sand and rock) at a depth of >2 m below the surface.In addition, data on the land system states that between 101 -150 cm depth there is mineral salts/minerals.Soil types in Yahukimo are dominated by 4 types of soil, namely organosol/alluvial soil, red-yellow hydromorph gray pedzolic, red-yellow rensia pedzolic, and brown pedzolic/padsol/litosol rensia.Meanwhile, in Dekai, as an area to be developed, the food center area development program is dominated by red yellow hydromorph gray pedzolic soil types, where pedzolic soil types originate from quartz sand rock, podzolic soils are spread over areas with wet climates without dry months, and have a low rainfall.rain that is more than 2,500 mm/year.Podzolic soils have a loamy to sandy texture, low to medium fertility, this type of soil has a red color and is dry.While the soil type of hydromort gray soil itself is more influenced by local factors, namely topography in the form of lowlands or basins, where this type of soil is almost always flooded and this soil has a gray to yellowish color.

Soil chemical analysis results
Results of analysis of soil chemical properties on soil samples taken on land developed for food crop production center areas by the Regional Government of Yahukimo Regency, Papua Pegunungan Province.In the observation indicators, namely pH H2O, C-organic, Total Nitrogen, available Phosphorus (P2O5), Potassium K2O, Total Iron (Fe), and Manganese (Mn).The results of the analysis conducted in the laboratory are presented in Table 1.  1, shows that the inhibiting factors for soil fertility based on analysis of the chemical properties of the soil at the activity location consist of soil pH, total iron (Fe), and manganese (Mn).The soil pH at the activity site is slightly acidic around 5.8 -6.04 with a potentially very acid pH of 4.03.On acid soils (pH <6.5) will be followed by a high manganese (Mn) content [2].Soil acidity can be used as an indication of the N element in the soil because it is a limiting factor for soil fertility [3].Total iron (Fe) based on Technical Guidelines for Soil Chemistry by the Soil Research Institute, Bogor 2009, is classified as very high > 53 ppm/mg/kg, while elemental manganese (Mn) > 23 ppm/mg/kg is also in the very high category.Mn acts as an activator of enzymes, including phosphate transfer enzymes and enzymes in the Krebs cycle.The element Mn is also important in oxidation-reduction reactions, metabolism of N, chlorophyll and carbohydrates [2].The base saturation in the study area is classified as low to very low, around 17 -45%.This low base saturation results in low nutrient availability and CEC, namely K + elements around 0.18-0.46cmol/kg, Na + around 0.06-0.13cmol/kg, and Ca + around 1.24-7 .15cmol/kg.

Cation exchange capacity.
Laboratory test results showed that the CEC value for Sample Point 1 was 16.98 cmol/kg, Sample Point 2 was 11.93 cmol/kg and Sample Point 3 was 21.09 cmol/kg.The interpolation of the three sample points resulted in 2 suitability classes for the irrigated lowland rice commodity, namely class 1 covering an area of 323.19 ha or 88.7% and class S2 covering an area of 42.6 ha or 11.6%.This indicates that clay minerals in the low land.This is in line with the study [5] that a high CEC clay content indicates a decreasing level of soil fertility.

The base saturation.
Base saturation in paddy fields is categorized as moderate to low.The results of sample point 1 were 17%, sample point 2 was 17% and sample point 3 was 45%.The results of the interpolation and reclassification obtained that the paddy fields were divided into 2 classes, S2 and S3.The following is the area and percentage of each base saturation presented in Table 2.

C-Organic.
The Organic C content of the three sample points was very high, with a range of 4.44 -9.08, this value was far above the S1 standard of >1.2%.So that the entire rice field area is categorized as S1 class.

Nutrients Available.
Land suitability class can be viewed from 3 parameters including Total N, P2O5, and K2O which are explained as follows: a. N Totals Laboratory test results showed that Sample Point 1 had a Total N content of 0.36%, Sample Point 2 was 0.26 and Sample Point 3 was 0.41.After interpolation, the three of them entered into the S1 class, which was a moderate percentage of 0.21 -0.5.

b. P2O5 Available
The P2O5 analyzed in this mapping is Available P2O5, with the lowest value of 21.2 mg/kg at Sample Point 2, placing the P2O5 content in class S1, using either the Olsen method or the Bray method.

c. K2O
For the K2O parameter, the results obtained were more diverse.It was known that sample point 1 was 15 mm/100g, sample point 2 was 164 mm/100g and sample point 3 was 32 mm/100g.with a fairly high variation in value between sample point 1 and sample point 2, resulting in 3 different classes.The distribution of land area based on K2O parameters is presented in Table 3.  [6].Meanwhile, Mn plays an important role in protein synthesis, and helps the utilization of N in plants.For this reason, iron and manganese should not be excessive or lacking because it will greatly affect the results to be achieved.Iron (Fe) and Manganese (Mn) poisoning occurs in various types of soil, but generally occurs in paddy soil with continuous flooding during plant growth.The general characteristics of sites contaminated with Fe are poor drainage and low macronutrient content.In addition, Fe poisoning is a complex physiological symptom caused by plant conditions including physical, nutrient, physiological, and soil conditions that contain excessive Fe, but Fe and Mn poisoning can occur in soils with a pH range of 4-7 [6].Therefore, Fe and Mn poisoning are the main problems in newly opened rice fields, tidal fields, and paddy fields in the basin area.For Fe poisoning in agricultural land it is indicated because the land is new opening land [7].Iron poisoning can occur in the vegetative and generative phases.During the vegetative phase, poisoned plants are characterized by being dry and abnormally tall.The dry weight of the plants also decreased and the tillers were much reduced and the chlorophyll was low which affected the quality of plant growth.
Factors that cause iron poisoning occur in paddy fields and swamps.Starting from the high concentration of iron in the soil (250 ppm to 550 ppm), the high concentration of iron in plants (300-500 ppm), poor drainage, low organic carbon (organic fertilizer) content.Immature, acidity level (low pH) to nutrient deficiency or imbalance.
The risk of iron poisoning is highest during the dry season due to high water acidification as a result of low water reduction and remineralization of Fe content due to low oxidation.Soils that tend to cause Fe poisoning are: poorly drained soils that receive water from more acidic soils; kaolinitic soils with little available P and K; alluvial or colluvial acid clay soils; light acid sulfate soils; application of undecomposed organic matter in large quantities; and lowland or upland acid peat soils.
Symptoms of Fe poisoning and its effect on growth, namely: the occurrence of small brown spots on the lower leaves starting from the tip, or the entire leaf is reddish yellow to brown, besides that there is a black coating on the root surface; and this iron poisoning appears after 3-4 weeks after planting and 8-9 weeks after planting.A reddish color appears from the old leaves and then the plant becomes stunted and the roots become thick, rough and short [8].
Prevention of Fe poisoning includes: planting lowland rice varieties that are resistant and strong against iron (Fe) levels, as disclosed by [2]; in temperate climates by direct seed sowing [9], (coating seeds with oxidant, e.g.Ca Peroxide, 50-100% seed weight) to improve germination and growth; with water management [9], by using intermittent irrigation and avoiding continuous flooding in poorly IOP Publishing doi:10.1088/1755-1315/1253/1/0120096 drained land containing high concentrations of Fe and organic matter; fertilizer management, namely by balancing NPK or NPK and lime fertilization to avoid nutrient stress; provide lime for acid soils, and do not apply excessive organic matter to soils containing a lot of Fe and organic matter or when drainage is poor; soil management by cultivating dry soil after rice harvest to increase Fe oxidation during the fallow period; apply additional K, P, Mg fertilizers; mix lime in topsoil to raise soil pH; and do drainage in the middle of tiller formation (25-30 HST/HSS, don't flood it but keep it moist for about 7-10 days to improve oxygen supply during tiller formation.Good water management is one thing that can be done to reduce Fe levels in cleared land new [7] and provide organic fertilizer, provide chemical fertilizer, provide lime, provide salt and inundate the land [8].
Organic farming systems and land optimization are highly recommended in the production of food crops in Papua in general, to support reducing carbon emissions from the land-based development sector and agricultural waste from the use of chemical fertilizers.Increasing the people's economy with an agricultural cultivation system as a land-based mitigation strategy [10][11][12][13]

Conclusion
The plan to develop a food production area in Yahukimo Regency, Papua Pegunungan Province, will be realized in Moruku Village, Dekai District.Based on the land suitability analysis of the soil samples taken in the cultivation area, it was concluded that the soil quality is based on the suitability of nutrient retention, that the Cation Exchange Capacity (CEC), H2O pH, and C-Organic in the lowland rice development land in Moruku Village are in the S1 class or very high.appropriate, base saturation is included in class S2 and S3 or appropriate but technological engineering is still needed.As for available nutrients, namely N Total, P2O5, it is included in class 1.As for the K2O content in the land at 3 soil sample points taken, it is included in 3 different land classes, namely class S1, S2, and S3.So that it is still necessary to reduce K2O levels in several areas for the development of lowland rice cultivation in Moruku Village.For the conditions of soil pH, Fe and Mn it was concluded that the potential pH was very acidic and the elements Fe and Mn were in the very high category, namely > 53 ppm/mg/kg and > 23 ppm/mg/kg.Based on these conditions, several technological engineering can be carried out to neutralize soil pH and reduce Fe and Mn elements in the soil.

Recommendation
Some recommendations based on the findings at the research location that for the development of lowland rice cultivation in Moruku Village, Dekai District, Yahukimo Regency, Papua Pegunungan Province are as follows: 1 Revitalizing irrigation networks as well as building dams and technical irrigation systems; 2 Optimizing the land by reducing Fe (iron) and Mn (manganese) levels by applying organic fertilizer, leaching and applying lime to increase pH; 3 Cultivated food crops should be adapted to the suitability of the land and the natural chemical content of the soil in order to facilitate the plant maintenance phase in order to produce maximum crop productivity.

Table 1 .
Results of soil chemical analysis in the field.
Suitability of nutrient retention on agricultural land in Moruku village which is presented in Table

Table 2 .
Data on the area and percentage of land suitability for lowland rice based on the level of base saturation.
3.2.3.pHH2O.The pH level of H2O in paddy fields is categorized as S1 or very suitable.Based on the test results in the laboratory, the highest score was 6.04 at Sample Point 3 and the lowest score was 5.82 at Sample Point 2. All of these values are still included in class S1.

Table 3 .
Data on land area and percentage of suitability of K2O parameters for the development of irrigated paddy fields.
3.2.4.2.Content ofIron (Fe)and Manganese (Mn).Iron (Fe) and Manganese (Mn) are essential nutrients for all plants.Iron (Fe) has an important role in biological processes such as activating enzyme systems, chlorophyll synthesis, and oxidation-reduction in respiration