Characteristics of soil physical and chemical properties on Arabica coffee land in Bener Meriah Regency

Bener Meriah Regency is one of the Arabica coffee producing areas in Aceh Province. This Arabica coffee has been cultivating for years by the Gayo people with a continuous cultivation system throughout the year. Continuous cultivation for years causes a decrease in soil fertility in both physical and chemical properties, resulting in a decrease in coffee production. This study aims to determine the physical and chemical characteristics of the soil on Arabica coffee land in Bener Meriah Regency. The study used a quantitative descriptive method through land surveys and analysis of data in the field and analysis of soil samples in the laboratory. Observations were made on 15 Land Units Type (LUT) obtained from the overlay of elevation maps, slope maps, soil type maps and existing coffee plantation maps of Bener Meriah Regency. Parameters observed included soil structure, soil permeability, soil aggregate stability, soil pH, total and available P. The results showed that the soil structure was classified as crumb, soil permeability was slow to fast, soil aggregate stability was classified as unstable to rather stable, soil pH was acid to rather acid, P total was very low to very high, and P available was very low.


Introduction
Coffee is one of the plantation commodities that has an essential role in the economy of society in Indonesia.Coffee farming is a livelihood and the backbone of the economy of farming families in almost all villages in Indonesia.Coffee farming is a type of people's agricultural activity carried out by farmers, by combining factors such as nature, labor, capital, technology and management aimed at increasing production [1].Coffee farming in Indonesia involves many smallholder coffee farmers.It is one of the employment providers and a source of income for coffee planters and other economic actors engaged in cultivation, processing, and the marketing chain [2].
Arabica coffee (Coffea arabica L. ) is one of the commodities the Indonesian government currently prioritizes.Arabica coffee exports from Indonesia are primarily marketed to a particular market segment (specialty coffee) because the quality of the taste is unique and is popular with coffee lovers in the main consuming countries [3].Bener Meriah Regency is one of the Arabica coffee producing areas in Aceh Province.This Arabica coffee have been cultivating for years by the Gayo people with a continuous cultivation system throughout the year.Over the years, the use of cultivated land has caused a decrease in land fertility, both physical and chemical properties of the soil, resulting in a decline in coffee IOP Publishing doi:10.1088/1755-1315/1297/1/012034 2 production.According to [4], the productivity of Arabica coffee in Bener Meriah Regency is only 780-840 kg ha -1 year -1 , while the potential for Arabica coffee production in this area can reach 2,000-3,000 kg ha -1 year -1 .
The ability of the soil to act as a plant habitat and produce materials that can be harvested is primarily determined by the soil fertility level.Soil fertility is essential for coffee plants to survive and grow well.Arabica coffee productivity is influenced by internal factors, namely genetic conditions, as well as external factors influenced by the environment.One of the environmental influences is land suitability/land characteristics, which include soil fertility, both physical, chemical, and land morphology.According to [5], land has limitations as a natural resource consisting of soil and environmental conditions, so careful planning must be utilized appropriately and sustainably.Furthermore [6], the potential of the land is usually determined by the biophysical and environmental conditions of the land, such as climate, topography, soil properties (physical, chemical, and biological soil properties), hydrology, and vegetation.Using land under land potential ensures land quality is maintained and can optimize production.
The physical and chemical properties of soil are elements of land characteristics that influence coffee production.The soil's physical properties affect water availability in the ground, determine root penetration in the soil, the drainage and aeration properties of the soil, and the availability of plant nutrients.The physical properties of soil also influence the chemical and biological properties of soil.

Materials
The materials used in this research are administrative maps, existing coffee maps, soil type maps, altitude maps, slope maps, and materials needed for soil analysis in the laboratory.The tools that will be used are GPS (Global Positioning System), Munsell soil color chart, soil drill, hoe, machete, spade knife, plastic bag, rope, tape measure, camera, stationery, and other things needed in the field.

Methods
The method used in this research is a quantitative descriptive method through land surveys and analyzing data and information obtained in the field and from analyzing soil samples in the laboratory.This research has several stages, namely preparation, determining Land Map Units (LUT), and observing land morphology.Overlay of altitude maps, slope maps, soil type maps, and existing coffee maps of Bener Meriah Regency was carried out to obtain LUT.LUT is needed to determine the observation site and make it easier to take soil samples in the field.The overlay results obtained were 15 Land Map Units.The altitude at the research location consists of 800-1000 masl, 1000-1200 masl, 1200-1400 masl, 1400-1600 masl and 1600-1800 masl.The slope consists of 0-8%, 8-15%, 15-25%, and 25-40% with soil types in the order Andisol, Inceptisol and Ultisol.The research location map is presented in Figure 1.

Analysis
Soil samples were collected in the field and then analyzed in the laboratory.The soil physical property parameters analyzed were soil permeability and soil aggregate stability, while field observations were carried out for soil structure.The soil chemical properties analyzed were soil pH, total P, and available P. Data on the physical and chemical properties of the soil obtained were then analyzed descriptively.

Characteristics of the physical properties of soil
Soil physical properties are soil properties that influence the growth and production of coffee because they determine root penetration in the soil, the soil's ability to hold water, soil aeration, soil drainage and the availability of nutrients in the soil.The results of the analysis of the physical properties of the soil at the research location can be seen in Table 1.
Table 1 shows that the soil structure on coffee fields in Bener Meriah Regency is crumb.This crumb structure is caused by the accumulation of litter originating from Arabica coffee plants, shade plants, and annual plants planted between coffee plants, which are a source of organic material.The presence of organic material will provide a crumbly soil structure.According to [7], litter plays an essential role in a sustainable coffee plantation system because it is related to suppressing soil erosion and nutrient cycling.Shade trees are the primary litter producers and suppliers of organic material in coffee plantations through leaf fall and pruning.In the coffee agroecosystem, litter is produced by mechanically controlled shade trees, coffee trees, and ground cover weeds, which restore and recycle nutrients together.
Soil permeability ranges from 0.51 cm hour -1 (slow to medium) to 24.44 cm hour -1 (fast) due to crumbly soil structure.A crumbly soil structure can allow more water to pass into the soil.According to [8], soil with a crumb structure has good drainage and aeration conditions, making it easier for the plant root system to penetrate and absorb nutrients and water, resulting in better growth and production.Aggregate stability is one of the most important physical properties of soil, which indicates soil quality and the soil's ability to resist erosion.Table 1 shows the soil aggregate stability at the research location is 29.09 -66.37 (unstable -rather stable).Unstable aggregate will result in the soil structure being easily destroyed due to the impact of raindrops.The destruction of soil aggregate will cause the soil pores to be blocked by crushed soil aggregate particles so that the soil will be quickly eroded.The stability of soil aggregates depends significantly on the type of soil.Arabica coffee fields in Bener Meriah Regency are generally located in sloping areas and are dominated by Andisol and Ultisol soil types [9].According to [10], Ultisol soil has aeration pores and a low stability index, causing the soil to become compacted and sensitive to erosion quickly.Andisol is soil with high total porosity, loose consistency, less plastic, and not sticky, and is porous with low bulk weight and high-water holding capacity.The aggregate structure is relatively weak with spongy lumps (ped), so it is easily destroyed.

Characteristics of the chemical properties of soil
If coffee plants lack one of the nutrients they need, this can result in stunted growth and production, so their productivity will also be less than optimal.The results of the analysis of soil pH, total P, and available P at each LUT can be seen in Table 2.
Table 2 shows the soil reaction (pH) on Arabica coffee fields in Bener Meriah Regency, ranging from 5.19 -6.08 (acid to rather acid).The low soil pH on Arabica coffee land is due to the application of inorganic fertilizer to Arabica coffee land.Using chemical fertilizers tends to reduce soil pH because these fertilizers will dissolve, thereby contributing to soil acidity.Urea dissolved in the soil will react with water and produce carbonic acid (H2CO3), which can lower the soil pH.It is in line with the opinion of [11] that prolonged application of nitrogen fertilizer to the soil results in increased nitrification reactions, releasing hydrogen ions so that the soil pH decreases.In addition, the very intensive level of leaching due to high rainfall causes the soil to react with acid, and base saturation is low.
The nutrient P is the second essential element after N, which plays a vital role as a constituent of high-energy compounds and is involved in photosynthesis, nutrient uptake, and plant development.Table 2 shows total P ranges from 5.52 -160.08 mg100g -1 (very low to very high).The high total P is due to additional P from inorganic fertilizer.In contrast, the low total P in Arabica coffee fields is considered low in P reserves from soil minerals because some farmers only use organic fertilizer as a P source.Besides that, it is also influenced by high bulk so that P compounds experience leaching.According to [12], of 91 coffee farmers interviewed on Arabica coffee fields in Bener Meriah Regency, 82.42% used inorganic fertilizer, and 17.58% used organic fertilizer.Furthermore, [13] high rainfall in tropical regions results in poor soil P reserves because many of these P compounds experience leaching along with soil development.Table 2 also shows that soil available P in Arabica coffee fields ranges from 0.90 -8.20 mg kg -1 (very low).Low P availability does not meet the nutrient needs of coffee plants.In Andisol, P is adsorbed by allophane minerals, whereas in Ultisol, the P element is fixed by Al-P and Fe-P so that P becomes unavailable.According to [14] , the high solubility of aluminum (Al) and iron (Fe) in Ultisol causes P to be fixed to form Al-P and Fe-P bonds so that P becomes unavailable to plants.Only 10-20% of the P applied to the soil can be used by plants.Andisol is soil formed from volcanic materials, dominated by the mineral allophane.This mineral can bind P so that P is not available to plants.

Conclusions
Arabica coffee fields in Bener Meriah Regency have soil physical characteristics, namely the soil structure is classified as crumb, soil permeability ranges from 0.51 cm hour -1 (slow to medium) to 24.44 cm hour -1 (fast), the soil aggregate stability ranges from 29.09 -66.37 (unstable -rather stable).The characteristics of soil chemical properties, namely soil pH ranges from 5.19 -6.08 (acid-rather acid), total P ranges from 5.52 -160.08 mg100g -1 (very low -very high), and available P ranges from 0.90 -8.20 mg kg -1 (very low).

Figure 1 .
Figure 1.Map of research locations in Bener Meriah Regency

Table 1 .
Soil structure, soil permeability and soil aggregate stability at the research location