Land suitability evaluation for elephant grass plant (Pannisetum purpureum) in Suka Maju Village, Malind District, Merauke Regency

Land suitability evaluation can be carried out to determine the level of suitability of elephant grass plants (Pannisetum purpureum). Information related to land resources is very important to determine livestock development programs, especially ruminants in a sustainable manner. This research aims to determine the actual land suitability class for developing elephant grass plants in Suka Maju Village, Malind District, Merauke Regency. This study used a survey method and soil sampling was carried out on two types of land, field and meadow. Data collection was carried out by direct observation, laboratory analysis, and data analysis. The data analysis technique to find out the sub-classes of land suitability is by matching the requirements for growing elephant grass with the quality and characteristics of the land according to The Technical Instructions for Land Suitability Assessment Guidelines for Strategic Agricultural Commodities Semi-Detailed Level 1:50,000 Scale in 2016. The results showed that the land suitability class for elephant grass on both land types (field and meadow) was classified as a marginal suitable class (S3) with limiting factor as base saturation (nr2) and K2O (na3). Basically the limiting factors in this study can be corrected by liming and adding organic matter.


Introduction
Merauke Regency is one of the regencies which has a very wide area reaching 46,791.63km 2 .Administratively, Merauke Regency has 20 districts, one of which is the Malind district with an area of 1,465.60 km 2 [1].Malind District is an area with a relatively flat topography, so it has high agricultural potential, especially for the cultivation of food crops and animal husbandry.One of the villages that has quite high potential for agriculture and animal husbandry in the Malind District is Suka Maju village.Most of the people of Suka Maju village work as farmers and breeders.Types of livestock cultivated are types of poultry and ruminants.The types of ruminant livestock kept are mainly cows and goats.The rearing system is still semi-intensive, namely by grazing on natural pastures, where cattle are allowed to graze freely while some livestock are tethered.This is one of the obstacles to increasing the productivity of ruminants.
One of the factors that causes failure in efforts to increase livestock productivity is the lack of feed available in an area.The low carrying capacity of feed which is not balanced with the livestock population results in low productivity, because feed is the largest input in the livestock system.One of IOP Publishing doi:10.1088/1755-1315/1341/1/012065 2 the livestock feed ingredients that is very necessary and of great benefit to the life and sustainability of the livestock population is forage which is commonly given to livestock from grasses and legumes (legumes) [2].
In tropical areas such as Indonesia, the production and quality of forage for livestock is generally still low.This is because the fodder grasses that are grown or planted are on soils that have a low fertility level.Therefore, the provision of high quality forage is a top priority in supporting the success of a livestock business [3].One important factor that plays a role in increasing livestock production at the farmer level is the availability of land for ruminant livestock feed.To get the availability of suitable land for animal feed can be done by knowing the suitability class, the potential of the land, and the inhibiting factors so that the productivity of ruminants can be increased [4].
Land suitability analysis is a commonly used method that can provide information about the actual condition of land and development opportunities so that it can assist in making decisions regarding the optimal use of land resources [5].In addition, land suitability evaluation is useful for knowing land suitability classes and limiting factors, so that appropriate management levels can be determined so that land can be used sustainably [6].
Increasing the productivity of ruminants can be carried out through the introduction of superior fodder grasses based on information on their potential suitability for land characteristics, especially in Suka Maju Village, Malind District.One type of superior grass as forage for livestock is elephant grass (Pennisetum purpureum).Elephant grass is a type of forage that has high nutrient and production value [7].Elephant grass has broad adaptability, deep root system, high growth rate, high biomass yield, so that elephant grass can grow and develop well even in drought conditions [8].
This research aims to determine the actual land suitability class for developing elephant grass plants in Suka Maju village, Malind District, Merauke Regency.

Method
This study used a survey method and soil sampling was carried out on 2 types of land, namely fields and meadow.The area of fields is 32.94 ha and meadow is 88.88 ha.The land use map in Suka Maju village can be seen in Figure 1.Soil sampling was carried out on fields and meadows.Soil sampling was done randomly.Soil samples were taken from the tilled layer (root layer) using a hand drill at a depth of 10 cm -30 cm.On field, soil samples were taken at 15 points while on meadow land at 9 points.Each point of the soil sample was taken as much as 250 grams.Each soil sample is labeled on the plastic sample packaging.The samples were then combined according to land type.Next, the soil sample is cleaned from plant root residues and mixed evenly in a container to obtain a homogeneous soil sample.Analysis of soil physical and chemical properties was carried out at the ICBB Laboratory (Indonesian Center for Biodiversity and Biotechnology) including soil texture, pH, C-Organic, N-total, K₂O, P₂O₅, CEC, salinity and alkalinity. .

Land suitability evaluatian
The actual land suitability class will be known by matching the land characteristics in the research area with the land suitability criteria for elephant grass (Table 1) [9].The collected data is then presented in tabular form and then analyzed descriptively of the relationship between various factors, especially limiting factors which really determine the land suitability class.The land suitability structure at the sub-class level includes classes S1 (very suitable), S2 (suitable), S3 (marginally suitable), N (not suitable) [10][11].

Result and Discussion
Elephant grass is a type of grass that has superior quality as animal feed.Based on the results of the analysis that has been carried out, Suka Maju Village, Malind District, Merauke Regency has the potential for developing animal feed plants (elephant grass).Matching results between land characteristics in fields and meadow with land suitability for elephant grass in Suka Maju village, Malind District, Merauke Regency (Table 2), land suitability for elephant grass is marginally suitable (S3) with the main limiting factor are base saturation (nr2 ) and K2O (na3).

Land characteristic
Land S3-nr2, na3 Cs = Class, SiCL = silty clay loam, CEC = cation exchange capability, S1 = highly suitable, S2 = moderately suitable, S3 = marginally suitable, nr2 = Base saturation, na3 = K2O Base saturation in field and grassland soils is classified as very low.Base saturation and pH are interconnected, where if the pH is low then the base saturation will be low and vice versa [12] [13] [14].The research area has a pH ranging from 4.9 -5.1 which is classified as acid.This condition is influenced by several factors, namely the soil layer which contains quite high levels of organic material on the surface of the soil which is mixed with soil mineral materials and undergoes decomposition by microbes which results in the formation of sulfide and acid.nitrate.When these acids get to the mineral parts of the soil, they do not provide H but displace the bases and increase the acidity of the soil [15].Low pH conditions will affect the availability of phosphorus and potassium nutrients [12].Soils with low base saturation and low pH can be toxic to plants [16].At low pH, phosphorus will react with iron and aluminum ions and form iron phosphate and aluminum phosphate.These two compounds cannot be absorbed by plants because they are difficult to dissolve in water [17] [18].High soil acidity is an obstacle that must be corrected, including increasing soil pH and reducing the high Al content in the soil.High Al content can directly poison plant roots so they cannot absorb soil nutrients, besides that it IOP Publishing doi:10.1088/1755-1315/1341/1/0120656 affects P and K nutrients which are not available for plants [19].At low pH and low base saturation, potassium is easily lost [14].The results of the research on both land types showed that the P content was classified as low and K was classified as very low.Neutral soil pH values strongly support high base saturation values, this is also supported by high levels of K-total cations [20].
High soil acidity is an obstacle that must be corrected.Lime has the ability to increase soil pH in acidic conditions because it contains the nutrient Ca.Increasing the pH value affects available P, increasing Ca2+ levels, and reducing Al-dd content.Liming can reduce Al-dd concentration, increase pH and increase P concentration [21].Application of dolomitic lime and compost is an effort to increase soil pH.Providing dolomite lime and compost is an effort to increase soil pH.Compost and lime will interact and cause an increase in organic compounds due to further weathering.Apart from that, the role of compost in increasing soil Ca-dd also influences the increase in soil pH by eliminating Al-dd in acidic soil.Providing compost fertilizer had a very significant effect on increasing the pH of H2O and Pavailable, and had a significant effect on base saturation, while dolomite lime had a significant effect on base saturation.The interaction of providing compost fertilizer and dolomite lime has a very significant effect on increasing the pH of soil H2O [22].When compost organic matter is added to the soil, some of the potassium will be fixed so that it becomes a form that cannot be exchanged.This equilibrium reaction will continuously cause some of the bound potassium to be released into a form that can be exchanged and then formed in the soil solution [23].The addition of organic material, apart from triggering an increase in the number of microorganisms in the soil, also stimulates the microorganisms in the soil to grow [24].Organic materials play a very important role in supporting sustainable plant productivity [25].

Conclusion
The land suitability class for elephant grass plants is marginal suitability (S3) for field and meadow in Suka Maju Village, Malind District, Merauke Regency.The limiting factors are base saturation and K2O.Liming and adding organic material (compost) are forms of effort that can be made to overcome these limiting factors.

Figure 1 .
Figure 1.Land use map

Table 2 .
Land characteristic and actual land suitability assessment of fields and meadow in Suka Maju