Comprehensive Assessment of Land Criticality and Agroforestry Suitability in the Upper Cikeruh Sub-Watershed, a Degraded Priority Area in Indonesia

Abstract

The Upper Cikeruh Sub-watershed, part of the Citarum Basin and designated as one of Indonesia’s 15 Super Priority Watersheds, is facing severe degradation due to land use changes and deforestation, particularly in the upstream areas. This study assesses land criticality and suitability for agroforestry to guide sustainable land management practices. A semi-quantitative approach was used to evaluate land criticality through a scoring method, while qualitative match table analysis determined land suitability for specific agroforestry crops. Fieldwork was conducted in the upstream areas of the Cikeruh Sub-watershed, covering the administrative areas of Bandung and Sumedang. The results showed that most areas showed critical land conditions, with productivity identified as the most limiting factor, with scores as low as 30. The agroforestry suitability analysis showed that specific land mapping units (LMUs A, C, D, E, F, and N) were marginally suitable (S3) for crops such as legumes, upland rice, corn, soybeans, and chilies, with the main constraints being slope steepness and soil pH. This study highlights the urgent need to implement agroforestry practices as a restoration strategy in degraded landscapes. The findings provide actionable recommendations to improve land productivity while promoting sustainable watershed management in one of Indonesia’s critical areas.

1. Introduction

Environmental sustainability and global agricultural productivity face the threat of land degradation. This has been a long-standing problem in Indonesia, especially in the upstream areas of river basins, such as the Upper Cikeruh Sub-watershed. This sub-watershed is located in the Citarum Basin, which includes 15 super-priority watersheds in Indonesia. This condition occurs due to deforestation, land-use changes, and unsustainable agricultural practices [1]. The expansion of residential areas, infrastructure development, and monoculture farming systems in hilly areas significantly impact the reduction of vegetation cover, soil stability, and water retention capacity. In addition, uncontrolled agricultural expansion activities with excessive tillage, overgrazing, and excessive use of chemical fertilizers impact the rate of soil erosion, soil fertility, and land productivity. Deforestation in the Upper Citarum watershed produces surface runoff and increases erosion in the catchment area [2]. The erosion rate in the Upper Citarum watershed increased from 62.04 to 137.66 tons ha⁻¹ yr⁻¹ from 1990 to 2013 [3]. Around 18.6% of the area of the upstream Citarum watershed is in the non-tolerable erosion class, and it is estimated that the land area in the non-tolerable erosion class in the upstream Citarum watershed will increase to 21.5% by 2029 [4].

Land degradation in the Cikeruh Hulu Sub-watershed is an environmental problem and a socio-economic challenge. Most people use the river basin as a source of clean water for agriculture, households, and industry, making them very vulnerable to declining land productivity and resource availability [1,5,6]. The government has issued a series of programs and policies to rehabilitate the watershed. The phenomenal program is the Citarum Harum Program through Presidential Regulation Number 15/2018 concerning the Citarum Watershed Rehabilitation Program. This national program controls damage and pollution and aims to restore the watershed [7]. The efforts currently being made have not yet achieved optimal results. One of the sustainable land management strategies that can ensure the resilience of local livelihoods is agroforestry.

Agroforestry is a land-use practice that integrates woody vegetation with crops or livestock [8]. This system has been widely recognized as a practical approach to restoring degraded land, especially in tropical areas such as Indonesia [9]. Previous studies have shown that agroforestry systems in tropical and temperate climates can reduce surface runoff and nutrient availability by an average of 58% and 49% compared to conventional systems [10]. In addition, this system is also friendly to climate change because it can increase carbon sequestration and reduce CO₂ emissions [11]. Although it has potential, the success of agroforestry is highly dependent on understanding the suitability and criticality of the land and the socio-economic conditions of the target area [12].

Exploration of the potential of agroforestry as a sustainable land management strategy in the Cikeruh Hulu Sub-watershed is fascinating. However, studies on assessing land criticality and suitability for agroforestry in this area are still minimal. Previous studies have emphasized the importance of spatial assessment by integrating biophysical and socio-economic parameters to guide land-use planning and policies [13]. Seeing this gap, this study aims to assess the level of land criticality and its suitability for agroforestry as a comprehensive guide for sustainable land management practices. These findings will provide information on sustainable land-management practices and recommendations for policymakers and stakeholders.

2. Materials and Methods

2.1. Description of the Study Area

2.1.1. Location

This research was conducted in the Cikeruh Sub-watershed upstream area (Figure 1a). Administratively, the Cikeruh Sub-watershed research locations are Bandung Regency and Sumedang Regency. The northern and southern study locations are at coordinates 6°48′41.50″ S–107°45′37.50″ E and 6°59′46.50″ S–107°40′57.50″ E, respectively, which translate to the Subang Regency and Rancaekek District border, and the western and eastern boundaries are at coordinates 6°53′55.50″ S–107°39′27.50″ E and 6°54′41.50″ S–107°48′55.00″ E, respectively, which translate to the Bandung City and Sumedang City border. According to Oldeman’s climate classification in the Cikeruh Sub-watershed, the rainfall type is C2 for the Bandung area and B2 for the Sumedang area.

2.1.2. Topography

The upstream area of the Cikeruh Sub-watershed is at an altitude of 900–1500 m above sea level (Figure 1b). In the northern and eastern regions, the landscape of the Cikeruh Sub-watershed tends to be hilly with a reasonably steep slope (8–15%) and steep (15–25%), and each level has a percentage area of 19% and 20% of the Cikeruh Sub-watershed land area. In the southern and western regions, the landscape of the Cikeruh Sub-watershed tends to be gentle (0–8%), with an area of 40% of the total Cikeruh Sub-watershed.

2.1.3. Land Use

Land use in the Cikeruh Sub-watershed upstream area includes conservation areas, agricultural land, and residential land (Figure 1c). The distribution of settlements in this area forms a scattered pattern (radial), in which the settlements form small units used as centers for activity. The scattered pattern is a pattern that is often found in highland areas because of the varying relief levels. The northern and eastern areas, such as dry fields and plantations, are used as agricultural land. Dry fields are dry land agricultural areas usually planted with short-lived crops. Crops planted in dry fields in this area include shallots (Allium cepa var. Aggregatum), cabbage (Brassica oleraceae var. Capitata), chilies (Capsicum annum L.), and cassava (Manihot esculenta). Plantations are large agricultural areas usually used to plant long-lived crops. The main crop planted on plantation land is coffee (Coffea arabica).

2.2. Land Survey

Delineation activities were carried out before the primary survey to select several parameters of the Land Map Unit (LMU) at the research location so that the research carried out was by the desired objectives. The parameters selected were slopes with a gradient of 0–40% (Figure 2a) and the use of dry land and plantation agriculture (Figure 2b). The white area in Figure 2a indicates the area with slope delineation > 40%. Then, these parameters were converted into a working map to determine sample points (Figure 2c).

Sampling was carried out using a purposive random sampling system, namely a method of taking soil samples by transect on land units and information in the field by purposive sampling. The number of sample points in one LMU is determined proportionally to the survey level. This study carried out survey activities at a semi-detailed level with a working map scale of 1:50,000. The number of sample points in one LMU is determined from the area divided by the average observation density at the semi-detailed level, which is 50 ha or 500,000 m [14]. The calculation of the determination of the number of samples is carried out using the formula:

Proportional Sampling = Area (m²):observation density (m²)

Research sampling was conducted at 37 points with a distance between observations of 500 m between points in one LMU (Figure 2d). Soil samples were collected as individual samples from the topsoil (0–30 cm). Disturbed soil samples were taken using a manual drill. Soil sampling was performed by rotating the manual drill clockwise until it reached the desired depth. The drill was then slowly withdrawn, and the trapped soil was put into a sealed plastic bag labeled according to the sample code.

2.3. Land Criticality Analysis

Determining land criticality refers to the criteria for critical land in agricultural cultivation areas by Permenhut number P.32/Menhut-II/2009, including productivity, land management, erosion potential, and slope. Data on productivity and land management were obtained from interviews with farmers. The erosion hazard value was estimated by determining the number of tons per hectare of soil lost to erosion per year (tons ha⁻¹ yr⁻¹) and the depth of the soil solum. In contrast, the slope value was calculated by calculating the percentage of slope gradient. The classification of critical land levels was obtained based on the number of critical land parameter scores, as shown in

Table 1. Critical land level processing.

Land Criticality Level
Slope (20%)		Productivity (50%)		Erosion (20%)		Management (10%)
Class	Score	Class	Score	Class	Score	Class	Score
Flat	5	Very good	5	Light	5	Good	5
Sloping	4	Good	4	Medium	4	Medium	3
Somewhat steep	3	Medium	3	Heavy	3	Bad	1
Steep	2	Bad	2	Very heavy	2
Very steep	1	Very bad	1

. The classification results can then be presented as a map [15].

2.4. Land Suitability Level Analysis

The determination of land suitability was carried out using the matching method between land characteristics and the growing requirements of commodities by referring to the land suitability criteria [16]. The analysis was carried out on soil samples from each point by analyzing climate criteria (rainfall), oxygen availability (drainage), rooting media (texture and root depth), erosion hazard (slope), and nutrient retention (soil pH, cation exchange capacity, base saturation), as shown in

Table A1. Soil nutrient retention in each Land Mapping Unit.

Land Mapping Units	pH	Cation Exchange Capacity (cmol kg−1)	Base Saturation (%)
A	5.1	22.1	35.9
B	4.9	24.5	28.8
C	5.5	21.6	33.4
D	5.7	22.1	34.3
E	6.5	24.5	67.6
F	5.9	32.1	42.0
G	4.8	21.0	31.3
H	5.6	21.8	46.5
I	5.4	21.2	45.6
J	5.5	33.8	35.4
K	5.5	39.3	14.6
L	5.4	28.1	38.1
M	5.1	35.5	10.2
N	4.8	23.0	34.7
O	4.6	24.1	15.3
P	4.8	25.1	24.4
Q	5.3	24.5	35.8

. The commodities analyzed for suitability were annual (coffee, rubber, cloves, cocoa), food (upland rice, corn, soybeans), and livestock commodities (Indigofera sp., which are included in the legume group). These commodities were selected based on their benefits in improving the farmers’ economy and as an effort to conserve soil at the study location. The results of the land suitability analysis were then spatially distributed in a land suitability map. The land suitability map and the critical land level map that were analyzed were then overlaid to obtain a potential map and land recommendations. The overlay results are expected to provide an overview of the potential in the area and can provide recommendations for future land use.

3. Results

3.1. Land Criticality Level

The critical land level analysis results in each critical land criterion had varying values at each location (Figure 3). The results of productivity scoring based on interviews with farmers (

Table A2. Land productivity scoring based on interviews with farmers.

Code	Commodity	Production (ton/ha)	Yield Potential (ton/ha)	Rasio (%)	Productivity Level	Score	Value
A1	Corn	1	6.65	15.0	Very Low	1	30
A2	Cassava	3	48	6.3	Very Low	1	30
A3	Cassava	1	48	2.1	Very Low	1	30
A4	Sweet potato	0.2	20	1.0	Very Low	1	30
A5	Corn	0.1	6.65	1.5	Very Low	1	30
B1	Coffee	0.2	1.2	16.7	Very Low	1	30
C1	Cassava	1	48	2.1	Very Low	1	30
C2	Corn	0.3	6.65	4.5	Very Low	1	30
C3	Peanuts	0.2	3	6.7	Very Low	1	30
C4	Cabai	1	14	7.1	Very Low	1	30
D1	Cassava	150	48	312.5	Very High	5	150
E1	Peanuts	1	3	33.3	Low	2	60
F1	Coffee	0.2	1.2	16.7	Very Low	1	30
G1	Quinine	0.2	0.17	117.6	Very High	5	150
H1	Cucumber	1	20	5.0	Very Low	1	30
H2	Corn	0.5	6.65	7.5	Very Low	1	30
H3	Cassava	4	48	8.3	Very Low	1	30
H4	Banana	0.2	40	0.5	Very Low	1	30
H5	Shallot	2	25	8.0	Very Low	1	30
H6	Corn	0.3	6.65	4.5	Very Low	1	30
H7	Banana	0.2	40	0.5	Very Low	1	30
H8	Coffee	0.5	1.2	41.7	Medium	3	90
H9	Coffee	0.4	1.2	33.3	Low	2	60
I1	Coffee	3	1.2	250.0	Very High	5	150
I2	Coffee	0.1	1.2	8.3	Very Low	1	30
I3	Coffee	0.3	1.2	25.0	Low	2	60
I4	Coffee	0.5	1.2	41.7	Medium	3	90
J1	Coffee	0.1	1.2	8.3	Very Low	1	30
K1	Coffee	0.3	1.2	25.0	Low	2	60
L1	Coffee	0.15	1.2	12.5	Very Low	1	30
M1	Coffee	2	1.2	166.7	Very High	5	150
N1	Tomato	2	30	6.7	Very Low	1	30
N2	Corn	1	6.65	15.0	Very Low	1	30
O1	Tomat	5	30	16.7	Very Low	1	30
P1	Cassava	10	48	20.8	Low	2	60
P2	Cassava	1	48	2.1	Very Low	1	30
Q1	Coffee	2	1.2	166.7	Very High	5	150

) showed that most of this area (67.57% of the area) has very low productivity (Figure 3a). The analysis of land management criteria showed that all areas are managed at a moderate level (Figure 3b and

Table A3. Land management scoring based on interviews with farmers.

Code	Manajemen	Management Level	Score	Value
A1	Multi cropping	Medium	3	90
A2	Terrace, Organic fertilization	Medium	3	90
A3	Multi cropping, Organic fertilization	Medium	3	90
A4	Multi cropping, Organic fertilization	Medium	3	90
A5	Multi cropping, Organic fertilization	Medium	3	90
B1	Organic fertilization	Medium	3	90
C1	Multi cropping, Organic fertilization	Medium	3	90
C2	Multi cropping, Organic fertilization	Medium	3	90
C3	Multi cropping, Organic fertilization	Medium	3	90
C4	Multi cropping, Organic fertilization	Medium	3	90
D1	Multi cropping, Organic fertilization	Medium	3	90
E1	Multi cropping, Organic fertilization	Medium	3	90
F1	Multi cropping, Organic fertilization	Medium	3	90
G1	Multi cropping, Organic fertilization	Medium	3	90
H1	Multi cropping, Organic fertilization	Medium	3	90
H2	Multi cropping, Organic fertilization	Medium	3	90
H3	Multi cropping, Organic fertilization	Medium	3	90
H4	Multi cropping, Organic fertilization	Medium	3	90
H5	Multi cropping, Organic fertilization	Medium	3	90
H6	Multi cropping, Organic fertilization	Medium	3	90
H7	Multi cropping, Organic fertilization	Medium	3	90
H8	Multi cropping, Terrace, Organic fertilization	Medium	3	90
H9	Multi cropping, Organic fertilization	Medium	3	90
I1	Multi cropping, Canopy plant planting, Organic fertilization	Medium	3	90
I2	Multi cropping, Canopy plant planting, Organic fertilization	Medium	3	90
I3	Multi cropping, Organic fertilization	Medium	3	90
I4	Multi cropping, Organic fertilization	Medium	3	90
J1	Multi cropping, Organic fertilization	Medium	3	90
K1	Multi cropping, Organic fertilization	Medium	3	90
L1	Multi cropping, Organic fertilization	Medium	3	90
M1	Multi cropping, Organic fertilization	Medium	3	90
N1	Multi cropping, Organic fertilization	Medium	3	90
N2	Multi cropping, Commodities interspersed with livestock grass, Organic fertilization	Medium	3	90
O1	Multi cropping, Organic fertilization	Medium	3	90
P1	Organic fertilization	Medium	3	90
P2	Multi cropping, Organic fertilization	Medium	3	90
Q1	Multi cropping, Organic fertilization	Medium	3	90

). This area has various levels of erosion hazard, ranging from very light to very severe. Specifically, 5.41% of the area is classified as experiencing very light erosion, 21.62% as severe erosion, and 72.97% as very severe erosion (Figure 3c and

Table A4. Erosion hazard scoring.

Code	Erosion Rate	Soil Solum (cm)	Level	Score	Value
A1	<15 tons ha−1 yr−1	100	SR	5	100
A2	>480 tons ha−1 yr−1	100	SB	2	40
B	>480 tons ha−1 yr−1	100	SB	2	40
C	>480 tons ha−1 yr−1	75	SB	2	40
D	>480 tons ha−1 yr−1	100	SB	2	40
E	>480 tons ha−1 yr−1	100	SB	2	40
F	>480 tons ha−1 yr−1	100	SB	2	40
G	>480 tons ha−1 yr−1	100	SB	2	40
H1	>480 tons ha−1 yr−1	100	SB	2	40
H2	180–480 tons ha−1 yr−1	100	B	3	60
I1	>480 tons ha−1 yr−1	100	SB	2	40
I2	180–480 tons ha−1 yr−1	100	B	3	60
J	180–480 tons ha−1 yr−1	100	B	3	60
K	180–480 tons ha−1 yr−1	100	B	3	60
L	180–480 tons ha−1 yr−1	100	B	3	60
M	180–480 tons ha−1 yr−1	100	B	3	60
N1	<15 tons ha−1 yr−1	100	SR	5	100
N2	>480 tons ha−1 yr−1	100	SB	2	40
O1	>480 tons ha−1 yr−1	100	SB	2	40
O2	180–480 tons ha−1 yr−1	100	B	3	60
P1	>480 tons ha−1 yr−1	100	SB	2	40
P2	180–480 tons ha−1 yr−1	100	B	3	60
Q	>480 tons ha−1 yr−1	100	SB	2	40

Source: REST Services KLHK (2022).

). The severity of erosion hazard is closely related to slope gradient, where steeper slopes have higher erosion rates. The slope gradient in this area ranges from 60% to 80%, with the highest erosion rates observed in areas with steeper slopes (Figure 3d and

Table A5. Slope gradient scoring.

Land Mapping Units	Slope Gradient	Score	Value
A	8–15%	4	80
B	15–25%	3	60
C	15–25%	3	60
D	8–15%	4	80
E	8–15%	4	80
F	8–15%	4	80
G	15–25%	3	60
H	15–25%	3	60
I	15–25%	3	60
J	15–25%	3	60
K	15–25%	3	60
L	15–25%	3	60
M	15–25%	3	60
N	8–15%	4	80
O	15–25%	3	60
P	15–25%	3	60
Q	15–25%	3	60

Source: Digital Topographic Map of Indonesia (RBI).

).

The results of the analysis of the criticality level of the Cikeruh upstream Sub-watershed land in

Table 2. Critical level of land in the Upper Cikeruh Sub-watershed area.

Land Map Unit	Productivity	Management	Erosion	Slope	Total	Criticality Level
A	30.0	90.0	70.0	80.0	270.0	Critical
B	30.0	90.0	40.0	60.0	220.0	Critical
C	37.5	90.0	40.0	60.0	227.5	Critical
D	150.0	90.0	40.0	80.0	360.0	Critical Potential
E	150.0	90.0	40.0	80.0	360.0	Critical Potential
F	30.0	90.0	40.0	80.0	240.0	Critical
G	30.0	90.0	40.0	60.0	220.0	Critical
H	36.7	90.0	50.0	60.0	236.7	Critical
I	60.0	90.0	50.0	60.0	260.0	Critical
J	30.0	90.0	60.0	60.0	240.0	Critical
K	30.0	90.0	60.0	60.0	240.0	Critical
L	30.0	90.0	60.0	60.0	240.0	Critical
M	150.0	90.0	60.0	60.0	360.0	Critical Potential
N	30.0	90.0	70.0	80.0	270.0	Critical
O	30.0	90.0	50.0	60.0	230.0	Critical
P	45.0	90.0	50.0	60.0	245.0	Critical
Q	150.0	90.0	40.0	60.0	340.0	Slightly Critical

show that each location has a different level of land criticality in the form of critical potential, slightly critical, and critical levels. LMU D, E, and M are potentially critical with 360.0 points. The area in LMU Q has a slightly critical condition, while the other LMUs (89.19% of the area) are in critical condition with a total value of around 220–270 points.

3.2. Land Suitability Level

3.2.1. Actual Land Suitability Class

The results of the matching table of land characteristics and quality against the results of the analysis of the suitability of plant commodities in

Table 3. Actual land suitability classification of the upstream area of the Cikeruh Sub-watershed using a matching table.

LMU	Upland Rice	Corn	Soybean	Leguminosae	Chilli	Tomato	Cucumber	Recommendation
A	S3eh	S3nr, eh	S3eh	S3eh	S3nr, eh	S3wa, nr, eh	S3wa, nr, eh	Upland Rice, Soybeans, Legumes
B	Neh	Neh	Neh	Neh	Neh	Neh	Neh	Conservation
C	Neh	Neh	Neh	S3eh	Neh	Neh	Neh	Legumes
D	S3eh	S3nr, eh	S3eh	S3nr, eh	S3eh	S3wa, eh	S3wa, eh	Upland Rice, Soybeans
E	S3eh	S3eh	S3eh	S3eh	S3eh	S3wa, eh	S3wa, eh	Upland Rice, Corn, Soybeans, Legumes, Chilies
F	S3eh	S3eh	S3eh	S3eh	S3wa, eh	S3wa, eh	S3wa, eh	Upland Rice, Corn, Soybeans, Legumes
G	Neh	Neh	Neh	Neh	Neh	Neh	Neh	Conservation
H	Neh	Neh	Neh	Neh	Neh	Neh	Neh	Conservation
I	Neh	Neh	Neh	Neh	Neh	Neh	Neh	Conservation
J	Neh	Neh	Neh	Neh	Neh	Neh	Neh	Conservation
K	Neh	Neh	Neh	Neh	Neh	Neh	Neh	Conservation
L	Neh	Neh	Neh	Neh	Neh	Neh	Neh	Conservation
M	Neh	Neh	Neh	Neh	Neh	Neh	Neh	Conservation
N	S3nr, eh	S3nr, eh	S3nr, eh	S3nr, eh	S3nr, eh	S3wa, nr, eh	S3wa, nr, eh	Upland Rice, Corn, Soybeans, Legumes
O	Neh	Neh	Neh	Neh	Neh	Neh	Neh	Conservation
P	Neh	Neh	Neh	Neh	Neh	Neh	Neh	Conservation
Q	Neh	Neh	Neh	Neh	Neh	Neh	Neh	Conservation

indicate that each location has different land suitability. The upstream area of the Cikeruh Sub-watershed has a land suitability class of marginal (S3) and unsuitable (N), with limiting factors of rainfall (wa), slope gradient (eh), and pH (nr). Based on the results of the analysis, there are 11 LMUs that are not suitable for planting. This is because the slope gradient in these LMUs is at a slope of >15%, where this condition has the potential for high erosion. In the actual land suitability analysis, there are 6 LMUs that can be categorized as marginally suitable (S3), namely LMUs A, C, D, E, F, and N.

The crops selected for use in each LMU are those with the highest suitability and the fewest limiting factors in the LMU (

Table 4. Actual commodity suitability in the Upper Cikeruh Sub-watershed area.

LMU	Commodity	Actual Suitability	Land Area (Ha)	Land Percentage (%)
A	Upland Rice, Soybeans, Legumes	S3eh	280.8	15.7
C	Legumes	S3eh	218.9	12.3
D	Upland Rice, Soybeans	S3eh	85.8	4.8
E	Upland Rice, Corn, Soybeans, Legumes, Chilies	S3eh	26.7	1.5
F	Upland Rice, Corn, Soybeans, Legumes	S3eh	14.3	0.8
N	Upland Rice, Corn, Soybeans, Legumes, Chilies	S3nr, eh	100.8	5.6

and Figure 4). These crops are recommended crops for agroforestry patterns in the Cikeruh Sub-watershed area. LMUs A, C, D, E, F, and N are recommended areas because of their suitability for the selected crops, namely legumes, dryland rice, corn, soybeans, and chilies. LMUs B, G, H, I, J, K, L, M, O, P, and Q are directed to become conservation areas because the land is unsuitable (N) for cultivation. This is due to the limiting factor of slope (eh) with a slope value of >15%.

3.2.2. Land Rehabilitation Strategy

The actual land suitability in the Upper Cikeruh Sub-watershed area is at the marginal suitability level (S3). This is caused by slope gradient (eh) limiting factors in LMU A, C, D, E, F, and N and pH (nr) in LMU N. The land suitability class in this area can be improved by land improvements that refer to the level of farm management (

Table 5. Land improvement strategy of the Upper Cikeruh Sub-watershed area.

LMU	Actual Suitability	Limiting Factors	Improvement Recommendations
A	S3	Slope (eh)	Organic mulching
C	S3	Slope (eh)	Organic mulching
D	S3	Slope (eh)	Organic mulching
E	S3	Slope (eh)	Organic mulching
F	S3	Slope (eh)	Organic mulching
N	S3	Slope (eh), pH (nr)	Organic mulching, increasing the dose of manure or maturing the organic fertilizer

) so that potential land suitability is obtained.

4. Discussion

The results of this study found the need for intervention on land degradation in the Cikeruh Hulu Sub-watershed. Around 89% of the Land Map Units in this area are included in critical land. This area has challenges in the form of steep slopes, low soil productivity, and high erosion potential. This is in line with previous studies on watersheds in tropical climates. Watershed degradation in this tropical region occurs due to biophysical and anthropogenic factors, such as deforestation, poor land management, and unsustainable agricultural practices [17,18].

The land criticality assessment showed that soil erosion and slope are the main limiting factors for land degradation in the Cikeruh Hulu Sub-watershed. The condition of most watersheds with steep slopes worsens the erosion rate and is exacerbated by poor vegetation cover [19]. In tropical areas, slopes of more than 15% accelerate soil erosion. This condition can be exacerbated by high rainfall intensity, which affects runoff and nutrient loss (nitrogen) on sloping land [20]. Around 72% of the land in the Cikeruh Hulu Sub-watershed has the potential for erosion, which is classified as very erodible. This condition is likely due to anthropogenic activities such as deforestation and active land cultivation in specific slope directions [21].

Agroforestry has been identified as a viable strategy to address land degradation in the Cikeruh Hulu Sub-watershed. The suitability analysis showed that six LMUs (A, C, D, E, F, and N) were moderately suitable (S3) for agroforestry crops, specifically annual crops such as legumes, upland rice, and maize. The primary limiting factors in these LMUs include steep slopes, while LMU N is additionally constrained by soil pH. These annual crops were selected because they improve soil fertility through nitrogen fixation, reduce erosion by providing continuous ground cover, and offer immediate economic benefits to local farmers. The recommended use of agroforestry has been shown to improve ecosystem services while supporting livelihoods [22]. Additionally, agroforestry improves farmers’ livelihoods by providing better access to food, timber, fodder, and fuelwood and increasing their access to livelihood capital [23].

Although agroforestry is generally associated with multi-strata systems, including long-term crops such as coffee, cocoa, and forest species, these perennial crops are less suitable for the Cikeruh Hulu Sub-watershed due to the challenging terrain and soil conditions. The combination of steep slopes and low soil fertility, particularly soil acidity in some areas, limits the viability of deep-rooted perennial species that require well-developed soil structure and stable conditions for long-term growth. Instead, implementing agroforestry with annual crops allows for more flexible land use, quicker soil fertility improvements, and effective erosion control while maintaining economic viability for farmers.

The application of agroforestry systems in the Cikeruh Hulu Sub-watershed area has discussion factors such as steep slopes and low soil pH. Soil quality restoration techniques for degraded land can be carried out through conservation agriculture, integrated nutrient management, sustainable vegetative cover (such as organic mulch and cover crops), and controlled grazing at appropriate stock levels [17]. Applying organic mulch and manure improves soil structure, texture, and water-holding capacity, increases organic matter content, and reduces erosion in degraded tropical soils [24,25]. The conservation of degraded land can also use terracing and contour farming [26]. The vegetated terrace method can reduce soil erosion and pest control by diverting pest attacks and conserving natural enemies [27].

The agroforestry system provides ecological benefits, but social and economic factors of the community influence the success of implementing this system. In implementing agroforestry, farmers in the Cikeruh Hulu Sub-watershed face limited access to resources, knowledge, and incentives. Increasing the implementation of agroforestry in this area can be performed through training programs and farmer capacity development [12]. In addition, support is also needed to finance policies for activities such as payments for ecosystem services (PES) and subsidies so that farmers can switch to sustainable practices. Agroforestry addresses soil and water conservation, increases biodiversity, sequesters carbon, and supports climate resilience [17,28].

Although this study provides valuable insights into land criticality and agroforestry suitability, several knowledge gaps remain. Future research should explore the long-term economic viability of agroforestry systems, including cost–benefit analysis and market opportunities for agroforestry products. In addition, the impacts of climate change on land suitability and crop performance in the Upper Cikeruh Sub-watershed require further investigation. Another area for future research is the role of governance and institutional frameworks in supporting watershed restoration.

5. Conclusions

This study found that most of the Cikeruh Hulu Sub-watershed area showed critical land conditions, with productivity identified as the most limiting factor, with a score as low as 30. Agroforestry suitability analysis showed that specific land mapping units (LMUs A, C, D, E, F, and N) were included in the marginally suitable category (S3) for food crops such as legumes, upland rice, corn, soybeans, and chilies, with the main constraints being slope steepness and soil pH. This study highlights the urgent need to implement agroforestry practices as a restoration strategy in degraded landscapes, but its success depends on addressing biophysical, socio-economic, and policy challenges. Collaboration between communities, policymakers, and researchers is needed to manage the Cikeruh Hulu Sub-watershed sustainably. These findings provide actionable recommendations to improve land productivity while promoting sustainable watershed management in one of Indonesia’s critical areas.