Identification of Suitable Sites for Jatropha curcas L. Bioenergy Plantation Using the AquaCrop Model

Abstract

Jatropha curcas (JC), as a biofuel plant, has been reported to have various desired characteristics such as high oil content seeds (27–40%), fast-growth, easy cultivation, drought tolerance, and can be grown on marginal soil and wasteland, requiring fewer nutrients and management and does not interfere with existing food crops, insects, and pest resistance. This investigation was the first study of its type to use climatological data, blue/green water footprints, and JC seed production to identify suitable sites for JC bioenergy plantation using the AquaCrop FAO model across the Khyber Pakhtunkhwa province in northwest Pakistan. The JC seed yield (10 ton/ha) was at a maximum in the districts of Bannu, Karak, Hangu, Kurram, North Waziristan, Lakki Marwat, South Waziristan, and Dera Ismail Khan, in addition to its frontier regions, Tank, Peshawar, Mohmand, Orakzai, Khyber, Kohat, Charsadda, Mardan, Swabi, and Nowshera, respectively. Green water footprint (264 m³/ton of JC seed) and blue water footprint (825 m³/ton) was less in these areas. Furthermore, the results revealed that, depending on climatological circumstances, the southern part of the Khyber Pakhtunkhwa province is more appropriate for JC bioenergy plantation than the northern region. The districts of Bannu, Karak, Hangu, Kurram, North Waziristan, Lakki Marwat, South Waziristan, Dera Ismail Khan, and its frontier regions, Tank, Peshawar, Mohmand, Orakzai, Khyber, and Kohat, in Khyber Pakhtunkhwa province were identified to be the most ideal places for JC bioenergy plantation. As a result, under the Billion Tree Afforestation Project (BTAP) and the Green Pakistan Project, the Forest Department of Khyber Pakhtunkhwa should consider planting JC species in the province’s southern region. Furthermore, this research will provide scientific information to government and private sector officials for better management and optimum yield of the JC biofuel crop, as well as for the promotion of energy forestry in Pakistan.

1. Introduction

The physic nut (Jatropha curcas L.) is a non-food seed and oil crop that is a well-known source for biodiesel production around the world [1]. This crop was first planted on the Indian subcontinent in the 16th century by Portuguese merchants [2]. The name Jatropha comes from the Latin words Jatros, meaning doctor, and trophe, meaning food, as it contains numerous medical qualities [3,4]. Jatropha curcas (JC) belongs to the Euphorbiaceae family and is a small tree (semi-perennial tree) or tall shrub, up to 5–7 m tall, with an average life duration equal to 50 years [5,6,7,8]. Initially, JC was a native plant of South American countries as well as Mexico, Meso-America, Central America, Africa, Brazil, Argentina, and Paraguay, but now it is grown in all tropical regions [5,9,10,11,12,13]. It is now found in all tropics and subtropics [9,14,15,16], and it has adapted to a wide range of precipitation and soil conditions [17]. It is currently grown on a 1.8 million ha area in Indonesia, China, Brazil, India, and Africa to satisfy the need for biodiesel production [18].

The fruit is a kernel that comprises three seeds each, but the yield of JC seed in various countries and regions varies from 0.1 to 15 tonnes/hectare/year (t/ha/yr) [19], and the production of JC is reported at 1590 kg/ha/yr [7,20]. By 2017, global biodiesel production is expected to reach 24 billion liters (Divakara et al., 2010). As a biofuel plant, JC has been reported to have various desired characteristics such as fast-growing, easy cultivation, drought tolerance, insect and pest resistance, high oil content seeds (27–40%), and good quality yields for biodiesel and bio kerosene fuel production performance [8,21,22,23]. Since JC oil is rich in unsaturated oily acids (equal to 3— oily acids in seeds) [24,25], it works as the best biodiesel feedstock in agreement with the worldwide standards [26]. Roughly 30% of protein by weight is contained in the seed kernel [27]. Since the 1970s oil crisis, JC has received major attention for making a recognizable alternative to the world’s oil resources [9,28]. The seeds contain about 30–35 percent non-edible oil [3,9,29,30]. One hectare of land will yield 158 to 396 gallons of oil. Depending on density [31], it is possible to extract 0.26 gallons of oil per 8.8 lbs [32] or around 11–12 lbs of seeds [33].

In addition to fuel, various parts of the plants have pharmaceutical qualities, and after the extraction of oil, they produce many important by-products that can be used commercially [22,34,35,36,37,38]. JC species’ oil content, physicochemical properties, fatty acid structure, and energy values have all been studied [35,39,40]. Jatropha cultivation is also important because mature crops consume approximately 18 lbs of carbon dioxide (CO₂) per year [41]. Growing plants and trees on one hectare of land sequester produces 20 tonnes of CO₂ per year [42]. JC crop is also easy to cultivate, a drought-resistant plant can be grown on marginal soil, and a wilderness plant needs fewer nutrients and management without interfering with an existing food crop [43,44,45,46]. Generally, the JC plant reaches maturity after 6 years, and the production of seeds continues for the next 30–40 years [47]. JC is a hardy tree with great oil that contains protein and little water demand [32]. It can be planted to recover degraded and desert soils [48].

Previous studies have focused on the biodiesel production potential of JC, with little attention given to the suitability of the site for its cultivation. Furthermore, no satellite-based study has been undertaken in Pakistan for this purpose. Field surveys are commonly used in JC plantation studies [49,50,51,52]. Some research studies assessed and selected potential JC plant sites using meteorological data, elevation, and slope [50,51,52,53,54] using remote sensing and GIS techniques [50,54,55]. The recent appearance of satellite technology has been shown to be quite useful in solving difficulties linked to ground features in a timely and cost-effective manner. As a result, some satellite data was used in the present study to identify suitable areas for JC plantations in the Khyber Pakhtunkhwa province of Pakistan. Using remote sensing data and geographic information system techniques, several climatic and topographic features, as well as the soil types of the study area, were investigated and examined to find the most suitable sites for JC cultivation in the Khyber Pakhtunkhwa province of Pakistan. Roughly 60% of the area of Pakistan is rangeland, and there is no accurate and reliable data on the yield of Jatropha curcas plantations under different environmental conditions. As a result, the goal of this study was to identify suitable sites for JC bioenergy plantation in Pakistan’s Khyber Pakhtunkhwa province using meteorological parameters, blue and green water footprint, and JC crop yield, as well as to provide scientific information to policymakers, government, and the private sector for better management and maximum yield of the JC crop in Pakistan.

2. Materials and Methods

2.1. Study Area

Khyber Pakhtunkhwa is one of Pakistan’s four provinces, as can be seen in Figure 1. Khyber Pakhtunkhwa has a total area of 101,741 km² and is located at 34.9526° N and 72.3311° E. The province is divided into two zones geographically: the northern zone, which stretches from the Hindu Kush mountains to the Peshawar basin’s borders, and the southern zone, which stretches from Peshawar to the Derajat basin [56,57]. With the exception of the Peshawar basin, which is hot in summer and cold in winter, the northern zone has cold and snowy winters, significant rains, and pleasant summers. It has a moderate amount of rainfall [58]. The southern zone is desert, with warm summers and chilly winters as well as little rain. Drought is common in the southern half of the province throughout the summer. The climate of Khyber Pakhtunkhwa is characterised by extremes and is indicative of most of Pakistan’s climate types. For the most part, it is usually dry [59], although the province’s eastern half is recognised for being the wettest in Pakistan, particularly during the monsoon season, which runs from June to mid-September. Khyber Pakhtunkhwa. The climate is extremely diverse for a territory of its size, including the majority of Pakistan’s climate types [60]. The province of Khyber Pakhtunkhwa, in Pakistan’s northwest region, is the country’s most forested area [61].

2.2. Site Suitability Modeling for JC Bioenergy Plantation

The site suitability investigation for JC bioenergy plantations in the Khyber Pakhtunkhwa province was performed in two steps, as shown in flow chart Figure 2. First, slope, elevation, soil types, rainfall, and temperature data were acquired for all the districts of the Khyber Pakhtunkhwa province of Pakistan. Second, the water footprint and yield of the JC crop were simulated through the AquaCrop FAO model as described in Section 2.3. The climatological parameters data were gathered from the National Centre for Environmental Prediction (NCEP) in Peshawar, the Pakistan Forest Institute (PFI) in Peshawar, and the Pakistan Meteorological Department (PMD) in Islamabad, and include information on maximum temperature, minimum temperature, and rainfall. Soil type information was obtained from the Harmonized World Soil Database (HWSB) (30 arc-second raster database) [62], and a soil type map was prepared using Arc GIS v.10.3 (ESRI, Redlands, CA, USA), as can be seen in Figure 3. The elevation and slope were derived from the Shuttle Radar Topography Mission (SRTM) with a spatial resolution of 30 m digital elevation model tiles as depicted in Figure 1 and Figure 4. The previous 30 years’ daily climate data (1986–2016) was further converted according to the study requirements into annual averages. Initially, criteria for a suitable site for JC bioenergy plantation in the Khyber Pakhtunkhwa province were developed, following [63] (

Table 1. Site suitability criteria for JC plantation [63].

S.#	Parameter	Range/Limitation	Suitability Classes			Data Source	Reference
			More Suitable	Moderate Suitable	Less Suitable
1	Elevation	0–1800 m	<1500 m	1500 m–2100 m	<0 and >2150	SRTM DEM	[54]
2	Slope	Not exceed 30°	<15°	15°–30°	>30°	SRTM DEM	[30]
4	Rainfall	250 mm–3000 mm	1000 mm–3000 mm	250 mm–1000 mm	<250 mm and >3000 mm	NCEP Data	[64]
5	Temperature	18 °C–28 °C	20 °C–28 °C	17 °C–20 °C	<17 °C and >28 °C	NCEP Data	[65]
6	Soil Type	Aerated sandy, gravelly, loamy or soil without/a little clay content	sandy or Loamy, gravelly, well-drained soil	Stony or rocky soil or a little part of clay/salt	Clay soil or waterlogged	Harmonised World Soil data based (HWSB)	[62,63]

). Based on meteorological parameters (temperature, soil, rainfall), elevation and slope, suitable sites were identified for JC bioenergy plantation in Khyber Pakhtunkhwa, Pakistan. Secondly, the water footprint and yield of the JC crop calculated in Section 2.2 were applied for the identification of suitable sites for JC bioenergy plantation in the Khyber Pakhtunkhwa province of Pakistan.

2.3. Estimation of Water Footprint and Yield of JC Bioenergy Plantation

The data for the JC cultivation stage, i.e., crop phenology, irrigation, and field management, were collected from field experiments that took place at the University of Science and Technology, Bannu, Pakistan. The meteorological data were collected from regional meteorological stations located in various districts of the Khyber Pakhtunkhwa province of Pakistan, as can be seen in Figure 5 and

Table 2. Details of meteorological stations in Khyber Pakhtunkhwa, Pakistan.

Name of Meteorological Station	Latitude	Longitude
Chitral	35.85	71.78
Drosh	35.57	71.78
Dir	35.2	71.85
Pattan	35.06	73
Timergara	34.83	71.84
Saidu Shaif	34.73	72.35
Balakot	34.55	72.35
Abbottabad	34.18	73.25
Resal pur	34.07	71.97
Peshawar	34.02	71.56
Bannu	32.98	70.6
D.I.K	31.82	70.93

. The data regarding rainfall and the maximum and minimum temperature from each weather station was collected for the last 30 years (1986 to 2016). Soil type data of the Khyber Pakhtunkhwa province of Pakistan was obtained from Harmonized World Soil Database (HWSB) [62], and then a soil type map was generated with the help of ArcGIS version 10.3 software. The whole province was divided into various sub-regions based on climate and soil data by using the Thiessen polygon method [66] as depicted in (Figure 3). For the soil characteristics of the Khyber Pakhtunkhwa province of Pakistan, SPAW (soil-plant-air-water) computer software version 6.02.75 (United States Department of Agriculture (USDA), Washington, DC, US) was used [67]. The soil characteristics of the Khyber Pakhtunkhwa province were thickness (m), sand fraction (%), silt fraction, (%), clay fraction (%), bulk density (kg/dm³), organic matter (wt.%), salinity (ds/m) stoniness (%), soil water data, permanent wilting point (PWP volume %), field capacity (FC), and saturation (sat volume %) saturated hydraulic conductivity (Ksat) (mm/day), all of which are summarised in (Table 2). Crop data such as (crop density (plant/ha), canopy cover, duration of flower (days), maximum rooting depth (meter), harvest index (%), threshold temp (lower and upper °C, salinity (ds/m) and soil fertility stress, and irrigation data (irrigation schedule), e.g., irrigation water conductivity (ds/m) were also measured. All these data were entered in the AquaCrop FAO model, and software was run for every meteorological station in the Khyber Pakhtunkhwa province. The annual green/blue water footprint for the JC cultivation was estimated for the entire Khyber Pakhtunkhwa province using AquaCrop model version 6.1 developed by FAO (Food and Agriculture Organization) [68,69]. According to [70], blue water footprint is an indicator of freshwater use (surface and groundwater) for a person or community development of goods and services. In comparison, green water footprint is the utilisation of rainwater, which does not run off or refill the groundwater but is retained as soil moisture within the soil. The blue and green water footprint of the JC crop was estimated following the global water footprint accounting standards [70]. The AquaCrop model of FAO (version 6.1) was used to simulate the soil water balance and JC productivity [68,69]. This model estimates the evapotranspiration (ET) and JC yield by simulating the dynamic soil water balance and biomass growth (Equation (1)).

S_i = R_i + I_i + CR − RO_i – Dr − ET i

(1)

where S is soil water content (mm) on a day i, R is rainfall (mm), I is mean irrigation (mm), CR is the capillary rise (mm), RO is mean surface runoff, Dr is drainage (mm), and ET is evapotranspiration [71]. The output of the AquaCrop simulation-crop growth characteristics and water fluxes were divided into blue and green parts using the method introduced by [72]. The blue and green components of JC crop water use (CWU) were estimated by summing the blue and green ET over the JC crop growing period as shown in Equations (2) and (3).

$${\mathrm{CWU}}_{\mathrm{b}}={\displaystyle {\sum }_{\mathrm{t}=1}^{\mathrm{T}}}\frac{{\mathrm{S}}_{\mathrm{bt}}}{{\mathrm{S}}_{\mathrm{t}}}{\mathrm{ET}}_{\mathrm{t}}\times 10$$

(2)

$${\mathrm{CWU}}_{\mathrm{g}}={\displaystyle {\sum }_{\mathrm{t}=1}^{\mathrm{T}}}\frac{{\mathrm{S}}_{\mathrm{gt}}}{{\mathrm{S}}_{\mathrm{t}}}{\mathrm{ET}}_{\mathrm{t}}\times 10$$

(3)

where CWU_b and CWU_g are blue and green water consumption (m³), S_bt and S_gt are change in blue and green soil water stock over the growing season, and 10 is the conversion factor from mm to m³. Ti = first day and tT = last day of the run of the AquaCrop model, the model was run 30 times for 30 years from 1986–2016. The WF_b and WF_g were obtained by dividing CWU by the crop yield Y using Equations (4) and (5) [70].

$${\mathrm{WF}}_{\mathrm{b}}=\frac{{\mathrm{CWU}}_{\mathrm{b}}}{\mathrm{Y}}$$

(4)

$${\mathrm{WF}}_{\mathrm{g}}=\frac{{\mathrm{CWU}}_{\mathrm{g}}}{\mathrm{Y}}$$

(5)

3. Results and Discussion

The site suitability for JC plantation in Khyber Pakhtunkhwa, Pakistan, was determined by two methods, i.e., one is based on meteorological parameters (temperature, rainfall, soil), elevation, and slope, and the other is based on JC water footprint and yield. The results of both methods are explained below.

3.1. Site Suitability for JC Plantation Based on Meteorological Parameters, Elevation and Slope

The site suitability for JC plantation is divided into three classes, i.e., “more suitable,” “moderately suitable”, and “less suitable” in the Khyber Pakhtunkhwa province of Pakistan. This suitability was computed carefully using meteorological analysis based on parameters including the temperature, elevation, slope, rainfall, and soil type information of different sites in the Khyber Pakhtunkhwa province of Pakistan [54,63]. The temperature is an important aspect that limits JC plantations [54]. The most suitable temperature for JC bioenergy plantation was (20–28 °C), the moderately suitable temperature was (17–20 °C), and the least suitable temperature was (17 °C and >28 °C), as shown in

Table 3. Soil characteristics of Khyber Pakhtunkhwa province, Pakistan.

Soil Type	Horizons	Texture USDA	Thickness (m)	Sand Fraction (%)	Silt Fraction (%)	Clay Fraction (%)	Bulk Density (kg/dm3)	Organic Matter (wt.%)	Salinity (ds/m)	Stoniness (%)	Soil Water
											PWP	FC	SAT	Ksat
											(Volume %)			(mm/day)
Calcisols	Top soil	Loam	0.3	39	40	21	1.32	0.7	1.6	4	13.5	27	46	196.5
	Sub soil	Loam	0.7	36	40	24	1.42	0.29	1.6	3	15	29	41	131.5
Cambisols	Top soil	Loam	0.3	42	36	22	1.37	1	0.1	9	14	27	42	100
	Sub soil	Loam	0.7	40	35	25	1.39	0.4	0.1	12	15.3	28	41	116
Rock Outcrop	Top soil	Loam	0.3	43	34	23	1.3	1.4	0.1	26	14.7	28	43	151.2
	Sub soil	Clay loam	0.7	42	30	28	1.37	0.3	0.7	3	17.1	29	41	118.56
Liptosols	Top soil	Loam	0.3	43	34	23	1.38	0.37	0.1	26	15.4	28.7	45.6	189.12
	Sub soil	Clay loam	0.65	30	42	28	1.34	0.29	0.1	30	18	33	47.7	62.64
Fluvisols	Top soil	Loam	0.3	35	47	18	1.39	0.6	0.7	10	12.6	28.2	46.5	211.2
	Sub soil	Loam	1	37	45	18	1.41	0.4	0.5	11	11.6	26	41.9	221.28
Regosols	Top soil	Loam	0.3	43	35	22	1.4	0.77	0.3	17	14.8	28.2	45.6	179.28
	Sub soil	Loam	1	38	36	26	1.52	0.53	0.3	18	16.2	29.5	42.8	115.44

[53,54,65,73,74,75,76,77]. Second is soil quality, which has some impact on JC site suitability. The more suitable soil types were loamy, sandy, or gravelly well-drained soil, while moderately suitable soil types were stony or rocky soil or a little bit of clay/salt, and less suitable soil was clay soil or waterlogged, as listed in Table 3 [65,77]. Rainfall is another factor that affects the JC plantation. Table 3 show the more suitable rainfall (1000 mm–3000 mm), moderately suitable rainfall (250 mm–1000 mm), and less suitable rainfall (250 mm and >3000 mm) for JC bioenergy plantation. The slope is one more factor that affects the JC bioenergy plantation. The most suitable slope was <15°, the moderately suitable slope was 15°–30°, and the least suitable slope was >30° for JC bioenergy plantation, as summarised in Table 3 [30,78]. Elevation also affects the suitable site for JC bioenergy plantation. As shown in Table 3 [26,50,54,65,77], the most suitable elevation for JC bioenergy plantation was 1500 m, the moderately suitable elevation was (1500 m–2100 m), and the least suitable elevation was (0 and >2150). On the basis of meteorological parameters (temperature, rainfall, soil), elevation and slope, the most suitable areas for JC bioenergy plantation in the Khyber Pakhtunkhwa province were found to be the Bannu, Karak, Hangu, Kurram, North Waziristan, Lakki Marwat, South Waziristan, D.I Khan, FR D.I Khan, Tank, Peshawar, Mohmand, Orakzai, Khyber, Kohat, Charsadda, Mardan, Swabi, and Nowshera districts, as summarized in

Table 4. More suitable, moderate suitable and less suitable districts for JC bioenergy plantation in Khyber Pakhtunkhwa, Pakistan.

More Suitable Areas	Moderate Suitable Areas	Less Suitable Areas
D.I. Khan	Buner	Lower Dir
FR DIK	Balakot	Malakand Agency
Tank	Mansehra	Bajaur Agency
Peshawar	Haripur	Upper Dir
Mohmand Agency	Abbottabad	Swat
Orakzai Agency		Chitral
Khyber Agency		Shangla
Kohat		Batagram
Charsadda		Drosh
Mardan		Kohistan
Swabi
Nowshera

and can be seen in Figure 6. In comparison, Buner, Mansehra, Haripur, and Abbottabad were found to be the moderately suitable sites for JC bioenergy plantation, as summarized in Table 4. Based on climatological parameters, Lower Dir, Malakand, Bajaur, Upper Dir, Swat, Shangla, Batagram, Kohistan, and Chitral were those areas which showed the least suitability for JC bioenergy plantation as summarised in Table 4 and can be seen in Figure 6. Based on these findings, the southern part of the Khyber Pakhtunkhwa province is more suitable for JC bioenergy plantation than its northern part.

3.2. Site Suitability for JC Plantation Based on Water Footprint (WF) and Yield of JC Seeds

A suitable site identified for JC plantation in Khyber Pakhtunkhwa is based on the water footprint and yield of the JC seeds. The results of the AquaCrop FAO model showed the yield and water footprint (WF green and WF blue) of JC crops in different districts of the Khyber Pakhtunkhwa province of Pakistan, as can be seen in

Table 5. Water footprint and yield of JC in different districts of Khyber Pakhtunkhwa, Pakistan.

District Name	WFgreen (m3/ton)	WFblue (m3/ton)	Yield (ton/ha)
Bannu	264	825	10
Karak	264	825	10
Hangu	264	825	10
Kurram Agency	264	825	10
North Waziristan	264	825	10
Lakki Marwat	264	825	10
South Waziristan	264	825	10
D.I.Khan	214	846	10
FR DIK	214	846	10
Tank	214	846	10
Peshawar	258	851	8
Mohmand Agency	258	851	8
Orakzai Agency	258	851	8
Khyber Agency	258	851	8
Kohat	258	851	8
Charsada	258	851	8
Mardan	239	869	8
Swabi	239	869	8
Nowshehra	239	869	8
Buner	757	926	5
Balakot	757	926	5
Mansehra	799	1016	4
Haripur	799	1016	4
Abbottabad	799	1016	4
Lower Dir	384	1688	3
Malakand Agency	384	1688	3
Bajaur Agency	384	1688	3
Upper Dir	941	1528	3
Swat	384	1688	3
Shangla	384	1688	3
Batagram	384	1688	3
Kohistan	384	1688	3
Drosh	384	1688	3
Chitral	384	1688	3

. The yield and WF in the Bannu, Karak, Hangu, Kurram Agency, North Waziristan, Lakki Marwat, and South Waziristan districts were found to be the same as, in these districts, the temperature, soil, elevation, slope, and rainfall are almost similar. Therefore, the yield and WF for each district is 10 tonnes/ha, WF green 264 m³/ton, and WF blue 825 m³/ton, respectively. The yield in Dera Ismail Khan and its frontier regions and Tank were also found to be similar (10 tonnes/ha) and the WF result for each district was also the same (WF green 214 m³/ton and WF blue 846 m³/ton) because these three districts have the same climatic conditions, edaphic factors, elevation, and slope. In Peshawar, Mohmand, Orakzai, Khyber, Kohat, and Charsadda, due to having similar meteorological conditions, the yield was239 m³/ton and WF blue 869 m³/ton) were also the same for each district. The yield in the Buner district was 5 tonnes/ha, WF green was 757 m³/ton, and WF blue was 926 m³/ton. The yield and WF in Balakot Mansehra were the same as in Buner. The same yield (4 ton/ha) and the same WF (WF green 799 m³/ton and WF blue 1016 m³/ton) were calculated for the districts of Mansehra, Haripur, and Abbottabad. For the districts of Lower Dir, Malakand, and Bajaur, the yield (3 ton/ha) and WF (WF green 384 m³/ton and WF blue 1688 m³/ton) were also similar for these areas. In Upper Dir, the yield was 3 tons/ha, and the WF was (WF green 941 m³/ton and WF blue 1528 m³/ton). The same yield (3 tonnes/ha) and the same WF (WF green 384 m³/ton and WF blue 1528 m³/ton) were assessed for the districts of Swat, Shangla, Batagram, Kohistan, and Chitral, because these areas have similar meteorological conditions, such as the same soil type, same frequent slope, and elevation. The yield was at a maximum in the districts of Bannu, Karak, Hangu, Kurram, North Waziri-stan, Lakki Marwat, South Waziristan, and Dera Ismail Khan and its frontier regions, Tank, Peshawar, Mohmand, Orakzai, Khyber, Kohat, Charsadda, Mardan, Swabi, and Nowshera whereas less WF (Green and Blue) was reported, respectively. Therefore, these are the areas that are most suitable for JC bioenergy plantation, because in these areas the yield is maximum with less WF (green and blue). The yield in Buner, Mansehra, Haripur, and Abbottabad were less than the above district and WF (Green and Blue) were high confirming that these are areas which are moderately suitable for JC bioenergy plantation. Based on JC crop yield and WF (green and blue), Lower Dir, Malakand, Bajaur, Upper Dir, Swat, Shangla, Batagram, Kohistan, and Chitral are areas that showed less JC seed yield and high-water footprint as compared to the most suitable site. Consequently, these areas are less suitable for JC bioenergy plantation in the Khyber Pakhtunkhwa province of Pakistan. The results also exhibited that the yield of the JC crop was decreasing from the southern part of Khyber Pakhtunkhwa province to the northern part, whereas WF was increasing accordingly. This indicated that the southern part of the Khyber Pakhtunkhwa is more suitable as compared to its northern part. Moreover, based on climatological conditions such as temperature, soil, slope, elevation, and rainfall, the northern part is less suitable for JC bioenergy plantation than the southern part. The yield and WF (green and blue) also revealed the same trend. Thus, results of both the criteria for identification of suitable site (climatological parameters and yield and water footprints of the JC crop) proved that the southern part of the Khyber Pakhtunkhwa province is more suitable for JC bioenergy plantation than its northern part.

4. Discussion

JC as a biofuel plant has been reported to have various desired characteristics such as fast-growing, easy cultivation, drought tolerance, insect and pest resistance, and high oil content seeds (27–40%) that are good quality for biodiesel and bio kerosene fuel production. The JC is a hardy tree with great oil, protein, and little water demand, so it can be planted to recover desert and degraded soils. The JC crop is easy to cultivate. The drought-resistant plant can be grown on marginal soil and wilderness areas without interfering with existing food crops. The JC plant could provide a percentage of the present sustainable biofuel demand with minimal environmental impacts [78]. The crude oil from JC has potential for the manufacturing of biodiesel, with little acidity and more oxidation stability in contrast to soybean oil. It has a lower viscosity than castor oil and has better cold qualities than oil from palm [79]. Therefore, JC oil is able to be directly used in diesel engines [80]. Biofuels such as biodiesel are used by several countries, such as Italy, Australia, the United States, Germany, Austria, and Brazil, as this trend is predicted to develop continuously and has been leading to more biofuel consumption [81,82]. Biodiesel has perhaps gained the greatest interest of all the biofuels because of its chemical structure and energy content [83]. Pakistan, with a population of over 200 million people, is an emerging, developing, and densely populated country [84]. Total energy demand in Pakistan has risen in recent years and is expected to follow the same pattern as many developing economies [85]. Main energy supplies have increased by more than 90% in recent decades, from 34 million tonnes of oil equivalent (MTOE) in 1992, to 64.7 in 2012 [86]. Pakistan is an energy deficient country, and an alternate source of energy is an urgent need. Biodiesel is a prototype in Pakistan and is a good source of renewable energy. Pakistan’s desire to blend biodiesel into fossil diesel up to 2025 and a huge amount of large-scale research work has been dedicated to this topic in different universities and organisations throughout the country. Considering the deadline of the year 2025 for blending biodiesel into fossil diesel, the government of Pakistan has mandated that 10% of the country’s use of fossil diesel be replaced by biodiesel [87]. However, to achieve this target, huge quantities of biomass feedstock will be needed, such as JC seeds, castor seeds, soya bean seeds, etc.

Therefore, the major goal of the present study was to identify suitable sites for JC bioenergy plantation in the province of Khyber Pakhtunkhwa, Pakistan, using meteorological parameters, elevation, slope, blue-green water footprint, and the yield of the JC plant, to provide scientific information to policymakers, the government, and the private sector in order to improve JC crop and yield management. Our results were in line with the previous research, where similar environmental parameters were considered for the identification of suitable sites for JC plantation [30,53,54,63,65,66,73,74,76,77,88]. These studies indicated more suitable, moderately suitable, and less suitable temperatures, soil quality, rainfall, slope, and elevation for JC bioenergy plantations in different countries. [89] in Southwest China, [53] in Mexico and continental Central America, [76] in Zimbabwe, [73] in Yunnan province, [77] in Brazil, [54] in China, and [64] in Rajasthan, India, conducted studies on site suitability for JC bioenergy plantations globally. Temperature, soil quality, rainfall, slope, and elevation are the basic environmental factors that have a tremendous effect on suitable sites for JC bioenergy plantations. Ref. [63] conducted a similar study, indicating the same suitability criteria for JC bioenergy plantations in Thatta tehsil of Pakistan’s Sindh province. The results showed that when we go to the northern part of the Khyber Pakhtunkhwa province, the yield is decreasing, and the WF is increasing, as summarised and shown in Table 5. According to Refs. [32,90,91,92], the water consumption is mostly due to the irrigation of the JC bioenergy plantation, which is necessary to sustain high productivity throughout the cultivation phase of JC crop growth. Ref. [93] calculated the water footprint of bioenergy plantations. Wani et al. [94] also conducted studies on the hydrological consequences of cultivating Jatropha crops in degradable wastelands and ecosystem trade-offs at a watershed scale in India. Ref. [95] conducted a comprehensive study on a field assessment of the agronomic performance and water use of JC in South Africa. Ref. [96] conducted a study on the water footprint of bioenergy from Jatropha curcas. Similar studies were conducted on the water footprint of JC by [53,70,93,97,98,99,100,101,102] in different countries. Our results were in accordance with the findings of these studies. A similar study was conducted by [55] on suitability analysis for JC cultivation in Ethiopia using a spatial modelling approach. Suitable locations for JC cultivation in Ethiopia were identified using GIS (Geographical Information Systems) and the Spatial Analytical Hierarchy Process (SAHP). Weighted overlay analysis results for biophysical suitability evaluation using spatial modelling methods identified 15.07 percent (166,082 km²), 76.57 percent (844,040 km²), and 8.36 percent (km²) of the land as highly suitable, moderately suitable, and not suitable for JC cultivation, respectively. Ref. [50] conducted a comprehensive study in China on the assessment of bioenergy potential on marginal land. According to the findings, the total area of marginal land usable for significant energy plant development was around 43.75 million ha. Similarly, Ref. [77] also conducted a study on the agro-climatic zoning of JC as a subside for crop planning and implementation in Brazil. Ref. [73] conducted a comprehensive survey on the investigation of the geographical distribution and evaluation of JC in Yunnan province, China. Another study was carried out by [75] on the division of suitable arable planting areas for JC in Sichuan Province, China.

5. Conclusions and Recommendations

This study was conducted on site suitability for Jatropha curcas (JC) bioenergy plantation in northwest Pakistan. The site suitability for JC plantation in Khyber Pakhtunkhwa was found based on meteorological parameters (temperature, rainfall, and soil), elevation, slope, JC water footprint, and seed yield. Globally, numerous studies have been conducted on site suitability for bioenergy plantations. However, no study has been conducted on the site suitability of bioenergy plantations such as JC in Pakistan. The results of the site suitability modelling of the present study found that the southern part of the Khyber Pakhtunkhwa province of Pakistan is more suitable for JC bioenergy plantation than its northern part. The present study provides a benchmark or baseline for future research work to investigate suitable sites for other bioenergy plants based on the climatological conditions, water footprint, and yield in Pakistan. The JC plant is a multipurpose, fast-growing tree that is easy to cultivate and has good pest and drought resistance. From the above results and the importance of the JC plant, it is highly recommended that it should be planted under the Billion Tree Afforestation Project (BTAP), Ten Billion Tree Afforestation Project (10-BTAP), and Green Pakistan Project recently launched by the Federal government of Pakistan.