Harnessing productivity potential and rehabilitation of degraded sodic lands through Jatropha based intercropping systems

Agriculture, Ecosystems and Environment 233 (2016) 121–129

Contents lists available at ScienceDirect

Agriculture, Ecosystems and Environment journal homepage: www.elsevier.com/locate/agee

Harnessing productivity potential and rehabilitation of degraded sodic lands through Jatropha based intercropping systems Yash Pal Singha,* , Vinay K. Mishraa , Dinesh K. Sharmab , Gurbachan Singhc, Sanjay Aroraa , Himanshu Dixita , Artemi Cerdàd a

Central Soil Salinity Research Institute, Regional Research Station, Lucknow, 226002, India Central Soil Salinity Research Institute, Karnal, 132001,Haryana, India Indian Council of Agricultural Research, New Delhi, 110012, India d Department of Geografia, University of València, BlascoIbàñez, 28, 46010-Valencia. Spain b c

A R T I C L E I N F O

Article history: Received 29 February 2016 Received in revised form 29 August 2016 Accepted 30 August 2016 Available online xxx Keywords: Sodic soil Jatropha carcus L Plant density Intercrops Soil amelioration

A B S T R A C T

This paper evaluates an intercropping model with Jatropha curcas L. (JCL) as an alternative crop on degraded sodic land in north India. Monoculture of JCL has not proven economically viable in India in view of its poor yield; therefore, intercrops in between JCL plantations were tried to optimize land use efficiency. The results revealed that the planting of JCL at 3
3 m spacing with inter-cultivation of sweet basil–matricaria (SB-M) cropping system for four years was more economically viable than planting at 3
2 m spacing and the other rotations tested in the study. Improvements in soil properties in terms of soil pH, EC and organic carbon were found with the SB-M cropping system with JCL as the main crop. Maximum soil microbial biomass carbon was recorded with the SB-M cropping system followed by sorghum-wheat (S-W) and maize-linseed (M-L), and the lowest values were found in the control plot where no intercrop was planted in between JCL plants. This study shows that intercropping with JCL on sodic soils stimulated the soil microbial population, which in turn led to high biological activity in the rhizosphere soil. Growing of medicinal and aromatic crops as intercrops between JCL plantations for four years appears to be a more suitable land use system than JCL mono-cropping to obtain maximum income. Simultaneously a soil improvement due to intercropping provides a new opportunity for even more competitive land use systems in the future. ã 2016 Elsevier B.V. All rights reserved.

1. Introduction The world is facing multiple challenges with an ever-growing population and a lack of sustainable land uses and managements, which results in changes in the soil, water, biota and energy resources available (Cerdà and Doerr, 2007; Muñoz-Rojas et al., 2015; Zhao et al., 2015; Brevik et al., 2016; Khaledian et al., 2016). Agricultural innovations are needed to find solutions to these issues (Brevik and Sauer, 2015; Rodrigo Comino et al., 2015; Cerdà et al., 2016; Keesstra et al., 2016a,b; Prosdocimi et al., 2016; GarciaDiaz et al., 2016; Novara et al., 2016; Yazdanpanah et al., 2016). Rehabilitation and appropriate management of degraded lands has been advocated as a priority issue in the agriculture and forestry

* Corresponding author. E-mail addresses: [email protected] (Y.P. Singh), [email protected] (V.K. Mishra), [email protected] (D.K. Sharma), [email protected] (G. Singh), [email protected] (S. Arora), [email protected] (H. Dixit), [email protected] (A. Cerdà). http://dx.doi.org/10.1016/j.agee.2016.08.034 0167-8809/ã 2016 Elsevier B.V. All rights reserved.

industries of India and in other developing and developed regions (Laudicina et al., 2015; Wildemeersch et al., 2015; Aksakal et al., 2016; Zhang et al., 2016). As a consequence several attempts have been made to develop these lands under productive land use systems (Muñoz-Rojas et al., 2015). Salt affected soils comprising more than 39% of world’s dry land area occur in many parts of subhumid, semi-arid, and arid regions of the world (Oo et al., 2015; Ahmad et al., 2016; Drake et al., 2016; Singh et al., 2016a,c). Out of the 329 M ha geographical area of India, 175 M ha is degraded and 6.9 M ha is salt affected (Abrol and Bhumbla, 1971) with excess amounts of soluble (saline) and/or sodic salts, which adversely affect crop/vegetation growth and yield (Shukla et al., 2011; Singh et al., 2012a). Part of the sodic lands have been reclaimed with government support and put under agriculture and forestry (Singh et al., 2012b; Lemenih et al., 2014; Tesfaye et al., 2015). Pandey et al. (2011) proposed some diverse land use systems to harness the productivity potential of these soils and plantation of Jatropha curcas (JCL) is one of the recommended alternate land uses for sustainable development of these lands to improve the livelihood

122

Y.P. Singh et al. / Agriculture, Ecosystems and Environment 233 (2016) 121–129

of resource poor farmers who cannot afford the costs to reclaim these lands. Because Jatropha curcas is highly drought tolerant and well suited to semi-arid conditions it is the most promising biodiesel plant that can be grown under degraded lands in India, including sodic soils which are not suitable for growing food crops (Singh et al., 2015a). However, there are several limitations like lack of sodicity tolerant genotypes, poor yield without the production of any fuel wood, and low fodder value that have triggered exploration of other crops that can be grown as intercrops with JCL and produce some income to promote the livelihood security of resource poor farmers that have salt affected soils. Under normal soils JCL has been successfully intercropped with groundnuts, sesame, green gram, green chilli and sunflower. Trials conducted in Uttar Pradesh, India, found that groundnuts could be grown successfully between lines of JCL trees spaced 3.0 m apart. It was found that intercropping helped with weed control in the plantation and the growth of JCL with intercrop was better than in the mono-cropped control (Singh et al., 2007). In fact, the common scenario recommends intercropping with JCL within the first few years before JCL attains a full canopy (Brittaine and Lutaladio, 2010). Despite the several advantages of growing JCL, there is limited scientific data showing the effect of JCL on rhizosphere soils, as this is still a research topic that needs more investigation (Ola et al., 2015; Mukhopadhyay et al., 2016). Jatropha cultivation on wastelands (even on arable lands) has not been found to be an economically feasible land use system. Therefore, investigation of salt tolerant intercropping systems that may be economically viable is warranted. The conventional ricewheat cropping system is not suitable to rehabilitate the sodic lands in the Uttar Pradesh agricultural sector due to financial limitations of the land holders (poor farmers) and the lack of lucrative return. Intercropping increases financial benefits and plays a significant role in biological soil amelioration to a greater depth. Although the intercropping models developed so far on sodic lands (silvipastoral) have addressed the integrated effects of agricultural and environmental issues, their wide adoption amongst the farming community is still far behind expectations. As a consequence, alternative land use systems were explored in this study with the following objectives: (i) To rehabilitate the barren sodic land with optimum density and suitable intercrops (ii) accomplish the goals of the ‘National Mission on biodiesel’ set by the government of India, and (iii) to assess the bio-reclamation potential of degraded soil. 2. Materials and methods 2.1. Site characterization A field experiment was conducted from 2007 to 2012 at ICARCentral Soil Salinity Research Institute, Regional Research Station, Lucknow, India (26 4704500 N, 80 460 3200 E). The study site is representative of large areas of abandoned alkali soils in the Central Indo-Gangetic Alluvial Plains of India. It occupies the concavity of gently sloping plains between 119 and 125 m contours. The climate of the experimental site is semi-arid, sub-tropical and monsoonal with average annual rainfall of 817 mm. Maximum rainfall is received between June–October amounting to 741 mm, which is 91% of the total annual rainfall. Average annual evaporation during the last five years was recorded as 1580  81.4 mm. The mean maximum temperature of 39  C in the month of May and mean minimum temperature of 7.1  C in January indicate a seasonal climate. The mean annual temperature during the study period was recorded as 24.6  C whereas mean annual soil temperature and the mean winter soil temperature were 31  C and 18  C, respectively (Fig. 1). Tube well water applied

Fig. 1. Monthly averages of climatic parameters at the study site for the period of study (2007–2012).

to the JCL plants had a pH of 8.2 and EC of 63.0 mS m1. Among the cations, Na dominated (3.2 m mol l1) over Ca + Mg (3.5 m mol l1) followed by K (0.1 m mol l1). However, anions (carbonates + bicarbonates) dominated (6.3 m mol l1) over calcium, while sulphates were absent. The residual sodium carbonate (RSC) of the water used was 2.8 m mol l1. 2.2. Initial soil properties of experimental site The soils of the experimental site were enriched in illite clay minerals in the A and B-horizons with the presence of clay skins justifying their placement in the Alfisol order. The presence of coarse columnar and angular structures, appreciable increase in total and fine clay, presence of clay skins (cutans), and regular decrease of sand in the B horizons and exchangeable sodium percentage more than 15 are evidence that the soils classify as Typic Natrustalfs. Before initiating the experiment, the site was generally abandoned and invaded by weeds such as Cynodon dactylon, Aristida adscendens, Verimonia cineraria, Desmostachya bipinnata, Vetiveria cineraria, and Leptochloa fusca. Soil samples were collected from the profile to 90 cm soil depth and analyzed to monitor the pre-planting soil status. Soil pH2 (1:2 w/v soil: deionized water) of the surface layer (0–15 cm) was 9.46 and it increased vertically to 9.86 at 90 cm depth. Electrical conductivity (EC2) determined with digital meters (pH meter 361-Systronics India Ltd, Ahmadabad and Lab-960, SI Analytics GmbH, Germany) decreased from 177 mS m1 to 62 mS m1accordingly. Exchangeable sodium percentage (ESP) estimated from exchangeable sodium ratio (ESR) and sodium adsorption ratio (SAR) drawn from the concentration values of soluble Na+, Ca2+ and Mg2+ was 40 at surface (0–15 cm) and increased to 70 with increasing depth (90 cm). Sodium was determined through flame photometer, whereas Ca2+ and Mg2+ were determined by titration methods (Richards, 1954). The soil organic carbon content analyzed using the chromic acid titration method (Wang et al., 1996) was higher (1.04 g kg1) at the surface and decreased to 0.6 g kg1at 90 cm depth. Carbonate and bicarbonate were determined in soil saturation extract by titration with 0.1N H2SO4 whereas; chloride and sulphate were determined by silver nitrate titration (Richards, 1954). Available N estimated by distillation of soil with KMnO4 and NaOH (Subbiah and Asija, 1956) was 93.8 kg ha1 in the surface layer and decreased to 45.02 at 60–90 cm depth. Available P and K were determined by the Olsen sodium bicarbonate extraction (Olsen and Dean, 1965) and sodium acetate extraction, respectively. The gypsum requirement (GR) of the experimental soil determined by Schoonover’s (1952) method was 10.5 Mg ha1.

Y.P. Singh et al. / Agriculture, Ecosystems and Environment 233 (2016) 121–129

The soil contained a CaCO3 concretion layer in the sub stratum (about 90 cm soil depths) that was about 40 cm thick, inhibiting water and root penetration. The bulk density of different soil layers was determined from intact cores extracted with a core sampler of 10 cm diameter and 15 cm height (Wilde et al., 1964). Infiltration rate was measured by double concentric infiltrometer cylinders with 60 cm outer and 30 cm inner diameters (Cerdà, 1999; Wang et al., 2016). The initial fall of water level was recorded after 5 min and subsequent observations were taken after 10, 20, 30, 40, 50, 60, 90, and 120 min. Infiltration rate was calculated for each interval and the final constant rate was measured. The soils of the experimental site had sandy loam texture in the surface, silty loam and clay loam in the middle, and sandy loam in the lower layers (Sharma et al., 2011). The soil was having physical and nutritional problems due to high bulk density (1.60 g cm3), poor infiltration rate (6 mm day1) and aeration, and the presence of salts. To monitor the combined effect of JCL plants and intercropping on soil physico-chemical and biological changes after five years of experiment, soil samples were collected from rhizosphere and non-rhizosphere zones. Three plants were selected from each treatment to analyze microbial biomass carbon in rhizosphere and non-rhizosphere soils. Soil microbial biomass carbon was estimated by the fumigation and extraction method of Vance et al. (1987). To analyze rhizosphere microbial population, soil samples were collected within 10 cm of the trunk and for non-rhizosphere 1 m away from the trunk from the 0–15 cm depth increment. Dehydrogenase activity was analyzed using a 3% 2, 3, 5-triphenyl tetrazolium chloride (TTC) solution (Dick et al., 1996). Fresh soil samples were serially diluted in sterile normal saline and 0.1 ml aliquots from which 102 to 104 dilutions were taken and spread on agar medium using sterilized glass L-rod for bacteria and on potato dextrose agar for fungi. Plating was done in duplicate and all the plates were incubated at 28  C for 5 days. After incubation morphologically different bacterial colonies were selected and streaked on nutrient agar plates and incubated at 28  C for 24–48 h. The number of viable bacterial cells per unit volume of a sample using agar plate media was enumerated. The inoculum sample was spread across the plate and the colonies that were formed after incubation were counted. The colonies were referred to as colony forming units (CFU). Similarly; CFU for assessing fungal population in soil was done. 2.3. Planting methodology Six month old seedlings of JCL genotype BTP 1-K of a uniform height of 60 cm raised in polythene bags were planted in 40 cm diameter at the top, 20 cm at the bottom and 120 cm deep auger holes. To standardize the plant spacing for optimizing the growth and productivity per unit area the seedlings were planted at spacing of 3 m
3 m (low density plantation) and 3 m
2 m (high density plantation) with a population density of 1111 and 1666 plants ha1, respectively. The experiment was conducted under a split plot design with 4 replications in a plot size of 144 m2. A uniform mixture of original soil + 4 kg gypsum and10 kg farmyard manure (FYM) was filled in each hole. Plants were irrigated immediately after planting and subsequently three irrigations of good quality water were given using the furrow irrigation method at monthly interval with 10 cm depth of water during first year of planting. Further, the irrigation was done once a year in the month of June when the temperature was more than 40  C. Nitrogen (N) and phosphorus (P) fertilizers were applied uniformly to all the trees @ 30 kg N and 40 kg P2O5 ha1 during the 2007 rainy season (July). No further fertilizer was applied to the JCL plants, however, the recommended dose of fertilizers were given to the understory crops each year. Plant mortality was recorded after every six months. To utilize the interspacing between the rows, three crop

123

rotations, viz. sorghum-wheat (S-W), maize-linseed (M-L), and sweet basil-matricaria (SB-M) were grown as intercrops and compared with the control where no intercrop was grown to evaluate their productivity and ameliorative effect on sodic soils. Sorghum (Sorghum bulgare), maize (Zea mays) and sweet basil (Ocimum basilicum), were planted following recommended practices for cultivation of these crops during Kharif season and wheat (Triticum aestivum), linseed (Linum usitatisimum) and matricaria (Matricaria chamomilla) were grown during Rabi season for four years until JCL developed full canopy. JCL plants were pruned during winter season (dormant period) when the plants attained 1 m height (after one year growth). The pruning was continued every year during February, which seems to be an efficient technique to get more branches (Behera et al., 2010). Sorghum yield was estimated on the basis of fodder yield, maize and wheat yield in terms of grain and straw. Sweet basil, being a medicinal plant, was uprooted and yield was estimated on dry biomass basis, and in the case of matricaria flower yield was recorded. 2.4. Biomass and yields Plant growth, biomass and seed yield were observed periodically. Three representative plants from each treatment were uprooted after five years of study for biomass assessment (air dry weight). The roots and shoots were separated and air-dried to measure air-dry biomass. As regards the seed yield estimation; the maturity of fruits in JCL occurs in a sequential order on the plant therefore repeated harvesting of the matured fruits was done at weekly intervals. Oven dry weights were recorded. The seeds from fruits were separated manually to extract seed from dried fruits and seed yield/plant was calculated. Litter collectors of 1
1 m size made with 0.5 mm mesh steel net, were used to measure annual litter fall yield and estimate total litter fall added to the soils during the five years of study. 2.5. Agronomic practices for different intercropping systems During the kharif season (June-October), sorghum, maize, and sweet basil were grown in between JCL rows. The maize crop was sown in the second week of July in rows, 60–75 cm apart, whereas the plants within each row were spaced at 20–25 cm with a seed rate of 20 kg ha1. The crop was fertilized with 100 kg N, 60 kg P2O5 and 40 kg K2O ha1. One third of nitrogen and total potash and phosphorus was applied at the time of sowing, while the remaining nitrogen was applied as top dressing at the knee high stage and at tasseling in two equal splits. The crop was harvested when the grains were near dry and did not contain more than 20% moisture. The sorghum crop was sown in the first week of July @50 kg seed ha1 at 25 cm row spacing. The crop was fertilized with 60 kg N, 30 kg P2O5 and 30 kg K2O. A half dose of N and full dose of P2O5 and K2O were applied at planting and the remaining dose of N at knee high stage. About 300 g of sweet basil seed was used for raising seedlings in 10 m long, 1 m wide and 20 cm high raised seedbeds in the month of June. Six week old seedlings at the 4–5 leaf stage were transplanted in 60
30 cm rows and in row plant spacing. The plots were irrigated immediately after transplanting. The recommended fertilizer dose of 120 kg N, 60 kg P2O5, and 40 kg K2O ha1 was applied. A half dose of N and entire dose of P2O5 and K2O was given at planting and the remaining N was applied 30 days after transplanting. During Rabi season (October–April), wheat, linseed, and matricaria were grown. The wheat crop was seeded at 100 kg ha1 and fertilized with 120 kg N, 60 kg P2O5 and 40 kg K2O. It was sown at 20 cm row spacing in the second week of November. A one third dose of N and full dose of P2O5 and K2O were applied at planting, one third at the crown root initiation stage, and the remaining one

124

Y.P. Singh et al. / Agriculture, Ecosystems and Environment 233 (2016) 121–129

third at the tillering stage. Linseed was sown at 5 kg seed ha1 in the first week of November with 30 cm row spacing. The recommended dose of fertilizer @ 80 kg N, 40 kg P2O5 and 40 kg K2O was applied. A half dose of N and full dose of P2O5 and K2O was applied at planting and the remaining N was applied at the flower initiation stage. Similar practice was followed with matricaria. Zinc sulphate (20%Zn) @ 20 kg ha1 was also applied to all crops before sowing because sodic soils are typically deficient in zinc. 2.6. Crop yield and economics The crops were grown in two seasons, viz. Kharif (monsoon) and Rabi (winter) seasons. The sorghum green fodder and straw of maize and wheat were sold through open auction at the field site and maize, wheat and linseed grain was sold at minimum support price of the produce. However, sweet basil dry biomass and matricaria flowers were sold in the open market at prevailing market rates. The cost of production was calculated on the basis of cost of inputs used in the production of crops. The gross return was calculated from the value of the output. The input and output were calculated per ha and then, these input and output data were multiplied by their cost. Net return, benefit/cost ratio and productivity were calculated as shown in Eqs. (1) and (2) (Ozkan et al., 2004; Canakci et al., 2005). Net return = Total production revenue  Total production cost (1)

Benefit to cost ratio = total revenue/total cost

(2)

Similar methodology was used to calculate the cost economics of JCL biomass and seed yield. A financial cost benefit analysis was worked out to estimate the costs involved in producing JCL as a mono crop versus when cultivating JCL with intercrops by smallholder farmers having salt affected soils. The methodology used to calculate economics includes costs of production of JCL including costs of land preparation, planting, weeding, pruning, harvesting, and disease and pest control up to the seed production level as well as intercrop products like grain, fodder, flowers and seed. The only direct and measurable benefit was obtained from the sale of crops and seed produced. To calculate the economics we did not use a high-tech agrarian concept that provides for maximum input and the delivery of bumper crops. On the contrary, we favored a practicable approach for smallholder farmers, considering that Jatropha biomass has no market value in fuel or fodder. 2.7. Statistical analysis Data for various growth parameters and yield related traits were subjected to statistical analysis and presented as means of corresponding replicates. Analysis of variance (F test) was applied to examine the significance of differences among the treatments.

Critical difference among the treatments was determined using AGRES Statistical Software Version 3.01. The treatment comparisons were made using t-tests at the 5% level of significance. 3. Results 3.1. Effect of plant density and intercropping systems on biomass and seed yield Tree biomass per plant five years after planting was significantly higher in low density plantations as compared to high density plantations but total biomass yield was more in high density plantations because of the greater number of plants per unit area (Table 1). Maximum total dry biomass was recorded under the sweet basil- matricaria cropping system in both the high and low plant densities and it was significantly higher than the control, S-W and M-L rotations. The observed data showed that the widest spacings gave the lowest seed yield. The seed yield per plant increased with increase in spacing from 3 m
2 m to 3 m
3 m but decreased per unit area. Seed yield per unit area was significantly higher at 3 m
2 m spacing than 3 m
3 m spacing. Heller (1996) also found higher seed yield of JCL at narrower spacing. In our experiment, JCL started fruiting the second year after planting but the yield was very poor (0.07–0.15 Mg ha1). Seed yield per unit area during all five years of growth was maximum (0.44 Mg ha1) at 3 m
2 m spacing. The seed yield in the SB-M cropping system was significantly higher than in the control, S-W, and M-L cropping systems at both the JCL plant spacings (Table 1). The average yield under different cropping systems at wide and narrow spacing ranged from 0.29–0.40 Mg ha1 and 0.31–0.44 Mg ha1 respectively. Maximum seed yield for JCL was recorded in the SB-M cropping system at both the JCL planting densities. SB-M intercropping at 3 m
3 m plant spacing produced 36.8, 18.2 and 8.3% higher seed yield over control, S-W and M-L cropping systems. A similar pattern was recorded with 3
2 m spacing. The seed yield enhancement due to high density plantation under the control, S-W, M-L and SB-M intercropping over wider spacing were 15.8, 27.3, 16.7 and 19.2%, respectively. 3.2. Effect of plant densities on crop yields Intercropping with JCL provided additional income to the farmers. Mono cropping of JCL is not an economical proposition. Crop yield increased up to the third year and during the fourth year there was a reduction in crop yield at both the plant densities. This was because of less light intensity due to canopy cover. Winter crops like wheat, linseed and matricaria were less affected by the JCL canopy than monsoon crops because 90% of the leaves dropped during the winter, allowing those crops to get sufficient light intensity. The average annual yield increment in the second and third years in the low-density plantation was 15.7 and 3.9%; in the high density plantations the increments were 8.3 and 6.1%, respectively (Table 2). During the fourth year of experimentation

Table 1 Biomass and seed yield of Jatropha curcas as affected by plant density and intercropping after 5 years. Treatments

3 m
3 m spacing Total biomass (Mg ha

Control S-W M-L SB-M LSD (p = 0.05) for cropping systems LSD (p = 0.05) for spacing

28.03  1.20 49.02  1.05 45.99  1.41 66.27  1.23 2.22 0.21

3 m
2 m spacing 1

)

1

Seed yield (Mg ha

)

0.29 0.34 0.40 0.34 0.014 0.021

LSD = Least significant difference. S-W: Sorghum-wheat, M-L: Maize-linseed, SB-M: Sweet basil-matricaria.

Total biomass (Mg ha1)

Seed yield (Mg ha1)

38.44  1.52 64.14  1.61 65.67  1.53 73.26  1.42 1.62 0.12

0.31 0.37 0.41 0.44 0.012 0.014

Y.P. Singh et al. / Agriculture, Ecosystems and Environment 233 (2016) 121–129

125

Table 2 Yields (Mg ha1) of different intercrops grown under two plant densities. Treatments

S-W M-L SB-M Mean LSD (p = 0.05) for cropping systems LSD (p = 0.05) for spacing

3 m
3 m spacing

Mean

2008

2009

2010

2011

18.59 1.46 6.22 8.75 0.52 0.06

19.64 1.89 6.38 9.30 0.64 0.12

21.00 2.21 6.89 10.03 1.12 0.21

20.22 1.93 6.84 10.20 0.53 0.16

19.86 1.93 6.58

3 m
2 m spacing

Mean

2008

2009

2010

2011

17.52 1.40 5.74 8.22 0.35 0.04

19.23 2.07 5.66 8.98 0.52 0.14

20.00 2.14 6.25 9.46 0.64 0.23

19.07 2.03 5.68 8.92 0.84 0.32

18.93 1.91 5.83

LSD = Least significant differences. S-W: Sorghum-wheat, M-L: Maize-linseed, SB-M: Sweet basil-matricaria.

the yield reduction started in both the low and high density plantations and was reduced by 3.22 and 4.62%, respectively. Thus, it is clearly evident that the yield reduction in the high-density plantation was more pronounced than in the low-density plantation. 3.3. Litter fall Litter fall was greatest in the SB-M cropping system. Intercropping variations in litter fall were relatively high at the 3
2 m spacing (Fig. 2). 3.4. Soil amelioration 3.4.1. Soil physico-chemical properties There was a significant improvement in physico-chemical properties of the soil due to the combined effect of JCL plantation and intercrops. Bulk density of the control plot, where only trees were planted and no intercrops were grown, was significantly higher over the plantation of JCL and cultivation of crops in between the trees. However, soil porosity and infiltration rate increased significantly. Plant density had a significant effect on soil physical properties (Table 3). Planting of JCL at a spacing of 3 m
2 m resulted in maximum reduction of soil bulk density and increase in soil porosity and cumulative infiltration rate because this treatment had the maximum litter fall and biomass yield (Yadav and Vasistha, 1989). The winter months accounted for 80% of total litter fall that was composed of about 75–80% foliage, which in turn helped to increase organic carbon and reduce soil pH. Among the cropping systems evaluated, the SB-M cropping system had more positive changes in soil properties than S-W, M-L, and the control. After five years of plantation of JCL and cultivation of crops in between JCL rows, the greatest improvement in terms of soil pH, electrical conductivity, and organic carbon, available N, P and K in the 0–15 cm soil layer was recorded under the plantation of JCL at

Fig. 2. Litter fall yield at 3 m
3 m and 3 m
2 m spacings under different intercropping systems after 5 years of Jatropha plantation.

3 m
2 m spacing and growing of SB-M as the inter-crops (Table 4). The average reduction in soil pH under S-W, M-L and SB-M was 1.72%, 1.72% and 4.09% and the increments in organic carbon were 28.94%, 31.57% and 42.10%, respectively over the control. Baumert et al. (2015) also reported an 84% increase in soil organic carbon due to JCL plantation. The increase in organic carbon content of the surface soils in a span of five years was about three folds higher in the case of intercropping with JCL and about two-folds higher in JCL mono crops in sodic soils in comparison to barren sodic soils. Growing SB-M under the JCL trees significantly improved the fertility status (N: P: K) of sodic soils in comparison to barren sodic land over five years. The N: P: K status under SB-M increased by 10.25%, 42.63% and 27.06% respectively over the control. 3.4.2. Rhizosphere microbiology The highest populations of bacteria, fungi, as well as dehydrogenase activity were recorded in the rhizosphere soil as compared to non-rhizosphere soil (Fig. 3). The number of bacteria in the rhizosphere soils was about 40% higher than the non-rhizosphere soils. This is because of higher mineralization in the canopy area than outside the canopy due to an improved C:N ratio. Similarly, the fungal population in the rhizosphere zone was more than the non-rhizosphere soils. Plant spacing did not have a significant role in microbial activities in the rhizosphere soil; however, the cropping system played an important role in microbial biomass in non-rhizosphere soils. Maximum microbial biomass carbon was recorded in soils under the SB-M cropping system followed by S-W and M-L and was lowest in the control where no intercropping was done (Table 3). Increases in microbial biomass under S-W, M-L and SB-M were 17.81%, 8.75% and 24.68% over the control. This study shows that plantation of JCL in sodic soils stimulated the soil microbial population, and biological activities particularly in the rhizosphere zone of the soil. 3.5. Cost economics Based on five years of study it was observed that planting of JCL at 3 m
3 m spacing was more economical and suitable for intercrops. The value of intercrops varied from 1737.2 to 5288.4$ ha1. The maximum value of 5288.4$ ha1 was recorded from SB-M intercropping where JCL was planted at 3 m
3 m spacing. This is because of the high yield and market rate of sweet basil leaves and matricaria flowers. Biomass yield from JCL planted at 3 m
2 m spacing with S-W, M-L and SB-M intercropping and monoculture of JCL was 12.0, 22.9 and 32.0 and 14.3% higher than that of the 3 m
2 m spacing. This is because of more plants per unit area. The maximum total economic value and benefit: cost (B: C) ratio of the JCL based intercropping system was highest in the SB-M (medicinal and aromatic crop) cropping system followed by S-W and lowest in mono cropped JCL (Table 5). Additional net income of $3225.2 and $2952.8 was obtained due to inter-cultivation of medicinal and aromatic crops (sweet basil-matricaria) for four years at 3 m
3 m

126

Y.P. Singh et al. / Agriculture, Ecosystems and Environment 233 (2016) 121–129

Table 3 Ameliorative effects of Jatropha and intercropping on soil physico-chemical properties 5 years after plantation. Parameter Initial 2006 Control S-W M- L SB-M

Spacing (m)

BD (g cm3)

SP (%)

IR (mm day1)

pH (1:2)

EC (mS m1)

ESP

3
3 3
2 3
3 3
2 3
3 3
2 3
3 3
2

0.60  0.04 1.57  0.03 1.56  0.02 1.54  0.14 1.52  0.12 1.56  0.08 1.53  0.12 1.48  0.14 1.48  0.11 0.08

48.6  0.42 50.2  0.34 51.2  0.42 52.8  0.32 53.4  0.30 51.3  0.28 52.2  0.33 54.3  0.30 54.8  0.28 2.34

8.6  0.12 14.2  0.14 15.4  0.21 18.7  0.16 21.2  0.18 16.6  0.20 18.4  0.16 21.2  0.13 22.1  0.14 4.23

9.46  0.15 9.22  0.11 9.34  0.21 9.12  0.15 9.13  0.16 9.13  0.21 9.11  0.14 9.05  0.17 892  0.21 0.03

177.0  8.62 210.2  9.11 450.1  10.13 670.3  10.25 210.3  9.65 130.5  8.66 620.2  9.20 450.3  10.32 300.0  9.68 0.08

40.1  2.23 36.2  1.15 32.4  1.68 32.4  1.85 35.4  2.12 32.5  2.21 35.2  2.10 30.2  2.13 35.3  2.43 3.2

LSD (p = 0.05)

BD, bulk density; SP, soil porosity; IR, infiltration rate; EC, electrical conductivity; .ESP, Exchangeable sodium percentage; LSD. Least significant difference. S-W: Sorghumwheat, M-L: Maize-linseed, SB-M: Sweet basil-matricaria.

Table 4 Ameliorative effects of Jatropha and intercropping on nutritional and biological properties of soil 5 years after plantation. Parameter Initial 2006 Control S-W M-L SB-M

Spacing

O.C (g kg1)

Av.N (mg kg1)

Av. P (mg kg1)

Av.K (mg kg1)

MBC (mg kg1)

3
3 3
2 3
3 3
2 3
3 3
2 3
3 3
2

1.0  0.02 1.8  0.03 2.0  0.12 2.4  0.20 2.5  0.14 2.5  0.13 2.5  0.16 2.7  0.20 2.7  0.08 0.002

41.9  1.12 103.6  1.15 110.1  1.16 95.2  1.23 107.8  1.42 95.9  0.86 114.8  1.12 103.6  1.21 111.9  1.32 34.2

11.1  0.26 9.6  0.23 10.1  0.26 12.3  0.31 13.5  0.22 10.9  0.25 12.1  0.26 13.6  0.30 14.5  0.26 1.12

173.5  22.50 137.6  17.62 146.9  16.50 166.9  18.10 171.0  18.21 148.9  16.42 199.2  17.52 171.8  16.16 189.7  18.21 13.6

96.4  3.23 96.4  2.56 100.1  2.48 112.2  3.12 119.3  3.22 102.5  2.86 111.2  3.1 120.5  2.80 124.5  3.10 2.32

LSD (p = 0.05)

O.C., organic carbon; Av.N., available nitrogen; Av.P., available phosphorus; Av.K., available potassium; MBC, microbial biomass carbon.LSD. Least significant difference. S-W: Sorghum-wheat, M-L: Maize-linseed, SB-M: Sweet basil-matricaria.

4. Discussion 4.1. Effect of plant density and intercropping systems on biomass and seed yield

3

2

/

/

/ /

Fig. 3. Combined effect of plant density and intercropping on microbial population and enzyme activities of rhizosphere and non-rhizosphere soils.

and 3 m
2 m spacings, respectively. Total income from mono cropping of JCL as well as intercropping with JCL increased significantly over the years at both the planting densities.

Rehabilitation of salt affected waste lands (about 6.73 M ha) in India, of which 3.72 M ha of sodic soils have limited options because they do not support cultivation of conventional crops. Therefore, the use of JCL plantation has been advocated (Kagamebga et al., 2011; Singh et al., 2015a). Jatropha based land use systems have been proposed by Pandey et al. (2011) which appear to be suitable for sustainable development of these lands and improving the livelihood of resource poor farmers who cannot afford large reclamation expenditures on these lands. Monoculture of JCL even on good land is not a profitable business. Several studies have been conducted on normal soils to grow intercrops like groundnut in between lines of JCL trees spaced 3.0 m apart till the tree attained full canopy. Intercropping helped with weed control in the plantation and also the growth of JCL with intercropping was better than the mono cropped control (Singh et al., 2007). Plant spacing plays an important role in growth and development of

Table 5 Cost economics of Jatropha curcas and intercropping systems at different planting densities (aggregate of 4 years). Inter-cropping systems

S-W M-L SB-M Only Jatropha curcas

Income from crop produce ($ha1)

Income from JCL seed ($ha1)

Gross income ($ha1)

Net income ($ha1)

B:C ratio

3m
3m

3m
2m

3 m
3m

3m
2m

3m
3m

3m
2m

3m
3m

3m
2m

3m
3m
m

3
2m

3319.8 1784.9 5288.4 0

3252.6 1737.2 4809.6 0

330.2 356.4 374.5 280.0

410.9 407.3 443.6 316.3

3650.0 2141.3 5662.9 280.0

3663.5 2144.6 5253.2 316.3

2352.2 1369.3 3332.2 107.0

2416.2 1549.1 3051.8 99.0

1.81 1.77 2.76 0.61

1.99 2.38 2.50 0.49

S-W: Sorghum-wheat, M-L: Maize-linseed, SB-M: Sweet basil-matricaria. Average sale prices: Sorghum fodder@US$22.7 per ton; Wheat@US$175.0 per ton; Maize@US$154.0 per ton; Linseed@US$440.0 per ton; Sweet basil@US$200per ton; Matricaria@US$206.3; Jatropha seed@US$181.0 per ton.

Y.P. Singh et al. / Agriculture, Ecosystems and Environment 233 (2016) 121–129

plants as well as the yields of intercrops. Total biomass yield was more in the high density plantations because of an increased number of plants per unit area but the biomass yield per plant was significantly higher in low density plantations because of a greater number of branches and increased plant height. Promoting JCL as a sole crop in sodic soils is a major constraint because of poor seed yield (Singh et al., 2013). There is high variability in yield among the individual trees because of the nonavailability of a high yielding salt tolerant variety. We have observed that the low-density plantation gave the lowest yield but seed yield per unit area was more under the high density plantation. Heller (1996) also found high seed yield of JCL at narrow spacing. In this study JCL started fruiting in second year after planting but the yield was very poor (0.07–0.15 Mg ha1). Seed yield per unit area was maximum (0.44 Mg ha1) at high plant density. Due to closer spacing, the competition for nutrients, water, and light was more, which resulted in less seed production per plant. The productivity of JCL in salt affected soils depends on soil moisture availability, soil fertility, and plant age and management practices (Jingura et al., 2011; Kumar and Sharma, 2008; Carels, 2009; Behera et al., 2010; Ghosh et al., 2011). Seed yield also varied with the nature of crops grown (Singh et al., 2015a,b). Inter cropping of sweet basil and matricaria crops enhanced JCL seed yield because of the addition of more nutrients and crop residues, which led to increased soil microbial activities. SB-M intercropping at 3 m
3 m plant spacing produced 36.8, 18.2 and 8.3% higher seed yield over the control, S-W, and M-L cropping systems respectively. 4.2. Effect of plant densities on crop yields Crop yield increased up to the third year and after that there was a reduction in crop yield at both the plant densities. This was due to the shade effect as the JCL plants grew. Winter crops like wheat, linseed and matricaria were less affected because JCL sheds all leaves by January, which are added to the soil and allow sufficient light intensity to make it through to the intercrop. The average annual yield increment during second and third years at low density plantation was 15.7 and 3.9% however, at high density plantation the increment was 8.3 and 6.1%, respectively. During the fourth year of the study, yield reduction started in both the low and high-density plantations and was reduced by 3.22 and 4.62%, respectively. Thus, it is clearly evident that the yield reduction in the high-density plantations is more pronounced than in the lowdensity plantations. Jatropha has been successfully intercropped with groundnut, sesame, green chilli, green gram and sunflower in India (Brittaine and Lutaladio, 2010). Maximum total economic value and B: C ratio in the JCL based intercropping systems were highest (2.50–2.76) from the SB-M (medicinal and aromatic crop) cropping system followed by S-W and lowest in of the mono cropped JCL plantations because of the higher income from intercropping. Mishra (1987) observed that matricaria can produce about 2.6 Mg ha1 of fresh flowers in an alkali soil with pH 9.5 and gives higher net income than wheat grown under similar soil conditions. Cost economics of a Prosopis based silvipastoral system conducted at the same site was comparatively less (2.89) than the JCL based SB-M intercropping system (Singh et al., 2015b; Francis et al., 2005). 4.3. Soil physico-chemical properties The physico-chemical properties of the sodic soils in this study were observed at 0 (before plantation) and 5 years of growth. Differences in bulk density, water holding capacity, and infiltration rate were significant when compared to the pre-plantation condition due to the combined effect of JCL and the intercrops. Sodic soils generally have poor physical conditions which restrict

127

the water movement and leaching of salts from the surface (Singh et al., 2012b, 2011). Reduction in bulk density in 0–75 mm soil depth over the initial value is due to the shallow root systems of JCL and the intercrops, which enhances the proportion of macropores to micropores (Wani et al., 2012). Soil infiltration rate increased from 8.62 mm day1 to 18.7 and 21.2 mm day1 due to structural improvement in the soil surface over the years (Ogunwole et al., 2008; Singh et al., 2011, 2014). A significant decrease in soil pH was recorded after 5 years of JCL plantation and cultivation of intercrops. This may be due to CO2 emission from root respiration and decomposition, organic matter decomposition and root exudation (Singh et al., 2013). Organic matter added through leaf litter and fine root mortality produces organic acids (humic and fulvic) that reduce soil pH. We found significant reduction in ESP after 5 years growth of JCL as compared to the initial value. This may be due to maximum dissolution of calcium carbonate in the presence of organic matter and increased leaching of soluble salt ions as infiltration rates increased. Organic carbon content increased about two fold due to the combined effects of JCL and intercrops, and confirms the positive impact of organic matter in soil infiltration (Cerdà, 1999; Singh et al., 2016a,b,c).This may be correlated to leaf fall of JCL plants and crops and decomposition of crop residues left in the soil. Wani et al. (2012) and Baumert et al. (2015) reported 19% and 84% increases in soil carbon content during 4 years of JCL cultivation. Singh et al. (2016b) and Singh et al. (2015a) have also reported a significant increase in organic carbon from a Prosopis based silvipastoral system. Plantations of JCL on degraded lands are supposed to improve the properties of degraded soils by varying extents corresponding to their growth, biomass, and age (Kaushik et al., 2007; Abhilash et al., 2010; Garg et al., 2011). JCL has been shown to improve the structural stability, carbon, and nitrogen contents of degraded Entisols in India (Ogunwole et al., 2008). Matricaria helps to improve sodic soils through its exceptionally high sodium uptake. It can be successfully grown in saline soils having ECe up to 12 dS m1 and it gives fresh flower yields of 4 Mg ha1 under saline conditions. In JCL monoculture the changes in soil pH were not significant. In contrast, in intercropping systems with JCL, there was a significant reduction in soil pH over the control. 4.4. Rhizosphere microbiology Soil organisms play a key role in soil biogeochemistry and in the soil biologic balance (Billings et al., 2015; Buyer et al., 2016; Yazdanpanah et al., 2016). Indeed, it is because of soil organisms that JCL is able to develop on poor soils of low fertility. The roots of JCL, in symbiosis with tree mycorhizian fungi, prevent deficiencies of nutrient elements (N, P and K) in the soil (Leye et al., 2009). Microbial biomass is an undifferentiated parameter of different microorganisms in soil, and these microorganisms play an important role in managing nutrient cycling and availability to plants. Changes in microbial biomass is an early indicator of changes in soil quality and microorganisms are essential for the role the soil plays in the Earth System (Smith et al., 2015). Growing of JCL plants and intercropping contributes to reduced soil sodicity, increased soil organic matter, and consequently to enhanced microbial activities in the soil. Significant increases in populations of bacteria, fungi, and actinomycetes as well as dehydrogenase activity were recorded in the rhizosphere soil as compared to nonrhizosphere soil. This indicates that rhizospheric interactions with sodic soils deliver positive effects on soil microbial biomass and enzyme activities (Ganjegunte et al., 2014; Singh, 2015; Singh et al., 2015a,b, 2016a,b,c). Numbers of bacteria, fungi and dehydrogenase activities were more in high density plantations than that in low density plantations. The supply of litter and root mass might be responsible for increasing bacteria and fungi as a prominent source

128

Y.P. Singh et al. / Agriculture, Ecosystems and Environment 233 (2016) 121–129

of added organic matter. The microbial biomass and the favorable temperature and humidity favor microbial activity and enhance the rate of mineralization (Anbalagan et al., 2012). Ogunwole et al. (2008) reported that microbial biomass is always higher under the canopy than outside the canopy. This indicates more biological activity in the rhizosphere zone, which increased microbial biomass carbon. This research shows that there are strategies that can help to reach a more sustainable soil management (Brevik et al., 2015; Keesstra et al., 2016a,b). 5. Conclusions This study revealed that plantations of JCL at 3 m
3 m spacing intercropped with a sweet basil-matricaria cropping system for four years was relatively more economical than planting at 3 m
2 m spacing and then the other crop rotations examined. Mono cropping JCL in sodic soils was not an economically viable proposition because JCL seed yield was very poor during the first five years of its plantation. Resource poor farmers cannot wait for such a longer period without getting any income from their land. Improvement in soil properties in terms of soil pH, EC and organic carbon was also higher in the SB-M intercropping system. So growing medicinal and aromatic crops in between JCL rows for four years was an economically viable proposition during rehabilitation of identical wasteland. Additionally, the intangible benefits of environmental conservation and land reclamation, which are not generally accounted for in conventional economics, provide a greater strength for the Jatropha based intercropping system with SB-M in order to increase the land use efficiency as well as to accomplish the national mission of biodiesel production. Acknowledgements We are thankful to the Director, ICAR-Central Soil Salinity Research Institute, Karnal, for providing financial support and critical advice to complete this project. The authors are thankful to Dr. Bajrang Singh, Ex- senior principal scientist, CSIR-National Botanical Research Institute, Lucknow for their technical guidance and support as and when required. The authors are thankful to the anonymous reviewers for their valuable suggestions. Eric C Brevik improved the original manuscript. References Abhilash, P.C., Srivastava, P., Jamil, S., Singh, N., 2010. Revisited Jatropha curcas as an oil plant of multiple benefits: critical research needs and prospects for the future. Environ. Sci. Pollut. Res. 18, 127–131. Abrol, I.P., Bhumbla, D.R., 1971. Saline and alkaline soils in India-their occurrence and management. World Soil Resource Report, vol. 41. FAO, Rome, pp. 42–51. Ahmad, S., Ghafoor, A., Akhtar, M.E., Khan, M.Z., 2016. Implication of gypsum rates to optimize hydraulic conductivity for variable-texture saline-sodic soils reclamation. Land Degrad. Dev. doi:http://dx.doi.org/10.1002/ldr.2413. Aksakal, E.L., Sari, S., Angin, I., 2016. Effects of vermicompost application on soil aggregation and certain physical properties. Land Degrad. Dev. 27, 983–995. doi: http://dx.doi.org/10.1002/ldr.2350. Anbalagan, M., Manivannan, S., Prakasm, B.A., 2012. Biomanagement of Parthenium hysterophorus (Asteraceae) using an earthworm, Eisenia foetida (Savigny) for recycling the nutrients. Adv. App. Sci. Res. 3, 3025–3031. Baumert, S., Khamzina, A., Vlek, P.L., 2015. Soil organic carbon sequestration in Jatropha curcas systems in Burkina Faso. Land Degrad. Dev. doi:http://dx.doi. org/10.1002/ldr.2310. Behera, S.K., Srivastava, P., Tripathi, R., Singh, J.P., Singh, N., 2010. Evaluation of plant performance of Jatropha curcas L. under different agro-practices for optimizing biomass—a case study. Biol. Bioenergy 34, 30–41. Billings, S.A., Tiemann, L.K., Ballantyne IV, F., Lehmeier, C.A., Min, K., 2015. Investigating microbial transformations of soil organic matter: synthesizing knowledge from disparate fields to guide new experimentation. Soil 1, 313–330. doi:http://dx.doi.org/10.5194/soil-1-313-2015. Brevik, E.C., Sauer, T.J., 2015. The past, present, and future of soils and human health studies. Soil 1, 35–46. doi:http://dx.doi.org/10.5194/soil-1-35-2015.

Brevik, E.C., Cerdà, A., Mataix-Solera, J., Pereg, L., Quinton, J.N., Six, J., Van Oost, K., 2015. The interdisciplinary nature of Soil. Soil 1, 117–129. doi:http://dx.doi.org/ 10.5194/soil-1-117-2015. Brevik, E.C., Calzolari, C., Miller, B.A., Pereira, P., Kabala, C., Baumgarten, A., Jordán, A., 2016. Soil mapping, classification, and modeling: history and future directions. Geoderma 264, 256–274. doi:http://dx.doi.org/10.1016/j.geoderma.2015.05.017. Brittaine, R., Lutaladio, N., 2010. JCL: a small holder bioenergy crop. The potential for pro-poor development. Intercrop Manage. 8, 1–114. Buyer, J.S., Schmidt-Küntzel, A., Nghikembua, M., Maul, J.E., Marker, L., 2016. Soil microbial communities following bush removal in a Namibian savanna. Soil 2, 101–110. doi:http://dx.doi.org/10.5194/soil-2-101-2016. Canakci, M., Topakci, M., Akinci, I., Ozmerzi, A., 2005. Energy use pattern of some field crops and vegetable production: case study for Antalya region Turkey. Energy Conserv. Manage. 46, 655–666. Carels, N., 2009. JCL curcas: a review. Adv. Bot. Res. 50, 39–86. Cerdà, A., Doerr, S.H., 2007. Soil wettability, runoff and erodibility of major dryMediterranean land use types on calcareous soils. Hydrol. Process. 21, 2325– 2336. doi:http://dx.doi.org/10.1002/hyp.6755. Cerdà, A., González-Pelayo, O., Giménez-Morera, A., Jordán, A., Pereira, P., Novara, A., Brevik, E.C., Prosdocimi, M., Mahmoodabadi, M., Keesstra, S., García Orenes, F., Ritsema, C., 2016. The use of barley straw residues to avoid high erosion and runoff rates on persimmon plantations in Eastern Spain under low frequency– high magnitude simulated rainfall events. Soil Res. 54, 154–165. doi:http://dx. doi.org/10.1071/SR.15092. Cerdà, A., 1999. Seasonal and spatial variations in infiltration rates in badland surfaces under Mediterranean climatic conditions. Water Resour. Res. 35, 319– 328. doi:http://dx.doi.org/10.1029/98WR01659. Dick, R.P., Breakwell, D.P., Turco, R.F., 1996. Soil enzyme activities and biodiversity measurements as integrative microbiological indicators. In: Methods for Assessing Soil Quality, Vol. 9. Soil Sci. Soc. Am. Madison, WI pp. 9–17. Drake, J.A., Cavagnaro, T.R., Cunningham, S.C., Jackson, W.R., Patti, A.F., 2016. Does biochar improve establishment of tree seedlings in saline sodic soils? Land Degrad. Dev. 27, 52–59. doi:http://dx.doi.org/10.1002/ldr.2374. Francis, J., Fond, L.R., Olsson, P., Schipper, K., 2005. The market pricing of accruals quality. J. Account. Econ. 39 (2), 295–327. Ganjegunte, G.K., Sheng, Z., Clark, J.A., 2014. Soil salinity and sodicity appraisal by electromagnetic induction in soils irrigated to grow cotton. Land Degrad. Dev. 25 (3), 228–235. doi:http://dx.doi.org/10.1002/ldr.1162. Garcia-Diaz, A., Bienes-Allas, R., Gristina, L., Cerdà, A., Novara, A., Pereira, P., 2016. Carbon input threshold for soil carbon budget optimization in eroding vineyards. Geoderma 271, 144–149. doi:http://dx.doi.org/10.1016/j. geoderma2016.02.020. Garg, K.K., Karlberg, L., Wani, S.P., Berndes, G., 2011. JCL production on wastelands in India: opportunities and trade-offs for soil and water management at the watershed scale. Biofuels Bioprod. Biorefin. 5, 4410–4430. Ghosh, A., Chikara, A., Chaudhary, D.R., 2011. Diminution of economic yield as affected by pruning and chemical manipulation of Jatropha carcus. Biol. Bioenergy 35, 1021–1029. Heller, J., 1996. Physic nut. Jatropha Curcas L. Promoting the Conservation and Use of Underutilized and Neglected Crops. 1. Institute of Plant Genetics and Crop Plant Research, Gatersleben/IPGRI, Rome (66 pp). Jingura, R.M., Matengaifa, R., Musademba, D., Musiyiwa, K., 2011. Characterization of land types and agro-ecological conditions for production of Jatropha as a feed stock for biofuels in Zimbabwe. Biol. Bioenergy 35, 2080–2086. Kagamebga, W.F., Thiombiano, A., Traore, S., Zougmore, R., Boussim, J.I., 2011. Survival and growth response of Jatropha curcas L: to three restoration techniques on degraded soils in Burkina Faso. Ann. For. Res. 54, 171–184. Kaushik, N., Kumar, K., Kumar, S., Kaushik, N., Roy, S., 2007. Genetic variability and divergence studies in seed traits and oil content of Jatropha (Jatropha curcas L.) accessions. Biol. Bioenergy 31, 497–502. Keesstra, S.D., Bouma, J., Wallinga, J., Tittonell, P., Smith, P., Cerdà, A., Montanarella, L., Quinton, J.N., Pachepsky, Y., van der Putten, W.H., Bardgett, R.D., Moolenaar, S., Mol, G., Jansen, B., Fresco, L.O., 2016a. The significance of soils and soil science towards realization of the United Nations Sustainable Development Goals. Soil 2, 111–128. doi:http://dx.doi.org/10.5194/soil-2-111-2016. Keesstra, S., Pereira, P., Novara, A., Brevik, E.C., Azorin-Molina, C., Parras-Alcántara, L., Jordán, A., Cerdà, A., 2016b. Effects of soil management techniques on soil erosion in apricot orchards. Sci. Total Environ. 551–552, 357–366. doi:http://dx. doi.org/10.1016/j.scitotenv.2016.01.182. Khaledian, Y., Kiani, F., Ebrahimi, S., Brevik, E.C., Aitkenhead-Peterson, J., 2016. Assessment and monitoring of soil degradation during land use change using multivariate analysis. Land Degrad. Dev.. http://dx.doi.org/10.1002/ldr.2541. Kumar, A., Sharma, S., 2008. An evaluation of multipurpose oil seed crop for industrial uses (JCL) a review. Ind. Crop Prod. 28, 1–10. Laudicina, V.A., Novara, A., Barbera, V., Egli, M., Badalucco, L., 2015. Long-term tillage and cropping system effects on chemical and biochemical characteristics of soil organic matter in a mediterranean semi arid environment. Land Degrad. Dev. 26, 45–53. doi:http://dx.doi.org/10.1002/ldr.2293. Lemenih, M., Kassa, H., Kassie, G.T., Abebaw, D., Teka, W., 2014. Resettlement and Woodland management problems and options: a case study from Northwestern Ethiopia. Land Degrad. Dev 25, 305–318. doi:http://dx.doi.org/10.1002/ ldr.2136. Leye, E.H.M., Ndiaye, M., Ndiaye, F., Diallo, B., Sarr, A.S., Diouf, M., Diop, T., 2009. Revue des energies renouvelables 12, 269–278. Mishra, P.N., 1987. German chamomile. In: Khoshoo, T.N. (Ed.), Eco-development of Alkaline Land: A Case Study. NBRI, Lucknow (80 pp).

Y.P. Singh et al. / Agriculture, Ecosystems and Environment 233 (2016) 121–129 Muñoz-Rojas, M., Jordán, A., Zavala, L.M., De la Rosa, D., Abd-Elmabod, S.K., AnayaRomero, M., 2015. Impact of Land Use and Land Cover Changes on Organic Carbon Stocks in Mediterranean Soils (1956–2007). Land Degrad. Dev. 26 (2), 168–179. doi:http://dx.doi.org/10.1002/ldr.2194. Novara, A., Keesstra, S., Cerdà, A., Pereira, P., Gristina, L., 2016. Understanding the role of soil erosion on CO2 loss using 13C isotopic signatures in abandoned Mediterranean agricultural land. Sci. Total Environ. 550, 330–336. doi:http://dx. doi.org/10.1016/j.scitotenv.2016.01.095, 2016. Mukhopadhyay, S., Masto Cerdà, S.E.A., Ram, L.C., 2016. Rhizosphere soil indicators for carbon sequestration in a reclaimed coal mine spoil. Catena 141, 100–108. http://dx.doi.org/10.1016/j.catena.2016.02.023. Ogunwole, J.O., Chaudhary, D.R., Gosh, A., Daudu, C., Chikara, J., Patolia, J., 2008. Contribution of Jatropha curcas to soil quality improvement in a degraded Indian entisol. Acta Agric. Scand. 58, 245–251 (Section B-Soil and Plant Sci.). Ola, A., Dodd, I.C., Quinton, J.N., 2015. Can we manipulate root system architecture to control soil erosion? Soil 1, 603–612. doi:http://dx.doi.org/10.5194/soil-1-6032015. Olsen, S.R., Dean, L.A., 1965. Phosphorus. In: Black, C.A. (Ed.), Methods of soil analysis. Am. Soc. Agronomy Madison, Wisconsin, USA, pp. 1035–1049 (Part 2). Oo, A.N., Iwai, C.B., Saenjan, P., 2015. Soil properties and maize growth in saline and nonsaline soils using cassava-industrial waste compost and vermicompost with or without earthworms. Land Degrad. Dev. 26, 300–310. doi:http://dx.doi.org/ 10.1002/ldr.2208. Ozkan, B., Akcaoz, H., Fert, C., 2004. Energy input–output analysis in Turkish agriculture. Renovable Energy 29 39–51. Pandey, V.C., Singh, K., Singh, B., Singh, R.P., 2011. New approaches to enhance ecorestoration efficiency of degraded sodic lands; critical research needs and future prospects. Ecol. Restor. 29, 322–325. Prosdocimi, M., Jordán, A., Tarolli, P., Keesstra, S., Novara, A., Cerdà, A., 2016. The immediate effectiveness of barley straw mulch in reducing soil erodibility and surface runoff generation in Mediterranean vineyards. Sci. Total Environ. 7, 323– 330. doi:http://dx.doi.org/10.1016/j.scitotenv.2015.12.076. Richards, L.A., 1954. Diagnosis and Improvement of Saline and Alkali Soils. USDA (Washington) Handbook (No. 60, pp.112). Rodrigo Comino, J., Brings, C., Lassu, T., Iserloh, T., Senciales, J.M., Martínez Murillo, J. F., Ruiz Sinoga, J.D., Seeger, M., Ries, J.B., 2015. Rainfall and human activity impacts on soil losses and rill erosion in vineyards (Ruwer Valley, Germany). Solid Earth 6, 823–837. doi:http://dx.doi.org/10.5194/se-6-823-2015. Schoonover, W.R., 1952. Examination of Soils for Alkali. University of California, Extension Service, Berkely, California. Sharma, R.C., Mandal, A.K., Singh, R., Singh, Y.P., 2011. Characteristics and use potential of sodic and associated soils in CSSRI experimental farm Lucknow, Uttar Pradesh. J. Indian Soc. Soil Sci. 59, 381–387. Shukla, S.K., Singh, K., Singh, B., Gautam, N.N., 2011. Biomass productivity and nutrient availability of Cynodon dactylon (L.) Pers. Growing on soils of different sodicity stress. Bio. Bioeng. 35, 3440–3447. Singh, R.A., Kumar, M., Haider, E., 2007. Synergistic cropping of summer groundnut with Jatropha curcas—a new two-tier cropping system for Uttar Pradesh. J. Agric. Res. 5, 1–2. Singh, Y.P., Singh, G., Sharma, D.K., 2011. Ameliorative effect of multipurpose tree species grown on sodic soils of Indo-Gangetic Alluvial Plains of India. Arid Land Restor. Manage. 25, 1–20. Singh, K., Pandey, V.C., Singh, B., Singh, R.R., 2012a. Ecological restoration of degraded sodic lands through afforestation and cropping. Ecol. Eng. 43, 70–80. Singh, K., Singh, B., Singh, R.R., 2012b. Changes in physico-chemical microbial and enzymatic activities during restoration of degraded sodic lands: ecological suitability of mixed forest over plantation. Catena 96, 57–67. Singh, K., Singh, B., Tuli, R., 2013. Sodic soil reclamation potential of Jatropha curcas: a long term study. Ecol. Eng. 58, 434–440. Singh, Y.P., Singh Singh, G., Sharma, D.K., 2014. Bio-amelioration of alkali soils through agroforestry systems in central Indo-Gangetic Plains of India. J. For. Res. 25, , 887–896.

129

Singh, Y.P., Nayak, A.K., Sharma, D.K., Singh, G., Mishra, V.K., Singh, D., 2015a. Evaluation of Jatropha Curcas genotypes for rehabilitation of degraded sodic lands. Land Degrad. Dev. 26, 510–520. doi:http://dx.doi.org/10.1002/ldr.2398. Singh, Y.P., Singh, G., Sharma, D.K., 2015b. Performance of pastoral: silvipastoral and silvicultural systems in Alkali soils of Indo-Gangetic plains. J. Soil Water Conserv. 14, 168–173. Singh, K., Mishra, A.K., Singh, B., Singh, R.P., Patra, D.D., 2016a. Tillage effects on crop yield and physico-chemical properties of sodic soils. Land Degrad. Dev. 27 (2), 223–230. doi:http://dx.doi.org/10.1002/ldr.2266. Singh, K., Trivedi, P., Singh, G., Singh, B., Patra, D.D., 2016b. Effect of different leaf litters on carbon, nitrogen and microbial activities of sodic soil. Land Degrad. Dev. 27, 1215–1226. doi:http://dx.doi.org/10.1002/ldr.2313. Singh, Y.P., Singh, R., Sharma, D.K., Mishra, V.K., Arora, S., 2016c. Optimizing gypsum levels for amelioration of sodic soils to enhance grain yield and quality of rice. J. Indian Soc. Soil Sci. 64 (1), 33–40. Singh, K., 2015. Microbial and enzyme activities of saline and sodic soils. Land Degrad. Dev. doi:http://dx.doi.org/10.1002/ldr.2385. Smith, P., Cotrufo, M.F., Rumpel, C., Paustian, K., Kuikman, P.J., Elliott, J.A., McDowell, R., Griffiths, R.I., Asakawa, S., Bustamante, M., House, J.I., Sobocká, J., Harper, R., Pan, G., West, P.C., Gerber, J.S., Clark, J.M., Adhya, T., Scholes, R.J., Scholes, M.C., 2015. Biogeochemical cycles and biodiversity as key drivers of ecosystem services provided by soils. Soil 1, 665–685. doi:http://dx.doi.org/10.5194/soil-1665-2015. Subbiah, B.V., Asija, G.L., 1956. A rapid procedure for estimation of available nitrogen in soils. Curr. Sci. 25, 259–263. Tesfaye, M.A., Bravo-Oviedo, A., Bravo, F., Kidane, B., Bekele, K., Sertse, D., 2015. Selection of tree species and soil management for simultaneous fuel wood production and soil rehabilitation in the Ethiopian Central Highlands. Land Degrad. Dev. 26, 665–679. doi:http://dx.doi.org/10.1002/ldr.2268. Vance, E.D., Brookes, P.C., Jenkinson, S.D., 1987. An extraction method for measuring soil microbial biomass. Soil Biol. Biochem. 19, 703–707. Wang, X.J., Methurst, P.J., Herbert, A.M., 1996. Relationships between three measures of organic carbon in soils of eucalyptus plantation in Tasmania. Aust. J. Soil Res. 34, 545–553. Wang, Y., Fan, J., Cao, L., Liang, Y., 2016. Infiltration and runoff generation under various cropping patterns in the red soil region of China. Land Degrad. Dev. 27, 83–91. doi:http://dx.doi.org/10.1002/ldr.2460. Wani, S.P., Chander, G., Sahrawat, K.L., Rao, C.H.S., Raghvendra, G., Susanna, P., Pavani, M., 2012. Carbon sequestration and land rehabilitation through Jatropha curcas (L.) plantation in degraded land. Agric. Ecosyst. Environ. 161, 112–120. Wilde, S.A., Voigt, G.K., Iyer, J.G., 1964. Soil and Plant Analysis for Tree Culture. Oxford Publishing House, Calcutta, India. Wildemeersch, J.C.J., Garba, M., Sabiou, M., Sleutel, S., Cornelis, W., 2015. The effect of water and soil conservation (WSC) on the soil chemical, biological, and physical quality of a plinthosol in Niger. Land Degrad. Dev. 26, 773–783. doi: http://dx.doi.org/10.1002/ldr.2416. Yadav, Y.P., Vasistha, H.B., 1989. Infiltration capacity of forest soils under Cryptomeria japonica. Indian For. 115, 435–441. Yazdanpanah, N., Mahmoodabadi, M., Cerdà, A., 2016. The impact of organic amendments on soil hydrology structure and microbial respiration in semi arid lands. Geoderma 266, 58–65. doi:http://dx.doi.org/10.1016/j. geoderma.2015.11.032. Zhang, A., Gao, J., Liu, R., Chen, Z., Yang, S., Yang, Z., Shao, H., Zhang, Q., Yoshikazu, N., 2016. Nursery-box total fertilization technology (NBTF) application for increasing nitrogen use efficiency in chinese irrigated rice land: N-soil interactions. Land Degrad. Dev. 27, 1255–1265. doi:http://dx.doi.org/10.1002/ ldr.2346. Zhao, X., Wu, P., Gao, X., Persaud, N., 2015. Soil quality indicators in relation to 3use and topography in a small catchment on the loess plateau of China. Land Degrad. Dev. 26, 54–61. doi:http://dx.doi.org/10.1002/ldr.2199.