Jatropha curcas Biodiesel, Challenges and Opportunities: Is it a Panacea for Energy Crisis, Ecosystem Service and Rural Livelihoods?
In context of energy crisis and global warming, Jatropha curcas offers a great potential to combat fuel shortage and minimize carbon emissions. J. curcas is a potential candidate for biofuel as it is drought tolerant, has high seed oil content and is not browsed by animals. The tested advantage of blended biodiesel lies in its use in vehicles without any engine modification. A lot of hype was created earlier for Jatropha as a “wonder shrub”, but much of it was without supporting data and the outcomes raised questions on its large scale cultivation. Our research showed great variability in germplasm for agronomic parameters, oil content, male: female flower ratio. Agronomic practices experiments showed response to fertility management, spacing, pruning, growth hormones and mycorrhizae application. Jatropha can survive under low water availability, but needs sufficient water for higher yields. Currently available plant material productivity is low (1–2 t ha−1) with variations among years due to rainfall variability. Low or high rainfall in waterlogging prone soils reduces yields significantly (0.1 t ha−1 during 2010 in black soils). In block plantations, insect pests and diseases are potential threats. The years 2009 and 2010 witnessed a large number of plant loss in Andhra Pradesh, Assam, Chattisgarh and Madhya Pradesh due to black rot disease caused by Botryosphaeria dothidea. In spite of the challenges, Jatropha has the potential of greening degraded lands by converting nonproductive evaporation into productive transpiration. During gestation period (4–5 years) of Jatropha plantation, yields of one ton or more can be obtained from intercropping with sorghum, pearl millet, chickpea and soybean based on soil fertility. In addition to biodiesel, the seed cake which is a byproduct is a good source of N (∼5 %) and other nutrients for use in plantation and crop production. Jatropha fixes and adds to soil per annum around 1,500 kg C ha−1 through deoiled cake, leaf fall plus pruned loppings and builds organic carbon content of degraded lands. Biofuel replacement of 250 kg C equivalent ha−1 in the fossil fuel and more than 5,000 kg C ha−1 sequestered in live plant biomass renders ecosystem service. Jatropha plant cover also reduces soil loss. Along with numerous benefits, being in domain of unprivileged, biodiesel plantation activities generates employment opportunities and social mainstreaming of the weaker sections. Current findings with available material show that with increased labour costs and low productivity, it is not a viable option for biodiesel. But, in remote areas, nonedible vegetable oil as a source of energy produced on degraded lands in decentralized manner is a viable option to meet energy demand in rural areas. In view of the current problems, there is a need to apply science to develop high yielding cultivars tolerant to pests, increase female: male flower ratios and address the problem of synchronized flowering to reduce harvesting costs.