Irrigation largely depends on local climatic conditions. Jatropha is well adapted to dry soils and can stand without water for long periods (as long as 2 years) and can resume growth once rains return (Nahar 2011). Jatropha with high-quality seeds has an average 1 L/plant/day water consumption rate throughout the growing season (PSO 2010). Although J. curcas by shedding its leaves, can survive on precipitation as low as 300 mm, but under such conditions it does not produce well. To produce healthy fruits, an indicative of economically sustainable oil production, minimum and optimal rainfalls are 600 mm ha-1 y-1 and 1,000-1,500 mm ha-1 y-1 (Henning 2007). The crop should be artificially irrigated during dry period whenever required.

17.3.3 Fertilization

Jatropha is adapted to low soil fertility, however organic or artificial fertilization might be required for plantations aiming at oil production. Application of N-P-K and cow manure annually is highly recommended (PSO 2010). Jatropha plantations on poor-quality soils when fertilized with phosphorus (P), nitrogen, calcium (Ca), potassium (K), magnesium (Mg), and sulfur (S) rich fertilizers produce higher yield than Jatropha planted on soils without fertilizers (Achten et al. 2008; Mohapatra and Panda 2011; Moore et al. 2011).