Agronomic and Ecological Implications of Biofuels Catherine Bonin and Rattan Lal Food Safety Issues for Mineral and Organic Fertilizers Rufus L. Chaney Mechanisms of Nickel Uptake and Hyperaccumulation by Plants and Implications for Soil Remediation Shanying He, Zhenli He, Xiaoe Yang and Virupax C Baligar Conservation Agriculture in the Semi-Arid Tropics: Prospects and Problems Ram A. Jat, Suhas P. Wani and Kanwar L. Sahrawat Green and Brown Manures in Dryland Wheat Production Systems in Mediterranean-Type Environments M. M. Roper, S. P. Milroy and M. L. Poole Productivity and Sustainability of the Rice-Wheat Cropping System in the Indo-Gangetic Plains of the Indian Subcontinent: Problems, Opportunities, and Strategies Bhagirath S. Chauhan, Gulshan Mahajan, Virender Sardana, Jagadish Timsina and Mangi L. Jat