1. Adams M (1995) Fundamentos de química de suelos. Consejo de Desarrollo Científico y Humanístico, Universidad Central de Venezuela, Caracas
2. Adams F, Burmester C, Hue N, Long F (1980) A comparison of column-displacement and centrifuge methods for obtaining soil solutions. Soil Sci Soc Am J 44:733–735
3. Addiscott T (2005) Nitrate, agriculture and the environment. CABI, Wallingford
4. Addiscott T, Whitmore A, Powlson D (1991) Farming, fertilizers and the nitrate problem. CAB International, Wallingford
5. Amberger A (2006) Soil fertility and plant nutrition in the tropics and subtropics. International Fertilizer Industry Association/International Potash Institute, Paris, France/Horgen, Switzerland