42. Types and Characteristics of Medium and Trace Elements+ 43. Scientific Application of Medium and Trace Element Fertilizers+ 44. Types and Characteristics of Compound Fertilizers+ 45. Scientific Application of Compound Fertilizers+ 46. Properties and Application of Common Compound Fertilizers+ 47. Qualitative Identification of Commonly Used Elemental Chemical Fertilizers+ 48. Scientific Application of Slow and Controlled Release Fertilizers+ 49. Scientific Application of New Water-soluble Fertilizers+ 50. Scientific Application of Other New Fertilizers+