The science of crop production and improvement is called

Agriculture Science is the science of crop production and its improvement. In Agriculture Science, scientists focus on research and development on various aspects of crop technology and production. 

Crop improvements include: 
1. Irrigation Management as a production technique
2. Minimizing the growth of pests 
3. Transformation of raw products to end-consumer products
4. Prevention of adverse environmental effects (e.g. waste management and soil degradation)
5. Supply and demand for food in a global basis 6. Crop quantity and quality 7. Study of other fields of agriculture (e.g. soil science)