- Agriculture 20
- Sustainable Development 16
- Climate Change 9
- Environment, general 9
- Soil Science & Conservation 9
- Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution 9
- Water Industry/Water Technologies 9
- Forestry 3
- Plant Physiology 3
- Plant Sciences 3
- Ecology 2
- Abstract Harmonic Analysis 1
- Analysis 1
- Functional Analysis 1
- Integral Transforms, Operational Calculus 1
- Plant Anatomy/Development 1
- Plant Pathology 1