Subject
- Soils -- Nitrogen content2
- Carbon cycle (Biogeochemistry)1
- Compost1
- Cover crops -- Environmental aspects -- Oregon1
- Cover crops -- Oregon1
- Crop residues1
- Digital soil mapping1
- Ectomycorrhizal fungi1
- Forest litter -- Oregon -- H.J. Andrews Experimental Forest1
- Grassland ecology -- Texas -- La Copita Research Area1
- Humus -- Oregon -- H.J. Andrews Experimental Forest1
- Invasive plants -- Texas -- La Copita Research Area1
- Manures1
- Nitrates -- Environmental aspects -- Oregon1
- Nitrogen cycle -- Oregon -- H.J. Andrews Experimental Forest1
- Nitrogen cycle -- Texas -- La Copita Research Area1
- Nitrogen-fixing trees -- Texas -- La Copita Research Area1
- Old growth forests -- Soils -- Oregon -- H.J. Andrews Experimental Forest1
- Soil biology1
- Soil chemistry1