Soil science 667 Agricultural chemistry 454 Soil Science 217 Soil chemistry 135 Agronomy 132 Soil fertility 104 Agriculture 101 Soils 94 Soil 90 Soil conservation 78 soil science 74 Soil microbiology 61 Soil Science and Agricultural Chemistry 58 Soil physics 58 Soil management 49 Soil analysis 48 Fertilizers 47 Soil conditioners 47 Irrigation 42 soil fertility 41 Soil erosion 39 Soil pollution 37 Soil mechanics 36 Soil ecology 34 SOIL 32 Engineering 31 Ecology 30 soil chemistry 30 Microbiology 28 Plants 27