The Farm That Won't Wear Out
The Farm That Won't Wear Out
For Better Crops
The Story of the Soil
Nitrogen Bacteria and Legumes
Soil Fertility Laboratory Manual
Lincoln's View of Agriculture--1859 (with Some Projections by Hopkins--1909)
The Story of the Soil
Circular
Soil Report No. 1 [etc.]. By Cyril G. Hopkins, J.G. Mosier, J.H. Pettit, and J.E. Readhimer. [With Maps.].
The Problem of Continued Prosperity
Special Instructions for Taking Samples of Sugar Beets for Analysis
Spraying Apple Trees, with Special Reference to Apple Scab Fungus
Some Errors in the Determination of Nitrogen
Composition and Digestibility of Corn Ensilage, Cowpea Ensilage, Soja Bean Ensilage, and Corn-fodder
Reading Course in Soil Fertility
Saving the Soil ...