The problem of maintaining the nitrogen content in our agricultural soils is one of vital importance to the development of a permanent system of agriculture. Any investigation, therefore, which tends to throw any light on the conditions which are necessary for maintaining the maximum supply of nitrogen in our soils needs no apology for its institution.
Stewart, Robert and Greaves, J. E., "Bulletin No. 106 - A Study of the Production and Movement of Nitric Nitrogen in an Irrigated Soil" (1909). UAES Bulletins. Paper 57.