Classic PA papers

An Empirical Law Describing Hetrogeneity in the Yields of Agricultural Crops
– H. Fairfield Smith (1938) Journal of Agricultural Science, 28: 1-23.

Studies in Soil Cultivation
I, The evolution of a reliable dynamometer technique for use in soil cultivation experiments. Bernard A. Keen and William B. Haines (1925) Journal of Agricultural Science, 15: 375-386.
II. Test of soil uniformity by means of dynamometer and plough. William B. Haines and Bernard A. Keen (1925) Journal of Agricultural Science, 15: 387-394.
III. Measurements on the Rothamsted classical plots by means of dynamometer and plough. William B. Haines and Bernard A. Keen (1925), Journal of Agricultural Science, 15: 395-406.
IV. A New form of traction dynamometer. William B. Haines and Bernard A. Keen (1928), Journal of Agricultural Science, 18: 724-733

Selection of efficient methods for soil sampling,
– W.J. Youden and A. Mehlich, (1937) Contributions of the Boyce Thompson Institute for Plant Research 9, pp. 59–70.

Land evaluation at farm level using soil survey information systems
– Pierre. C. Robert (1989) In ‘Land Qualities in Space and Time’. (Eds J. Bouma and A.K. Bregt) pp 299-311. (PUDOC, Wageningen, The Netherlands).