John Percival

"The chief processes for the improvement of soils which may be discussed here are: liming, claying and marling, warping, paring and burning, and green manuring. Most of these more or less directly improve the land by adding to it certain plant food constituents which are lacking, but the effect of each process is in reality very complex. In the majority of cases the good results obtained are more particularly due to the setting free of " dormant " or " latent " food constituents and to the amelioration of the texture of the soil, so that its aeration, drainage, temperature and water-holding capacity are altered for the better."

"Among the world's crops wheat is pre-eminent both in regard to its antiquity and its importance as a food of mankind. In prehistoric times it was cultivated throughout Europe, and was one of the most valuable cereals of ancient Persia, Greece, and Egypt."

"The wheat taxonomist has a difficult job. The variation in Triticum/Aegilops is extraordinary and one has only to look through the enormous herbarium collection of wheat that John Percival amassed to see the diversity. Hybridization and polyploidy have occurred frequently and been assisted by man over a long period, complicating the systematics enormously."