4 CHAPTER I 



The Use of Legumes. — As previously stated, the Komans 

 were aware of the beneficial residual effect of these plants on 

 the land, and their use has been since then increasingly 

 advocated. Towards the end of last century bacteriologists 

 discovered the relationship that exists between legumes and 

 nitrogen-gathering bacteria. This definite knowledge gave a 

 decided impetus to the use of legumes, and to-day the greater 

 number of rotations practised in all countries contain one or 

 more of these plants. 



Rotations. — In a sense Varro had advocated rotative ^ 

 cropping , and it is known that in a very intensive manner 

 'fhe Chinese have practised crop rotations for centuries. 

 Systematic cro^jo rotations, as understood to-day, were not 

 common until the beginning of the eighteenth century, when 

 Lord Townshend introduced the famous Norfolk rotation. 

 The subject of rotation is dealt with more fully in a later 

 chapter. 



Manuring. — The beneficial effect of the use of animal 

 excreta on the soil, and even the superiority of that of certain 

 animals over others, was known to the ancients, and the 

 liming of soils had been practised in the days of Varro. How- 

 ever, it was not until after de Saussure, about 1805, had shown 

 the mineral character of plant-food that the use of artificial 

 manures was practised. Their use has grown rapidly in all 

 parts of the world and they are utilised in the cropping 

 systems of all countries to-day. Apart from the points above- 

 mentioned, the remarkable advance in field husbandry of the 

 last two centuries is due to a great many factors, chief among' 

 whicli are the following : — 



(1) The discovery of the gaseous assimilation by plants. 

 (2) The use of improved farm machinery. In 1701, Jethro 

 TuU invented the seed-drill, to be followed afterwards by 

 others, with improved ploughs, and, later, mowing and thresh- 

 ing machines. (3) The application of genetic laws to the 

 improvement of plants. (4) Economic entomologists and 

 plant pathologists came forward with remedial measures 

 against insect pests and plant diseases. (5) The establishment 

 of technical agricultural institutions. 



Agronomy and Animal Husbandry. — Histoi-y shows 

 that the productivity of the soil is best maintained, and often 

 increased, in those parts where the rearing of animals is an 

 essential feature of the farming practised; more particularly, 

 of course, where concentrates are fed and the manure returned 



