Oil the Agriculture of the Netherlands. 



53 



size of the particles. This is very easily ascertained by means of 

 the simple instrument, consisting of metallic sieves, which is de- 

 scribed in the Essay on the Analysis of Soils, in the first number 

 of this Journal. When a considerable proportion of the dry pul- 

 verised earth passes through the finest sieve, it is a sure sign that 

 the soil, if not already fertile, can be easily made so. That 

 which is most readily improved consists of a small portion of 

 coarse sand, mixed with a larger portion of finer, and with a con- 

 siderable portion of impalpable earth, partly silicious, and partly 

 argillaceous and calcareous, so that, when it is moistened, it does 

 not form a tough paste, but dries into clods easily pulverised 

 between the fingers. The degree of fertility will depend alto- 

 gether on the quantity of humus which is incorporated with this 

 loam, and which the specific gravity readily discovers ; the richer 

 soils being the lighest ; for humus is much lighter than any of 

 the simple earths. 



Keeping this in view, it is easy to show the advantage or dis- 

 advantage of different modes of proceeding, which should vary 

 with the nature of the original soil. In the natural earth, which 

 has never been cultivated, or which is dug up from a considerable 

 depth below the surface, portions of different kinds of earth are 

 found in thin layers, or in separate pieces, which, being pulverised 

 and mixed together, want nothing but the addition of humus to make 

 them a fertile soil. Here the use of the trenching-spade is evident. 

 No other instrument could so well divide the earths, and mix 

 them in due proportions. The more the ground is stirred, the 

 better it becomes ; and by a course of cultivation, which, instead 

 of exhausting the humus, gradually increases its quantity, it 

 becomes at last a rich mould, like that of a garden, in which all 

 plants suited to the climate thrive luxuriantly. In the progress 

 to this state of fertility the soil must have passed through every 

 intermediate state ; and the same process which at any one period 

 effected the improvement must be judicious, if applied to any 

 soil similar in its nature. In agriculture, as well as in most arts 

 and sciences, to stand still is the prelude to going back. The 

 soil, under the hands of a skilful agriculturist, must not only be 

 made to produce all that it is capable of producing, but its capa- 

 city for production must be continually increasing, until it arrives 

 at that state, when a further increase of humus v/ould loosen its 

 texture too much to produce many of the most valuable plants, 

 which are the chief objects of cultivation ; for, beyond a certain 

 proportion, the increase of humus does not always increase the 

 produce. 



These preliminary observations appear necessary to enable 

 those who may not have paid much attention to the theory of 

 vegetation to trace their accordance with the practice which ex- 



