296 EXPERIMENTAL FARMS 



1-2 EDWARD VII., A. 1902 



A bare definition of physical condition will indicate but imperfectly the reasons 

 for the results claimed. 



Physical condition may be said to mean the degree of friability or openness or 

 crumbliness of a soil, its power to retain moisture, and its immediate water-content. 



To show the importance attached to good physical condition by one of the most 

 famous of agriculturists, let me quote from the works of the late Sir John Lawes, 

 chief of the celebrated Kothamstead experiment station, who, after an experience 

 of over 50 years in soil cultivation and fertilization, said : ' All our experiments tend 

 to show that it is the physical condition, its capacity for absorbing and retaining 

 water, its permeability to roots, and its capacity for absorbing and retaining heat that 

 is of more importance than its chemical composition.' 



Conditions of Plant Growth.— -To discuss 'good physical conditions, it is neces- 

 sary to consider for a few moments the requirements of the healthy, growing plant. 

 They are : Light, air, moisture, heat and food. The lack of any one, or the super- 

 abundance of any one, means death to the plant. Their presence in too small or too 

 large proportions means sickly plants. 



Light, we cannot control, therefore it need not be discussed. 



Air will, of course, always surround the stems and leaves of our crops, but it is 

 just as necessary to the roots. Water-soaked, baked, or puddled soils do not permit 

 any air to circulate among their particles. They are, therefore, not suited for plant 

 occupation. It is to lack of air in such cases rather than superabundance of water 

 or impermeability of the soil to roots that failure is due. 



Moisture, or water is necessary as a solvent for much of the plant's food. It 

 serves as a vehicle for carrying the food from the soil to the leaves of the plant. An 

 abundance is absolutely indispensable, an over-supply is fatally injurious. 



The heat necessary for seed germination and plant growth is a relative condition, 

 and so dependent upon the other factors for its effectiveness as to need but little dis- 

 cussion at this point. That high temperatures with abundant moisture induce rank 

 growth is well known to every farmer. To secure such a combination in our northern 

 latitudes requires careful cultivation. It really depends on good physical condition. 



Food is, of course, an important requirement in plant growth. Acting on the 

 assumption that food is the all in all, the one great factor in plant life, many have 

 followed this premise to its logical conclusion and supplied the plant with food in 

 specially prepared forms in more or less homeopathic (relatively speaking) doses. 

 Most soils contain immense quantities of plant food. It is not always in an available 

 form. Adding to this supply in practically the same form will not guarantee good 

 results. The following of a course likely to secure good physical conditions would in- 

 sure an abundant supply of plant food in the form best suited for sustaining plant life 

 by converting the erstwhile unavailable food into available forms. 



Influences Affecting Physical Condition of Soils. 



The influences affecting physical condition are various, and it cannot be hoped 

 to discuss them at any length at the present moment. To name the more important 

 conditions, without reference to their relative importance, they might be said to be : — 



1. The character of the soil ; that is, whether a clay, a clayey loam, sandy loam, 

 sand, gravel, muck or peaty and, generally speaking, whether of a drift or an alluvial 

 formation. 



2. The water-line or water-level of the area. 



3. The condition of the soil at time of cultivation ; that is, whether wet or dry 

 when last ploughed or cultivated. 



4. The crop that has been grown the previous year. 



5. The amount of humus in the soil and the character of the same. 



