REPORT OF THE CHEMIST. 151 



The value of these qualities will be seen on a brief consideration of the factors 

 which go to make up a soil's fertility. These are (1) climatic influences (rainfall, tem- 

 perature, &c), (2) tilth or physical condition, and (3) chemical composition. 



In tilth, the relative proportions of clay, sand, limestone and organic matter, play 

 an important role, culture and the weather often materially assisting. Retentivity 

 of moisture and fertilizing material, permeability to air and water, freedom for root 

 growth, stability and strength with friability are among the chief ^qualities of well 

 tilled soil. Though the total amount of plant food is in direct relation to the kinds and 

 amounts of organic and inorganic materials which compose the soil, the percentage of 

 such food immediately available for crop use is largely dependent upon tilth and climatic 

 influence. 



The importance of a good physical state is, therefore, obvious, and judging from 

 the present sample, the tilth of this prairie soil must be regarded as of a high order. 



This loam is characterized chiefly by its very high percentage of organic matter and 

 nitrogen, and its remarkable richness in potash ; it thus stands pre-eminent in two of 

 the three essential constituents of plant food. 



Experience and scientific investigation have shown that the most fertile soils the 

 world over are invariably rich in organic matter (humus) and nitrogen. The presence 

 of humus regulates the soil's temperature, increases its water-holding capacity, and is of 

 much value from a physical standpoint in loosening and aerating the soil, By nitri- 

 fication that valuable and important element, nitrogen, is set free in an available form — 

 as nitrates. The decomposition of the humus in the soil also gives rise to the production 

 of carbonic acid gas, by the agency of which, when dissolved in the soil-water, much 

 inert inorganic material is rendered soluble and useful for plant growth. 



Nitrogen. — The percentage of nitrogen may usually be considered an indication, 

 or rather a measure, of a soil's fertility. This soil has an average depth, over a large 

 area, of two feet, but if we calculate the weight of nitrogen in the first foot only (assum- 

 ing the weight of soil to that depth over one acre to be 3,500,000 lbs.), we find a store of 

 nitrogen that may become available amounting to 33,145 lbs. Ordinary fertile soils to 

 a like depth contain from 3,500 to 10,000 lbs. of nitrogen per acre ; hence the vast 

 reserve of this valuable constitutent in this prairie soil is apparent. 



Nitrogen is essentially the fertilizer for cereals, especially when associated with 

 phosphoric acid. It is for this reason that nitrate of soda, sulphate of ammonia, dried 

 blood, and other seurces of easily assimilated nitrogen, are so extensively used in conjunc- 

 tion with superphosphate for obtaining lucrative yields of the grains on partially ex- 

 hausted soils. 



Potash. — Soils derived from clay are usually rich in potash, and it is probably 

 owing to this cause that this soil contains an amount of potash far in excess of that 

 ordinarily met with. Potash is necessary for all crops, but proves especially useful for 

 roots, grasses, clover, Indian corn and most leafy fodder crops. We may therefore 

 infer that this soil is well adapted to raise in large quantities such food as is necessary 

 to economically maintain stock. Using the factors already given (See table of analyses), 

 we obtain by calculation 33,950 lbs. of potash per acre. 



Phosphoric Acid. — This constituent may be considered of the greatest importance, 

 next to nitrogen, to the wheat plant, and indeed is very effective for all cereals. In 

 this soil it is present to an amount somewhat above the average. A calculation based 

 on the results of the present analysis shows 9,450 lbs. to the acre. 



Lime. — After the constituents already discussed, lime stands next in importance, 

 not only because it serves directly as food few plants, but also for the reasons that 

 it materially assists in the nitrification of the organic matter in the soil and liberates 

 potash from its locked up sources. This soil is not rich in calcareous matter, but on 

 the other hand must not be considered deficient — clay loam possessing as a rule from 2 

 per cent to 3 per cent of carbonate of lime. 



It will be unnecessary to call particular attention to the percentages of the other 

 ingredients of this soil, since this sample forms no exception to the rule that of mineral 

 matter, other than that specially reported on here, all soils contain a sufficient amount 

 for all the requirements of farm crops. 



