134 MISSOURI AGRICULTURAL REPORT. 



You are all familiar with the substance obtained by chewing wheat ; 

 this we often call gum, but it is really gluten, a substance containing 

 nitrogen and sulphur in addition to the elements contained in starch 

 and cellulose. The quantity of nitrogen in the bundle of wheat (shown 

 here in the form of one of its most concentrated compounds, sulphate of 

 ammonia), is quite large and the amount of it in most soils is not large 

 and is subject to constant loss by leaching, as well as by removal in 

 crops. Hence, this element is referred to as an essential plant food. 



These three substances, nitrogen, phosphoric acid and potash, the 

 so-called essential plant foods, must be furnished to agricultural plants 

 in the right amounts, in the right forms and at the right times if we are 

 to make a proper use of our soils. 



It is true, that a chemical analysis can show the total amount of 

 plant food in any soil, but very little of this is available at one time or in 

 one season. Moreover, the plant is like the rest of us, it gets its food 

 as easily as possible, and so takes the most available plant food first. 



A little of the plant food in the soil is available, a part can be made 

 available in a reasonable time, but the most of the mineral elements are 

 in such a condition that by no known means can they be made available 

 in a reasonable time or at a reasonable cost. It is only an irritation to 

 the farmer to learn that there is enough potash in his soil to raise one 

 thousand corn crops and then to find out that it will not become avail- 

 able in ten thousand years. 



Improved tillage can do much to make soil nitrogen more rapidly 

 available, but can do little to increase the rate at which the more re- 

 sistent compounds of phosphoric acid and potash change ■ into available 

 forms. 



Of course, the manurial resouces of the farm in the form of ma- 

 nures and leguminous crops should be utilized to the utmost. But the 

 use of these will frequently fail to make good some marked soil deficiency 

 •which is limiting the crop. This lack may be due either to the origin of 

 the soil or to a system of cropping whch has removed nearly all of the 

 available supply of one or more elements and left the soil in a condition 

 in which it will no longer yield profitable crops. Often a liberal use of 

 minerals is necessary to produce a crop of the legume on which we de- 

 pend for the increase of the nitrogen supply. 



Hence, it very often happens that in spite of the great stores of 



total plant food in some soils, the application to them in an available 



form of what seems a trifling amount of plant food, produces most 



striking and profitable returns. The way to find out whether fertilizers 



■ can be profitably used is to try it. But it is essential that one should 



;Start right in making such a trial. One should use known quantities of 



