910 



Rural School Leaflet 



contains the material necessary for the best results. Most soils contain 

 the necessary ingredients in greater or less amount for plant growth. 

 For example, all soils contain an adequate amount of iron, which is needed 

 for the production of the green substances in plants ; but most soils do not 

 have enough available nitrogen, phosphoric acid, and potash for the 

 best plant growth. The lack of one or more of these, together with lack 

 of water, generally causes small crops. 



The first step, therefore, if one would have a successful potato crop, is 



to consider the soil. If the soil does 

 not contain the necessary ingredients, 

 they must be supplied either by the 

 use of commercial fertilizer or stable 

 manure. Plant food in the form of 

 commercial fertilizer is expensive, 

 the nitrogen costing twenty-two and 

 one half cents per pound, the phos- 

 5^^^ phoric acid four and one half cents 

 ■'^ ' * ' per pound, and the potash five cents. 

 Therefore it is essential to learn how 

 to make the best use of any of the 

 materials already in the soil. Good 

 cultivation is valuable because it 

 admits pknty of air into the soil and 

 prevents the loss of water by evapora- 

 tion from the top of the soil. It also 

 aids beneficial soil bacteria, allowing 

 them to cor. vert the soil nitrogen into 

 an available form for the plants to 

 use ; and it keeps in check all harmful 

 bacteria. This valuable nitrogen, costing over four times as much per 

 pound as the other foods of the plant, may also be added to soils by the 

 bacteria that grow on the roots of legumes, such as clover, alfalfa, peas, 

 beans, and the like. Hence, for economy, a crop such as clover may 

 well precede a crop of potatoes. In fact, most of the best crops of 

 potatoes are grown on a clover sod, abounding with bunches, or tubercles, 

 in which these bacteria live. 



Fertilization. — No specific information can be given in regard to the 

 kind or quantity of fertilizer for a potato crop. This will vary with the 

 fertility and nature of the soil. 



If the potato crop has been preceded by a crop of clover, only a small 

 application of nitrogen may be necessary and this should be in an easily 

 available (soluble) form. A small quantity of nitrate of soda will supply 



Roots of red clover showing nitrogen- 

 gathering nodules 



