Rural School Leaflet 911 



this nitrogen in the best way. The amount of phosphoric acid and potash 

 will depend on the natural fertility of the soil. A fertiHzer analyzing 3 

 to 4 per cent of nitrogen, 6 to 8 per cent of phosphoric acid, and 9 to 10 

 per cent of potash may be considered an average for most soils. The 

 amount of this mixture per acre will depend again on many conditions; 

 perhaps 600 to 900 pounds may be considered an average. 



If the ingredients of this fertiHzer are bought separately, they should 

 be mixed thoroughly before applying. There should be a thin layer of 

 dirt over the fertilizer so as to prevent the seed from being burned or injured. 

 If large quantities of fertilizer are applied to the acre, two applications 

 may be made instead of one. 



In order to produce the best yields of potatoes, the ground should be 

 prepared several years in advance; that is, a careful rotation of crops 

 should have been followed so as to get the land in good tilth. A soil is 

 thus made friable by plowing and harrowing and by the gro"wth of roots 

 for several years. In this length of time the soil will be rendered mellow 

 by constant tillage and the addition of stable manure or other organic 

 matter, and it should have good water-holding capacity and aeration. 



The best crop to imm.ediately precede the potato is clover. It leaves 

 the land well filled with roots and, being a nitrogen-gathering crop, the 

 roots will retain an abundance of this valuable element of plant food. 



Plowing.— The plowing should be done carefully. This may be either 

 spring or fall work, except in hilly fields which ma}^ wash if plowed in the 

 fall. Remember that the object of plowing is to loosen the soil so that 

 the subsequent operation of harrowing may pulverize it, thus increasing 

 its water-holding power and allowing the free circulation of air among the 

 soil particles. Deep plowing is desirable, although if the ground has never 

 been plowed very deeply this should be accomplished gradually and not 

 all in one year. If very deep plowing follow shallow plowing, too much 

 subsoil is brought to the surface at once and the crop suffers. 



Plowing should be followed by harrowing, to be carried on until the soil 

 is thoroughly pulverized. The kind of harrow to use will depend some- 

 what on the soil. In general, a disk or cutaway harrow is preferable, 

 because if the work is thoroughly done such a harrow cuts the soil into 

 fine particles. The use of modern machinery is very desirable in com- 

 mercial potato culture. It saves expensive hand labor and does the work 

 better. 



Marking the field. — This is the next operation if the potatoes are to be 

 planted by hand. It is often better to mark the field both ways; the seed 

 pieces dropped at the intersection of the lines will thus form straight rows, 

 permitting easy cultivation in both directions. Great care should be taken 

 to have the rows straight, insuring ease of cultivation and of spraying. 



