18 THE DEPARTMENT OF AGRICULTURE. 



whether the stock has been fed uncooked scabby potatoes. If scabby potatoes are 

 cooked before feeding, the seed-potatoes dipped for scab, and no scabby potatoes 

 have been grown on the land within six years, the use of manure should not cause 

 any scab in the crop. 



From 8 to 15 tons of manure may be applied per acre. Smaller amounts can 

 be applied with good results. Manure is better handled with a spreader, so as to 

 be more evenly distributed. 



A crop of clover, furnishes as much nitrogen as 10 tons of barnyard manure 

 per acre ; the greater part of the nitrogen being gathered by the clover from the air. 

 Clover brings up phosphoric acid and potash from great depths and adds humus to 

 the soil, which makes the soil hold moisture better. Barnyard manure adds nitrogen, 

 phosphoric acid, and potash to the soil, increases the humus content, and the soil is 

 therefore more retentive of moisture. 



It has been estimated that a crop of 6 tons of potatoes removes from the soil 

 approximately 40 Ib. nitrogen, 20 Ib. phosphoric acid, and 70 Ib. potash. A ton of 

 barnyard manure contains approximately 10 Ib. of nitrogen, 5 Ib. phosphoric acid, 

 and 9 Ib. of potash; although the chemical elements are not all available for the 

 crop, nevertheless from this it should be possible to estimate the approximate amount 

 of manure required for potato land. 



Fertilizers. Where farmyard manure is not available, applications of com- 

 mercial fertilizers can be profitably given. Fertilizers should on no account be used 

 to replace either barnyard manure or clover, but rather act as a supplement. There 

 are many potato fertilizers on the market, several of which have given very satis- 

 factory returns. Definite commercial fertilizer mixtures cannot be recommended, 

 because the soils of British Columbia vary so greatly. In some places the best 

 results are obtained from an application of potash, in others from phosphoric acid, 

 in others nitrogen, and in others from an application of a complete fertilizer. A good 

 fertilizer for potatoes has been made by mixing 250 Ib. nitrate of soda, 350 Ib. 

 superphosphate, and 200 Ib. sulphate of potash. However, experiments should be 

 carried out on each soil to determine the most profitable fertilizer to use. 



In applying fertilizers several methods may be followed. In some instances fer- 

 tilizer attachments are available in connection with the planter; however, in the 

 majority of cases in this Province hand-sowing has to be reverted to. In this case 

 care must be taken not to allow the fertilizer to come in direct contact with the 

 seed. It is preferable to scatter broadcast and harrow the fertilizer in after the seed 

 has been planted and covered. 



Lime. Much of the soil in this Province requires lime, and therefore in many 

 instances will give greatly increased yields when same is applied. However, with 

 potatoes, lime makes favourable conditions for certain diseases of the tuber, such as 

 common scab, and for this reason it is undesirable. In fact, very heavy yields of 

 potatoes are often "grown on soils too acid to grow clover. 



PREPARATION OF THE SOIL. 



Land may be fall or spring ploughed for potatoes. Where the soil is heavy or 

 where early planting is desirable, fall ploughing may be advisable. However, better 

 results are usually obtained from spring ploughing. Fall-ploughed land is usually 

 packed too hard when the time comes to plant the main crop of potatoes. Occa- 

 sionally some farmers find it necessary to resort to fall ploughing in order to lessen 

 their spring's work. No hard-and-fast rule can be given for the preparation of the 

 land; nevertheless, enough work must be put on the land to ensure having a good 

 mellow seed-bed. The ploughing-under of barnyard manure will loosen the soil, 

 furnish plant-food, and increases the water-holding capacity of the soil. 



In some districts, if a grower has the time, it has been found more satisfactory, 

 when potatoes follow alfalfa, to double-plough the land. This is best done by plough- 

 ing in the very early spring just deep enough to cut the roots of the alfalfa a short 

 distance below the crown. The plough is then followed by the harrow, which drags 



