CHAPTER VII 

 TILLAGE OPERATIONS AND MANURING 



IN order that seeds may germinate the seed bed must supply to 

 them warmth, moisture, and oxygen. Subject to this supply 

 the seedling plant requires nothing else until it has exhausted 

 the store of food material contained in the seed. When that 

 point is reached the plant begins to draw upon the soil for mineral 

 substances, in a soluble condition, containing nitrogen, phosphorus, 

 sulphur, potassium, iron, magnesium, and calcium. Of these 

 seven elementary substances, four, namely, sulphur, iron, 

 magnesium, and calcium, are nearly always present in the soil in 

 sufficient quantity, although not necessarily in a soluble condition. 

 On the other hand, nitrogenous, phosphatic, and potassic com- 

 pounds tend to become deficient in the soil, and must therefore 

 be supplied either by means of farmyard manure or by such 

 artificial manures as nitrate of soda, sulphate of ammonia 

 (nitrogenous), superphosphate of lime, steamed bone flour, basic 

 slag (phosphatic), sulphate of potash, and kainit (potassic). 

 Nitrogenous manures appear to encourage vegetative growth 

 and the production of foliage. The chief nitrogenous artificial 

 manure is nitrate of soda, and as this substance is readily soluble 

 in water it should be applied to the soil in spring, when it will 

 be absorbed quickly by the roots of the growing plants, and there 

 will not be the same risk of loss. Experience shows that about 

 three pounds per rod may be applied with advantage in most 

 cases. Basic slag and steamed bone flour become soluble only 

 slowly, and may therefore be applied in the autumn at the rate 

 of four pounds per rod. Sulphate of potash is the most suitable 

 potassic manure for the garden. Like nitrate of soda, it is soluble 

 in water, and should therefore be applied in the spring, at the 

 rate of two pounds per rod. It frequently gives good results 

 with potatoes and strawberries. Whether the garden soil would 



TC8 



