202 SEEDING AND PLANTING 



the soil to less depth. It is believed that implements patterned 

 somewhat after the better of the European forest plows of the 

 wheel and roller types could be advantageously introduced into 

 the United States. 



Artificial regeneration on heaths is always very 'difficult, due 

 to the mineral soil being too poor to support satisfactory growth. 

 The organic matter overlying the mineral soil contains humic acid 

 and other sour humous constituents deleterious to tree growth. 

 The difficulty is often increased by the presence of pan at shallow 

 depths. Greve 1 recommends the burning of the surface as the 

 first operation, care being taken to injure the organic matter in 

 the surface soil as little as possible. The surface layer of organic 

 matter is then thoroughly mixed with the mineral soil beneath. 

 It is usually useless to attempt artificial regeneration on heaths 

 without previous soil preparation. 



17. SHALLOW TILLAGE 



Various types of harrows, drags, cultivators, hoes, and rakes 

 are used in working forest soil to a depth less than 5 inches. 

 Harrows, drags, and cultivators with rigid frames and teeth are 

 not suited for working forest soil. The implement should be 

 of the roller type or the teeth should be flexible. Weinkauff 2 

 recommends the spring harrow as the most efficient implement 

 for working ordinary forest soil to a depth less than 5 inches 

 either as an aid to natural regeneration or previous to full seeding. 

 The latter implement has been used by the U. S. Forest Service 

 in soil preparation for full seeding on the National Forests. In 

 Europe the Danish roller harrow is used for the same purpose. 

 Rakes and hoes in great variety are used in the shallow tillage of 

 forest soil. As a rule, light and medium soils are worked imme- 

 diately before the seeding or planting is begun. Heavy soils, par- 

 ticularly those containing considerable raw humus, are worked in 

 the autumn and left exposed to the action of air and frost over 

 winter. 



1 Greve, Forstmeister: Flachbearbeitungs-Verfahren bei Heideaufforst- 

 ungen. (Zeitschrift f. Forst- u. Jagdwesen, S. 581-604. 1906.) 



2 Weinkauff, Forstmeister: Neue Bodenbearbeitungsmethoden und Zu- 

 kunfts-werkzeuge. (Forstw. Centralblatt, S. 46-48. 1910.) 



