292 PARKS 



materially improve the condition of soil which is poor in texture or deficient 

 in plant food. This composting should be done as soon as the topsoil is 

 stripped, and all sods or other vegetable matter should be included in the 

 piles. From eight to 12 cubic yards of soil may be used to each cubic yard 

 of good barnyard manure. The manure may be green if the piles are to 

 remain over winter or for a whole season, but only partly decomposed 

 manure should be used if intended for use in a month or two. It is always 

 advantageous to turn over piles of compost, and it is necessary to turn 

 them three or four times if green or strawy manure is used. In any event 

 the piles should be built up with straight sides and a concave top so made 

 as to conserve all the rain water falling on the pile. Sometimes it is worth 

 while to wet a compost pile down thoroughly if it is not possible to turn 

 it over and the manure shows signs of fire fanging, or burning. When first 

 made, the layers of soil and manure should not be over six inches deep 

 and, of course, after it has been turned once the layers will disappear and 

 the danger of burning will be past. The last time the pile is turned, one-half 

 the amount of lime or bone meal which it is intended to use on the lawn 

 may be added to the compost. See also discussion of composts in Construc- 

 tion Notes XV (Landscape Architecture, July 1925). There is no danger 

 of having too deep a layer of topsoil, but it very often happens that the 

 topsoil layer is too shallow. It is probably safe to say that no really perma- 

 nent lawn is ever established when sown down on a layer of topsoil less 

 than 12 inches deep. What is known as a good garden soil, when underlaid 

 with a good subsoil of a clayey character but open texture, provides the 

 ideal seed bed. All sticks, stones, clods, and rubbish must be removed, 

 especially from the top layer of soil to at least one spade depth. If the 

 already existing topsoil is sufficient in depth ajid of good character, plow- 

 ing and harrowing on large areas or spading on small areas will generally 

 put it in good tilth. Disc or cut-away harrows have proven very efficient 

 in this work, and clod crushers may often be used to break up as many 

 lumps as possible before raking. When the topsoil layer i* spread it will 

 be necessary to allow for settlement, and if the subsoil layer is also made 

 land, this should be allowed to settle over winter if possible so as to prevent 

 wastage of topsoil required to fill in any unusually deep depressions. Much 

 less settlement will afterward occur if the layers of soil are shallow never 

 over six inches in depth and are rolled or tamped lightly when laid. 

 An iron rake and a .water-ballasted hand roller are very effective tools to 

 use in bringing the seed bed to a state ready for the sowing of the seed. 

 The final state of the seed bed should be firm, even, fine, and true to grade. 

 As grass seeds are fine and never need to be covered deeper than one- 

 quarter of an inch, it is important that the seed bed be firm so that seeds 



