14 MASS. EXPERIMENT STATION BULLETIN 436 



Stone Removal. In the hands of an experienced operator a large caterpillar 

 tractor with regular bulldozer attachment is probably the most efficient and 

 practical means of removing large stones. Rocks weighing from a few hundred 

 pounds up to several tons can be removed in the course of a few minutes. A 

 bulldozer was also found to be useful in leveling off uneven "hummocky" land 

 by dragging the blade and operating the machine in reverse. This breaks down 

 the hummocks and tends to tear them apart. 



The renioval of smaller stones is a more difficult problem. There seems to be 

 no other way except to pick them up by hand, and this is a slow, arduous opera- 

 tion. If there is grass growing, many stones become so imbedded in the sod that 

 the use of a bar is necessary to pry each one loose. A preliminary disking with a 

 bog harrow after the large stones and boulders have been removed will help to 

 dislodge many of the smaller stones and thereby facilitate their removal. 



Character of Native Vegetation. The effectiveness of different tillage imple- 

 ments is greatly influenced by the nature and quantity of native vegetation. 



1. Moss cinquefoil association: a bog harrow is particularly effective in de- 

 stroying this type of cover. One thorough disking is usually sufficient. 



2. Grass sod: The destruction of a grass sod can be accomplished with a bog 

 harrow, but several diskings are usually required. So far, disking at intervals 

 of one to two weeks during midsummer has been the most effective means of de- 

 stroying bluegrass and bentgrass sods. If operations are begun in July, a satis- 

 factory seedbed can usually be prepared for seeding in late August. If seeding 

 is delayed until the following spring, there may be considerable recovery of the 

 native grasses. 



3. Herbaceous woody plants {hardhack, meadow sweet, ground pine, laurel, etc.): 

 If the proportion of woody plants is high, a bog harrow is not particularly ef- 

 fective unless most of the native growths are first mowed and removea. The 

 mowing operation, too, is most successful if carried out in midsummer. Where 

 the land is not too stony or rough, a brush-breaker plow can be used satisfac- 

 torily, in which case mowing the native vegetation may not be necessary. 



Time of Seeding. Thus far late-summer seedings have been much more suc- 

 cessful than spring seedings. This may have been partly due to the abnormally 

 warm weather early in the spring of 1944 and again in 1945 which was unfavorable 

 to new seedings. Probably more important than unusual weather conditions, 

 however, were the difficulties encountered in preparing a well-consolidated seed- 

 bed with so much undecomposed plant material present. These soils tended to 

 dry out more quickly than regularly cultivated soil until some of this raw organic 

 matter had broken down. It was observed that dry weather following spring 

 seedings was more damaging than dry weather following fall seedings. 



Studies on the Causes of Winter Injury to Ladino Clover. (Wm. G. Colby.) 

 Although most stands of Ladino clover show evidences of winterkilling every 

 spring, injurj' is much more severe after some winters than after others. In the 

 summer of 1943 a field experiment was laid out with the objective of studying 

 some of the factors associated with this trouble. Seedings were made of Ladino 

 clover alone and in combination with orchard grass (S 143), smooth brome grass 

 (northern strain), meadow fescue (Svalof Early), and timothy. Different cul- 

 tural treatments were also included. 



It was not until the spring of 1946, when Ladino clover stands generally suf- 

 fered extensive winter injury, that significant differences between treatments 

 were evident. The plots which were mulched with straw showed no injury 



