30 



and a half times as much fruit and showing more than double the 

 increase in growth. In color, the mulched fruit excels by more 

 than 30 per cent.,"^ and in average size of apples it excels by about 6' 

 per cent. This last fact is undoubtedly connected"- with the smaller 

 crop on the mulched trees. 



The results of Tables VI and VII are apparently contradictory. 

 They are all explainable, however, on the bases of soil moisture and 

 age of trees. In the young orchards, with the herbage and three-ton 

 addition of straw, an effective mulch of sufficient extent was main- 

 tained, while in the old orchard we were unable thus to cover more 

 than probably half the root area. In the latter case the term sod 

 mulch was distinctly appropriate since at least the outer half of the 

 roots was under a t^^pical sod and often in dust-dry condition. 



The results in Table VI indicate that, even in tr3dng seasons, 

 such as the last two have been, the moisture in orchard soils may be 

 conserved more effectively by a good mulch than by tillage. This 

 conclusion is corroborated by moisture determinations made by 

 Shutt, of Ottawa, Canada, in 1905 and 1906.^ He also has found 

 that leguminous plants, particularly those of dense and matted 

 growth like hairy vetch, are much less severe in their drain on soil 

 moisture than the grasses; and that the shade of the growing vetch 

 is a better moisture conserver than the mulch formed by cutting and 

 leaving it in place. In other words, the loss b^^ capillarity a^d sur- 

 face evaporation from the practically bare ground was greater, 

 under the conditions at Ottawa, than the transpiration through the 

 legume." 



The cover on our mature orchard is grass only, w^hile on the 

 young orchards a scattering growth of alsike or medium red clover 

 has been maintained in addition. 



In further explanation of the difference in effectiveness of the 

 mulch and cover-crop methods in Tables VI and VII, we may call 

 attention to the hastening influence on bearing, which sod undoubt- 

 edly exerts under favorable conditions. This was shown in our 

 results of last year,* where sod on these same three orchards sur- 

 passed clean tillage in 3deld by 13 per cent. It is also shown here 

 later, especially in the sod-manure plot of Table IX. But the fact 

 that this sod influence can be easily overdone and made to disappear 

 under unfavorable conditions, is clearly shown in our results from 

 the unfertilized sod plots of Table VI. 



The next table is introduced to show the effect of adding fer- 

 tilizers to the four cultural methods. All unfertilized plots are ex- 

 cluded from this table, and the yields given include both the manured 

 and commercially fertilized plots under each method. 



^Really the mulch excels in color by 52.4 per cent, using the amount of 

 color on the cover crop area as a base. 

 ^Central Experimental Farm. Report of the Chemist, p. 151, 1906. 

 ^Ibid, 1904, p. 158. 

 *Pa. Bui. 91 : 15. 1909. 



