SOIL PREPARATION 81 
material. Where the soil is fairly well supplied with humus the 
coarser part should be taken off and removed from the houses, 
and the finer portion worked into the soil. 
“We are not prepared to say what effect the use of summer 
mulch may have on the diseases affecting lettuce, except that the 
station greenhouses have been very free from all diseases of lettuce 
since we have been using this method of treating the soil. The 
lettuce in the Toledo house has also been practically exempt from these 
diseases during the two years they have been mulching. In no case 
where the mulch has been used have we observed an increase in the 
number of diseased plants over an equal area not mulched. These 
facts, taken together with results secured by Stone and reported in 
this circular, would lead us to expect beneficial rather than detri- 
mental results from the proper use of summer mulch, in so far as 
it affects the disease of lettuce.” 
The Ohio station later compared manure mulch with 
straw mulch. The details of the experiment are pub- 
lished on pages 85 and 86 of the official proceedings of the 
Vegetable Growers’ Association of America for 1909, 
1910 and 1911. The yields varied little at first, but the 
fertility under the straw mulch became depleted quite 
rapidly, as shown by the following report of 28 tomato 
plants on an area of 120 square feet: 
PLot 1—MaAnure MuLtcu 
Total number 
Variety fruits Pounds Ounces 
Magnitis: =-=.-.-------=---- 326 102 9 
Stone: 2.22els2 226023 Sos 299 104 13 
Beauty’ 222+22-2--2--0-eces 256 72 5 
Total senses eeedces 881 279 11 
Magnus -__---------------- 234 63 6 
Stone 234 75 11 
Beatty’ cos sos-sesseceee es 254 76 12 
Slop aa-neene ener 722 215 13 
The results with lettuce were not so marked. There 
