T^ien too, the Icavea help supply the phosphoric acid the 

 seed needs to sprout. Every leaf that falls gives back to the 

 earth some of the fertility talccn away "by the growing tree. In 

 other words, the falling leaves help fertilize the forest. 



Leaves contain the "big three of plant foods. They add 

 nitrogrn, potash, and phosphoric acid to the soil. 



Of course, you knov/, .70 don't ordinarily use the richest 

 soil for growing trees. That is why wt3 can grow a crop of trees 

 on land which it may not pay to farm in field crops. 



But that doesn't mean that trees don't need plant food. Hhc 

 leaves that fall this fall form a layer on top of leaves which 

 fell last fall. In the unhurncd forest, there is an accunralation 

 of several years loaf litter on the floor of the woods. 



Mr. ?Iattoon called my attention to the layers of leaves laid 

 do\7n in the woods, in different years. You may have noticed them. 

 Tlio different layers arc different color and texture. It is often 

 very plain where one Itiyer of loaves ends and another begins. And, 

 hy the Tja^r , Mr. Hat to on suggests that is v/hy cattle often do so 

 much damage v/hen left to run in the vroods. Ihey kick up and break 

 up those regular mats of leaves. Once loosened up, the v/inds and 

 \7ater can get hold of the litter and sweep it away, and expose the 

 roots of the trees to d^jnage from trampling and injury from ex- 

 cessive dr;)-ing. 



That dc'image shows up in the "stag-headed" tree tops often seen 

 in woods, which has been heavily grazed by livestock. 



In order to find out just how nuich plant food one ycar»s fall 

 of litter in the pine woods amounts to, the foresters at the Lake 

 States Forest I!:q"jcriracnt Station in Wisconsin laid down strips of 

 burlap on the forest floor, and then a. year later came back and 

 collected the litter which had fallen in the meantime. 



They had that litter ar^lyzed by the chemists to sec just how 

 much plant fo )d was in it. Ihey found there was about fifteen pounds 

 of nitrogen alone in the litter w'.iich fell on one acre. Tfacn you 

 figure that in an unburned forest there is an accumulation of litter 

 and leaf mold for alnost a decade of years, you begin to realize 

 xihr.t damage a little ground fire burning up the leaves on the floor 

 of the woods docs, even if you don't count the direct damage to the 

 trees. At that rate, a fire that destroys the accumulation of leaf 

 litter robs the soil on an acre of wor-ds of from 50 to 2 or 3 hun- 

 dred pounds of nitrogen. It talccs from $9 to $50 worth of sodiur.: 

 nitrate to make up for that. 



With other leaves in other \TOods the figures night even be 

 bigger, I Just mention that to remind you that the loaves wc 

 think of as discarded by the trees still liave a considerable value 

 to the future crops of wood.. 



