THE MANURING OF FOREST TREES 



By Arthur Smith 



OURING the past quarter of a cen- 

 tury the question of manuring 

 forest trees has been given con- 

 siderable attention in Europe, and, 

 among other experiments, that of using 

 sewage effluent has been tried. 



Near Berlin irrigating a forest of 

 trees having considerable size by a 

 monthly application of sewage water 

 during two growing seasons was a de- 

 cided failure and it caused the death of 

 many of the trees. A similar irrigation 

 at Gerlitz gave better results. In this 

 case, however, the growth was consid- 

 erably younger. The city of Berlin has 

 obtained encouraging results by top 

 dressing the soil of coniferous woods 

 with city refuse. 



In view of the long period between 

 the planting and the cutting of a forest 

 the direct application of manure in any 

 form is not likely in a general way to 

 prove remunerative. At the same time 

 the question of helping along a planta- 

 tion of young trees, especially conifers, 

 is worth considering and in the earlier 

 stages in the life of forest trees growing 

 in poor soil the value of some form of 

 manuring may possibly become an 

 acknowledged fact in practical forestry. 

 _^For instance on poor sandy soils 

 where the nitrogen content is very small 

 the problem of supplying this neces- 

 sary plant food in a slowly available 

 form is worthy of consideration. The 

 idea of applying nitrates or other com- 

 mercial forms of nitrogenous fertilizers 

 may be put aside as impracticable both 

 on account of cost and because they are 

 too rapid in action, besides causing an 

 excessive growth of weeds. Making 

 use, however, of atmospheric nitrogen 

 by growing on the land some form of 

 the Leguminosae appears to be feasible 

 an dworthy of trial. Upon some sandy 

 soils in Europe lupins have been used 

 tor this purpose and good results are 

 reported. Lupins would scarcely be so 



suitable for this country as some of the 

 clovers, such as the White Clover, 

 Trifolium repens and Alsyke, Trifolium 

 hybridnm. An ideal method would be 

 to plow in a crop of clover the season 

 previous to planting, then sow clover 

 again and plant the trees in the young 

 clover. Failing, this clover could be 

 broadcasted over he ground in the 

 spring. To obtain a stand of clover 

 upon the more sandy soils the applica- 

 tion of some form of line would be ob- 

 viously necessary. 



It is of course well known that the 

 amount of mineral matter retained in 

 himber is comparatively small, and, by 

 the fall of their leaves, trees during 

 their growth return to the soil the 

 greater part of the mineral matter taken 

 f'-om it; this applies, however, more to 

 deciduous species than to conifers. But 

 the main point to be considered is that 

 of giving young newly planted trees a 

 good start and helping them along dur- 

 ing the first few years of their life, 

 when they have the greatest struggle for 

 existence. It is in this connection that 

 the value of giving the soil some 

 previous preparation upon the lines sug- 

 gested above comes in — of course w^here 

 it is practicable — as not only is plant 

 food added to the soil in a slowly avail- 

 able form but, what is of the greatest 

 importance, the early growth is ac- 

 celerated, being measured by feet in- 

 stead of inches. 



Another means which works to the 

 same end and which is more applicable 

 to the heavier classes of soils is that of 

 keeping the ground in clean cultivation 

 during the first two or three years of 

 the trees' growth. During the past sea- 

 son the writer has. kept about 8,000 two- 

 year-old conifers under clean cultiva- 

 tion and another block of 5,000 has 

 only had the weeds out and left lying. 

 The soil of the latter is, if anything, 

 better than the former, but the growth 



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