50 MISC. PUBLICATION 4 3 4, U. S. DEPARTMENT OF AGRICULTURE 



Maintenance of Soil Fertility 



Although a tract of good fertile soil may be selected as a nursery 

 site, it cannot be expected to be cropped repeatedly without the 

 necessity of taking some measures to maintain its productivity. More- 

 over, the area selected for a nursery site will in most cases be land that 

 has been used in the past for production of farm crops, and may need 

 attention at the outset if the highest quality of nursery stock is to be 

 produced. 



DRAIN ON SOIL NUTRIENTS AND THEIR REPLACEMENT 



The actual drain on soil nutrients by nursery stock will vary accord- 

 ing to species, density of sowing, amount of effective water applied, 

 and length of growing season. In the southern part of the prairie- 

 plains the longer growing season and greater production of material 

 per acre per year result in a heavier drain than farther north. Compu- 

 tation of the total green weight of 1 -year-old honeylocust seedlings 

 produced in two successive years, 1935 and 1936, in a nursery at 

 Tecumseh, Okla., gave fresh weight of seedlings per acre (without 

 foliage but including roots dug to a 10-inch depth) as 7,640 and 3,730 

 pounds respectively. The variation was due largely to annual 

 differences in rainfall and is quite comparable with that for many 

 agricultural crops. 



Table 12 gives some additional data on the weight of the material 

 removed from a nursery by the digging of the stock. Since the 

 moisture content of deciduous trees at time of lifting is generally about 

 half the fresh weight of the plant, it is apparent that the dry weight 

 of the crop produced in Oklahoma nurseries per acre per year ranges 

 roughly from 650 to 4,550 pounds, with an average of about 2,450 

 pounds. Similar data for nurseries in the northern and central parts 

 of the prairie-plains show the crop weights to be one-half to two- 

 thirds the values given in table 12. 



On the basis of several analyses of hardwood seedlings from a 

 North Dakota nursery, the actual drain caused by removal of a crop 

 of which the oven-dry weight is 1 ton per acre would be 28 pounds 

 nitrogen, 3 pounds phosphoric acid, and 9 pounds potash. The 

 nitrogen, phosphorus, and potash contents of American elm in this 

 nursery were 1.795, 0.1563, and 0.452 percent respectively, and for 

 green ash the values were 1.035, 0.1475, and 0.443 percent respectively. 



Table 12. 



Green weight of 1-0 ' seedlings -produced per acre in Oklahoma nurseries 

 in 1935 



Nursery and species 



Spacing 



between 

 rows 



Trees per 



foot of 



row 



Trees per 

 acre 



Total green 

 weight 



Tecumseh: 



Inches 

 40 

 20 

 20 

 40 



42 

 42 

 40 

 42 



Number 

 4.5 

 4.5 

 4.5 

 3.8 



4.3 

 4.2 

 4.5 

 4.7 



Number 

 58, 800 

 117. 600 

 117, 600 

 49, 700 



53, 500 

 52, 300 

 58, 800 

 58, 500 



Pounds per 

 acre 



9,050 



Osage-orange 



Honeylocust 



Black locust __ _ . 



7,870 

 7,640 

 3,970 



Oklahoma City: 

 Western walnut 



4,470 



American elm. _ 



1,820 



Green ash.. . 



1, 250 



Enid: Hardy catalpa.. . 



3,110 







1-year seedlings not transplanted before field planting. 



