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



A pH of 8.8 or over indicates the probable presence of some sodium 

 carbonate, and one of more than 9.0 indicates this compound to be 

 present in considerable quantities. This would immediately suggest 

 the necessity of supplementing underdrainage with treatments of 

 gypsum or sulfur. 



A pH of 8.2 to 8.8 would indicate presence of white alkali, and this 

 test can be supplemented by a test for sulfates and chlorides. If the 

 latter exceeds 2,000 parts per million there is a certainty that these 

 materials are present in sufficient quantity to interfere with normal 

 development of the seedlings, and will require corrective measures. 

 Some of the .more sensitive tree species may show adverse effects 

 from quantities as low as 1,500 parts per million. Such tests can be 

 supplemented by observations on stunting or chlorosis of the seedlings, 

 and of any accumulation of alkali in the form of a white crust or dark- 

 colored spots on the surface of the soil. 



All observations available to date on value of pH as a test indicate 

 when values are below 8.2 that most shelterbelt tree and shrub species 

 are not adversely affected. It is in the range of pH 8.2 to 8.8 that 

 more or less serious symptoms of "salt sickness" appear. 



Minimum Fertility Requirements 



The determination of a proper balance of nutrients for growing 

 hardwood seedlings remains to be worked out in detail for various 

 species. Minimum standards of fertility have, however, been worked 

 out on the basis of the present available information and experience, 

 as given in table 11. The values represent what may be considered 

 minimum requirements for the average nursery, and there is no 

 doubt that a soil with twice the amount of nitrogen, phosphorus, 

 potash, calcium, and magnesium, and twice the base-exchange 

 capacity listed in table 11 would produce excellent nursery stock. 

 If the analysis of the soil from a proposed nursery site runs consider- 

 ably below the standards shown, a better site should be selected, 

 unless other factors which are in favor of the site, such as ideal loca- 

 tion, good water supply, or low cost of land, outweigh the lack of 

 adequate fertility. In such case the soil must be built up by fertiliza- 

 tion and use of soiling crops. 



Table 11. — Minimum standards of fertility for growing of hardwoc 



-plains planting 



for • prairie- 



Fertility standard 



Minimum 

 level of 

 fertility 



Approx- 

 imate 

 equiva- 

 lent 



Fertility standard 



Minimum 

 level of 

 fertility 



Approx- 

 imate 

 equiva- 

 lent 



Preferred pH_ __ _ __ 



Percent 



6. to 8. 



.15 



.002 



.005 

 .015 



Pounds 

 per acre 



3,~666 



40 



100 

 300 



Replaceable calcium 



Replaceable magnesium 



Base-exchange capacity 



Mittiequiva- 



Jents per 

 100 urams 



10 

 3 



15 



Pounds 



per acre 



2,400 



Total nitrogen 



Available nitrogen (Am- 

 monia nitrogen + nitrate 

 nitrogen) __ ._ .. 



720 



Available phosphorus (as 

 P2O5) 





Available potash (as K20)___ 





