74 



Journal of Agricultural Research 



Vol. XIX, No. 2 



NUTRIENT COMPOSITION OF SOLUTIONS 



The need for a basic nutrient culture of favorable physiological balance 

 was recognized. The attempt was at first made to adjust Shive's solu- 

 tions No, R5C2 and R3C3 (24) / which he found best suited to the growth 

 of wheat seedlings, to the various reactions desired for the work by 

 additions of the requisite amounts of an acid or base. However, because 

 of the extensive precipitation of phosphates of calcium and magnesium 

 in the more alkaline members of such series, these solutions were found 

 unsuited to the work at hand. 



Two series of solutions were eventually employed which varied some- 

 what in composition from Shive's best solutions. The maximum partial 

 ionic concentrations in volume equivalents for the two solutions used are 

 given in Table I, the composition of Shive's solutions being included for 

 purposes of comparison. 



Table I. — Maximum ionic concentrations of solutions 

 [Expressed as gram-equivalents per liter] 



The salts, acids, and base used and their volume-molecular concentra- 

 tions were as follows : 



Series A. — Dipotassium phosphate (K2HPO4), 0.0180 m.; sodium nitrate (NaNOj), 

 O.OIOO tn.; calcium chlorid (CaClj), 0.0025 m.; magnesium sulphate (MgSO^), 0.0025 m.; 

 sodium hydroxid (NaOH), o.cooo to o.oioo m.; and citric acid (H3C8H5O7), o.oioo to 

 0.0000 m. 



Series B. — Potassium sulphate (K2SO4), 0.0040 m.; potassium nitrate (KNO3), 

 O.OIOO m.; CaClj, 0.0025 m.; MgS04, 0.0025 m., phosphoric acid (H3PO4), 0.0180 m., 

 sodium hydroxid (NaOH), 0.0000 to 0.0360 m. 



To each 500 cc. of culture solution there were added 5 drops of a ferric 

 phosphate solution containing 0.25 gm. of FeP04 per 100 cc. 



VARIATION OP REACTION 



The ideal method of adjusting the reaction in such a series of cultures 



1 Reference is made by number (italic) to " Literature cited," p. 93-95. 



