8 BULLETIN 42, U. S. DEPARTMENT OF AGRICULTURE. 



Each of the manganese salts caused a stimulation in growth in 

 this soil. The degree of stimulation, however, varied with the salt 

 and with the amount. Manganese chloride and sulphate seem to 

 have had the most effect, the chloride causing the greatest improve- 

 ment. There was an increase in this case of 31 per cent when 50 

 parts per million were used. Smaller amounts caused a correspond- 

 ing increase. Amounts larger than 50 parts per million were not so 

 beneficial. With manganese sulphate there was an increase of 22 

 per cent in amounts of 10 to 100 parts per million. The result with 

 50 parts per million would seem to be abnormal or inaccurate, since 

 there is shown only an increase of 1 per cent, while with 25 and 100 

 parts per million the increase was 21 and 22 per cent, respectively. 

 Again, 250 parts per million was not as effective as smaller amounts. 



Where manganese nitrate was used the largest improvement was 

 with 25 parts per million, which gave an increase of 21 per cent. 

 Amounts larger than 25 parts per million caused no appreciable in- 

 crease. There was a similar effect in the case of manganese carbo- 

 nate. The largest increase here was 19 per cent with 25 parts per 

 million. Ten parts per million increased growth 11 per cent. Quan- 

 tities higher than 50 parts per million were harmful. The dioxide 

 was the least effective of the manganese salts. While there was no 

 harmful action with any of the amounts used, the largest increase 

 was only 11 per cent where 100 parts per million were used. 



Tiiis experiment was repeated with the same soil at a later time. 

 The test was conducted in the same way as the one just described. 

 The same salts were used in the same concentrations. This time 

 the plants grew from November 17 to December 20. There were in- 

 creases with each sait. Again the chloride and sulphate caused the 

 largest increases, and the dioxide the least. The best growth was 

 secured with 25 to 50 parts per million of the manganese, this being 

 true with each of the salts. 



These two experiments seem to indicate that manganese in small 

 quantities is beneficial on this soil. The chloride and sulphate gave 

 largest increases. Twenty-five to 50 parts per million of the element, 

 Mn, which is 12£ to 25 pounds per acre, to a depth of 6 inches, gave 

 the largest growth. Applications higher than this gave no corre- 

 spondingly larger increases and in some cases were even harmful. 



Another soil was worked with in a similar manner as the poor sandy 

 loam just discussed. This was a clay loam soil from Pennsylvania, 

 and was a productive field soil. The soil had been manured and well 

 cultivated for a number of years. A four-year crop rotation had 

 been practiced. The soil at the time the sample for this work was 

 taken was growing a good crop of wheat. The relative green weights 

 obtained in this experiment are given in Table II. The plants grew 

 from January 5 to February 6. 



