REPORT OF THE CHEMIST 



129 



SESSIONAL PAPER No. 16 



The experiments now to be described had for their object the estimation of the 

 amount of nitrogen that became part and parcel of the soil nitrogen through the growth 

 of clover. By the analysis of the soil before sowing and after the decomposition of the 

 legume it was thought that data of a valuable character would be obtained. The work 

 was carried on in experimental pots and on a small plot simultaneously, soil poor in 

 nitrogen being purposely selected for the investigation. The plan was to determine 

 as accurately as possible its nitrogen content at the outset, to sow it with clover, to 

 return the crop to the soil and after its decay to again determine the soil's nitrogen. 

 The experiments were continued over a period of two seasons. 



Pot Experiments. — Twenty-one pots, each having a diameter of 8 inches and a 

 depth of 12 inches, were filled to a height of 9 inches with soil containing 0-0393 per 

 cent nitrogen. These were sown with Mammoth Red clover on May 13, 1902. The 

 pots were then sunli in the soil, level with tTie surface, so that moisture and temperature 

 conditions for the clover might be as nearly normal as possible. On October 13 of the 

 same year (1902) the crop (including the roots) was taken up, cut very fine and re- 

 turned to the soil — the cut clover and the soil being thoroughly mixed. Throughout 

 the following winter the pots were kept in the laboratory building and the soil main- 

 tained in a moist condition, so that the decay of the clover might be as complete as 

 possible. 



On June 13, 1903, the pots were again sown with Mammoth Red clover, and the 

 growth returned to the soil in the autumn as in the previous year. In the spring of 

 1904 (May 14) the soils were again thoroughly mixed and sampled, the undecomposed 

 fibre being carefully sei^arated, and analysed. The result was 0457 per cent nitrogen. 



Plot Experiment. — The plot used was Vqqo of an acre. Its soil to a depth of 8 inches 

 was removed and replaced with soil thoroughly uniform throughout and containing 

 "0437 per cent nitrogen. The plot was sown with Mammoth Red clover on May 13, 

 1902. During the season's growth the clover was cut twice and allowed to decay on 

 the soil. At the close of the season (October 17) the crop was turned under, the soil 

 being stirred to a depth of 4 inches. In the following spring (1903) the plot was again 

 sown with clover which made a very fair growth. This was cut twice and finally 

 turned under as diiring the previous year. On May 14, 1904, the soil of the plot was 

 sampled to a depth of 4 inches and its nitrogen-content determined. This was now 

 -0580 per cent. The following tabulated statement permits of a ready review of the 

 results obtained : — 



NiTROGEX — Content' of Soil before and after the Growth of Clover. 



16—9 



