.Tatindra Natii Sex 33 



in this connection, Mr Howard had quoted the anal^-sis of a sample of 

 well water at Jais in the district of Ilae Bareli, where rich crops of good 

 quality tobacco are grown with the help of irrigation water from wells. 

 The water was rich in nitrates and potash and the amount of dissolved 

 oxygen was high. In all these respects the sample was markedly superior 

 to the well waters at Pusa. Mr Howard has pointed out that the Jais wells 

 are situated in land where potsherds exist in abundance and where the 

 aeration of the soil is copious. At Pusa, on the other hand, the alluvium 

 is fine and soil aeration is difficult. Here the well waters do not possess 

 any great manurial value, whereas the Jais waters are much valued for 

 irrigating tobacco. 



With a view of finding out the extent to which nitrification is 

 influenced by the presence of potsherds in Pusa soil, some prehminary 

 experiments have been undertaken. 



As the nitrification of organic materials may be accepted as a fair 

 criterion of the availabiUty of the nitrogen contained in them, instead 

 of examining the complete nitrogen cycle, only the formation of nitrates 

 — the final oxidation products — has been studied. 



Experiments in Jars. 



In this set of experiments, manured soil mixed with different amounts 

 of potsherds was used and the drainage waters from these were examined. 

 Farm yard manure, containing 68-22 per cent, moisture and 0-47 per cent, 

 nitrogen, was applied at the rate of three pounds per cubic foot. The 

 following proportions of potsherds were used: nil, ten per cent., twenty 

 per cent., and thirty per cent, of the total volume. 



Stoneware cultivation jars, provided with drainage holes at the 

 bottom, were filled with the soil mixtures. First, a two inch layer of 

 bajri (small, roundish, hard pieces of bricks from | to | inch in diameter) 

 was placed at the bottom of each jar to serve as a percolation layer. The 

 proper soil mixture was then put in ; each handful, as it was introduced, 

 being levelled and uniformly pressed in. Attempt was made to pack the 

 soil in an uniform manner in all the jars and to have it as nearly compact 

 as in the field. 



There were altogether twelve jars, consisting of three groups of four 

 jars each. They were filled up with per cent., ten per cent., twenty per 

 cent, and thirty per cent, potsherds respectively. In the first group, the 

 soil layer was eight inches deep, in the second it was twelve inches and 

 in the third, twenty inches. 



Joum. of Agric. Sci. ix 3 



