40 Tlte Iiiftaence of Potsherds on Nitrification 



The river rose up to the end of July. After this it began to fall till 

 the end of August (with one slight rise in the first week of this month). 

 Afterwards the level rose rapidly attaining the maximum height during 

 the first half of September. Then it fell, with slight fluctuations. The 

 fall was pretty rapid up to the first week of November but afterward 

 was slower (though steady). 



The fall of the water level is seen to be associated with an increased 

 nitrate content of the soils. The downward movement of the water 

 causes a greater aeration of the soil and ultimately results in a more 

 energetic formation of nitrates. 



In the decay and nitrification of the organic materials in the soil, 

 a most important part is taken by the micro-organisms of the soil. 

 These latter are most active within certain ranges of temperature. 

 Hence the temperature of the soil is an important factor in the formation 

 of nitrates in the soil. 



Records of the temperature of the soil are not, however, available, 

 but, as Major Leather^ has shown that there is a close connection between 

 the temperatures of the air and the soil, the 8 a.m. air temperatures are 

 shown in the chart. Till October the temperature has varied between 

 80° and 85° F. After this there has been a steady fall till the end of the 

 year. After January, the temi:)erature began to rise with occasional 

 fluctuations. It is interesting to note that the fall of the temperature 

 coincides with the beginning of increased production of nitrates which 

 has continued up to the end of the experiment. 



It is also interesting to note here another point which shows a close 

 relation between the growth of plants and the nitrification processes 

 going on in the soil. The period during which nitrates began to accumu- 

 late in the soils investigated coincides with one of the periods of rapid 

 plant growth in Bihar. In the case of established trees, it has been noted 

 that after a period of vigour coinciding with the early monsoon jahase, 

 growth slows down as the monsoon advances. It is not till October that 

 growth begins again^. 



I wish to express my sincere thanks to Mr Howard for the facilities he 

 accorded me in carrying out the above experiments in the Botanical 

 Area at Pusa and for the interest he has taken in the work. 



' "Soil Temperatures," Memoirs Dept. Agr. India, Chem. Series, 4, no. 2. 



' A Howard, "Soil Ventilation," Agr. Research Inst., Pusa, Bull. 52. pp. 10. II. 



