526 



Journal of Agriculture . Victoria. [10 Sept.. tqi: 



While the cleared or fallow strip made a gain of 49 lbs. nitrate nitrogen, 

 the cropped land lost 39 lbs. 



Nitrates Formed Near Surface. 



Looking to Table VII., it will be seen that the increase of nitrates ir^. 

 the fallowed strip during the nineteen days was confined to the top foot 

 of soil. The reason is that nitrate production requires plenty of fresh air, 

 and the less porous the soil the more superficial will the action be. Where- 

 any considerable supply of nitrates is found below the second foot of soil, 

 they will have passed down by diffusion and drainage. As the upper portion. 

 of a soil in particular may become very dry under a crop or neglected 

 fallow (Table IV.), it is the more necessary in a dry climate that the land 

 be well supplied with nitrates before the vegetative period commences. 



At Sparrovale the oat crop was the third in succession on the ground. 

 On the cropped plot during the experiments no nitrates were ever found 

 below 18 inches at any date of sampling. The same was true for all the- 

 plots at the first sampling, and the oat crop undoubtedly started growth 

 under bad nitrate conditions. Had September not been exceptionally 

 wet (532 points) it would have been still worse. The interposition 

 of a fallow between two crops allows the soil to lay up a store of 

 nitrates. With moderate winter rains, the.se will pass more or less down- 

 wards in the soil, and can be drawn upon by next .season's crop for the- 

 purpo'ses of growth. 



Nitrates Available for Next Crop. 



That the nitrates produced in fallow must exercise a beneficial effect 

 upon the next crop is clearly indicated in a table by King and reproduced 

 by Hall. Analy.ses were made in spring of two similar soils, one of which 

 had been fallowed and the other cropped during the previous year. The- 

 figures represent lbs. of nitrate nitrogen per acre. 



Table VIII. 



Land previously fallow 

 Land previously cropped 



lb. 

 212 



25 



lb. 

 56 

 15 



lb. 

 22 

 10 



lb. 

 13 



