140 



On the Nitrate of Soda. 



and healthy, hut was touched hy the cold nights of March, which left 

 the leaves of a bluish colour. 



April 21. — The nitrate, at the rate of 1 cwt. to the acre, was sown 

 and hoed in over all the field, except two square portions, which were 

 staked out and left unnitrated. April was peculiarly dry ; the average 

 quantity of rain of that month being 1*786 inches ; while the "April 

 showers " of this year, according to the register of the Royal Society, 

 did not exceed 0*254, or less than a seventh of the usual average. 

 There was no rain here between April 1*1 and May 8, nor the slightest 

 apparent difference in the two crops, on which day we had moderate 

 showers. On the 16th the usual effect of the nitrate was seen in the 

 dark green colour of the plant.* From the 8th to the 18th great quan- 

 tities of rain fell here. In London, as much in three days as 1'347 

 inches, or five times more than in the whole month of April; and it 

 could scarcely be less towards the west, as the wind blew from that 

 quarter and the south during the heavy rains of that month. Concur- 

 rent with this state of the weather, the nitrated part of the field continued 

 to advance in its deep luxuriant colour and strength, while that which 

 was not nitrated presented a curious contrast in its pale, thin, strawy 

 appearance — a difference which continued till the wheat came into ear. 

 About the end of May it was affected by the disease known as the red 

 rust, the leaves being marked by blotches of a rusty colour, the pow- 

 der coming off" as usual on being touched. This disease is described by 

 Loudon, in his Encyclopaedia of Agriculture, much as it occurred in 

 this instance. He states it to be generally preceded by cold moist 

 weather, which, happening in the warm month of July, suddenly chills 

 and checks vegetation. The disease here appeared earlier, but is pro- 

 bably to be traced to the same cause. The heavy rains in the middle 

 of May were accompanied by a cold north wind, the thermometer being 

 as low as 41°. At the end of the month the temperature rapidly in- 

 creased, and on June 1 the thermometer was as high as 83" ; and 

 again on the night of the 4th fell to 48°*3. Under these circumstances, 

 it was certainly to have been expected that the nitrated wheat, which 

 was now three or four inches higher than the other, and apparently 

 much more luxuriant, should have been more injured than the other. 

 This, however, did not seem to be the case. At this time both crops 

 appeared to be equally affected : whether the future difference in the two 

 is to be traced to this period is not easy to decide. 



* The deep green of every crop where the nitrates of soda or potash are used is their 

 remarkable characteristic, and has perhaps sometimes led to an estimate of the crop not 

 proportionately borne out by its yield. The strength and size of the plant is certainly 

 at the same time increased ; but some degree of that tint and apparent luxuriance may 

 be due, notwithstanding the generally received opinion of the cause of colour in leaves, 

 to the chemical action of the alkali, in turning vegetable colours green. The farmer, 

 therefore, who uses nitrate, should observe that, when this appearance results, the crop 

 may probably not be as good as it would indicate. Otf-hand estimates of the quantity 

 of produce are often most deceptive. Weight and measure is the only criterio?i. In 

 what mode and proportion the alkali is absorbed by the plant, and whether it really 

 does act chemically on the colour without proportionately increasing the luxuriance, 

 are matter of interesting and useful speculation for the vegetable chemist ; but it can 

 scarcely be repeated too often, that the true test of a farmer's experiment is to be found 

 in the bushel and the scales. 



