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1921.] Notes on Manures for November. 75& 



pieces thus sown with seeds, it must have gone a long way 

 towards paying in this great drought in one crop. But in one 

 place last year the chalk had a wonderful effect on winter oats, 

 there being a tremendous crop as far as the chalk went, but a 

 great falling off on the rest. This piece was winter oats again 

 this year and there was again twice as big a crop, but much 

 less than last year." 



It is noticed, however, that all chalk is not equally effective: 

 it will probably be found that the softer chalk is the more use- 

 ful as it will more quickly come into action than the harder 

 deposits. . .. \ .. ' \ . ' \ 



Nitrogen Starvation on Water-logged Soil. — A very interest- 

 ing point is raised by a farmer who writes: ** I noticed if one 

 has a piece of water-logged land the crops have the appearance 

 of starvation of nitrogen, but if a drain is dug across this piece 

 of land to any depth, say 10 ft., and no care is taken how the 

 soil is returned the crops that follow are in most cases many 

 times larger just over where the drain is dug, but no wider, 

 while it seems that the rain must have a better chance of wash- 

 ing nitrogen out of the soil over the drain than elsewhere; yet 

 2 cwt. sulphate of ammonia per acre would not make the crops 

 at the side equal to those immediately over the drain." The 

 explanation is that nitrogen starvation has occurred on the un- 

 drained soil, but it is caused not by washing out of nitrates from 

 the soil but by the decomposition of nitrates which sets in as soon 

 as air is excluded. A number of soil organisms have the power of' 

 decomposing nitrates in absence of air, and they do it with so 

 much rapidity that the plant suffers. The remedy is to let in 

 air, when the loss is completely and automatically stopped; 

 this can best be done by arranging for drainage. 



Non-fertilising Constituents of Manures.— A farmer whites 

 to ask what amounts of substances are present in the ordinary 

 artificial manures besides the nitrogen, phosphate and potash 

 shown in the analysis. The constituents in three common 

 cases are as follow^s:— 



Nitrate of soda :^'?\?ci\\,lQ<^d, in 1 cwt. : Nitrogen, 17 lb., the same amount 

 as is present in 106 lb. of albuminoid or protein; Soda, sufficient to form in 

 the soil 188 lb. of ordinary carbonate of soda or 1 cwt. of bicarbonate of soda. 

 This soda has some effect as manure, but is apt to injure the texture of a 

 heavy soil. 



Sulphate of ammonia: — Plant food in 1 cwt. : Nitrogen, 22 lb., equal to the 

 amount present in 137 lb. of albuminoid or protein; Sulphuric acid, sufficient 

 to consume 85 lb. of calcium carbonate or about 100 lb. of ordinary good 

 grade limestone. 



Superplwsphate : — Plant food in 1 cwt. of 26 per cent, grade: 29 lb. pure 

 tricalcic phosphate ; about 56 lb. dry gypsum (or 62 lb. ordinary gypsum) 

 which has some fertiliser effect. 



