Field Experiments i)i Manuriny, 1003-4. 6i>7 



The Poisonous Effect of Potash Chloride. 



It is well known that the chloride of potash, as other chlorides, is 

 ^capable of exercising- a poisonous effect upon plants after a certain 

 degree of concentration. Certain facts in connection with results 

 obtained in earlier Victorian field experiments from the use of potash 

 chloride suggested the advisability of comparative tests being made 

 with the sulphate and chloride of potash, both in combination with 

 a phosphatic manure and with sulphate of ammonia. A very fine 

 series of experiments to determine the poisonous action of chlorides on 

 plant life has recently been carried out at the Rhode Island Experi- 

 ment Station, U.S.A. In the "Fifteenth Annual Report" of this Station 

 appears the following: — "The results of numerous experiments in the 

 Massachusetts Experiment Station indicate further that sulphate of 

 ammonia should not be used in connection with fertilizers which con- 

 tain chlorides, such, for example, as muriate of potash or kainit. If 

 .so used there is likely to be an interchange of acids and bases ; the 

 sulphuric acid which was a part of the sulphate of ammonia leaves the 

 ammonia and combines with potash or soda, and the chlorine combines 

 with ammonia forming chloride of ammonia. This compound is 

 highly injurious to plants." The outcome of the Rhode Island ex- 

 periments is expressed in the following words, " These results lead 

 to the belief that chlorides of calcium magnesium and ammonia in 

 reasonable quantities are not likely to prove poisonous to plants, so 

 long as carbonate of lime or other basic substances are present in 

 sufficient quantities to pi-event the occurrence of an acid reaction, or 

 at least a strong acid reaction of the soil. Such being the case, it 

 would seem more rational to teach the farmers to look out for the 

 reaction of their soils by testing it with blue litmus paper, and to advise 

 them to correct undue acidity by using lime or wood ashes than to 

 discourage unconditionally the use of combinations of manures likely 

 to give rise to ammonium chloride or other chlorides, which, of them- 

 selves, may be beneficial rather than injurious, if the soil is in the 

 best condition for the production .of the majority of farm crops." 



From the results of the Victorian field tests last year, it would 

 appear that, in reasonable quantity, the chloride of potash will exercise 

 no deleterious effect on Southern soils generally, although there are 

 instances, owing probably to reasons similar to those advanced in the 

 Rhode Island experiments, where this might take place. Some of the 

 Bunyip soils appear to offer an illustration of this. 



The Results from the Sulphate and Chloride of Potash Combined. 



Reference to the returns of the 27 fields of Table B will show 

 that, on 13 out of the number, the sulphate was given instead of the 

 chloride of potash. The average yields of these 13 fields, as also the 

 average yields of the remaining 14, indicating the effect of the two 

 forms of potash fertilization work out as follows : — 



