838 



Agricultural Gazette of N.S.W. 



[Dec. 2, 1920. 



Cowra Experiments. 



The soil on which these experiments were carried out is of granitic origin, 

 typical of a large area of the Central Western Slopes, and may be described 

 as a loam overlying a clay subsoil at a depth of from 8 to 10 inches. 



The costs per acre of ploughing with disc and mouldboard ploughs at 

 different depths, and of subsoiling have been estimated as follows : — Disc 

 ploughing, 4 inches, 6s. ; disc ploughing, 6 inches, 7s. ; disc ploughing, 

 8 inches, 8s. ; mouldboard ploughing, 4 inches, 6s. 6d. ; mouldboard ploughing, 

 6 inches, 7s. 6d. ; mouldboard ploughing, 8 inches, 8s 6d. ; sub-soiling, 10.s. 



These costs are rather difficult to arrive at, and vary slightly from year to 

 year, according to the prices of fodder, &c., but they are sufficiently accurate 

 to serve their purpose. Wheat is taken as being worth 7s. 6d. per bushel. 

 Costs and yields on the disced 4 inches are taken as the standai'ds of 

 comparison. 



The area of each plot was approximately one-third acre. In the following 

 table is shown on a monetary basis the average of the results for the period 

 1905-13 (not including 1907, when a windstorm so mixed the stooks as to 

 prevent the results being obtained, and 1909, when the crop was destroy^ 

 by a bush fire) : — 



Treatments in order of merit. 



Yield per 

 acre, based 

 on percent- 

 age yield. 



Increase due 

 to Treat- 

 ment. 



Value of 

 Increase. 



Increased 



cost of 



Treatment. 



Net 

 Gain. 



Net 

 Loss. 



Mouldboard, S inches 



Disc 8 inches (average of 10 

 check plots) 



Mouldboard 8 inches and sub- 

 soiled 



Mouldboard, 4 inches 



Mouldboard, 6 inches 



Disc, 4 inches ... 



*Disc, 6 inches 



Disc, 8 inches and subsoiled 



bus. lb. 



26 19 



26 8 



27 23 

 25 43 

 25 42 

 25 3 



24 45 



25 58 



bus. lb. 



1 16 



1 5 



2 20 

 40 

 89 



18* 

 55 



12 

 

 1 



1 

 12 



d. 

 6 



6 

 6 

 6 





 



s. d. 3. d. 

 7 



6 1 



5 -0 

 4 6 

 3 4 



3 3 



5 2 



* Decrease, not increase. 



The difference between the highest and lowest of these results is less than 

 10 per cent., but this peix'entage should be allowed as a margin of possible 

 error in such an experiment, so that the results as far as yield is concerned 

 may be said to be fairly uniform. Slightly increased yields may be expected 

 fiom deep ploughing when the system of farming followed is similar to that 

 practised at Cowra Experiment Farm, but the above figures would probably 

 not result if ploughing were delayed until just prior to planting, and even 

 assuming that they would apply in the latter case, it must be remembered 

 that the experiments take no account of the extra time involved in deep 

 ploughing, beyond extra cost, whereas under the system practised on the 

 average farm in the central west, time is so important a factor at ploughing 

 time that it would scarcely pay to plough deeply for a problematical extra 

 return of a few shillings per acre. 



