460 Journal of AgriciiTtiirc , Victoria. [10 Aug., 1912. 



unless it provides, not only for the conservation of moisture, but also 

 for the conservation of fertility. Attention was concentrated on the f(jrmer 

 principle in the preceding article. Let us now c(jnsider the latter prin- 

 ciple. The weak point in the i)ractice of barefallowing is that it 

 tends to deplete the soil of organic matter. Organic matter — by which 

 is meant vegetable or animal matter in the process of decay — is the soil's 

 iiio.st valuable constituent. Tt has an important physical, chemical, and 

 biological effect upon the soil. It acts physically, by increasing the 

 capacity of the soil for holding moisture, and by improving its texture ; 

 chemically, by supplying nitrogen necessary for the growth of the crop 

 and by unlocking the dormant stores of plant food and making them avail- 

 able ; and, biologically, by affording the necessary material for the promo- 

 tion of vigorous bacterial growth within the son. 



It may readily Ije understood, therefore, that the presence of this 

 important ingredient in ample quantity will mean success, whilst its 

 absence will mean disaster, and when the organic content of the soil 

 becomes lessened, the crop-producing power will be seriously impaired. 



Alternate barefallowing and wheat cropping, without a period of rest 

 or pasturage, will ultimately deplete the soil of its organic matter, and 

 this depletion will be hastened by the practice of burning the stubble. 

 Local figures are wanting as to the rate at which organic matter is lost 

 by slow oxidation in the process of fallowing ; but there can be little 

 doubt that the loss in dry, hot districts is considerable. The loss through 

 burning of the stubble of a 15-bushel crop, however, may be set down at 

 1,145 lbs. of organic matter per acre {vide page 203). To counteract 

 these losses should be the aim of every practical farmer. It is a 

 matter of common observation that many of our old wheat lands 

 are becoming more difficult to plough and reduce to a satisfactory tilth 

 compared with virgin land of the same character in the same locality. 

 I'his is one illustration of the effect of a reduction of the organic content 

 of the soil. There are three general ways of supplying the soil with the 

 organic matter necessary to maintain its fertility — 

 (i) By the application of farmyard manure. 



(2) By pasturing and by rest. 



(3) By green manuring. 



Lender the conditions that obtain in the wheat areas, the application 

 of farmyard manure as a practical means of counteracting the depletion 

 of organic matter is out of the question. The average wheat holding is 

 far too large to be appreciably affected by the totality of farmyard manure 

 produced on the farm. In districts where intense culture is practised, 

 however, and where individual holdings are relatively small, the use of 

 farmyard manure as a means of restoring organic matter becomes prac- 

 ticable. The average wheat-farmer, with his relatively large holding, 

 must, therefore, depend either on pasturing, rest, or green manuring for 

 the maintenance of the organic content of his soil. 



til. — Rotation Systems for Wheat. 

 Thus arises the necessity for some sort of rotation in a system of 

 cropping. Continuous cropping with the same crop, and the biennial 

 system of cropping and barefallowing, have been shown to fall short 

 of the requirements of a permanent system of agriculture. It is very 

 rarely, however, that a wheat-farmer follows the strict practice of alternate 

 crojjping and fallowing. Sheej) have now become an integral part of 



