74 THE FARMERS HANDBOOK. 



With regard to the kind of crop to be used for the purpose of green- 

 manuring, a good deal of latitude is permissible. Any crop that is rapid 

 and luxuriant in growth, and that can be readily turned under, is suitable 

 for the purpose, and the selection will be guided by considerations such as 

 the time of year at which it is to be grown, its suitability to soil and district, 

 &,c. Amongst the most effective class of crops for the purpose are legumin- 

 our plants, such as clover, cowpeas, &c, since these are specially valuable on 

 account of their power of obtaining their nitrogen from the air. They are, 

 therefore, especially suitable for soils poor in nitrogen, and are of high value 

 in enriching the soil with this ingredient. There are, however, many other 

 crops which are suitable for the purpose, and frequently used, such as oats, 

 rye, &c. These are all rapid growers, and can be grown as catch-crops — that is 

 to say, after the main crop has been harvested and before the succeeding one 

 is sown. The practice of growing a crop of tares or vetches after the wheat 

 crop has been harvested is very common in Europe, and can be followed 

 successfully here in districts where the autumn rainfall is sufficient. Such a 

 catch crop occupies the ground only at a time when it would be otherwise 

 unoccupied, and, during its growth, is collecting plant-food from air and 

 soil, which is utilised for manuring the succeeding crop. 



The practice of green-manuring is of special value in orchard work, where 

 the green crop can be grown and ploughed under between the rows. 



It must be borne in mind, in all cases, that green-manuring depends for 

 its success upon conditions favourable to the decomposition of the buried 

 green crop, namely, sufficient warmth and moisture. A crop ploughed under 

 in the late autumn or winter will nitrify only slightly, and the same applies 

 to ploughing under a crop in a dry season. If the land is quite dry the crop 

 will remain buried without decomposition for a considerable period, and its 

 benefit is lost. 



Proportion of Nitrogen supplied to Soil by Green Manuring. 



With regard to the actual amount of material supplied to the land by 

 ploughing under a green crop, some experiments were carried out at the 

 suggestion of Mr. W. J. Allen, the Fruit Expert of the Department. 



The produce of one square yard of crops of vetches, at Wagga, Bathurst, 

 and Hawkesbury College, was harvested carefully, tops and roots, and for- 

 warded for analysis. In the case of the Wagga sample, the roots were 

 obtained by washing away the soil, and the Manager calculated that he 

 succeeded in obtaining 95 per cent, of the total weight of roots in the soil. 

 The produce of tops from one square yard was 4 lb. 14V2 oz., or 10 tons 

 12 cwt. per acre; and of roots, 1 lb. 9 oz. per square yard, or 3 tons 7 cwt. 

 per acre. Analysis showed that the tops contained 87 per cent, water (13 

 per cent, dry matter) and -506 per cent, nitrogen; the roots contained 83 per 

 cent, water (17 per cent, dry matter) and -213 per cent, nitrogen. 



When, therefore, this crop was ploughed under, it added to each acre of 

 the soil, in the shape of dry matter, 1 ton 7 cwt. tops, and HV2 cwt. roots, 

 including 120 lb. nitrogen from the tops and 16 lb. nitrogen from the roots ; 

 a total of 136 lb. nitrogen per acre. Assuming that conditions were favour- 

 able for nitrification, this would be equivalent to a dressing of nearly 7 cwt. 

 sulphate of ammonia per acre, or over 11 cwt. dried blood — an enormous 

 dressing. 



