i] GREEN MANURE AND CATCH CROPS 5 



favour of ground limestone. It has usually given somewhat better 

 crop returns. It can also be stored in the bags in which it is 

 sent, while ground lime cannot. 



The smaller dressings of any of these can be put on with a 

 distributer but the larger ones must be applied from a barrow, 

 working against the wind. 



Lime and limestone can go on either in winter or spring, and 

 the most convenient crops on arable land are the seeds, the clover 

 or the stubbles that are going to be ploughed up for corn or roots. 

 All these may be expected to give immediate returns. .It is shown 

 in Aberdeen reports 1 that the lime must not be applied v.oo close 

 to the time of sowing the turnips, otherwise the yield may be 

 depressed. 



Nor should lime or limestone be put on to potatoes or oats 

 unless actual trials have shown that benefit will be obtained; 

 as a general rule these two crops respond less than others 

 (Fig. 1) : and in the Kilmarnock trials 2 , lasting over eight years, 

 potatoes were actually injured by lime, though oats benefited 

 by it. 



Basic slag reduces the need for lime, but superphosphate does 

 not. Sulphate of ammonia increases the need for lime. 



Green Manuring and Catch Cropping. 



The ploughing-in of green crops is well known to bring about 

 a great improvement in the soil. Very beneficial results have been 

 obtained on light sands by means of lupines : elsewhere tares and 

 mustard have proved beneficial. 



On the old method a whole season was allowed for the green 

 crops during which two, or sometimes three, could be taken, 

 each being ploughed in before the next was sown. This method 

 is still used in some of the best known experiments on the subject. 

 In practice, however, it has been modified. Instead of devoting 

 the whole season to green crops they are commonly grown between 

 two staple crops so that the rotation is not disturbed: for this 

 reason they were often called "stolen" crops in the olden days and 



1 Aberdeen Bull. No. 4, 1904. 



2 West of Scotland Agric. CoU. Bull. No. 55, 1911 (pp. 193-222). 



