6 THE IMPROVEMENT OF THE SOIL [CH. i 



are now called "catch." crops. A sufficient interval is necessary 

 to allow of growth : they come in well, for example, between barley 

 and mangolds. Instead of ploughing them in they are often fed 

 off by sheep or cut green for horses and cattle. The effect on the 

 soil is good whichever course is adopted, and each farmer must 

 decide which is most convenient. In dry districts the chief 

 difficulty is the water supply : the stubbles are often too dry to 

 allow of germination of the seed of the catch crop, and after its 

 growth it leaves the ground too dry for the next crop. In wet 

 districts the drying caused by catch cropping is an advantage: 

 it is claimed, for example, that the succeeding potato crop can be 

 got in earlier because the land is dryer. 



The effect on the soil depends on the nature of the crop and 

 its bulk. Leguminous crops increase the stores of nitrogen in 

 the soil : instances are afforded by the autumn sown trifolium 

 harrowed in on the stubbles, or spring sown clover put in with 

 the wheat or, in parts of Scotland, with the lea oats. Non- 

 leguminous crops do not add nitrogen, but some of them, especially 

 mustard, are nevertheless extremely effective. 



Whether the crop is to be fed or ploughed in it must not be 

 left after flowering time or it becomes too woody. And, of course, 

 the bulkier it is the better, although even a small crop may have 

 a good effect on the soil. There can be little doubt that the intelli- 

 gent extension of this system would be very helpful. 



War on Weeds. 



Weeds do a considerable amount of damage, and ought to be 

 kept down vigorously. It is difficult to find any good in them, 

 and easy to find a good deal of harm : they take water and food 

 that the crop ought to have: they interfere with the proper 

 benefits that a fallow ought to produce: they harbour diseases 

 and pests: and they have other faults. Therefore they should 

 be kept down by cultivation, and, if necessary, by hand weeding 

 done with child labour, if it can be obtained. 



