FERTILIZERS 17 



The clovers are usually sown in the spring or early 

 summer following an early crop of vegetables. The pro- 

 cedure varies as to when the crop is to be turned under. 

 The crop may be allowed to grow during the season of sowing, 

 and all of it ploughed under the following spring, or a cutting 

 may be had and then the second growth ploughed under. 

 This may be done either in the fall or spring, depending upon 

 whether an early planting is desired. For early results, 

 the crop should be ploughed under in the fall. 



Cow peas and Canadian field peas are desirable legu- 

 minous crops used for green manuring. Neither of these 

 crops is hardy and they must therefore be ploughed under 

 in the fall. The Canadian field pea is one of the best of the 

 crops grown to add humus to the soil. 



24. Non-Legumes. Rye is considered more of a catch 

 crop than most of the cover crops grown. It may be sown 

 quite late in the fall, and will make a good growth even in 

 a rather poor soil. Very often poor soils are built up by 

 first growing rye on them, which is turned under and followed 

 by some leguminous crop. 



25. Ploughing Under. The older or more mature a 

 green crop becomes before ploughing under, the longer it 

 will take for the crop to decompose and for its plant food 

 and humus to become available. The more mature the crop 

 when ploughed under, the more danger there is that the 

 capillarity of the soil may become more or less disturbed, 

 because of the layer of undecayed vegetable matter under- 

 lying the ploughed soil. The furrow should be turned on 

 edge as much as possible to avoid- this condition. Thorough 

 discing is a great help in restoring the soil to its former 

 capillarity, and also in cutting up the green crop ploughed 

 under. 



26. Effects of Green Manuring. Green crops are valu- 



