CH. XII J Manures for Crops 211 



Manures for crops. No definite scheme for manuring 

 crops can be given for universal use because of the 

 varjdng factors of soil, climate, market prices, and 

 available capital, but certain guiding principles hold 

 fairly generally and can be adapted to each locaHty. 



All of the fertilising constituents, nitrogen, potash, 

 phosphoric acid, lime and organic matter must be 

 applied to the land in the course of the rotation. The 

 nitrogen being liable to loss should be distributed, a 

 certain amount being added either each year or each 

 alternate year: the other four constituents are less liable 

 to loss and may be applied to any crop that is most 

 convenient. The Saxmundham experiments show that 

 equal financial returns are obtained wherever super- 

 phosphate is applied in the rotation, while nitrate of 

 soda could not be used in this indiscriminate manner 

 but gave better returns when applied to roots or wheat 

 than to barley. In practice it is usual to give a good 

 dressing to the root crop and lighter dressings to the 

 intervening cereal crops. Care has to be taken, also, to 

 avoid unequal intervals between dunging and folding 

 the land. The distribution of manure is often effected 

 somewhat as follows : 



The root crop commonly receives a mixture of farm- 

 yard manure and a complete dressing of artificials, phos- 

 phates preponderating in the mixture for swedes, tur- 

 nips, rape, etc., while potash forms a larger proportion 

 of the dressing given to mangolds, sugar beet, and 

 potatoes. It should be stated, however, that direct 

 experiments have rarely justified the use of artificials in 

 addition to farmyard manure for swedes. 



The succeeding cereal crop may be wheat or oats, 

 in which case it may need a little nitrogen in spring 



142 



