rotation of crops. 199 



The Experiments on Rotation made at Eothamsted. 



The experiments have been conducted in Agdell Field. 

 An area of 2| acres is devoted to the purpose. The ordinary 

 four-course rotation of — turnips, barley, clover (or beans), or 

 fallow, and wheat, was adopted. The experiments were com- 

 menced in 1848, so that the eleventh course of four years 

 each was completed with the harvest of 1891 ; and the wheat 

 which has just been sown (October 1894) is the fourth crop 

 of the twelfth course, and will complete the forty-eighth year 

 of the experiments. 



The area of 2£ acres was divided into three main divisions, 

 which have, respectively, been under the following conditions 

 as to manuring: — 



1. Without manure from the commencement. Manures 



2. For the first nine courses, manured with superphosphate MS f* J n 



, , . , , „ . ; r r . r . rotation ex- 



alone, applied only lor the turnip crop commencing each pertinents. 

 course ; that is, once every four years. For the tenth, and 

 each subsequent course, salts of potash, soda, and magnesia, 

 have been applied as well as superphosphate. 



3. A complex artificial manure, also applied every fourth 

 year ; that is, for the turnips commencing each course. This 

 manure comprises — superphosphate, salts of potash, soda, and 

 magnesia, ammonium-salts, and rape-cake ; and it supplies 

 about 140 lb. of nitrogen per acre for the four years' course ; 

 that is, an average of 35 lb. of nitrogen per acre per annum. 



The complex manure (3) was designed to be, in great 

 measure, a substitute for farmyard manure; and it was used 

 instead of it, in order that the amount of the different con- 

 stituents supplied might be more accurately known than 

 would have been the case if farmyard manure had been 

 employed. 



It should be further explained, that when the land is under Removal 

 turnips, the roots, with their leaves, are removed from one and C ?V" 

 half of each of the three differently manured plots ; whilst, of roots. 

 on the other half of each, the produce is consumed on the 

 land by sheep ; or, if the weather be unsuitable for this, the 

 roots are sliced, and both roots and leaves are spread on the 

 land. Thus, each of the three main divisions is divided into 

 two, making, so far, six in all. 



Then again, after the first course of four years, in the third 

 year of each course the leguminous crop was grown on only 

 half of each of the three differently manured plots, and the 

 other half was left fallow. Lastly, as clover cannot be relied 

 upon on such land so often as once in four years, beans have 

 frequently been grown instead. 



We have finally, therefore, twelve plots instead of only 



