THE SOIL AND THE PLANT 



149 



very badly after rain. If a storm happens to come any time 

 after the young plant is through, and before it has grown very 

 much, there is great danger that it may be beaten down into the 

 sticky soil and not pick up again ; an excellent illustration is 

 afforded during the current season. These cultivation difficulties 

 are very serious from the practical point of view and effectually 

 prevent continuous cropping with any one plant except where 

 a liberal amount of organic matter is present in the soil, when 

 tillage is a much simpler matter. A rotation is therefore always 

 followed in practice — the benefit to the crop is seen in the 

 following table of wheat yields at Rothamsted : 



Total Produce lb. per Acre and total Grain lb. per Acre 



The 191 1 crops are shown in Plate. 



On Agdell field the wheat is grown in a rotation — fallow, 

 wheat, roots, barley — wheat being sown only once in four years. 

 On Hoos field the course is fallow, wheat, the wheat coming 

 every alternate year ; on Broadbalk wheat is grown every year. 

 No manure is added to any of these three plots, and in the 

 particular plot on Agdell field under consideration no clover is 

 grown. Yet the differences in yield are striking ; the wheat 

 grown in rotation without manure is not only greater in yield 

 than the unmanured wheat grown continuously but it even 

 exceeds the crop on the Broadbalk plot that receives annually 



