1905.] The Winter and the Wheat Crop. 719- 



of root growth upon a fairly dry condition of soil. He grew 

 two lots of barley in pots containing the same kind of soil,, 

 maintaining the soil water in one case at almost 76 per cent., and 

 in the other at about 49 per cent, of the maximum water content 

 of the soil. As a result the barley in the drier soil developed 

 twice the weight of roots as did the barley grown under wetter 

 conditions. 



It follows, then, that if we have a saturated soil throughout 

 the winter the wheat plant will make a poor foundation of roots,, 

 and from this bad start it can never recover ; in other words, 

 wet winters are invariably followed by poor wheat crops. In 

 Table II. the experimental wheat crops for the last thirty-four 

 years have been divided into two lots according to whether the 

 winter rainfall and percolation have been above or below the 

 average, and the figures show the average rainfall and percola- 

 tion for the group of winters which was above and that which was . 

 below the average. Lastly come the yields which were associated 

 with these two series of years, and it will be seen at once how 

 marked has been the effect of the winter's rain upon the crops 

 of the following harvest. It is clear, indeed, that the earlier 

 months of the wheat's growth are amongst the most critical, , 

 and the crop is largely made or marred at this early stage in 

 its history. 



Table II. 



Comparison of io wettest and 10 dryest 

 winters (1852-1902), Rothamsted. 



10 Wettest. 



10 Dryest. 



Rainfall, Nov. to Feb. inclusive ... inches 

 Average crop per acre, plots 6, 7, 8... bushels 



13-01 

 26*2 



579 

 34*9 



Comparison 'of winter percolation with crop 

 1870-1904. 



19 Winters 

 above 

 average. 



15 Winters 

 below 

 average- 



Percolation through 60 in. bare soil, 



Nov. to Feb. inches 



Average crop per acre, plots 2, 6, 7 ... bushels 



9*43 

 26-8 



5 '02 



3i'5 



Another factor in the yield is the extent to which the autumn 

 formed nitrates are allowed to remain in the soil by the winter 

 rains. The wheat crop, though very dependent on the supply 



