3o6 Bulletin 72. 



relation of cover crops to moisture. Some contend that any crop 

 which shades the ground, will keep the surface moist and conserve 

 moisture, whilst others, knowing that all plants exhale water, con- 

 sider that any crop tends to make the land dry. Both these 

 opinions are partly correct. A crop which occupies the soil the 

 entire season and which does not allow of cultivation will make 

 the land dry, whilst one sowed late in the season upon land which 

 has been thoroughly tilled during May, June and July, will not 

 seriously rob the soil of moisture. At all events, there need be 

 no fear of drying out the soil by sowing a late crop, for the serious 

 injury of drouth is usually effected before such crops are estab- 

 lished ; and the tree needs to be checked, rather 'than stimulated, 

 at this season, by the transfer of the nitrates and moisture to 

 other plants. The most marked way in which such crops con- 

 serve moisture is by means of the fibre and humus which they 

 impart to the soil when plowed under ; but even this humus can- 

 not compete with cultivation as a retainer of moisture. 



An experiment now continuing in one of our orchards illustrates 

 the value of cultivation over green manuring alone, in this dry 

 year. The orchard is a hard clay, — just the soil which is 

 benefitted by the loosening effects of green manures. The orchard 

 was divided into three portions in 1890, a year after the trees were 

 set. One-third has received liberal annual dressings of commer- 

 cial fertilizers,* and has been well tilled ; another third has had 

 no treatment except good tillage ; and the remaining third has had 

 liberal applications of potash and has then been sown early to a 

 nitrogenous (leguminous) green crop. This third portion has 

 simply been plowed and fitted well each spring, and then sown, 

 having received no subsequent tillage. The crops were all 

 plowed under the following spring. The following are the crops : 



1890. Mixed beans. Sowed June 16. 



1891. Field peas. Sowed June 24. 



1892. Vetch. Sowed June 16. 



1893. Cow peas. Sowed June 19. 



1894. Field peas. Sowed June 14. 



*This experiment has not yet progressed far enough for report upon meth- 

 ods of fertihzing, and is mentioned here only for the purpose of contrasting 

 methods of cultivation. 



