144 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



PECAN NUTS. 



As in previous years the larger activities in connection with the 

 nut-culture investigations have been with pecans. Because of the 

 increased interest in the growing of this nut, it has become increas- 

 ingly important to determine, as accurately as possible, the geo- 

 graphical range of the species from the standpoint of its culture. 

 Evidence has been secured which tends to confirm a previously ex- 

 pressed conviction that the fruiting of the pecan is uncertain north of 

 the thirty-ninth degree of latitude. While individual trees may be 

 found growing considerably north of this latitude and occasional 

 crops are produced, the uncertainty of bearing appears to be too 

 great to warrant the planting of them for nut production farther 

 north than the latitude specified. 



In the study of pecan varieties from the standpoint of their 

 adaptability they may be said now to constitute three groups — 

 Southern, '.' West Texas," and what may be termed " Indiana " 

 groups. With further studies of varieties from Tennessee and 

 Arkansas, another group may be added to the above. 



Individual tree records, with a view to securing accurate data on 

 yields, were continued with the crop of 1916. There is a growing 

 conviction that there are cultural problems with the pecan which are 

 not fully understood. This is apparent in the fact that certain 

 varieties at least usually shed a large portion of the crop that sets, 

 the dropping occurring early in the summer. As nearly as con- 

 ditions can be correlated, this appears to be connected with the soil- 

 moisture conditions. In much of the pecan-growing territory a 

 rather severe drought usually occurs during the early part of the 

 summer, and it is during this period that much of the trouble occurs. 



CXDRN VARIETIES. 



Some investigations have been centered on the requirements of the 

 corn crop from the standpoint of soil temperature. Last year's tests 

 confirm previous results in showing that varieties of too small size 

 are often chosen and that the earlier planting of larger varieties will 

 usually result in better yields and profits. By very early seed-bed 

 preparation and frequent early cultivation larger and more pro- 

 ductive varieties can be profitably substituted for very small early 

 maturing varieties. 



WHEAT IN ROTATION. 



The results of cooperative work in Georgia to the present time 

 indicate that better yields are obtained when wheat follows cotton 

 than after corn. This is a fortunate condition in the southern part 

 of the cotton belt, because of the fact that velvet beans are sown with 

 the corn and the combination is best utilized as pasture. Also good 

 farm practice under boll-weevil conditions makes it necessary to 

 plow under the cotton stalks as soon as the cotton is picked, thus 

 making wheat a desirable crop to follow cotton. 



DRY FARMING. 



Work is now being conducted at 24 field stations on the Great 

 Plains. At the end of 1916 five of these had completed a continuous 



