GROWING ALFALFA SEED. 453 



addition, sub-surface packing is advised for all spring-plowed land, 

 but may often be omitted in the case of fall plowing, as natural 

 settling supplemented by harrowing and rolling usually pro- 

 duces a sufficiently firm seed bed. If firming is not done there 

 will be at the bottom of the new furrow a dry, porous stratum 

 of the old topsoil. This condition, which is present in all freshly 

 plowed fields where the surface is dry, may result fatally to the 

 young alfalfa plants, as their roots can not make the necessary 

 development in this layer, containing dry soil, clods, and air 

 spaces. If the field is not to be left fallow long enough for 

 harrowing and natural settling to make the ground sufficiently 

 firm below, this injurious condition should be remedied by sub- 

 surface packing with suitable implements. It is necessary that 

 there be sufficient moisture in the soil at seeding time to enable 

 the plant to make a sufficiently rapid growth to permit of surface 

 tillage without covering up the young plants. 



The purpose of subsurface packing is not to prevent loss of 

 moisture, but to re-establish the capillary column which was in- 

 terrupted by the plowing under of the dry topsoil. Unless this 

 is done the moisture from the lower soil can not reach the roots 

 of the plant. Immediate harrowing also prevents considerable 

 loss of moisture from the new topsoil. 



In regions where the greater part of the annual rainfall comes 

 during the winter and where the ground does not freeze to a 

 great depth or remain frozen for a long period, as is the case in 

 a large part of the intermountain area and in the southern part 

 of the Great Plains, it may be undesirable to level and firm im- 

 mediately after plowing, as is indicated for the middle and north- 

 ern Great Plains region. This applies only to fall-plowed land. 

 The reason for this is obvious, as both these operations may work 

 against the conservation of the winter precipitation by preventing 

 penetration and promoting run-off. Rough plowed land under 

 the conditions described holds a large portion of the moisture due 

 to rain or melted snow and gives it an opportunity to soak in 

 after each thaw. Spring-plowed fields in the intermountain area 

 and southern Great Plains should be given the treatment previ- 

 ously indicated for similar fields in the colder portions of the 

 Great Plains. 



A promising method of securing the desired seed bed, developed 

 by Dr. W. J. Workman, of Ashland, Kan., has been found to 

 give satisfactory results on buffalo-grass sod. The principal diffi- 

 culty in the growing of alfalfa in cultivated rows for seed is the 

 weediness of the ground during the first season after seeding. This 

 is avoided by the utilization of sod land. A 16-inch sod plow is 



