PELLET SEEDING OX WESTERN RAXGELAXDS 9 



bounce and do not penetrate the soil, even on loose, freshly plowed 

 soil (Hull, 1959). 



Coated pellets absorb water readily. The clay pellet coating 

 disintegrates immediately on wetting, but the plastic-feldspar coating 

 remains intact. After 50 drops of water were dropped on feldspar 

 pellets there was no sign of breakdown (Hull, 1959). Alternate 

 wetting and drying in the field cause the plastic-feldspar pellets to 

 swell and split open on the upper surface and then gradually disin- 

 tegrate. During this period the encased seeds are held off the ground 

 surface by the layer of pelleting material. The seeds in coated seed 

 pellets, like those in compressed earthen pellets, are more susceptible 

 to drying than nonpelleted seeds lying on the ground surface. 6 



Extruded Seed Pellets 



Extruded seed pellets have been studied only in the laboratory and 

 in one greenhouse test, hence are but briefly mentioned. 



Manufacture and composition 



In the manufacture of extruded pellets a hard paste-like seed-and- 

 soil mixture is forced under great pressure through round openings. 

 The brittle extruded cylinders are broken up to form short cylindrical 

 pellets. 



Effects of pelleting 



Tisdale and Piatt (1951) reported an average of 7.6 seeds of crested 

 wheatgrass per extruded pellet, of which 41 percent were broken. 

 Germination of seed in extruded pellets was 10.5 percent in the labora- 

 tory and emergence was 11 percent in the greenhouse. 



General Characteristics of Pellets 



Pellets do not bury themselves in normal range soil nor does the 

 pelleting material provide seed covering (Wagner. 1949: Hull. L959 

 Except for the rare occasions when natural covering is provided by 

 loose soil, deep ashes, or leaf fall, pelleted seeds that germinate do >o 

 on the soil surface. As often happens when nonpelleted seed is sown 

 broadcast, seedlings from pellets are poorly rooted, and the part o\ the 

 plant that should develop into a root crown is above ground. 



Troughton (1957) cites the work of several investigators who 

 have shown that development of a nodal root system is necessary 

 for establishment and survival of perennial grass plants. This nodal 



6 Unpublished data from the Intermoiintain Forest and Range Experin 

 Station. Ogden, Utah. 



