veloped on mica schist parent ma- 

 terials were capable of releasing over 

 twice as much potash as the soils 

 developed on granitic till, 495 lbs. 

 potassium as against 220 lbs. potas- 

 sium for the combined A and B hori- 

 zons. 



The soils developed on mica schist 

 till also had more readily available 

 exchangeable potash than did the 

 granitic soils. The granitic group of 

 soils, Gloucester and Essex, had an 

 average content of 55 pounds of ex- 

 changeable potassium while the mica 

 schist group, Paxton and Charlton, 

 had 75 pounds of exchangeable po- 

 tassium. In neither case would the 

 quantity of potassium be regarded 

 a"? adequate for good growth. 



The study further indicated that 

 when large amounts of potash fer- 



tilizers are added to a soil in long- 

 time potato fertilization, considerable 

 quantities of the potash accumulate 

 as the exchangeable form and as a 

 relatively insoluble reserve supply. 

 For example, one potato-soil which 

 had been fertilized annually for 15 

 years contained 664 pounds of ex- 

 changeable potassium and 1,133 

 pounds of reserve supply potassium. 

 A sample taken nearby in adjacent 

 woodland contained only 114 pounds 

 of exchangeable potassium and 463 

 pounds of reserve supply potassium. 

 Thus there was an apparent net accu- 

 mulation of 1,222 pounds of potas- 

 sium in these two forms. 



L. T. Kardos 

 P. T. Blood 

 R. Feuer 



Weed Control 



Japanese-Bamboo Can Be Controlled 

 With the New Brush-Killer Herbicides 



Japanese-bamboo or Japanese 

 Knotweed is one of our most trouble- 

 some weeds around houses and build- 

 ings and it has been one of the hard- 

 est to control. Experiments carried 

 out during the past two years demon- 

 strate that three applications of equal 

 mixtures of 2,4-D and 2,4,5-T, known 

 a& brush killers, will destroy most of 

 the root systems as well as shoots. 

 The same concentration recommended 

 for foliage treatment of woody plants 

 was used or Ji/o parts of 2,4-D and 

 lli/o parts of 2,4,5-T per 1000 parts 

 of water. The first application was 

 made in early summer followed by a 

 second application immediately after 

 new growth had occurred. The third 

 treatment was made the following 

 spring. A few scattered and much 

 weakened shoots still sprouted which 

 have had to be treated individually to 

 prevent any revival of the weed. 



A. R. HODGDON 



Recent Developments in 

 Quackgrass Control With TCA 



During the past two years our ex- 

 periments have been directed to find- 

 ing out the most suitable concentra- 

 tions and conditions for application 

 of TCA. Without exception we have 

 obtained the most satisfactory con- 

 trols at low concentrations with the 

 midsummer applications. This was 

 noted in 1949 and again more strik- 

 ingly in 1950. These were both very 

 dry and hot summers, particularly 

 in late July when the most effective 

 treatments were made. In midsum- 

 mer, provided the weather is hot and 

 dry, Quackgrass can be killed com- 

 pletely by applications of no more 

 than fifty pounds of 90 percent So- 

 dium TCA per acre. We recommend 

 also cutting the grass before appli- 

 cations of the chemical. Probably 

 considerably lighter applications 

 would be effective if followed in a 

 week or ten days by harrowing or 

 plowing of the treated area to dis- 

 turb the grass-rhizomes. 



A. R. HoDGDON 



38 



