The Soils and Their Nutrients 231 



as a result of more precipitation. Whenever soil solution was sampled im- 

 mediately following precipitation, large increases in nutrient concentra- 

 tions were observed, suggesting that leaching of aboveground plant ma- 

 terials may be a major factor in nutrient transport. 



Of the major cations, only potassium occurs to a significant extent 

 in a mineral form in soils. The clay mineral illite, which contains fixed 

 potassium, is the dominant mineral in the clay fraction of the soils of the 

 Barrow tundra (Douglas and Tedrow 1960). However, the bulk of the 

 available potassium and almost all of the other metallic cations are 

 bound on the exchange complex and are supplied from it to the soil 

 solution. 



Nitrogen and Phosphorus 



The distribution of nitrogen and phosphorus is similar in that these 

 elements are found mainly in the organic form in soil. The pools of nitro- 

 gen and phosphorus of the moist meadows were calculated for the upper 

 10 cm of the soil (Table 7-3), since this portion is relatively homogeneous 

 and includes more than 15% of the Hve root biomass (Dennis et al. 1978) 

 and microbial biomass (Chapter 8). A total of 432 g N m"^ was found in 



TABLE 7-3 Pools of Nitrogen and Phosphorus 



(g m'^ 10 cm'^) in the Upper 10 cm of 

 Soil in Moist Meadow 



'Nitrogen and phosphorus in fungi (Laursen 1975). 



