ISSN:
0931-1890
Keywords:
Key words K
;
P
;
Pseudotsuga menziesii
;
Root/shoot ratio
;
Soil acidification
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract In a pot trial growth and transpiration of 3-year-old Douglas-fir seedlings on an acid, sandy soil was examined at a deficient (30 kg N ha – 1 year – 1) and an excessive level (120 kg N ha – 1 year – 1) of NH4 application. Dissolved ammonium sulphate was applied to the pots weekly for two growing seasons. In half of the pots a complete set of other nutrients was applied in optimal proportions to the applied nitrogen. Water supply was optimal and transpiration was recorded. At the end of the second treatment season irrigation was stopped for 2 weeks during dry and sunny weather. Both high application of NH4 and additional nutrients increased shoot growth and transpiration demand in the first treatment year. The root system was smaller at higher N level and this reduced water uptake accordingly. In the second year the combination of high NH4 + and additional nutrients affected root functioning predominantly due to salinity effects and this seriously decreased water uptake capacity and shoot water potentials, finally resulting in tree death. Without addition of other nutrients the high NH4 + application resulted in a high degree of soil acidification, which damaged the roots, that showed a decrease in water uptake capacity. At the low NH4 supply level soil acidification was lower, and root functioning was not affected, and the trees recovered quickly from the imposed drought. Higher needle K and P status depressed transpiration rates at the low NH4 application rate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004680050037
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