ISSN:
1432-0789
Keywords:
Carbon-dioxide production
;
Climatic factors
;
Microbial biomass
;
Microbial nitrogen
;
Mineral N flush
;
Nitrogen mineralisation
;
Pasture production
;
Seasonal changes
;
Water-soluble carbon
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary A 2-year study (1983–1984 to 1984–1985) was conducted to estimate temporal and seasonal changes and the effects of fertiliser on some soil chemical, biochemical and microbiological characteristics. The soil used was a Typic Vitrandept under grazed pasture. Soil samples were taken regularly to a depth of 75 mm from paired unfertilised and fertilised (500 kg ha− 30% potassic superphosphate) plots. Except for organic C, fertiliser had little or no effect on the characteristics measured. Organic C averaged about 9.2% in unfertilised soil and was about 0.3% higher in the fertilised soil. The size of the microbial biomass fluctuated widely in the 1st year (3000 μg C g−1 in February to 1300 μg C g−1 in September) but there was less variation in the 2nd year (range 1900 μg C g−1 to 2500 μg C g−1 soil). CO2 production values (10- to 20-day estimates averaged 600 μg of CO2-C g−1 soil) were generally higher in spring compared to the rest of the year. Water extractable C increased over winter and declined through spring in both years (range 50 μg C g−1 soil to 150 μg C g−1 soil). Mineral-N flush values were higher in summer (300 μg N g−1 soil) and lower in winter months (200 μg N g−1 soil). The pattern of variation of microbial N values was one of gradual accumulation followed by rapid decline. This rapid decline in values occurred in spring and autumn (range 130–220 μg N g−1 soil). N mineralisation and bicarbonate-extractable N showed no clear trend; these values ranged from 100–200 and 122–190 μg N g−1 soil, respectively. There was a significant correlation (0.1%) between N mineralisation and bicarbonate-extractable N in the late summer-autumn-early winter period (February–August) in both years but not in spring. These results and their relationships to climatic factors and rates of pasture production are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00261022
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