Cyanobacterial inoculation of heated soils: effect on microorganisms of C and N cycles and on chemical composition in soil surface
Citation
N Diz-Cid, M J Acea, and A Prieto-Fernandez, Cyanobacterial inoculation of heated soils: effect on microorganisms of C and N cycles and on chemical composition in soil surface: .
Summary
Physiological groups of soil microorganisms, total C and N and available nutrients were investigated in four heated (350 °C, 1 h) soils (one Ortic Podsol over sandstone and three Humic Cambisol over granite, schist or limestone) inoculated (1.5 μg chlorophyll a g−1 soil or 3.0 μg chlorophyll a g−1 soil) with four cyanobacterial strains of the genus Oscillatoria, Nostoc or Scytonema and a mixture of them. Cyanobacterial inoculation promoted the formation of microbiotic crusts which contained a relatively high number of NH4+-producers (7.4×109 g−1 crust), starch-mineralizing microbes (1.7×108 g−1 crust), cellulose-mineralizing microbes (1.4×106 g−1 crust) and NO2− and NO3− producers (6.9×104 and 7.3×103 [...]
Summary
Physiological groups of soil microorganisms, total C and N and available
nutrients were investigated in four heated (350 °C, 1 h)
soils (one Ortic Podsol over sandstone and three Humic Cambisol over
granite, schist or limestone) inoculated (1.5 μg
chlorophyll a g−1 soil or 3.0 μg
chlorophyll a g−1 soil) with four cyanobacterial
strains of the genus Oscillatoria, Nostoc or Scytonema and a mixture of
them. Cyanobacterial inoculation promoted the formation of microbiotic
crusts which contained a relatively high number of NH4+-producers
(7.4×109 g−1 crust),
starch-mineralizing microbes (1.7×108
g−1 crust), cellulose-mineralizing microbes
(1.4×106 g−1 crust) and
NO2− and NO3− producers
(6.9×104 and 7.3×103 g−1
crust, respectively). These crusts showed a wide range of C and N
contents with an average of 293 g C kg−1 crust and 50
g N kg−1 crust, respectively. In general, Ca was the
most abundant available nutrient (804 mg kg−1 crust),
followed by Mg (269 mg kg−1 crust), K (173 mg
kg−1 crust), Na (164 mg kg−1
crust) and P (129 mg kg−1 crust). There were close
positive correlations among all the biotic and abiotic components of the
crusts. Biofertilization with cyanobacteria induced great microbial
proliferation as well as high increases in organic matter and nutrients
in the surface of the heated soils. In general, cellulolytics were
increased by four logarithmic units, amylolytics and ammonifiers by
three logarithmic units and nitrifiers by more than two logarithmic
units. C and N contents rose an average of 275 g C
kg−1 soil and 50 g N kg−1 soil
while the C:N ratio decreased up to 7 units. Among the available
nutrients the highest increase was for Ca (315 mg
kg−1 soil) followed by Mg (189 mg
kg−1 soil), K (111 mg kg−1 soil),
Na (109 mg kg−1 soil) and P (89 mg
kg−1 soil). Fluctuations of the microbial groups as
well as those of organic matter and nutrients were positively
correlated. The efficacy of inoculation depended on both the type of
soil and the class of inoculum. The best treatment was the mixture of
the four strains and, whatever the inoculum used, the soil over lime
showed the most developed crust followed by the soils over schist,
granite and sandstone. In the medium term there were not significant
differences between the two inocula amounts tested. These results showed
that inoculation of burned soils with alien N2-fixing cyanobacteria may
be a biotechnological means of promoting microbiotic crust formation,
enhancing C and N cycling microorganisms and increasing organic matter
and nutrient contents in heated soils. Published in Soil Biology and
Biochemistry, volume 35, issue 4, on pages 513 - 524, in 2003.
