Microbial biomass and microbial biodiversity in some soils from New South Wales, Australia

Soil Research ◽  
2004 ◽  
Vol 42 (7) ◽  
pp. 777 ◽  
Author(s):  
Nargis A. Banu ◽  
Balwant Singh ◽  
Les Copeland

Eight surface soils (0–15 cm) including 1 Ferrosol, 2 Tenosols, 2 Kurosols, 1 Sodosol, 1 Chromosol, and 1 Kandosol were collected from mainly pasture sites in New South Wales. The soils had different physico-chemical properties and there were some differences between the sites in climatic conditions. Soil microbial biomass carbon (MBC) was estimated by the chloroform-fumigation extraction method, and substrate utilisation patterns determined by the Biolog method were used to assess the amount, functional diversity, substrate richness and evenness, and community structure of the microorganisms in these soils. The amount of MBC (585 µg C/g) and the microbial diversity (H´ = 3.24) were high in soils that had high clay (33%), organic C (5.96%), total N (0.45%), free iron (7.06%), moisture content (50%), and cation exchange capacitiy (133.5 mmolc/kg). These soil properties, e.g. soil moisture (r2 = 0.72), organic C (r2 = 0.58), total N (r2 = 0.63), free iron (r2 = 0.44), and EC (r2 = 0.53), were positively correlated with MBC and microbial diversity index, whereas pH and sand and silt content showed negative correlations. The climatic factors (temperature and rainfall) had no significant influence on either MBC or diversity.


1999 ◽  
Vol 79 (1) ◽  
pp. 73-84 ◽  
Author(s):  
C. A. Campbell ◽  
V. O. Biederbeck ◽  
G. Wen ◽  
R. P. Zentner ◽  
J. Schoenau ◽  
...  

Measurements of seasonal changes in soil biochemical attributes can provide valuable information on how crop management and weather variables influence soil quality. We sampled soil from the 0- to 7.5-cm depth of two long-term crop rotations [continuous wheat (Cont W) and both phases of fallow-wheat (F–W)] at Swift Current, Saskatchewan, from early May to mid-October, 11 times in 1995 and 9 times in 1996. The soil is a silt loam, Orthic Brown Chernozem with pH 6.0, in dilute CaCl2. We monitored changes in organic C (OC) and total N (TN), microbial biomass C (MBC), light fraction C and N (LFC and LFN), mineralizable C (Cmin) and N (Nmin), and water-soluble organic C (WSOC). All biochemical attributes, except MBC, showed higher values for Cont W than for F–W, reflecting the historically higher crop residue inputs, less frequent tillage, and drier conditions of Cont W. Based on the seasonal mean values for 1996, we concluded that, after 29 yr, F–W has degraded soil organic C and total N by about 15% compared to Cont W. In the same period it has degraded the labile attributes, except MBC, much more. For example, WSOC is degraded by 22%, Cmin and Nmin by 45% and LFC and LFN by 60–75%. Organic C and TN were constant during the season because one year's C and N inputs are small compared to the total soil C or N. All the labile attributes varied markedly throughout the seasons. We explained most of the seasonal variability in soil biochemical attributes in terms of C and N inputs from crop residues and rhizodeposition, and the influences of soil moisture, precipitation and temperature. Using multiple regression, we related the biochemical attributes to soil moisture and the weather variables, accounting for 20% of the variability in MBC, 27% of that of Nmin, 29% for LFC, 52% for Cmin, and 66% for WSOC. In all cases the biochemical attributes were negatively related to precipitation, soil moisture, temperature and their interactions. We interpreted this to mean that conditions favouring decomposition of organic matter in situ result in decreases in these attributes when they are measured subsequently under laboratory conditions. We concluded that when assessing changes in OC or TN over years, measurements can be made at any time during a year. However, if assessing changes in the labile soil attributes, several measurements should be made during a season or, measurements be made near the same time each year. Key words: Microbial biomass, carbon, nitrogen, mineralization, water-soluble-C, light fraction, weather variables



Soil Research ◽  
2013 ◽  
Vol 51 (8) ◽  
pp. 726 ◽  
Author(s):  
G. D. Schwenke ◽  
M. K. McLeod ◽  
S. R. Murphy ◽  
S. Harden ◽  
A. L. Cowie ◽  
...  

Sown tropical perennial grass pastures may be a means to restore soil organic carbon (C) lost by cropping with conventional tillage to the levels originally present in native grass pastures. To assess this, total organic carbon and related soil properties were measured under sown tropical pastures, conventionally cultivated cropping, and native pastures on 75 Chromosols and 70 Vertosols to 0.3 m depth in the New South Wales North-West Slopes and Plains region of Australia. The impact of several perennial pasture species on soil organic carbon was also assessed in a 6-year-old, sown pasture experiment on a previously cropped Chromosol. Soil cores in 0.1-m segments to 0.3 m were analysed for total organic carbon, total nitrogen (N), pH, and phosphorus (Colwell-P). Mid-infrared scans were used to predict the particulate, humus, and resistant fractions of the total organic carbon. Bulk density was used to calculate stocks of C, N, and C fractions. In Chromosols, total organic carbon in the surface 0–0.1 m was greater under sown tropical pastures (23.1 Mg ha–1) than conventional tillage cropping (17.7 Mg ha–1), but still less than under native pastures (26.3 Mg ha–1). Similar land-use differences were seen for particulate and resistant organic C, and total N. The proportional differences between land uses were much greater for particulate organic C than other measures, and were also significant at 0.1–0.2 and 0.2–0.3 m. Subsurface bulk density (0.1–0.2 m) was lower under sown tropical pastures (1.42 Mg m–3) than conventionally tilled cropping (1.52 Mg m–3). For Vertosols, total organic carbon in the surface 0–0.1 m was greater under sown tropical pastures (19.0 Mg ha–1) and native pastures (20.5 Mg ha–1) than conventional tillage cropping (14.0 Mg ha–1). Similar land-use effects were seen for the particulate and humus organic C fractions, and total N. In the sown pasture species experiment, there was no significant difference in total N, total organic carbon, or any C fraction between soils under a native-grass species mixture, two improved tropical grass species, or a perennial pasture legume. Regular monitoring is required to better discern whether gradual changes are being masked by spatial and temporal variation. The survey results support previous research on Vertosols within the New South Wales North-West Slopes and Plains that show sown tropical grass pastures can improve total organic carbon. Improvements in total organic carbon on Chromosols have not previously been documented, so further targeted soil monitoring and experimentation is warranted for the region.



1987 ◽  
Vol 27 (2) ◽  
pp. 317
Author(s):  
GE Stovold ◽  
A Francis

The pod and stem blight and seed decay fungus Phomopsis phaseoli was detected in soybean crops in coastal districts of New South Wales as a symptomless infection in the lowest petioles at flowering. Up to 90% of petioles from a second year crop yielded the fungus compared with 17% from a first year crop. Similar effects of paddock history were evident during pod fill when 43% of pods from a first year crop were infected compared with 76% in a second year crop. Visible symptoms of infection only appeared after crops reached harvest maturity. Crops in the North West of the state were infected at a much lower level. As in coastal districts the highest levels of infection occurred in fields which had been sown previously to soybeans. Only negligible levels of infection were detected in crops grown in the Riverina district. Only seed from coastal crops carried significant infection with P. phaseoli. The level of infection varied within and between seasons and was determined by prevailing climatic factors, especially atmospheric humidity and rainfall during pod fill and after maturity. Humidity and rainfall are greater for coastal than for inland districts, but prevailing temperatures in coastal and inland districts are only slightly different.



Soil Research ◽  
1998 ◽  
Vol 36 (4) ◽  
pp. 621 ◽  
Author(s):  
N. R. Hulugalle ◽  
P. C. Entwistle ◽  
J. L. Cooper ◽  
S. J. Allen ◽  
D. B. Nehl

Reduced crop growth rates (‘long-fallow disorder’) can be a feature of long-fallow cotton (cotton, alternating with a bare fallow, is sown every other year). This is usually attributed to decreased development of arbuscular mycorrhiza (AM), although associated soil physical, chemical, and biological properties are very rarely reported. A study was conducted from 1993 to 1997 in a grey, self-mulching Vertosol in the central-west of New South Wales to characterise soil properties under long-fallow cotton with a view to identifying soil factors other than AM that could contribute to cotton growth rate reductions. Soil quality indicators monitored were compaction (bulk density and air-filled porosity), strength (cone resistance), plastic limit, exchangeable cations, nitrate-N, pH, organic C, development of AM, and incidence of cotton root diseases. In comparison with continuous cotton, long-fallow cotton had lower soil strength, and lower plastic limit. Exchangeable Ca and Mg were higher with continuous cotton only in 1994. Higher nitrate-N was also observed with long-fallow during the first fallow phase of the experiment. Long-fallow did not have any significant effect on soil organic carbon. However, a net decline in soil organic C and exchangeable Mg occurred with both treatments. During the cotton phase, subsoil nitrate-N and incidence of black root rot were lower with long-fallow cotton. Uptake of nitrogen by continuous cotton may have been reduced by greater severity of black root rot. Vegetative and reproductive growth, water extraction, and cotton lint yields in long-fallow cotton plots were higher than those in continuous cotton plots. AM development was similar with continuous cotton and long-fallow cotton. Compared with long-fallow cotton, the lower lint yield in continuous cotton was thought to be due to the interactive effects of declining nutrient availability, higher soil strength, and greater severity of black root rot causing decreases in nutrient and water uptake.



Soil Research ◽  
2006 ◽  
Vol 44 (5) ◽  
pp. 467 ◽  
Author(s):  
N. R. Hulugalle ◽  
T. B. Weaver ◽  
L. A. Finlay

The residual effects of cotton (Gossypium hirsutum L.) based crop rotations on soil physical and chemical properties were evaluated in 2 irrigated on-farm experiments located at Warren (1999–2001) in the central-west and Merah North (2000–05) in the north-west of New South Wales. The soils in both sites were grey, self-mulching Vertosols. The rotations sown at Warren from 1993 to 1998 were: (1) continuous cotton (cotton sown every year); (2) long-fallow cotton (cotton alternating with a bare fallow); (3) cotton–high input wheat (Tricticum aestivum L.), in which wheat was sown at a rate of 100 kg/ha and fertilised with 180 kg/ha of urea; (4) cotton–low input wheat, in which wheat was sown at a rate of 40 kg/ha and did not receive any N fertiliser; and (5) cotton–green manured field pea (Pisum sativum L.). At Merah North the rotations sown from 1993 to 2000 were: (1) continuous cotton; (2) long-fallow cotton; (3) cotton–green manured faba bean (Vicia faba L.) until 1999 when sorghum was sown during the 1999–2000 growing season; (4) cotton–dolichos (Lablab purpureus L.)–green manured faba bean from 1993 to 1994 followed by cotton–unfertilised wheat in which wheat was sown at a rate of 50–70 kg/ha thereafter; (5) cotton–dolichos; and (6) cotton–fertilised dolichos with P and K removed by cotton replaced as fertiliser. Soil was sampled to a depth of 0.6 m at 0.15-m increments and analysed for pH (in 0.01 m CaCl2), EC1 : 5, ESP, specific volume, nitrate-N, organic C (SOC), plastic limit, and dispersion. Residual effects of rotation history were reflected in subsoil specific volume at both sites, and nitrate-N in the surface 0.3 m and SOC in the 0–0.6 m depth at Warren. In general, higher values of specific volume occurred where cotton–wheat rotations, and in particular, fertilised wheat, had been sown. At Merah North, subsoil specific volume in ex-long-fallow cotton was similar to that in the cotton–wheat rotation. At Warren, ex-continuous cotton had lowest subsoil specific volume, the ex-cotton–high input wheat rotation and ex-long fallow cotton had greater SOC sequestration, and the ex-cotton–high input wheat rotation had higher nitrate-N. These differences mirrored those present when the rotation treatments were in place. Residual effects of crop rotations are more likely to occur where the residues of the rotation crops are relatively recalcitrant or where cropping intensity is lower.



1970 ◽  
Vol 25 (1) ◽  
pp. 21-25
Author(s):  
SM Abdur Rahman ◽  
ARM Solaiman

Microbial biomass carbon (C) and nitrogen (N) and their contribution to soil organic carbon and total N contents were assessed in soils collected from Bilashchara Tea Estate under Bangladesh Tea Research Institute (BTRI), Srimangal of Moulavibazar district, and Sripur Tea Garden under Jaintapur of Sylhet district. Microbial biomass C and N in Bila shchara Tea Estate soils varied from 90.4-144.0 and 20.5-29.0 mg/kg soil, and that of Sripur Tea Garden soils varied from 120.7-362.0 and 26.6-59.5 mg/kg soil, respectively. Within the two tea growing areas biomass C/N ratios ranged from 3.35-6.12. Relationships between biomass C and organic carbon and biomass N and total N were positively correlated. The contribution of biomass C to soil organic C was 1.23%, ranging from 0.9-1.55% and the contribution of biomass N to total N content of the soils ranged from 1.19-2.89%. Keywords: Biomass carbon (C); Biomass nitrogen (N); Organic C; Total N; Tea soilDOI: http://dx.doi.org/10.3329/bjm.v25i1.4850 Bangladesh J Microbiol, Volume 25, Number 1, June 2008, pp 21-25



1964 ◽  
Vol 15 (4) ◽  
pp. 586 ◽  
Author(s):  
GJ Snowball ◽  
RG Lukins

The paper describes fruit sampling carried out in eastern Australia during January 1960–March 1962 to assess the status of parasites of the oriental fruit fly (Dacus dorsalis) liberated in Australia during 1956–1959 against the Queensland fruit fly (Strumeta tryoni). Opius oophilus was the only introduced parasite extant on the mainland in 1962, parasitizing up to 78% of the host fly stages in Averrhoa carambola in north Queensland and 0–35% in other fruit types. O. oophilus was well established in north Queensland at five localities near Cairns and two near Innisfail, and less well established at three localities near the Queensland–New South Wales border. It had died out during 1960 from two localities further south in New South Wales in which it had been well established since late 1958. O. oophilus was present on Lord Howe Island from October 1959 to March 1961 but died out subsequently. O. longicaudatus was extant in low numbers on the island in 1962. Under Australian conditions Opius oophilus mated satisfactorily. The parasite was able to utilize as hosts fruit flies of the following species: Strumeta barringtoniae, S. cacuminata, S. humeralis, S. tryoni, and possibly Afrodacus jarvisi and S. kraussi, but preferences could not be measured with available techniques. Although it was reared from a total of 14 types of fruits, O. oophilus displayed marked discrimination between fruits, but the preferences varied with season and locality. The most consistent preference was for Averrhoa carambola in north Queensland. O. oophilus showed no preference for operating in the more highly infested fruits of any of the six fruit types tested. The maximum dispersal recorded of a population of O. oophilus from a liberation site was 5 miles, 46 months after establishment. A review of climatic factors indicated that winter temperatures of 60°F or less were unfavourable to the persistence of O. oophilus. The presence of O. oophilus was not associated with a reduction in the degree of infestation of fruits. It is suggested that this is contributed to in the north, where climatic conditions for the parasites are favourable, ,by the presence of abundant fruits which are infested by Dacinae but not favoured by the parasite.



2007 ◽  
Vol 47 (11) ◽  
pp. 1377 ◽  
Author(s):  
K. Y. Chan ◽  
C. Dorahy ◽  
S. Tyler

About 0.3 million t/year of composted garden organics (CGO) including mulches and soil conditioners are produced annually in New South Wales, Australia, although only a small proportion of this material (<4%) is used in agriculture. A lack of information on product characteristics and agronomic performance has limited the development of agricultural markets for CGO products. These CGO products are the coarse and fine fractions separated by screening after composting. This paper presents the results of a survey of CGO mulches and soil conditioners (unblended or blended with a mixture of other organic materials including biosolids, animal manures and paper), which are commercially produced in the metropolitan areas of New South Wales and assesses their agronomic and soil amendment values in terms of chemical and biological properties. It also evaluates the short-term effects of applying increasing rates (0, 25, 50 and 100 t/ha) of selected composted soil conditioners on radish growth in a pot experiment. The mulch products had low nutrient concentrations but had high carbon (C) contents (mean C = 45%) and C/Nitrogen (N) ratios (mean C/N = 72) and are most suitable for use as surface mulch. The unblended soil conditioners were low in nutrients, particularly N (average total N = 1.0%, range 0.9–12%), and had lower and variable C contents. The pot trial results indicated lack of growth response of radish at application rates up to 100 t/ha of unblended soil conditioners from garden organics. The blended soil conditioners were more variable in quality and as confirmed by pot trial results produced highly variable plant responses. The high variability in product quality and performance of the soil conditioners, particularly the blended products might be related to the source and type of blending material as well as the composting conditions used in the manufacturing process. These results highlight the need to improve compost quality and consistency and the need for further research to advance understanding of the benefits using CGO in terms of improving soil quality, crop productivity and net economic returns to growers.





2009 ◽  
Author(s):  
F. Von Mueller


Sign in / Sign up

Export Citation Format

Share Document