Mobility and persistence of three sulfonylurea herbicides in alkaline cropping soils of south-eastern Australia

1999 ◽  
Vol 39 (4) ◽  
pp. 465 ◽  
Author(s):  
I. D. Black ◽  
R. N. Pederson ◽  
A. Flynn ◽  
M. Moerkerk ◽  
C. B. Dyson ◽  
...  
Keyword(s):  
Field Trials ◽  
Biologically Active ◽  
Alkaline Soil ◽  
Sampling Depth ◽  
Metsulfuron Methyl ◽  
South Eastern ◽  
Eastern Australia ◽  
Sampling Zone ◽  
Low Levels ◽  
South Eastern Australia

Biologically active residues of the herbicides metsulfuron-methyl, chlorsulfuron and triasulfuron were estimated with field pea bioassays in soil samples to 80 cm depth from 4 field trials in south-eastern Australia situated on neutral to highly alkaline soil. Residues were both mobile and persistent at low levels. Leaching occurred beyond the lowest sampling depth during the winter–spring growing season. Metsulfuron-methyl was the most mobile of the 3 herbicides. Plant-back experiments involving susceptible crop and pasture species on 2 of the sites showed that the rates of decline of these residues in the sampling zone were slower than might be inferred from label plant-back recommendations in 1 of 2 seasons.

Crop damage caused by residual acetolactate synthase herbicides in the soils of south-eastern Australia

2006 ◽  
Vol 46 (10) ◽  
pp. 1323 ◽  
Author(s):  
K. L. Hollaway ◽  
R. S. Kookana ◽  
D. M. Noy ◽  
J. G. Smith ◽  
N. Wilhelm
Keyword(s):  
Acetolactate Synthase ◽  
Clay Soils ◽  
Alkaline Soil ◽  
Alkaline Soils ◽  
Metsulfuron Methyl ◽  
Herbicide Residues ◽  
South Eastern ◽  
Eastern Australia ◽  
The Impact ◽  
South Eastern Australia

Grain growers in south-eastern Australia have reported unexpected crop failures with theoretically safe recropping periods for acetolactate synthase herbicides in alkaline soils. This experience has led to the concern that these herbicides may degrade very slowly in alkaline soils, and herbicide residues have at times been blamed for unexplained crop losses. To address this issue, we established 5 recropping trials across Victoria and South Australia with 5 acetolactate synthase herbicides (chlorsulfuron, triasulfuron, metsulfuron-methyl, imazethapyr, and flumetsulam). The herbicides were applied to separate plots in years 1, 2 or 3, and sensitive crop species were sown in year 4 to measure the impact of herbicide residues. We observed that the persistence of the sulfonylureas (chlorsulfuron, triasulfuron, metsulfuron-methyl) varied between herbicides, but all persisted longer in alkaline soils than in acid soils, and were, therefore, more likely to damage crops in alkaline soil. Imazethapyr persisted longer in clay soils than in sandy soils and was, therefore, more likely to damage crops in clay soils. All herbicides persisted longer when rainfall was below average. Canola was more sensitive to imazethapyr than either pea, lentil or medic, but was less sensitive to the sulfonylureas. In contrast, lentil and medic were the most sensitive to sulfonylureas. Despite some damage, we found that safe recropping periods could be predicted from the product labels in all but one situation. The sole exception was that metsulfuron-methyl reduced dry matter and yield of lentil and medic sown 10 months after application in a soil with pH 8.5. We hypothesise that the real cause of crop failure in many situations is not unusual herbicide persistence, but failure to take full account of soil type (pH and clay content including variation in the paddock) and rainfall when deciding to recrop after using acetolactate synthase herbicides.

Persistence and leaching of sulfonylurea herbicides over a 4-year period in the highly alkaline soils of south-eastern Australia

2006 ◽  
Vol 46 (8) ◽  
pp. 1069 ◽  
Author(s):  
K. L. Hollaway ◽  
R. S. Kookana ◽  
D. M. Noy ◽  
J. G. Smith ◽  
N. Wilhelm
Keyword(s):  
Crop Damage ◽  
Sulfonylurea Herbicides ◽  
Alkaline Soils ◽  
Metsulfuron Methyl ◽  
South Eastern ◽  
Eastern Australia ◽  
Current Product ◽  
Potential Damage ◽  
Ph Range ◽  
South Eastern Australia

The sulfonylurea herbicides are commonly used in the cereal belt of south-eastern Australia and there is concern that their persistence in alkaline soils is long enough to damage subsequent rotational crops such as legumes and oilseeds. In this study, we investigated leaching and persistence of 3 commonly used herbicides (chlorsulfuron, triasulfuron and metsulfuron-methyl) in alkaline soils of south-eastern Australia (pH range 7.4–8.6) for at least 4 years after treatment. In general, chlorsulfuron was predicted to persist for 3–5 years [time to degrade to 1% (DT99) of 33–63 months after treatment depending on the field site], triasulfuron for 1–3 years (DT99 of 13–37 months after treatment), and metsulfuron-methyl for less than 1 year (although data were insufficient for degradation estimates) after its application. However, this varied between sites and years of application. Although, the majority of residues remained in the top 20 cm of the soil profile throughout the study, leaching of a small fraction of the residue to deeper layers of the profiles (up to 1 m) was observed. Despite their slow rate of degradation, the herbicides did eventually dissipate, even in soils with very high pH (8.5). In most cases, the current product labels provide an adequate safety period to protect sensitive rotational crops from potential damage due to excessive persistence. However, in particular years at 3 of the 5 field sites, metsulfuron-methyl and triasulfuron persisted beyond the recommended recropping period (9 months for metsulfuron-methyl and 22 months for triasulfuron in soils up to pH 7.5 or 24 months in soils pH 7.6 and above). An accurate measurement of soil pH and its variability within the paddock is essential to minimise any subsequent crop damage by these herbicides.

Wheat roots proliferate in response to nitrogen and phosphorus fertilisers in Sodosol and Vertosol soils of south-eastern Australia

Soil Research ◽  
2009 ◽  
Vol 47 (1) ◽  
pp. 91 ◽  
Author(s):  
S. J. Officer ◽  
V. M. Dunbabin ◽  
R. D. Armstrong ◽  
R. M. Norton ◽  
G. A. Kearney
Keyword(s):  
Root Growth ◽  
Root Length ◽  
Fine Roots ◽  
Root Diameter ◽  
Soil Types ◽  
Alkaline Soil ◽  
South Eastern ◽  
Eastern Australia ◽  
Root Responses ◽  
South Eastern Australia

Root growth responses to separately placed of bands of N and P fertiliser were examined at the 3-leaf (GS13) and stem extension growth stages (GS30) for wheat (Triticum aestivum L. cv. Yitpi) growing in 2 major alkaline soil types from the rainfed (375–420 mm) grain production regions of south-eastern Australia. Intact cores of a Sodosol and a Vertosol were destructively sampled and changes in root length density (RLD) and root diameter distribution within the soil profile were examined using restricted maximum likelihood analysis and principal component analysis, respectively. At GS13, RLD increased in the Vertosol when only P was applied, although there was no shoot growth response. The root response to P consisted of a spatially generalised increase in RLD, rather than a specific increase in the vicinity of the P fertiliser band. There was a substantially greater, but still generalised, increase in RLD in the Vertosol when both N and P fertiliser were applied, although there was no response to N fertiliser (without P). The distribution of root length in diameter classes changed with depth in the profile at GS13 but was otherwise similar, regardless of soil types and fertiliser treatment. The root responses to fertiliser at GS30 also consisted of a generalised proliferation of RLD in the topsoil, with no detectable fertiliser-specific changes in the location or structure of the root system. Shoot and root growth increased to a similar level at GS30 when plants were supplied with N, irrespective of P, and root diameter distributions were again insensitive to fertiliser treatment. Plants responded to N by increasing the RLD of relatively fine roots (100–250 μm), which was a P style of acquisition strategy that was possibly triggered by moisture limitations. Consequently, the root responses to fertiliser under realistic semi-arid conditions did not follow expectations based on nutrient acquisition studies. Instead, wheat plants responded to N or P fertiliser with a generalised proliferation of fine roots, apparently to better compete for finite water and nutrients.

Population ecology of the velvet gecko,Oedura lesueuriiin south eastern Australia: Implications for the persistence of an endangered snake

2008 ◽  
Vol 33 (7) ◽  
pp. 839-847 ◽  
Author(s):  
JONATHAN K. WEBB ◽  
DAVID A. PIKE ◽  
RICHARD SHINE
Keyword(s):  
Population Ecology ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

Combining management and breeding advances to improve field pea (Pisum sativum L.) grain yields under changing climatic conditions in south-eastern Australia

Euphytica ◽  
2011 ◽  
Vol 180 (1) ◽  
pp. 69-88 ◽  
Author(s):  
L. S. McMurray ◽  
J. A. Davidson ◽  
M. D. Lines ◽  
A. Leonforte ◽  
M. U. Salam
Keyword(s):  
Pisum Sativum ◽  
Climatic Conditions ◽  
Field Pea ◽  
Grain Yields ◽  
South Eastern ◽  
Pisum Sativum L ◽  
Eastern Australia ◽  
South Eastern Australia
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