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phosphorous management

Catalogue: GRDC Updates
The structure of roots is a consequence of their primary functions- growing through an abrasive medium (the soil), acting as plumbing to absorb and transport water to the shoot, and actively and selectively absorbing essential nutrients such as mineral N (nitrate and ammonium), inorganic P and K. the structure of leaves is designed to absorb radiation for photosynthesis, regulate evaporative losses of water, act as a sink for nutrients and water transported from the root system, and produce carbohydrates from photosynthesis... The root surface comprises a layer of epidermal ('skin') cells (some with extensions or 'root hairs') that absorb water through their cell walls and cell membranes and which have specific sites where nutrient forms such as nitrate, ammonium, phosphate and potassium are bound onto 'carrier' molecules and transported across the cell membrane into the interior of the cell... Any so-called microbial activators or mineral-solubilising microorganisms are operating in a hostile environment full of competitors...
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Catalogue: GRDC Updates
One proposal is that supplying a concentrated source of P allows the root system to forage more widely and exploit a greater volume of soil, and a greater amount of P may be available to generate biomass, and ultimately yield... Observing real root behaviour, examining root length, density and proliferation and converting that to C allocated allows us to understand whether we can use both our applied P investments more effectively, and create root architecture that is more profitable... We are currently using micro-CT scanning to monitor cereal root behaviour in response to patches of P. These techniques involve growing cereals in small columns that are able to be easily scanned, and reconstructing the root systems of these cereals in 3D to allow root responses to be observed as they develop...
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Catalogue: GRDC Updates
Since the soil P tests that growers and advisors use for their fertiliser decisions were calibrated using conventional tillage and narrow row spacing's, we are investigating the effect of increasing row spacing, and increased concentrations of P in the seeding furrow, on P fertiliser responses... The Temora trial was dry sown and received rain shortly after sowing whereas the Condobolin trial was sown into good moisture, but in both cases establishment percentage declined as seeds were sown more closely together, whether from increasing seeding rate or widening row spacing... A row spacing by phosphorus trial from 2008 was re-sown in 2009, using 2 cm auto steer so that treatments of on-row and inter-row seeding were superimposed at rates of 0, 4 or 8 kg/ha of phosphorus, using the same row spacing for each plot as used in 2008...
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Catalogue: GRDC Updates
The trial consisted of a comparison between 2 wheat and 2 barley varieties, grown either at 15 or 30 cm row spacing's with 4 rates of either granular MAP or liquid P fertiliser - in this case ammoniated phosphoric acid (Easy NP )... Trials were sown to Crusader wheat, at 30 and 40 cm row spacing with 6 rates of P as granular MAP or ammoniated phosphoric acid (Easy NP )... Liquid vs. granular fertilisers Trials conducted by NSW DPI and Incitec-Pivot Ltd in 2004 under high yield potential on the Liverpool Plains compared wheat responses between liquid starter fertilisers (Easy NP and DAP-H2SO4) and granular products (DAP and MAP)...
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Catalogue: GRDC Updates
Current research on row spacing widths has not been conclusive in the higher rainfall zones throughout SE Australia, especially now with recent acquisitions of RTK guidance systems and farmers aiming to achieve inter-row seeding, lessening the need to manipulate crop residues post harvest and prior to seeding operations for the new season program... Yield variance under alternate row spacing, nitrogen and variety treatments In 2007, a completely randomised block design field trial with four replicates was undertaken at the Southern Farming Systems Mininera research site to evaluate the yield variance across two row spacings (200mm & 300mm), three wheat maturities (Kellalac (L), Bolac (ML) & Beaufort (M)) and two nitrogen timings (GS00 & GS31)... A typical farmer input scenario may see Kellalac sown at 200mm row spacings widths, with nitrogen applied at GS31, yielding 4.64t/ha, but when compared to Beaufort sown at 300mm with nitrogen applied up front (GS00), there was an average yield deficit of 0.98t/ha (Table 1.)...
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Catalogue: GRDC Media
The innovative website, www.soilquality.org.au , will enable growers to compare the condition of their soils with that of their regional farming counterparts... The SA node of the interactive website will be launched later this month at a soil quality workshop at Clare where growers, consultants and advisers will gather to put Mid North soils under the microscope... Program (SCaRP) which is managed by CSIRO and funded by GRDC and the Department of Agriculture, Fisheries and Forestry (DAFF), more than 100 SA farm soils (half of which were in the Mid North) have been sampled and analysed for carbon stocks, as well as a range of other chemical, physical and biological indicators of soil health...
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Catalogue: GRDC Updates
The aim of the investigation was to assess the infectivity and the subsequent effect of salinity on mycorrhizal fungal communities in a saline environment... That there was no difference in total mycorrhizal root length between the non-saline and moderately saline treatment at week 15 could also suggest that the mycorrhizas were able to germinate and colonise roots at some salt levels, highlighting a degree of tolerance... The results of the experiment have demonstrated that the mycorrhizal fungi at this field site display low infectivity at high salinity levels but do express a degree of salt tolerance at lower saline levels...
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Catalogue: GRDC Updates
Williams and Lipsett (1961) found that 50-60 years of wheat cultivation in NSW resulted in a loss of 30% of organic C but only 17% organic P. In natural soils the extent of net immobilization of P in organic matter and probably soil organic matter levels may often be set by the P supply in the parent material... Many authors only consider supply to occur by mass flow and diffusion (the interception component in Table 2.2 is combined with the diffusion component)... Plants can access a greater volume of soil through the formation of a mycorrhizal symbiosis...
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Catalogue: GRDC Updates
" Date: 08.10.2009 USING ROTATION CROPS TO IMPROVE SOIL QUALITY.. Soil structural differences are measured with a cone penetrometer which determines the force needed to push a metal probe slowly into the soil to 600 mm depth... We measured the microbial properties using surface soil samples (0-10 cm) from the crop rotation experiment...
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Catalogue: GRDC Updates
Soil factors affecting micronutrient availability... Even though needed in small quantities, Copper (Cu), Manganese (Mn), Iron (Fe), Zinc (Zn), Boron (B) and Molybdenum (Mo) are all essential for plant growth, although the demand is small relative to nitrogen and phosphorus... The discussion aims to review these issues relative to micronutrients...
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