• Cu increased with Zn added to superphosphate.  
• Zn depressed yield when no  Cu was applied
• Higher the Zn rate the greater the depression at nil Cu..
• Combination of Cu sulfate (2.75 kg Cu sulfate) and 0.8 kg Zn oxide required for maximum yields.
• Plain superphosphate (PS) gave greater yield than aerophos+gypsum (AG).
• PS grester than AG indicates Zn is reqired for oats and a clover ley.
• .

• Cu increased with Zn added to superphosphate.  
• Zn depressed yield when no  Cu was applied
• Higher the Zn rate the greater the depression at nil Cu..
• Combination of Cu sulfate (2.75 kg Cu sulfate) and 0.8 kg Zn oxide required for maximum yields.
• Plain superphosphate (PS) gave greater yield than aerophos+gypsum (AG).
• PS grester than AG indicates Zn is reqired for oats and a clover ley.
• .

• Cu increased with Zn or without Zn added to superphosphate.  
• Zn depressed yield when no  Cu or where 2.75 kg Cu sulfate /ha was applied
• Higher the Zn rate the greater the depression at nil Cu..
• At 5.5 & 8.25 kg Cu sulfate /ha, 1.6 & 3.3 kg Zn oxide depressed grain yield 
• Combination of Cu sulfate (2.75 kg Cu sulfate) and nil Zn oxide or 5,5 kg Cusulfate and 0.8 KgZno /ha required for maximum yields.Comments combinations are not significantly different
• Plain superphosphate (PS) gave greater yield than aerophos+gypsum (AG).
• PS grester than AG indicates Zn is reqired for oats and a clover ley.
• .

• Zn application gave varying results in grain yield
• Cu increased with Zn or without Zn added to superphosphate.  
• Combination of Cu sulfate (8.25 kg Cu sulfate) and nil  KgZnO  /ha  gave for maximum yield.
• Plain superphosphate yield same as  Aerophos +gypsum.

• Cu increased with Zn or without Zn added to superphosphate.  
• All Zn depressed yield when no  Cu had been applied.
• Combination of Cu sulfate (2.75 kg Cu sulfate) and nil  KgZno /ha required for maximum yields.
• .Best combination of the soil type for both 1967 & 1967 Cu Sulfate at 2.75  and nil  ZnO/ha.
• Plain superphosphateyield higher than Aerophos +gypsum suggested  Zn soil is marginal and Zn addition recommended for Oats and Clover.

• Cu increased with Zn or without Zn added to superphosphate.  
• All Zn levels may have aslight depression on yield with nil Cu 2.75 & 5.5 Cu levels, particularly 3.3 kg /ha of ZnO application.
• Combination of Cu Sul at 5.5 kg/ha and nil  kg/ha ZnO or 8.25 kg Cu/ha& 1.6 kg/ha ZnO was required for maximum yield.
• Plain superphosphate out yielded  Aerophos +gypsum suggested  Zn soil was inadequat for oats and or clover.

• Cu increased  graiin yield with  all Zn.
• No depression of 3.3 kg ZnO on grain yield across Cu levels
• Concluded that Cu sulfate at 2.75 kg/ha and ZnO @ 0.8 kg /ha .
• Plainsuperphosphate gave higher yield than aerophos + gypsum Zn addition required for grain yield of oats and also clover growth..

• Cu increased  graiin yield with  all Zn.
• No depression of 3.3 kg ZnO on grain yield across Cu levels
• Concluded that Cu sulfate at 2.75 kg/ha and ZnO @ 0.8 kg /ha .
• Plainsuperphosphate gave higher yield than aerophos + gypsum Zn addition required for grain yield of oats and also clover growth..

• Neither Cu or Zn increased grain yield.  Nil Cu & Nil Zn near maximum grain yield.
• Zinc oxide at 3.3 kg/ha did reduced yield of wheat with Cu.
• Cu application gave  no yield increase or decrease without Zn applied.
• Combination of 2.75 kg Cu sulfate and 0.8 kg Zn oxide suggested as best combination although not different from the Nil treatments.
• Plainsuperphosphate and aerophos+gypsum gave maximum yield.
• .

• Neither Cu or Zn increased grain yield.  Nil Cu & Nil Zn near maximum grain yield.
• Zinc oxide at 3.3 kg/ha did reduced yield of wheat with Cu.
• Cu application gave  no yield increase or decrease without Zn applied.
• No combination of Cu sulfate and kg Zn oxide suggested as a best combination.
• Plainsuperphosphate and aerophos+gypsum gave maximum yield.
• .

• Neither Cu or Zn increased grain yield
• Zinc did not reduced yield of wheat with Cu nil. Cu application gave  no yield increase without Zn applied.
• Combination of 5.5 kg Cu sulfate and 8.25 kg Cu sulfate depressd yield.
• Plainsuperphosphate and aerophos+gypsum gave maximum yield.
• .

• Cu increased with Zn or without Zn added to superphosphate.  
•  ZnO application had no consistent effect on grain with Cu applied.
• Combination of Cu Sul at 5.5 kg/ha and  nil  ZnO was required for maximum yield.
• Plain superphosphate yielded  the same as Aerophos +gypsum suggested  Zn soil was adequate.

• Cu increased with Zn or without Zn added to superphosphate.  
• All Zn levels depressed yield with nil Cu other levels of ZnO application increased grain with Cu applied.
• Combination of Cu Sul at 5.5 kg/ha and 0.8 kg/ha ZnO was required for maximum yield.
• Plain superphosphate out yielded  Aerophos +gypsum suggested  Zn soil was inadequate.

• Cu increased with or without Zn added to superphosphate.  
• Zinc oxide increased yield of wheat with Cu (2.75 & 5.5  Kg Cu sulfate/ha).
• Combination of Cu sulfate (5.5 kg Cu sulfate) and 0.8 kg Zn oxide required.
• Plain superphosphate gave higher yield than aerophos+gypsum.
• .

• Summary of 2 experimental sites 
• Cu increased with or without Zn added to superphosphate.  
• Zinc oxide increased yield of wheat with Cu (2.75 & 5.5  Kg Cu sulfate/ha).
• Combination of Cu sulfate (5.5 kg Cu sulfate) and 0.8 kg Zn oxide required.
• Plainsuperphosphate gave higher yield than aerophos+gypsum.
• .

• Summary of 2 experimental sites 
• Small additions of Cu or Zn added to superphosphate increased grain yield.  
• Zinc oxide at 3.3 kg/ha did  reduced yield of wheat with Cu (0 & 2.75 Kg Cusulfate/ha).
• Cu application at 8.25 kg Cusulfate without Zn applied decreased grain yield.
• Combination of Cu sulfate (2.75 kg Cu sulfate) and 0.8 kg Zn oxide required.
• Plainsuperphosphate gave higher yield than aerophos+gypsum gave maximum yield.
• .

• Cu increased with Zn or without Zn added to superphosphate.  
• All Zn levels followed no consistent pattern some depressed yield other levels of ZnO application increased.
• Concludedd Zn application not real & Zn had no clear reffect on grain yield.
• Combination of Cu Sul at 2.75 kg/ha and nil ZnO was requyired for maximum yield.
• Plain superphosphate yield was the sane as Aerophos +gypsum suggested  Zn soil was adequate; hence no further Zn was recommended for Oats and Clover.

• Cu increased with Zn or without Zn added to superphosphate.  
• All Zn levels depressed yield with nil Cu 2.75 & 5.5 Cu levels, particularly 3.3 kg /ha of ZnO application.
• Combination of Cu Sul at 5.5 kg/ha and nil  kg/ha ZnO or 2.75 kg Cu/ha nil Zn was required for maximum yield.
• Plain superphosphate out yielded  Aerophos +gypsum suggested  Zn soil was inadequat for oats and or clover.

For results please see the attached trial report.

Applying gypsum can reduce soil pH and lower the concentration of dissolved organic carbon (C) to 30 cm depth within a year. Soils with pH > 9 will benefit most from gypsum. The solubilisation of soil organic C increased markedly at pH above 8.5. The availability of aluminium (Al) in soil increases at pH above 9. There was no significant effect of gypsum on the biomass or yields of crops within 2 years.

Applying gypsum can reduce soil pH and lower the concentration of dissolved organic carbon (C) to 30 cm depth within a year. Soils with pH > 9 will benefit most from gypsum. The solubilisation of soil organic C increased markedly at pH above 8.5. The availability of aluminium (Al) in soil increases at pH above 9. There was no significant effect of gypsum on the biomass or yields of crops within 2 years.

• Deep placement of organic master improved root development and increased overall yield.
• Site needs ongoing monitoring to gauge the long term effectiveness (and profitability) of sub soil manuring.
• First commercial machine has now been developed by a farmer in Victoria.

• For the third year in a row and now over a variety of seasonal conditions the deep placement of organic matter has increased both crop yield and quality.

• More salts in the high input soil which can be detrimental to some plants. 
•  Significantly higher residual phosphorus and potassium in the high input soil, along with higher levels of sulphur. 
•  A soil structural problem in both soil types indicating a need for gypsum and possibly lime. • A crop could be grown in the high input soil with minimal fertiliser input in 1999, whereas significant fertiliser input would be required for the district practice treatment. 

• Similar to previous years and at other sites on Kangaroo Island, adding soil improvement agents to the subsoil did not produce any tangible benefits to wheat performance. However, chemical analysis of the soil to a depth of 40 cm below the surface did not reveal any major constraints to growth at this site except low fertility. This would help explain why adding lime and gypsum to the soil (either to the surface or into the subsoil) had no impact on crop productivity.
• In trials with deep placed nutrients in other environments, spectacular yield benefits have been measured in sandy profiles with all their fertility concentrated close to the surface and top soil drying being a frequent  occurrence during spring. Although fertility decreased at the site tested here, there was still reasonable fertility in the 10-20 cm layer and rarely did the top soil get a chance to dry in spring last year. Perhaps both of these features decreased the value of nutrients placed deep into the profile.
• Some treatments will be re-applied in 2006 in this trial so we will be able to test whether they will have an impact in a different season, and if so, how fresh applications compare to those applied in the previous year.

• Similar to previous years and at other sites on similar KI soils, adding soil improvement agents to the subsoil did
• not produce any tangible benefits to wheat performance in last year’s trial.
• However, chemical analysis of the soil to a depth of 60 cm below the surface did not reveal any major constraints to growth at this site except low fertility.
• This would help explain why adding lime and gypsum to the soil (either to the surface or into the subsoil) had no
• impact on crop productivity.
• Deep ripping did not produce any benefits to crop performance in the very dry year of 2006.

• There was no effect of stubble retention on canola yield because it followed chickpea and there was very little, if any, stubble of chickpea.
• There was no significant effect of gypsum application on the yield of both canola and chickpea.

The main agronomic issues to be assessed in 2012 are:

• Targeting of seeding and post seeding nitrogen applications in line with identified changes in soil water characteristics ie changes in the ‘bucket’
• Assessment of gypsum applications over soil zones identified as having variations in sodicity levels. A trial has already been implemented which will allow economic assessment for several years.
• Sound agronomic and economic phosphorus fertiliser management in line with changes in productive capacity of soil zones and responsiveness of soil types to phosphorus applications.

• The application of lime or dolomite increased soil pH significantly and increased exchangeable Ca and Mg, while the application of gypsum increased soil conductivity levels.
• The nodulation of lupins sown on the gypsum plots was impaired probably because of the high salt levels in the soil.
• Following a drier than average season, lupin yields were lowest where gypsum had been applied in the previous year but benefited from the application of lime or dolomite.

Lime or dolomite were both effective tools for increasing pH in this trial.

The use of gypsum in combination with either lime or dolomite gave the highest yields for both wheat and barley.

 

• Changes in soil chemistry were found 14 years after application of high rates of lime and gypsum.
• The source of Ca (lime, gypsum or lime + gypsum) had no significant impact on the long term displacement of Na hy Ca.
• The practical message is that any source of Ca, applied at an equivalent Ca rate, gives equal long term benefits in Na displacement.
• Soil chemistry did not change below 30 cm depth.
• Plant yields have been low due to drought. In 2002 there was no significant difference in plant growth after different ameliorants. This result may not be true and may have occurred because of the low yields.

• It was not surprising that no response to sulphur was obtained, when we consider that the KCI sulphur level in the soil rose from 5-7 mg/kg before bed forming to 16 mg/kg after bed forming. 
• For further discussion please see the attached trial report.

• There are no significant differences between average yields for different levels of applied gypsum in the trial in 1995.
• There are also no significant differences between average yields for the different tillage treatments.

• The laboratory analysis indicated the site would be zinc responsive.
• Zinc sulphate was no applied and no zinc deficiency symptoms were observed.
• Extensive trials in the Forbes district have never shown a response to zinc fertiliser in wheat.

• The application of lime and gypsum to a sodic soil has improved soil structure (observations) and fertility (soil test results) in the top soil (0-10cm). However, despite the lime and gypsum being applied 5 years ago, soil tests indicate there has been no change in the sub soil (10-30cm).
• Gypsum produced a greater soil ameliorant effect in the early years, but after 5 years appears to have largely 'run out of puff. In contrast, lime produced smaller benefits in the early years, but it's effects have lasted longer and are still clearly visible after 6 years.

• The application of lime and gypsum to a sodic soil has produced improvements in soil structure observable to visitors of the trial site.
•  Improvement in soil structure have been associated with variable responses in grain yield and quality across years, apparently in response to varying available soil moisture over the last 5 crop years (2000 to 2004).
• Yield increases with soil amelioration are associated with years where crop growing conditions were conducive to high yield and/or reasonable levels of sub soil moisture were available to the crop (years 2001 and 2002).
• In contrast, barley yield declines of 40% - 80% and quality downgrades have occurred in the last two very dry years (2003 and 2004). This is thought to be due to the soil amelioration treatments promoting additional early season vegetative growth but being followed by severe spring conditions leading to the crop "haying off”.
• The trial has sown no economic benefit of soil amelioration in 5 years.

No significant differences were found from either the different rates of gypsum applied in 1994 or from the tillage practices.

The results so far (after three dry seasons) indicate that:

- deep ripping has resulted in significantly lower yields, and

- gypsum has had no affect on yield.

There was a significant yield improvement of the triticale to applied gypsum.

The data would suggest that Deep Ripping had an effect on increasing the total water content of the soil, thereby making more moisture available to the barley crop during the spring months at a time when the crop was filling the grain. This may have resulted in a higher grain yield for both Ripped and Ripped + Gypsum treatments by comparison to the Direct Drilled and Shallow Cultivation treatments (although yield difference not statistically significant). 

For further conclusions please see the attached trial report.

• The addition of sulphur increased wheat grain yield at both trial sites.
• Grain yield at the clay loam site was consistent for all of the sulphur rates, sources (gypsum and SoA) and application times tested
• In contrast, there was variation in grain yield for the sulphur treatments tested at the sandy dune location due to the poor nutrient holding capacity of this soil type.

The high rate of gypsum (3.0 t/ha) was the best ameliorant, with all other ameliorants and rates performing better than the control (no ameliorant).

A yield increase is apparent in figures 2 (circled) and 3 (see attached Trial report) at the ripped only treatment in the eastern plot, however this is not seen in the western plots and does not stand out in graph 1. Results presented in Graph 1 generally show only slight differences with the greatest response observed in the gypsum only treatment on the eastern plots. This soil was highly sodic at 10cm and as could be expected the gypsum would make a quicker impact on sodicity, thus allowing for improved drainage that may have improved crop production. Gypsum would take longer to impact on subsoil sodicity and may show a response after several years of data are collected

VRT Performance

Matching fertiliser inputs to productivity zones (VRT) was rarely the most profitable strategy. Table 1 summarises the 9 successful trials undertaken in 2006 and 2007. These were above 5 average production years for the Corrigin area. It is assumed that the low, medium or high fertiliser treatments were blanketed across the whole paddock. The VRT treatment involved apply low inputs to the poor productivity zone, medium inputs to the average productivity zone and high inputs to the good productivity zone. This summary shows that in 8 of the 9 trials a blanket application of low or medium fertiliser rates was the most profitable way to fertilise the paddocks. High inputs were never the most profitable approach. The VRT approach was only most profitable in 1 of the 9 trials. The high input treatment was the least profitable strategy in 6 of the 9 trials.

Phosphate responses

Many of the paddocks where we had our trials were un responsive to phosphate. Our research has shown that many soils now have sufficient levels of phosphate that crops either don’t respond to additional applied phosphate or the responses are very small. The WA wheat belt has been in a phosphate building phase since clearing. Many farms now have sufficient phosphate levels. Fertiliser regimes could now be reduced to a maintenance regime. This would offer significant savings to growers especially given that the price of phosphate has tripled in the past two years. There would also be some significant environmental benefits to preventing over fertilising.

Best Fit for VRT

We feel that in the Corrigin area the most economic use of VRT will be for patching out potassium on responsive soil types as well as ameliorating soil with applications of lime or gypsum in the areas which have the highest requirement, rather than blanket applications on areas that do not require amelioration. VRT could also be used for tactical applications of nitrogen. Where the paddock is blanketed with N and P for and average production season. In an above average season additional nitrogen should be applied to the high productivity zones where the demand for additional nitrogen is likely to be highest.

• The ameliorants were applied in 2014, where 3.0 t/ha of gypsum proved to be the most effective in increasing establishment.
• However all treatments have had no effect in subsequent seasons.