• KEN
    • KEN
    • Fertiliser
    • 22 Mar 2013

    When is the best time to apply P to pastures for it's most efficient use? Please consider P leeching to the water table as well as financial issues.

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    • 1

      Phosphorus applications are best applied at the time of sowing in annual pasture or pasture establishment situations. P is relatively immobile in the soil so should ideally be placed below and close to the seed. P is critical in root development and plant energy transfer, so having P at sowing is critical. Although P is relatively immobile in the soil it can leach on very light sandy soils - these soils are typically confined to coastal areas and small more frequent application tend to be a favoured method of timing. Surface run-off can be a greater issue where heavy rain (on sloped country) follows a fertiliser application within a couple of days of application. Ideally do not broadcast if heavy rain is forecast within a week of application and fertiliser is best broadcast where some organic matter is present and surface soil is unlikely to wash. P will move into the topsoil with light dews or rain. The remnant of a Superfect granule 7 days post spreading is most likely the P carrier Calcium Sulfate. In perennial pastures P is also typically applied in the autumn although some favour spring applications when production is peaking. If soil P levels are adequate either is fine, however if soil P levels are low I would favour an autumn application.

  • Colin
    • Colin
    • Fertiliser
    • 20 Jul 2012

    I have been wondering about applying fertilizer to last year's Superdan stubble which has only recently become dormant with the series of frosts. We will expect a regeneration when the ground temperature reaches about 15 degrees and have very recently had 3 inches of rain. Our location is in the Narrabri area. The area is small [18.6 Ha] but is strategically placed. We will almost certainly sow a legume interrow to enhance the overall fodder value. Further, we are developing an old pasture paddock to sow to forage sorghum and would like a recommendation for this area, probably 23 Ha of brown clay loam. The forecast for the next 3 months [and 12 mths] is not too encouraging but long experience suggests that although the El Nino may develop further, a well established fodder crop may draw on the deep moisture reserves with satisfactory conclusion, provided the SOI doesn't fall much below -12/14 during Spring.

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      Thanks for the question. If you have suitable machinery available banding nitrogen in the inter row is the preferred option for the second years grazing, Placing N in the soil reduces the reliance on follow up rain post application if broadcasting urea to move it into the soil. I would apply mid August if possible, this allows adequate time for conversion of N to the plant available nitrate form as soil temperatures rise and the forage crop commences growth. Available N at the commencement of growth reduces the time to the first grazing. If you are also putting in a legume it may be an opportunity at the same time to increase the Superdan plant population if it has thinned out over winter. Without a soil test result and if the soil moisture profile is full 60-80kgs/ha/N (130-175kgs/ha/urea) may be needed. If sulphur has not been applied in the past, there is the option of including 10-15kgs/ha of sulphur as a Urea/Gran Am blend. For the new block I would suggest a soil test (0-10cm) as soon as practical with your local Incitec Pivot Fertilisers dealer to assist with a nutrient recommendation. If sulphur or phosphorus or potassium or possibly zinc is limiting dry matter responses to nitrogen may be less than ideal.

  • Rod
    • Rod
    • Fertiliser
    • 4 Jul 2012

    What is a Urease Inhibitor with regard to nitrogen fertilisers and how does it work?

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    • 1

      A Urease Inhibitor is a substance generally applied to urea fertiliser (ie. forming Green Urea). The substance contains an active constituent which can temporarily block the action of the urease enzyme. Blocking the urease enzyme activity has been shown to reduce nitrogen loss to the atmosphere via. ammonia volatilisation.

  • Chris
    • Chris
    • Soil & Plant
    • 22 Aug 2012

    With a price put on carbon, will it be profitable to build organic matter levels in the soil?

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      Organic matter in the soil is very important for many desirable soil properties and can be a measure of soil health. It is most likely that the organic matter in the soil will contain significant amounts of fixed carbon but as it decomposes much of the carbon will be lost as carbon dioxide. However, if one tonne of organic matter by some miracle contains one ton of carbon dioxide equivalents, it may be worth $20-30. The nutrients contained such as Nitrogen in this organic matter can be around 5% N or 50kg/t of organic matter. This nitrogen alone, without the consideration of other nutrients is worth $54 if urea is worth $500

  • Daniel
    • Daniel
    • Soil & Plant
    • 26 Jul 2012

    I want to know if the burning of stubble is still considered a valid crop management tool. Every year I hear different stories from different people.

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    • 1

      If the decision has been made to burn harvest residue as part of this year's cropping preparation, it is important to consider the potential for loss of nutrient. Nutrients from fertilisers may also be lost if they have been broadcast onto the stubble and no significant follow-up rain or irrigation has moved them into the soil. When cereal stubble is burnt, 80% of its nitrogen and sulphur and 40% of its phosphorus and potassium can be lost in gaseous forms to the atmosphere. In hot fires, some of the surviving phosphorus and potassium can be lost off-site in wind blown ash. Growers can also expect to lose 80% of the carbon from the stubble.

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