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Tag archive: fertilizer

Looking closer at Colwell-K on heavy soils

Colwell potassium (K) is the go-to K test in many growing regions. Colwell-K measures extractable K and is used to estimate plant-available K.  But interpreting Colwell-K values gets tricky on heavier soils. This is partly because research on critical values has been dominated by Western Australian sandy soils. There is […]

An updated Nitrogen Nutrition Index to check in-crop N

The Nitrogen Nutrition Index (NNI) is one way to help gauge in-season crop status. The NNI is the ratio of the amount of N in the crop to the critical N concentration (Nc) of the plant tops. By comparing crop N (from lab tests) to a dilution curve with Nc […]

The best of 2018

open ebook and Cover of ebook

GRDC’s Crop Nutrition Community of Practice continues to be an important extension initiative for industry, providing reliable information sourced from key research scientists across Australia.  Throughout 2018, we published 46 articles (that’s a lot!). So, we collected our most popular articles from this period – those that best reflect the […]

Register now: Australian Fertilizer Industry Conference 2019

“Register now for the 2019 Australian Fertilizer Industry Conference.”

Register now for the 2019 Australian Fertilizer Industry Conference. Early bird registration closes at midnight on July 26.  When: 4–6 September 2019. Where: RACV Royal Pines Resort, Gold Coast. With a diverse conference program, just some of the topics of interest include: Fertilizer application technology The potential for potassium fertilizer […]

A closer look at sulphur in the southern region

Critical values for sulphur (S) in the southern region may be lower than originally thought. Established critical values are 4.5 mg/kg for wheat and 7 mg/kg for canola. These values are based primarily on WA data that use the KCl-40 S test. Do these values apply in other regions? A […]

Sow close to the row to boost crops after a dry year

On-row or edge row sowing means sowing a new crop immediately alongside or in the previous crop row. Grain crops are usually sown inter-row (between the old crop rows). On-row sowing for phosphorus On-row sowing can make use of last year’s phosphorus (P) fertiliser. Phosphorus is not a very mobile […]

What is the benefit of deeper phosphorus sampling?

Testing deep phosphorus (P) can improve fertiliser recommendations with a more accurate look at soil P stocks. It can help to know how much P is in the profile, and where it is. The topsoil is usually the most nutrient dense part of the soil. Maturing crops also rely on […]

What is the phosphorus buffering index?

The Phosphorus Buffering Index (PBI) approximates a soil’s ability to ‘fix’ phosphorus (P). Soils with a high PBI quickly and tightly bind fertiliser P making it unavailable to plants. Low PBI soils can’t lock-up much P, leaving most applied P for plant uptake. Use PBI to improve interpretation of critical […]

How to adjust phosphorus after a dry year

A poor or failed crop last season will affect nutrient budgets this season. Cereal hay removes about 1–2 kg of phosphorus (P) per tonne of dry matter. Canola removes about 3 kg of P per tonne (see Table 1). Table 1. Comparison of nutrients removed in grain, straw, canola hay, […]

Chicken manure improves sandy soils

Chicken manure is helping to ameliorate sandy soils on South Australia’s Yorke Peninsula. Trial results over three years indicate that high-rate surface applications combined with deep ripping are delivering the highest marginal returns. Positive results The marginal returns from applying chicken litter (or a comparable, inorganic fertiliser), and deep ripping, […]

Why should you use a lab with ASPAC certification?

Without tests, crop nutrition is best guess. Plant and soil testing guide best practice on the farm. But who guides best practice in the lab? What is ASPAC? The Australasian Soil and Plant Analysis Council (ASPAC) has an inter- laboratory proficiency program (ILPP). Certification under this program means a lab […]

What is the DGT Phosphorus test and when should you use it?

The Diffusive Gradient in Thin-films (DGT) Phosphorus is an alternative P soil test. Colwell-P can overestimate available P on calcareous soils, and acid gravel soils. How does the DGT test work? The DGT is a cylindrical plastic device that uses an iron oxide gel as a P-sink, which attracts available […]