Give spring OSR the best start for greater profitability

Following a difficult winter, many growers will be relying on spring crops to deliver farm profits. For those drilling spring oilseed rape, getting the crops established and away quickly will be key to productivity. David McLellan, agronomist at Omya UK, says there are some quick wins growers can take advantage of.

osr field

“One of the easiest things you can do for a successful oilseed rape crop is make sure your soil pH is at or above neutral,” Mr McLellan says. “Early crop establishment depends on roots being able to penetrate the soil and find nutrients easily. Soil pH has a significant impact on both soil structure and nutrient availability, so it’s worth getting it tested and correcting it if it’s too low.

Acidic soil is caused by excess hydrogen ions, which can be removed by applying calcium carbonate (lime) to the soil. The hydrogen ions are replaced by calcium ions on the soil colloid, and then react with the carbonate ions to form carbon dioxide and water. Many farmers have historically used agricultural lime every five years or so, but as Mr McLellan explains, this won’t necessarily deliver the results you need consistently or quickly enough.

“To make a difference in time for this season, you need to use a granulated lime, like Calciprill, which will break down quickly in soil moisture. Because the granules are made of ultra-fine particles, they have a much higher surface area so they react more quickly with the hydrogen ions that make the soil acidic, correcting it in just a few weeks.”

Nutrient availability

One of the biggest advantages of a correct soil pH is the effect it has on nutrient availability. “At a pH of 6.5, 100% of your applied NPKs are available to the crop, as well as a very high percentage of other nutrients,” says Mr McLellan. “Maximising nutrient availability not only gives the crop the best chance of getting away quickly, it also makes better use of your fertiliser budget by improving nutrient use efficiency. A pH of 6.0 could waste 20% of your applied fertilisers, making them unavailable to the plant and lost to leaching, volatilisation and runoff or locked up in the soil, so it’s an easy way to protect farm profitability.”

Adding Calciprill to soil has another major advantage, which is its effect on soil structure. Mr McLellan says this is an important benefit that some farmers are unaware of. “The calcium ions in Calciprill improve soil structure by increasing soil flocculation, which allows better root penetration, air circulation and drainage. And of course, it also supplies available calcium to the crop which is necessary for cell wall structure and strength. In a spring crop which has to get to maturity much more quickly than a winter crop, a continuous supply of calcium is needed to support rapid growth.”

Mitigating club root risk

Once the crop is established, growers need to be aware of the dangers of club root, which affects all brassica crops including oilseed rape. Mr McLellan suggests raising soil pH offers a way to mitigate the risk: “Clubroot spores can live in the soil for up to 20 years before germinating, presenting a risk to all oilseed rape growers, but you can minimise the risk of germination by increasing soil pH to neutral or even slightly alkaline as clubroot prefers acidic soil.”

normal osr root and osr root with clubroot
Normal root (left) versus clubroot (right).

Calciprill can be applied using standard spreading equipment to 36m and is ideal for precision application. Omya recommends soil testing to establish starting pH levels, then depending on your soil type applying up to a tonne of Calciprill per hectare to achieve a half point improvement in pH (e.g. moving from 6.0 to 6.5). It will start to deliver results within just a few weeks. Mr McLellan concludes: “Applying Calciprill gives three major benefits to oilseed rape growers: better rooting, better nutrient availability and better protection against clubroot.”

To find out more, visit the Omya website

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