How to get the best from nutrients this spring

Crops must have all nutrients needed to get best returns this season

Nutrient availability will be vital for growers wanting to get the best returns from crop inputs this spring.

Primary nutrients such as phosphorus (P) and potash (K) are vital for plant growth. But high fertiliser prices could tempt some growers to reduce application rates in a bid to save money.

This could be a good way to reduce expenditure in the short term. But experts say growers should fully assess the longer term impact on soil reserves – and nutrient availability – before adopting what could be a risky strategy.

Although fertiliser prices have eased since last year’s highs, they are  still stubbornly expensive – prompting more growers to consider ways nutrients can be used more efficiently.

Maintenance dressings

Eastern region crop nutritionist and agronomist Toby Ward has been advising farmers on the role nutrients play in the soil ­– and how they can help increase nitrogen use efficiency.

“It is understandable that some growers scaled back on applications of other nutrients to maintain nitrogen inputs last year, especially as commodity prices remained high,” says Mr Ward who works for Origin Fertilisers.

“But plants require up to 14 nutrients for growth and not applying maintenance dressings of P and K for an additional year could be detrimental for soil reserves. Nitrogen provides the building blocks of life and is key for protein formation within plants.

“Growers across the region will be nervous of scaling back too much on this essential input. But making more from what you apply is
essential. Ensuring other nutrients are available to the plant will increase nitrogen use efficiency.”

Crops grown in fields where growers decided to take a P and K holiday last year could still have access to these vital nutrients – so long as soil indices are maintained at or above target levels in previous years, says Mr Ward.

Extended holiday

But an ongoing P and K holiday could see soil nutrient levels drop too low to support optimum crop yields. Even dropping from a low level index 2 for P or K, to a high level index 1 could result in deficiencies within the crop.

“It can take years to build reserves back up to the previous levels,” says Mr Ward. The RB209 Nutrient Management Guide warns that it will need more than a regular maintenance dressing – costing growers additional spend, he adds.

Potash is a macronutrient that is important for water regulation. A deficiency will be displayed by a scorching of the leaves along with lodging, while reduced protein formation and lower disease resistance are also factors.

Phosphorus is essential for plant establishment and growth. Without it, plants will lose root structure. This will inhibit the crop’s ability to access other nutrients, such as nitrogen.

“If the plant available P and K levels are being run down over successive years, it is essential that growers test the soil regularly to avoid levels dropping below required indexes. Growers should be exploring ways to optimise the application of any nutrient.”

This could mean applying a coated phosphorous fertiliser to avoid nutrient lockup – which in turn means applying less fertiliser because it is used more efficiently.

The coating within Origin Enhanced Phosphate is designed to prevent phosphorous being fixed in unavailable plant forms, explains Mr Ward. “It can be added onto any fertiliser containing phosphorous.”

Manure applications

This coating allows a higher percentage of the applied fertiliser to be available to the plant – which could reduce phosphorus fixation by 10-15%.”

Other ways of boosting P and K levels will be incorporating manures, both in the spring and autumn, which will have further benefits to soil structure, says Mr Ward.

“The value of good quality manures is becoming greater as growers can see the benefits to reducing bought-in fertiliser costs.

“Chopping straw behind the combine will return some of the nutrients taken up by the crop back into the soil.”

“Although prices remain high, giving the crop with what it needs is essential to get the most from inputs. Growers should be thinking long term about how decisions this season can affect crop growth and future nutrient availability.”