The latest updates from the Lemken: Agrii soils programme were delivered to a group of tillage farmers in Northern Ireland, courtesy of a workshop recently hosted by John McElderry Tractors.

The event was held in the company’s Ballymoney premises.

Lemken has forged a close working relationship with Agrii, the UK-based arable consultancy. The aim of the partnership is to develop and utilise tillage equipment in ways that put the needs of the soil first.

Courtesy of his presentation, Agrii’s Tom Land confirmed that nutrient use efficiency and improving soil health are the key drivers of profitability within the tillage sector.

The 2022 growing season

Reflecting on the 2022 growing season, he said that fertiliser application levels were down, year-on-year, adding that this was due to “farmers actively deciding not to sow as much fertiliser as usual or not being able to physically source product”.

“However, the end of the year saw near-record yields being achieved across most crops,” he said.

Land attributed these bumper yields to the high levels of sunshine and accompanying solar radiation that impacted on crops as they matured during the summer months.

He also believes that the 2022 cropping year saw a significant draining of soils’ nutrient reserves, and that “this may well have an impact on the fertiliser strategies implemented by growers this year”.

Grain analysis

While 2022 cereal crops were very high yielding, another trend that quickly became apparent was that of low grain nitrogen levels.

“In quite a number of cases wheat crops did not have the protein levels required to qualify them for bread-making purposes,” Land explained.

“Grain analyses have also confirmed that, across the board, nitrogen levels were 4% down.

“The equivalent figures for phosphate (P) and potash (K) were -8% and +4% respectively.”

Land attributed the enhanced K levels in grain to a number of factors, including the lack of respiration within crops as the 2022 drought took hold.

“K plays a crucial role in allowing plants to take up water and in its interaction with N, where plant protein synthesis is concerned,” he said.

Significant number of tillage farmers in the east of England reported the phenomenon of pink straw within their crops at harvest time.

2o21 review harvest combine

According to Land, this was a K-related effect. During senescence of the plant prior to harvest, K is normally translocated back down into the soil.

But if moisture is lacking, this process does not occur as efficiently, leading to higher than normal offtakes.

“This is further evidence of the need for growers to focus on the exact nutritional needs of their crops, as they plan for 2023,” the agronomist continued.

Land specifically recommended the benefits of regular grain testing as part of the information mix required by tillage.

He also highlighted the value of tissue-testing crops in order to identify their exact nutritional requirements throughout the growing season.

As a consequence, growers get a clear and real-time picture of what is happening in a crop at any given point.

The tissue-testing process can identify what nutrients are being taken up by a crop, allowing growers to make alterations to nutritional programmes to rectify any deficiencies.

Nitrogen Use Efficiency

Nitrogen use efficiency (NUE) was defined by the Agrii representative as an important way for cereal growers to identify exactly what’s happening on their own farms.

“Grain testing is a good on-farm metric. Knowing the final yield for a crop is the starting point. Accurate information on the total amount of nitrogen in the system is also important,” Land said.

“Harvested grain N content is also important. In the case of those growers, who have not sent off grain to be specifically analysed, the protein value of the cereals supplied to a miller can be used to derive this value.

“The protein value divided by 5.7 provides the N content value. By dividing the amount of N that is taken off by the total amount of N put on a crop, including all organic sources, one arrives at an efficiency factor.

“If this figure is high then the scope exists to reduce artificial nitrogen applications. However, if it is low then it is a case of finding out what is influencing this.”

There are three factors that impact on NUE. These are: How well nitrogen is taken up by the plant, how well nitrogen is utilised within the plant, and how well it is converted into grain.

“Last year N uptake and utilisation levels were good because the sun was actually doing the job for us,” said land.

“However, the actual partitioning of N into the final grain was quite poor. This was a direct result of the prevailing weather conditions.

“Roots are hugely important. There is a direct correlation between root density within a crop and final yield.

“And this is a fundamental driver for cereal crops. The stronger the root density, the better is the chance of a crop extracting nutrients from the soil.

“A stronger root system also mitigates the impact of unfavourable weather patterns,” he added.

Soil organic matter

Recent Agrii trials have confirmed extremely low residual N levels in many soils, post-harvest. And in some cases deficiency scenarios have been identified.

“This is because crops removed a lot of N last season,” Land further explained.

“But it’s all about building up a picture. Farmers know their land best. A visual assessment of fields will help. In addition all organic manures can be tested for N.

Soil testing

“Understanding the nitrogen that comes from soil organic matter is also important. This is a subject that is being investigated in some detail at the present time.

The production of grain is the last step in a cereal crop’s journey.

And, according to Tom Land, getting a broad spectrum analysis of the grain can tell a lot about the journey that the crop actually took as it developed through its various growth stages.

“For example, the analysis will tell if P was the limiting factor. Or was the limiting factor?” he said.

“All these issues will show up in the final analysis of the grain. My overall fertility factors would include the levels of nitrogen, phosphorous and zinc in the grain.”

Early nitrogen

Land suggested that a significant proportion of fertiliser N for cereal crops should be applied before growth stage 31.

“This would be particularly the case in areas where dry spring weather conditions predominate,” he said.

“The N taken up can then be stored in the plant and remobilised both before and after flowering.”

Where N fertilisers are concerned, Land drew a clear distinction between Calcium Ammonium Nitrate (CAN) and urea.

“CAN is an immediate acting product,” he indicated.

“The nitrate component of the chemical is taken up by the plant immediately. On the other hand, the ammonium fraction is initially held on to by the clay fraction of the soil, making it a slow release source of N.

“It has to be nitrified to be made available. But, in essence, the CAN applied is adding to the N pools that exist naturally in the soil.

“The problem with urea is that once added to the soil, some of the N can be lost to the atmosphere under warm conditions.

“This is also the case if soils have a calcareous base. In addition, urea is a relative slow acting N source.

“The N coming from organic matter is also important form a crop production point of view.

“On farms with a long tradition of using organic manures, measuring organic matter is a very efficient effective way of determining how much more N will be available from the soil relative to a location where this was not the case.

Tissue testing

Once N has been applied, the issue becomes one of uptake and its utilisation in the plant. Land stressed the role of micronutrients in this context.

“The crop must be kept green and healthy,” he further explained.

“Tissue and soil testing will help create a picture as to which of the trace elements are required.

“Soils in Ireland tend to have high P levels. And it might well be that the P is blocking the take-up of zinc by the crop.

“This possible state-of- affairs can be determined by a tissue test.

“Alternative a zinc deficiency can be determined by a grain test. If required, zinc should be applied at growth stage 30 to 32.

“Molybdenum is another micro nutrient of note. It plays a crucial role in the assimilation of N.

“However, the action of molybdenum is determined by the availability of sulphur. We know that most soils are now sulphur deficient: Hence the importance of making this nutrient available by way of a fertiliser application.”

The redistribution of N within a plant is of crucial importance in determining crop growth rates and final yield. The partition of N within the grain is another contributor to overall yield and crop quality.

The importance of P and K

According the Land, the availability of both P and K are critically important in making all of this happen.

“Many growers think that P is only important during a plant’s early growth stages. In fact, this is far from the case. Plants need available P throughout their life cycle,” he said.

“And the same principle holds where K is concerned.

“In our own case at Agrii we are currently using products that act to free up P in the soil.

“They act to mimic the action of the chemicals exuded by the roots of plants to convert unavailable P in the surrounding soil,” he said.