Post-harvest grain analyses are proving a valuable aid to improving crop nutrition, reveals extensive research on Agrii iFarms across the country.

Co-ordinated by R&D manager, Jim Carswell, the most recent studies involved some 300 samples of winter wheat, OSR, winter and spring barley from 2018/9 seedbed fertiliser, technical seed treatment and foliar nutrition trials on nine sites with a wide range of soils and growing conditions.

Detailed analysis at Lancrop Laboratories has revealed clear correlations between the concentration of key nutrients in the grain and tailored nutrition delivering improved crop performance.

“Our investigations show we can use grain analyses to assess the extent to which the enhanced nutrient management programmes we are investigating are actually improving crop nutrient status to support better performance,” explained Mr Carswell.

“More than this, though, they point the way to wider farm use of analyses to improve future  performance by identifying and correcting important gaps in the nutrition of previous crops.”

Mr Carswell accepts that there remains much to learn about grain analyses and how best to employ them in what he calls a ‘holistic approach’ to crop nutrition.

However, he is convinced they have a valuable role to play in pinpointing areas for future nutritional improvement. Especially so, if used alongside broad spectrum soil analyses to establish a baseline for programmes and growth stage-based tissue analyses to identify and correct imbalances in-season.

“In recent years, our work with Lancrop has led us to rewrite the tissue analysis rulebook  to take into account crops’ varying requirement for key nutrients with both growth stage and yield,” he pointed out.  “Turning our attention to grain analyses, we are finding they can tell us a lot about the nutritional status of crops we can use to further improve their feeding to yield.

“Grain analyses have long been central to determining protein levels in wheat and are widely accepted in establishing N:S ratios and plant phosphorus status to improve future fertilisation.  So we thought they could be equally useful in monitoring levels of the micronutrients that give the greatest responses to supplementation in our trials.

“Lancrop analysed grain samples from a large number of our iFarm nutritional trials last season for the 12 key nutrients we routinely measure in our broad-spectrum soil and tissue analyses. And the result have been very revealing.

“Across our OSR work, for instance, we saw no reduction in the rapeseed concentrations of most micronutrients from seedbed fertilisation that improved yields by 0.43t/ha. Yet, without supplementation we would have expected such an output increase to noticeably dilute them.

“Interestingly too, the response was consistent across nutrients not supplied in our mainly N and P-Reserve (protected phosphate) fertiliser. This suggests improved nutrient uptake through better early rooting.

“The analyses were also valuable in suggesting we may not have been supplying sufficient boron and manganese, as well as in highlighting the widely-recognised interaction between sulphur and molybdenum in the crop,” Jim Carswell added.

A similar lack of nutrient dilution was recorded in Agrii’s wheat seedbed fertilisation work. This, despite the 0.81t/ha yield increase achieved from best performing treatment – 125 kg/ha of TSP with Wolftrax manganese and P-Reserve.

Technical seed treatments – mainly Vibrance Duo with iMan (manganese) plus Agnition (copper) or Zax (zinc) – further raised manganese levels in wheat on all nine sites, copper at five of the sites and zinc and phosphorus at six. Again, this was alongside higher yields.

“Higher yields with by little or no reduction in key grain nutrient levels were also evident from the same seed treatments in both our winter and spring barley trials,” reported Jim Carswell. “The greatest responses were definitely in spring barley where we saw yield increases of almost 1t/ha (12%) over our single purpose dressing control.

“In wheat, we also saw very rewarding interactions between the nutritional seed treatments we used and subsequent foliar nutrition. There was only a small yield response to our specialist manganese and copper seed treatments with a basic foliar nutrition programme. But with an enhanced foliar programme the yield increase was almost two thirds of a tonne/ha; again reflected in maintained or increased grain nutrient concentrations.

“This strongly suggests a more robust supply of nutrients at drilling can produce plants better able to take advantage of subsequent, more tailored foliar nutrition.

“We may only have a single year of detailed grain analyses so far. But they are already proving highly informative in our work to improve crop performance through more effective nutrition. And we feel targeted analyses could be equally valuable for many growers.”