How crop nutrition and structure can boost yield potential
© Tim Scrivener Yield enhancement is possible almost anywhere in the UK, according to more than a decade’s worth of UK data collected by the Yield Enhancement Network.
Simple strategies to address the stagnation of UK crop yields include prolonging the growing season to maximise photosynthesis, managing soils to enhance rooting and providing sufficient crop nutrition.
Prof Roger Sylvester-Bradley, director and founder of the Yield Enhancement Network (YEN), notes how yield data collected over the past 12 years reveals consistent farm-to-farm differences, but overall no yield increases.
“We must ask ourselves: Why this is and, importantly, is it to do with crop nutrition?,” he says.
“Excellence in crop nutrition is evident on farms that measure the nutrients they harvest and yields. Measure to manage should be every grower’s maxim.”
See also: YEN Awards: Round-up of this year’s highest-yielding farms
Traits of YEN high-yielding winter wheat crops
- The YEN data highlights that higher-yielding winter wheat crops often have more nitrogen and sulphur applied, with more frequent nitrogen applications.
- These crops then go on to produce more grain per kg of N applied.
- The data also found a positive association with the recent use of organic manures and with soil phosphorus levels. Higher yields tended to be grown on fields with a soil P Index of up to 3.
- Higher-yielding crops also experienced prolonged water and nutrient capture as a result of a more developed and extensive root system.
Crop structure and colour
Early crop senescence is perhaps one of the biggest factors preventing crops from reaching their true yield potential.
Nutrition, disease control, water availability and rooting all have their part to play in prolonging green area and maximising sunlight capture.
Roger points out that growing long-lived canopies is a matter of “painstaking preparations”.
There’s no magic wand available, or rescue act. It comes from building a deep root system, good disease protection and early comprehensive nutrition.
Crop structure plays a vital role in the production of yield and grain quality.
High ear numbers and high biomass both above and below ground is key for building yield.
He recommends growers to target more than 500 fertile shoots/sq m.
“Crop colour is then crucial as we aim to keep these shoots alive for as long as possible.
“We want to protect the canopy to prolong photosynthesis which in turn generates harvestable grain yield,” he explains.
“Premature canopy senescence happens far too often in many crops.
“Crop inspection at flowering and the period after should be much more formalised.
“To me, this is the biggest difference between high- and low-yielding crops.”
Nutrition snapshot
Leaf analyses and sap tests can provide a “snapshot” of a crop’s nutritional status during the growing season and help identify nutrient deficiencies.
It is also worth checking any specific adjustments used, to note how well they worked.
“I’ve seen enough failures of adjustments over the years to say it’s always worthwhile to compare changes,” says Roger.
What’s more, he highlights how leaf analysis data does not necessarily foretell the future nutritional status of the crop or the final grain nutrient content.
Leaf analysis is better used as a snapshot. It is not so much of a predictive tool until you get to growth stage (GS) 59, by which time it is generally too late for any crop nutrition adjustments.
YEN analysis highlights the positive relationship between leaf analysis at GS59 and grain yield for most nutrients.
“The longevity of the green leaf correlates convincingly with the nutrient status of the leaf just before flowering.”
Grain analysis
In general, the nutrient content of grain over the past nine years has been decreasing, explains Roger.
Both macronutrient and micronutrient grain content levels are on the decline, with the exclusion of potassium, magnesium and manganese.
“We do not know the explanation behind this, but one theory is that shorter grain filling periods mean there is less time for nutrients to get into the grain,” says Roger.
This is why measuring grain nutrients on each field, each year, can be beneficial to growers.
“Unless we measure what we’re harvesting as nutrients, how do we know what we’re doing and how can we improve?
“By simply measuring the nutrients in the grain and knowing the crop yield, the nutrient offtake can be calculated.
“Field plans can be adjusted accordingly to recent crop nutrition checks,” says Roger.
“If you know the nutrient offtake, you can use more accurate data instead of RB209 guidelines.
“On-farm nutrient offtake values are typically less than RB209, which seems to be quite generous across all nutrients and crop types.
“The savings in fertiliser spend will pay for the additional cost of grain analysis.
“In my book, it’s worth every penny and it gives you that confidence to make decisions.
“Flexibility is essential for good nutrition management.”
Prof Roger Sylvester-Bradley and Dr Sarah Kendall were talking at the recent YEN conference held in Peterborough, Cambridgeshire
Nutri-Check Net project
A novel crop nutrition platform is aiming to promote field-specific nutrient management practices across Europe to increase farm income and reduce nutrient losses.
Key learnings from the Yield Enhancement Network (YEN) have been expanded to form a European-wide network known as Nutri-Check Net to promote the YEN’s “measure to manage” approach across Europe.
The initiative will focus on improving crop nutrition precision by compiling decision-making tools and facilitating knowledge exchange, explains Dr Sarah Kendall, Adas crop physiologist and co-ordinator of the project.
A three-step approach to nutrition management has been established:
- Plan
- Check and adjust
- Review
“Nutrition is cropping’s biggest expense to farmers, and on-farm decisions often suffer from inaccuracy.
“This project is all about sharing expertise with particular focus on nitrogen, phosphorus and potassium management in wheat, maize and potatoes,” says Sarah.
“Crop management doesn’t always go to plan – seasons change, weather alters, and that’s why it’s important growers check and adjust accordingly.
“When it comes to harvest, reviewing results so that we can learn from the outcomes is vital,” she says.
Across nine European countries, the Nutri-Check Net project partners have collated information on three key topics to help farmers, advisers and researchers.
The platform delves into the following, which is available to view online:
- Recommendation systems for nitrogen, phosphorus and potassium have been summarised to provide an overview of nutrient management processes across several European countries.
- Tools and services available to farmers and advisers have been catalogued to facilitate the use of each phase of the three-step approach.
- Relevant research projects have been identified to provide evidence to support current recommendation systems and various nutrient management methodologies, which in turn provides scientific evidence to support tools.
