Responsive crop nutrition timings in cereals

Can changing when to apply nutrients in response to the health of the plant result in a healthier wheat crop than conventional applications? This is one of the questions being tested at Strategic Cereal Farm Scotland. 

Nutrient application timings and plant health

  • Start: October 2020                          
  • End: Harvest 2021


To baseline the effect of adjusting nutrition in response to tissue testing as well as baselining the relationship between plant health and brix readings

Should I test plant health to time nutrient applications?

We have an extensive nutrient management research programme for arable crops, including work to improve and optimise nutrient applications that are both environmentally and economically sustainable.

Timing nutrient applications correctly is as important as applying the right amount. Crop demand varies throughout the season and is greatest when a crop is growing quickly, therefore results from standard laboratory tissue testing may be quickly outdated.

Rapid development of leaves and roots during the early stages of plant growth is crucial to reach the optimum yield at harvest, and an adequate supply of all nutrients must be available during this time. Excess application of nutrients, or application at the wrong time, can reduce crop quality and cause problems such as lodging of cereals or increases in foliar pathogens.

Many growers are moving away from regimented fungicide applications to assessing a crop before application as part of an effective IPM strategy. The aim of this trial is to see if amending nutrient applications in response to testing the plant, results in a healthier crop than when conventional nutrient applications are made.

How are we assessing nutrient application timings?

This tramline trial is in Tank Wilsons March (13.5 ha) with a sandy silt loam soil. The crop is Skyscraper winter wheat.

The treatments are designed to be representative of the industry as well as the farm standard as a control.

Standard agronomy
  • Using SAC Techincal Notes without fungicide to compare how nutrition alone affects plant health
Farm standard
  • Led by the farm’s agronomist to see how adjusting nutrients affects crop health in comparision to farm standard
Nutrient adjusted
  • Regular brix assessments are taken at the same time of day to use the tissue’s sugar as an indication of photosynthetic rate and therefore give an impression of crop health.
  • When the brix reading falls below 10, a bulk tissue sample is sent for rapid analysis and within a week the trial steering group decide the inputs as a product of the results.

In addition to the soil health, plant health and biodiversity baselining assessments taking place at the Strategic Cereal Farm Scotland, the following assessments are completed at each sampling point:

  • Growth stage
  • NDVI
  • GAI
  • Above-ground fresh and dry biomass
  • Tissue sampled for full nutrient analysis
  • Brix meter
  • Plant pH
  • Sap nutrient assessments

At harvest, the farm will collect combine yield data for SRUC to analyse.

The Farm Economics team will calculate the economic cost of production of the crop in each trial field. Using Farmbench, they will produce costs per hectare and per tonne. The calculations will use:

  • Seed, fertiliser and crop protection
  • Farm labour, machinery and equipment
  • The regional average for property, energy and administration

Research results on nutrient application timings so far

At GS23, sap analysis showed manganese was low but all other nutrients tested were ‘good’ or in excess for each treatment.

  1. Standard agronomy: manganese – low (74)
  2. Farm standard agronomy: manganese – low (62)
  3. Nutrient adjusted: manganese – low (49)

At GS30, the nutrient levels were as follows:

  1. Standard agronomy: manganese in excess (189), magnesium low (65)
  2. Farm standard agronomy: manganese ‘good’ (88); magnesium (59), nitrate-N (74) and ammonia-N (74) were all low
  3. Nutrient adjusted: manganese ‘good’ (90), magnesium low (79)

Research Review 93 reported that crop material testing as well as soil analysis may provide guidance on nutrient use and thus help direct crop nutrient management. 

Useful resources

Nutrient Management Guide (RB209)

Wheat growth guide

Barley growth guide

Oilseed rape growth guide

Our Strategic Farms are an opportunity to see how to use our research on a commercial farm. Find out more about our Strategic Cereal Farm Scotland programme

Image of staff member Chris Leslie

Chris Leslie

Knowledge Exchange Manager – Cereals & Oilseeds