Growing sunflowers as a companion crop to maize - Final Update

Key results

  • Growing sunflowers with the maize crop increased overall Crude Protein level of the silage from 9.5% to 11.5% but this was also associated with a decrease in the Metabolisable Energy(ME) level from 11.0 to 9.53ME  
  • Inclusion of zero grazed Westerwolds ryegrass in the ration enabled a reduction in the amount of supplementary protein required amounting to a daily saving of £130 in feed cost
  • Milk yield increased by 2 litres/cow/day when the Westerwolds was included, amounting to an additional 420 litres/day worth £189

Background

The Griffiths family at Tafarn y Bugail, near Cardigan, produce milk from 500 pedigree Holsteins, growing most of the feed that goes into the Total Mixed Ration (TMR). A total of 67ha (165 acres) of maize are sown which helps to meet the energy and forage requirements of the herd, but they were interested in finding ways of displacing some of the bought in protein required to balance the lower protein content of maize silage.  

The project explored the viability of growing sunflowers alongside maize as a companion crop. Sunflowers offer a higher protein content than maize, potentially reducing the need for expensive bought-in protein sources like soya. In Germany, as much as 7% of the maize crop is grown with sunflowers.

Additionally, a Westerwolds ryegrass mix was sown directly after maize harvest to minimise soil erosion over the winter and provide a potential source of high D value green fodder in late winter.

Both these actions serve to improve the sustainability of growing maize by balancing its high energy/low protein content plus ensuring that there is no bare soil left over winter when heavy rainfall incidences can wash soils from fields.   

Purpose of the work

  • To examine the potential of growing sunflowers in west Wales in climatic conditions similar to those in Germany and as a companion crop to maize
  • To evaluate whether sunflowers can provide an increase in the protein level of the combined harvested forage compared to straight maize silage
  • To sow a Westerwolds ryegrass mix immediately post maize harvest to stabilise soil over the winter
  • To evaluate potential savings in winter feed costs by including the maize-sunflower silage and the cut and carted Westerwolds ryegrass mix in the dairy cow ration over winter  

What was done

The selected 20 acre field received 3000 gallon slurry/acre as well as 10 tonne/acre of FYM (Farm Yard Manure) prior to ploughing and seed bed preparation with a Sumo harrow. The field was drilled on 1 June 2024, 50kg urea went down the spout in front of the seed at a rate of maize seed 42,000 seeds/acre at a spacing of 9.8cm and a depth of 5cm.

The sunflower seeds were sown at the same time as the maize was drilled at a rate of 41,000 seeds/acre with a row width of 450mm at a drilling depth of 7cm (Figure 1).


Figure 1: Gaspardo Monica 250 Maize drill with maize seed (red) and sunflower seed (black)

Following harvest of the crop, the Westerwolds rye grass mix was direct drilled into the maize stubble at a seed cost of £20/acre.

Outcomes

Maize and sunflower

It proved to be a challenging summer for maize production with the lack of sunlight leading to poorer quality maize crops in general. However, it appeared that the growing of sunflowers as a companion crop with maize served to further negatively impact on the maize silage in terms of quality. The maize was lower in energy (9.5ME v 11.0ME for straight maize) and far higher in NDF fibre with the fibre being very indigestible, as demonstrated by the high uNDF (240 hr) figure in Table 1. Due to the weather conditions, the maize cobs in the companion field did not ripen and harden like the straight maize field, possibly due to shading by the sunflowers.

The companion crop was being grown mainly for its increase in protein however, and a 2% increase was seen in Crude Protein analysis to 11.5% compared to straight maize silage. The first cut grass silage analysis for the farm however showed a 16.5% protein level, leading to the surmise that it would be more beneficial to harvest more grass silage to use with and mitigate just using straight maize silage in the ration.


Table 1: Sunflower-maize silage analysis from DM Scientific, Pennsylvania, USA

With the sunflower/maize silage clamped as a layer in the maize silage clamp, this was fed out together with the straight maize silage and the complete ration is shown in Table 2. With only 8kg fresh weight of the sunflower/maize silage included in the ration there was little opportunity to vary the ration from that formulated including all maize silage.

Westerwolds ryegrass mix

Zero grazing of the Westerwolds began on 11th March 2025; the excellent analysis showed a Metabolisable Energy of 12.8 and 24.9% Crude Protein (Figure 2).   

 

Figure 2: Westerwolds ryegrass mix analysis

Inclusion of the Westerwolds in the dairy cow ration (Table 2) enabled a reduction in the use of NovaPro protein supplement from 2kg to 1.2kg/cow/day, a saving in daily feed cost of £130 per day.

Milk yield also responded to the inclusion of the fresh grass by 2 litres/cow/day contributing an additional 420 litres/day in the bulk vat amounting to an extra income of £189 per day. 

Table 2: Milking cow ration including maize/sunflower silage and following introduction of Westerwolds in March

Please contact timtechnegolcff@menterabusnes.co.uk if you would like to receive a factsheet on the agronomy of sunflowers.