A 2 year appraisal of Bridgeway in Sugar Beet

The subject of biostimulants is one of those that divides opinion. Work conducted by Deborah Green of CMI Ltd, shows that Bridgeway application to sugar beet produced significant yield responses in both 2018 and 2019:

There are a wealth of new products appearing in the agricultural market loosely classed as bio-stimulants.  These are receiving a lot of attention in agricultural research in the hope of countering the pressure, in terms of both legislation and biochemistry, on current pesticide usage.

One school of thought suggests bio-stimulants may help plants through periods of stress. The growing season of 2017-2018 was notable for a very wet winter of extreme high and low temperatures, followed by a wet spring and a hot, drought during June and July.  This was followed at the end of August by more rain throughout September and October.

In contrast, 2018-2019 has been recorded as a mild winter with above average rainfall in March and in the summer months, especially in June.

During these two seasons CMI Ltd conducted research work on sugar beet for Interagro UK Ltd.  The aim was to investigate the application of bio-stimulants to sugar beet grown in a commercial situation.  Application timing to the canopy was modified in an attempt to define optimum stages and sequences for the use of bio-stimulants.  In both years, ‘Bridgeway’ was the chosen product applied at one or two rates and a range of timings.  These were two markedly different growing seasons.

The growing season of 2018 provided an ideal opportunity to study the application of amino acid solutions to a crop that was to become stressed by heat and potential water shortage.  The experiment site was drilled into moist conditions after a wet spring, but the month of June proved very hot and below average rainfall.  July and August followed in a similar trend.

The first three applications of ‘Bridgeway’, which formed the basis of all but the last treatment, were applied prior to the onset of a period of excessive heat and drought.  The final three applications were made during the period of high temperature and drought in June and July.

There were significant differences between treatments in the weight of beet per hectare at all dig dates (by post hoc analysis: P<0.05).  All treatments increased the weight of beet at all dig dates, but the biggest differences were at the earliest dig date on 28 August 2018 (Fig 1).

After this date, the drought broke and the additional moisture from rainfall allowed the untreated plots to ‘catch up’ and so treatment differences were reduced (Fig 2).  However, there were still significant increases from some treatments (P<0.05).  The biggest effects arose from the multiple applications and a single application of the highest rate of Bridgeway (2.0 L/ha) at 6 true leaves (which was the timing immediately prior to the drought period).  Six applications of ‘Bridgeway’ made no significant difference to beet yield compared to three treatments applied sequentially at 2, 4 and 6 leaves.

From the work conducted in 2018 it would be easy to conclude that applying Bridgeway to sugar beet at 6 leaves was favourable, and that three applications were better than 1, but more applications conferred no further benefit.

In 2018 or 2019 visual observations of the canopies were no indicator of what was going on underground.  Neither green scans (with a hand-held Crop Circle Scanner) nor dig weights of canopies showed any significant differences at any dig date.  It was therefore a surprise when such big differences in beet yields manifested themselves in either year.  In 2018, these differences could easily be explained with reference to the hot, drought and the known ‘stress busting’ capabilities of amino-acid applications such as ‘Bridgeway’.  What was unexpected was the massive response found in 2019 when the summer had been dominated by above average rainfall.  In both years, the same trend in beet yields was found across the treatments tested, in that six applications conferred no benefit over three, while three were more favourable than one.  The difference between 2018 and 2019 was that the single application could have been applied at 2, 4 or 6 leaves to the same effect in 2019 while 6 leaves was the favourable timing in 2018. It should be noted that on 22 October 2018, untreated yields were 46 t/ha while on 21 October 2019 they were 65 t/ha.  The two sites were on two different farms, but the difference would also have been affected by the available moisture.

Fig 3. 2019 trial during year of adequate moisture: Final dig – change in beet yield compared to untreated plots which were yielding 65 t/ha on 21st October 2019.

Conclusions – 2 years of trials

• 2018 & 2019 visual observations were no indicator of what was happening below ground
• Green scans nor dig weights of canopies showed significant difference
• 2018 & 2019 yield improvements surprising
• 2018 explained by hot, droughty conditions, 2019?
• 2018 & 2019 showed the same trend in yield increases
• 3 applications of Bridgeway optimal