A J Stephenson and Son, Withernsea – A first year with the N-Sensor
Author: Chris Mason – Precision Decisions Ltd
The Stephenson family farm at Withernsea, East Yorkshire, just inland from the Yorkshire Coast, is approximately 1400ha of quite variable arable land.
The Stephensons are new ALS N-Sensor users this season, having decided to take one on lease as a first move into variable rate farming. Installed in January of 2016, the early applications were used on a spreader and the last applications by Chafer sprayer.
During 2016, Precision Decisions have dealt with the Stephensons from an initial meeting through the N-Sensor workshops in the early New Year and continuing, as part of our follow up service. We then spoke to them after harvest to find out how they had got along with this new piece of variable rate Nitrogen technology.
One of the first things that Keith Stephenson (Senior) mentioned to me on the phone was a comment from their combine driver David Stephenson “An unbelievably better harvest”. Keith then said “we are entirely happy with the performance of the sensor during this first season”
After these comments I thought it would be worthwhile going to meet with the Stephensons to gather more information about their experiences.
When we met again at Northfield Farm, David and Keith took me through their experience with the N-Sensor through this first season, and then went on to show me in more detail how well it had performed through Biomass and N–Application maps as recorded by the sensor.
Whether on OSR or cereals, they felt that the N-Sensor had performed as promised. Within a short time, particularly by second application, they had passed through “the sceptical stage” as Keith said, and could see from the maps, particularly the Biomass ones, that the crops were being evened up across the fields. They used the N-Sensor in Absolute mode on OSR, and both Target and N–Application mode on cereals depending on circumstances in the field.
Having attended the N-Sensor workshop at Lincoln Showground in January of 2016, they found the learning and familiarisation process when first using the sensor a little daunting. Once up and running the Stephensons settled into the mind-set of letting the N-Sensor “do its thing”, even though at times this may have seemed a little counter intuitive based on past flat rate experience.
By the second application of Nitrogen, the difference on the maps of Biomass and N-Application was quite evident. The first variable rate application had removed a huge amount of growth variation, and evened up the crop across different soil types within the same field. On the first application the sensor was up and down on its rates as the field was driven, but on the second application there was much less rate variation and a more consistent rate.
As the growing season progressed, which wasn’t not one of the best due to low levels of sunlight throughout May and June, both Keith and David could see just how even their crops were looking. This visual impression was confirmed by Biomass maps recorded by the N-Sensor.
Harvest time proved what they thought to be the case. Overall the harvest was by far the smoothest they had ever experienced. David was particularly impressed by the way that the combine drove. The much more consistent crops reduced RPM variations and header height movements markedly. Overall even-ness of the crops made the whole “harvest unbelievably better” from previous years.
Since 2004, when David started driving the combine for Stephensons, one field (R36), has a particular area at ‘Wood Corner’ that when flat rate N applied, even with manual variation in previous years, it has always suffered lodging. This year there was no lodging here or anywhere else on the farm.
Overall, taking a poor growing season into account, the Stephensons feel that the N-Sensor has contributed to at least 0.5 tonnes/ha additional yield on both OSR and cereals.
David went on to say that the N-Sensor “has definitely paid for itself during this first year of operation, in increased yields and a much easier harvest”. He went on to say “it’s not necessarily about saving costs or reducing inputs, it’s about maximising the effective use of Nitrogen by putting it where it’s needed”
Another benefit they noticed was, “A much reduced need for growth regulators on specific areas”. Looking at a couple of fields in detail shows what an improvement the N-Sensor has made in increasing yields, ironing out variation, reducing lodging and improving the combining process.
Field R36 – Wood Corner. Biomass Map 1, WW 30-04-16 Biomass Map 2, WW 19-05-16
Note the dark green area Relative Biomass >7.5 at April 30 2016 just to the east of Wood Corner.
This is the area (approx 2ha) mentioned above that has lodged every year since 2004 until this year.
Note standard deviation figure in Map 1 is 0.61, reduced to 0.39 in Map 2 dated May 4 2016.
Corresponding N-Application Maps for Field R36 showing how the first application markedly reduced
the variation in N-Applied at the last application. Standard deviation lowered from 8.3kg N/ha to 3.9kg
Field OH2 ‘Battenberg’ Biomass Map 1 WW, 01-04-16 Biomass Map 2, WW 20-05-16
Known by the Stephenson as ‘Battenberg’ field, OH2 has always yielded variably in four discrete
areas when at flat rate. After variable rate N applied this season the field became far more
homogenous with standard deviation of biomass figure reducing from 0.50 to 0.31.
Corresponding N-Application Maps for Field OH2 showing how the first application markedly reduced
the variation in N-Applied at the last application. Standard deviation lowered from 8.1kg N/Ha to 3.9kg
TOTAL AREA OF Oil Seed Rape 2015-16 – 300Ha.
Figures in the red boxes show range of Kg N/Ha applied to OSR fields. From 59 to 111 kg/ha. David commented that in the past they would never have gone above 88 kg/ha as a flat rate.
Note figure in the green box of 85 kg/ha for the total average across all 300ha. This shows a small reduction in total N applied over the previous target rate of 88 kg/ha.