CS vs 750a – The Grand Finale

The end is almost nigh. On October 20th 2015 we found ourselves with a Cross Slot and a John Deere 750a in the same field, at the same time, drilling the same crop at the same seed rate. What better start for a test that had been much debated amongst all the saddo internet farmers (myself included).

A rare sight

A rare sight

Over the following months I published updates on plant counts, tiller counts, and then finally ear counts. In the middle were some stitched drone maps, and visual analyses. In case you missed them all, here’s a comprehensive list.

Day 408 – Cross Slot vs 750a

CS vs 750a Xmas update

CS vs 750a new year update

CS vs 750a early spring update

Cross Slot vs 750a super spring special

750a vs CS May data

CS vs 750a June Update

CS vs 750a: The Penultimate Post?

Anyway…harvest is almost done here now, we are just waiting for the spring beans and spring linseed to be ready. All the wheat is done, it was a rather disappointing year, with an average yield of 9.1t/ha, slightly below our long term average. The two fields which looked worst all year, both growing Reflection wheat, actually ended up yielding the best. One of them was this field, with a final result of 10.41t/ha. Incidentally, the other field, drilled three weeks earlier, yielded 10.73t/ha.

The Boring Bit

Of course, it would have been stupid to go to all this trouble, and then not get an accurate yield from the different drill areas. So that ruled out using our combine, and our kind neighbours at KWS came to the rescue with a plot combine.

It meant making a bit of a mess of the field with wheelings all over the place, but we ended up with a set of plots at both ends of the field ready to be cut with a small combine

It meant making a bit of a mess of the field with wheelings all over the place, but we ended up with a set of plots at both ends of the field ready to be cut with a small combine. It is possible to see the 750a plot which is a different colour to the CS and CO8 areas

What we decided to do, after consultation with the trials experts, was cut six strips for each drill, at each end of the field. We took three each from the boundary of each drill’s plot, so we could compare them directly with a different drill only a couple of meters away. I think it’s easier to make a picture actually:

The blue area is the CS, the red 750a. I have put an X everywhere we cut a plot. This picture is is not to scale, it's just give an idea of what I'm talking about.

The blue area is the CS, the red 750a. I have put an X everywhere we cut a plot. This picture is is not to scale, it’s just give an idea of what I’m talking about.

Obviously we did not cut any tramlines, and all the plots were either 10 or 12m long, and 1.5m wide. The same method was used on both the light and heavy end of the field, giving us 12 plots per drill, and 36 in total. I did end up moving the heavy plots up the field by around 100m to get out of the black grass, which could have affected the data. The combine measures weight, moisture and bushel weight. All yields were corrected to 15% moisture.

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The Interesting Bit

We all know from watching Who Wants To Be A Millionaire that the wisdom of crowds is infallible. So when I made a Twitter poll to see what people thought the results were going to be in this experiment, I was not surprised at what came out of it:

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But the crowd is wrong. Because yes, that deafening sound you can hear really is the STATISTICALLY SIGNIFICANT RESULT klaxon. Let’s cut to the chase, so everyone who doesn’t want to read on can go home:

The 750a produced statistically significantly higher yields than the other two drills

At the end of this post I will put an appendix with all the data, so anyone who has too much time (I’m looking at you Sills) can do whatever they want with it. For now though, here is a summary.

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Clearly there is a big difference between what happened at the light end vs the heavy end of the field. Not surprisingly, there is no significant difference at the heavy end between the drills. At the light end it is a very different story, with the 750a yielding around 0.8t/ha more than the other two drills. If we talk about just the top end, the result is highly significant, with p<0.001. For those people like me who have forgotten their A level maths, this means that there is a less than one in a thousand chance of the results being from coincidence rather than an actual effect.

When we combine both the results from both the light and heavy parts of the field, we find the 750a has a yield benefit of 0.4t/ha. This is still statistically significant, with p=0.023, meaning there is roughly a one in forty chance the results are coincidental. [For reference, anything with a p value of less than 0.05 is considered to be statistically significant]. It is this result which leads me to the conclusion I wrote at the start of this section, which is that the 750a has produced significantly higher yields.

The other data that came out of the experiment was the bushel weight for each sample. In short, there is no correlation between drills or yields and bushel weights. Here’s a pretty scatter diagram. You’ll find a statistical analysis of drill vs bushel weight at the end.

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What this all means

I think the first thing to point out is that these results are from one season, in one field, growing one variety on one (maybe two) soil types. What I’m saying is that they are by no means the definitive “answer”. However, I’m not aware of any other trial that put these two drills up against each other in a fully no-till situation. Certainly there is not one that has been done in UK conditions. So for now it is as good as we have got.

I do wonder what has actually caused the yield difference. For me it can only be one of two things. Firstly there is row width – which was significantly narrower on the 750a than the other two drills. Secondly there is establishment and plant populations. The 750a did much better on these numbers; I suspect they would be statistically significant, but the analysis hasn’t been done yet. I think though that once a seed is in the ground at the correct depth, and has germinated, any effect from the drill is finished. On that criteria, the 750a has clearly performed the best.

Where does that leave the Cross Slot? As I outlined in the first blog post, it is much more expensive to buy than a 750a, at around 2.5-3x the price per meter of drill – for much wider row spacing. If you felt that this was a problem then it is possible to go closer, but it will cost even more and take more pulling. The running costs also seem to be much higher as well. All of this pales into insignificance if a higher yield can be achieved, but…

I do not believe for one second that in every year in every situation this result would be repeated. What I do believe to be more likely is that sometimes the 750a would win, sometimes a Cross Slot (although possibly the row spacings would need to be matched to even things up fully). That’s all nice, but I can’t see the point in paying a lot more money to not get a performance increase.

After the plot combine had visited

After the plot combine had visited

There are of course some USPs to a Cross Slot. They are very well built, and will no doubt last a long time. The ground I saw in NZ was amazing, with huge boulders not an uncommon sight. Our farm, though, is real boys land in comparison. Our current drill is 16 years old and still in great shape. A second USP is the very large, 50cm, range of vertical travel for the coulters. Again, great on the rough NZ pastures, but not something we need. As for the whole point of the Cross Slot opener, which puts the seed in a high humidity slot – I have no reason to doubt that it happens. But how often is a lack of moisture at establishment a problem for us? Very rarely in a no-till situation, even with a basic tine drill.

So all in all, on our farm, in our conditions, I personally do not see a need for these characteristics. In the absence of any evidence of a yield benefit, I couldn’t see wanting to buy a Cross Slot. This may well be different on someone else’s farm in the UK, I have no idea. But spending this amount of money without trying it first in your own conditions, is in my opinion totally nuts. You pays your money and you takes your choice…

And the John Deere? No doubt a good drill, it was clearly the best performing in this trial, from day one through to harvest. Is it any better than a Sumo, Weaving, or any of the others? I don’t know. What it does have going for it is a proven track record and strong residuals. I can’t help but feel it may be getting a bit left behind in technology though, as the design is basically unchanged in two decades. That could be a good or a bad thing depending on your preferences.

So there we have it. I still can’t quite believe we got a Significant result, I would not have ever predicted that. Not too bad for a farmer trial. But was it really a farmer trial? I had a lot of help: Ian for providing the Cross Slot, Huw at Ben Burgess for bringing the 750a. Christina and Robert at ProCam for spending hours counting plants, tillers and ears. John, Kim and Ed at KWS for organising the harvesting and yield measurement, and doing the stats. Thanks all.

Walston Out.

[PS Please do not use any of this blog or the data in it without asking first]

Appendix

CSvs750a Raw Data

Stats Analysis

CS vs 750a: The Penultimate Post?

I’ve just had the data in for ear and grain counts. I have multiplied them up using an assumed TGW (thousand grain weight) of 45g. I’m going to go out on a limb and say they will not be very representative, although I hope very much to be proved wrong!

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I think harvest will be in roughly 10 days. I have one concern at this point which is there has been a lot of spring germinated black grass at the bottom (heavy) end of the field. I am going to have to try and select a strip for cutting the trial plots that does not have any BG in it, because it is at levels that will affect the yield. I think this will be possible, but it will probably mean not cutting in exactly the same areas the the plant counts have been done in. Luckily there are no weeds at the other end of the field, so we should get on well there.

750a vs CS May data

Small problem this month, in that the person doing the plant counts on the heavy end had a GPS problem, and couldn’t find the stakes marking the count plots for the 750a and CO8. This month’s data from those plots is marked in yellow, and was taken from a similar area. The heavy land CS plot and all the light counts are in consistent locations.

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Cross Slot vs 750a super spring special

Unfortunately spring hasn’t really sprung yet, but hopefully it will soon. Regardless, here is the latest tiller count data from the drill trial. Same old same old.

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If you’ve read recent posts here you will know about the drone I’ve bought. It may have had a slight altercation with a tree, putting it out of action for the time being, but before that I made a map of the drill trial field. Here it is, along with some more photos taken the same day, but from a somewhat lower altitude. You can click on any of them to get larger versions.

Here is a large version of the whole field photo. Aside from the different drill areas, which will be explained in the next picture, you can see in the top left quadrant a zigzag darker line where we did not spray any Pacifica (a herbicide for killing grassweeds). Alo in the bottom left you can see the remains of some sort of Roman or bronze age settlement.

Here is a large version of the whole field photo. Aside from the different drill areas, which will be explained in the next picture, you can see a zigzag darker line running from half way up the left side to halfway along the top. This is where we did not spray any Pacifica (a herbicide for killing grassweeds). Also in the bottom left you can see the remains of some sort of Roman or bronze age settlement. A stream runs along the bottom, curved, headland and we normally get some flooding, which is what the brown patches are

I tried, and failed, to make some sort of clever overlay of this info on the previous image. The blue section is the Cross Slot area, the red is 750a. Everything else is CO8. The 750a area is very obviously different to the other two, which are indistinguishable. From this perspective the crop looks pretty ropey, so I went down to ground level and took the following photos, the locations of which are also marked on this image

I tried, and failed, to make some sort of clever interactive overlay of this info on the previous image. The blue section is the Cross Slot area, the red is 750a. Everything else is CO8. The CS and CO8 are indistinguishable, but the 750a area looks distinctly different. From this perspective the crop looks pretty ropey, so I went down to ground level and took the following photos, the locations of which are also marked on this image

1 - CO8. Looks much better from the ground!

1 – CO8. Looks much better from the ground!

2 - Cross Slot. Looks similar to CO8, not surprising given that all the numbers match up too

2 – Cross Slot. Looks similar to CO8, not surprising given that all the numbers match up too

3 - The Cross Slot / 750a seam. There was a little bit of overlap between the drills here, so the difference is not as apparent as I thought it would be

3 – The Cross Slot / 750a seam. Is it slightly lighter green than the Cross Slot? I wonder if that could be due to the same amount of nitrogen divided amongst a greater number of plants & tillers.

4 - 750a. Slightly less ground visible, but the difference seems much smaller down here compared to from the drone

4 – 750a. Slightly less ground visible, but the difference seems much smaller down here compared to from the drone

5 - 750a / CO8 seam. Not a very good comparison because of the coincidental tramline it landed in. Still - not a massive difference though

5 – 750a / CO8 seam. Not a very good comparison because of the coincidental tramline it landed in. Still – not a massive difference though. Again, 750a looks maybe a slightly lighter shade of green

So there we have it. Until next time.

CS vs 750a Xmas update

It’s about 6 weeks since drilling, and the field is looking good, with only a small amount of blackgrass. Excellent.

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The 750a (left) / CS (right) seam, November 13

The nice people at ProCam have set up some plant population experiments for me, and have now performed two counts. At one end of the field (slightly lighter soil) there are 10 sample locations for each drill, so the results should be statistically significant. At the other, heavier, end we have just got one sample site per drill. The first set of results were interesting, but it turns out that there had been a bit of an error, and the varying drills’ row widths had not been taken into account. In a nutshell, that’s bad news for the CS and CO8, as their plant counts had been overstated by around 45%.

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The CS plots being counted, December 4th

Let’s get on to the data. Remember, all drills put seed on at the same rate, which was 225kg/ha AKA 480 seeds/m2. Here’s the lighter land bit, with 10 samples per drill:

light

And the heavier bit, with just the one sample:

heavy

Clearly, the 750a has managed quite a lot better rates of establishment than the other two. There has been slug activity, which probably explains the decreasing plant counts over the last month; the heavier section was pelleted, the lighter bit was not. The differing growth stages are interesting, but at this point, I don’t know what is “best”. Could it be the CS is the lowest disturbance, and less mineralised N means slower plant development? That’s not what a certain S.Townsend preaches, but I have no idea if he is right or not.

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33.33cm x 33.33cm

My personal feeling is that the differences in growth stages will even out by the time summer comes around. Luckily we will be measuring the yields scientifically (and hopefully significantly), and that, as always, is what matters here.

Next update in the spring.

Day 408 – Cross Slot vs 750a

[This blog post will be of no interest to anyone sane]

I don’t think my Nuffield report mentioned hardware once. It’s pretty well incidental to the bigger picture, but that is not to say we don’t all like arguing about it anyway. Way back in March 2014 I went to visit Cross Slot in NZ, and since then have…participated…in the long and tedious debates that seem to crop up every time the drill is mentioned. The main point in summary is that the drill is incredibly expensive, and its ability to create extra yield to mitigate this is, depending on your viewpoint, unproven.

I have been trying since September 2014 to get a Cross Slot on this farm, so that I could see it with my own eyes. I had pretty well given up getting anywhere, when an opportunity arose not so long ago. There are now a handful of drills floating about this country, and one was based not far away. All it took to tempt it over here was a chequebook – it seems that demos are not possible or deemed necessary by the dealer. I had never intended to perform a trial, but it seemed like a good opportunity to try and get something done, and luckily John Deere stepped up at very short notice to send one of their machines. I had really wanted to get a Weaving GD as well, but that also proved impossible.

IMG_5774Anyway, 408 days after I first tried, a Cross Slot finally turned up at the farm. We had a few fields of wheat left to drill: mainly second wheats, but also a large field that had been peas. One second wheat field was split in half, and drilled with both our normal Horsch CO8 with narrow points, and the other half with CS. The pea field was drilled mainly with the Horsch, but one 8.8ha gap was left in the middle, which was the right size to allow two drills to put in a tonne of seed each, side-by-side. Let battle commence.

The field

At least half our farm is super easy working light/medium soil. Any drill will produce good results. The trial field is however just about our heaviest. It is classified as clay (54% clay, 30% silt, 16% sand), but is relatively easy working because there is so much calcium in there from the chalk subsoil (87.6% Ca vs 3.7% Mg). There was plenty of moisture in the soil, but still just dry enough to drill. Even so, a Horsch prototype single disc direct drill could not actually get in deeper than about 10mm when we tried a few weeks previously. As far as this farm is concerned, if a drill works here, it will probably work anywhere else.

The Cross Slot

This was a 5m drill, with 21 openers, giving a 238mm row spacing. What is really incredible is the weight in such a physically small looking drill. 12t empty is almost unbelievable, but is accomplished by filling the frame with tiny bits of steel. This gives a theoretical pressure per opener of 571kg. Massive. There was a 280hp Claas tractor on the front.

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The John Deere

The elder statesman of direct drills. Well proven, but still flawed. And seemingly unloved, until this year at least, by its parents. The opening disc is much smaller than the Cross Slot, and the drill itself is much lighter, at 6.3-6.8t depending on how much ballast is added. This particular machine had none at all, which gives a theoretical pressure per opener of 175kg at a row spacing of 167mm. The standard closing wheels are often changed by owners, and here we had one side with originals, and one side with Guttlers. The tractor was a 195hp John Deere.

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Doing the job

As it happened, the timing was totally perfect and both drills started off within minutes of each other. With only a tonne of seed to do each they wouldn’t be around for too long either.

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Both machines were already set up for drilling wheat at around 30-40mm deep. The following are some of my thoughts from what I saw.

Left CS, right 750a. This is fairly subjective, but I would say there is more disturbance with the 750a. HOWEVER i think this is due to there being 50% more openers per meter with the 750a, I would rate the disturbance per opener as being very similar

Left CS, right 750a. This is fairly subjective, but I would say there is more disturbance with the 750a. HOWEVER I think this is due to there being 50% more openers per meter with the 750a, I would rate the disturbance per opener as being similar

This is seed placement from the John Deere, which was nicely consistent. It seemed to be penetrating with no trouble at all, and with no ballast. I was very surprised at this after the Horsch DD could not get in at all with 25% more weight per opener. Both types of closing wheel were doing a decent job, but the Guttlers did seem a little better perhaps

This is seed placement from the John Deere, which was nicely consistent. It seemed to be penetrating with no trouble at all, with no ballast. I was very surprised at this after the Horsch DD could not get in at all with 25% more weight per opener. Both types of closing wheel were doing a decent job, but the Guttlers did seem a little better perhaps

The CS also placed the seed well, but I was slightly shocked that at one end of the field which required every gram of the 12t to get in. You can see in the video below that there was no weight at all going through the drill’s wheels whilst it was in work.

I find this very worrying given that the conditions were soft. In a dry autumn I really doubt that no-till would be possible on these heavier fields with this drill.

Here are a couple of slo-mo videos of the drills working. Obviously the CS one I took in the wheat stubble from the first field it drilled. There looks to be a lot more soil throw from the 750a, but it’s much looser in pea stubble compared to wheat, so not a fair comparison. I should have got a video of the CS in the peas but ran out of time.

The details

Here are some numbers that came up after the trials were done. I’ve added in our current drill for fun.

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And now for some financials. The purchase price for the CS is a bit of an estimate based on a few things, one of which is a quote I have for a NZ made machine which came in at £175,000 for a 6m. Running costs are averaged out from multiple owners I have spoken to for both machines. I am assuming 1,000ha of drilling per year, for 10 years. To begin with I was going to try and estimate depreciation and use that cost, but then I started thinking about the extra finance and opportunity costs involved in buying more expensive machinery, and decided it was too complicated for a simple soul like me. So I have just gone with dividing the initial cost over the full term.

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So we are looking at a difference between the 750a and CS of around £20/ha, otherwise known as about 2% wheat yield increase at current prices. [BUT very importantly, don’t forget that these are very different machines in terms of output, so to match up here would require a hugely more expensive CS setup].

What next?

I’m not sure how scientific this will get. It would be good to take plant and head counts as the year goes on. Obviously the real result, and the only one that matters here, is yield. I have some ideas on how to measure this accurately, but it will depend on some people being generous with their time and machinery. In the meantime all I can do is wait and see what the emergence looks like.

Conclusions(?)

Both drills put the seed in the ground (just) and covered it with soil. I can’t see any reason at this point in time why one will give a better result than the other. I am struggling to see why for me, on this farm, at this time, there would be a benefit to spending more money to get a drill with a lower workrate that is more expensive to run. CS has a big potential benefit in that it can reduce hair pinning compared to a 750a when going in to cereal straw stubbles. For me this is not relevant as I would keep a tine drill for those jobs (cover crops and OSR mainly). CS also has incredible vertical travel on the openers (14″ IIRC), but that is about 12″ more than exists on our fields. The same goes for durability; CS has shown it can handle super rocky conditions, but then we do not have those. We farm very soft land, and some people have put tens of thousands of hectares through their 750as without much trouble (unlike this guy!).

Maybe though we will see what CS says we might, and get a 13-23% yield increase:

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