Day Five

I’m now at the geographical apex of my tour of the north island.

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Murry Lane is a technical extension officer at one of the big local co-ops, and he was kind enough to put me up for the night. He used to work for Monsanto, and is a big fan of biotech in all its forms. Having been at Monsanto during the advent of Roundup, he has some pretty strong views about its use, in particular selecting for resistance in weeds. We have been guilty at home of using multiple small doses of glyphosate to control blackgrass, on the advice of a certain local agronomy company. I’ve been worried about it for a few months, but the more I hear the more I’m certain that we will have to stop. We cannot afford to have Roundup resistant anything, and the methods we have been told to use seem to be designed to select for exactly this. I’ve met a few of my contemporary scholars from Australia who are using Roundup Ready crops, and some of their fields get 8 applications per year. Is it surprising that they now have a big problem with resistant weeds?

Murray’s current job has him working with fertilisers, and he was keen to show me some trials they had done on using DAP as a placed starter in turnip crops for grazing.


This is a pretty striking result, although I suspect there may be some cherry picking going on (sorry Murray). Apparently neither straight urea or straight TSP had the same effect, so he is sure that it is a combination of both the nutrients together, and the specific form they are in. However, Murray did admit that in the end the non fertilised crop did catch up – but if you wanted it to grow quickly for grazing, it could be very useful. It is also easy to imagine that weed pressure will be a lot less in the denser crop.

No-till : Strip-Till : Disc & power harrow

No-till : Strip-till : Disc & power harrow

A quick visit to a maize trial site run by the Foundation for Arable Research showed a very good, if unsurprising, example of different tillage regimes. They have been growing continuous maize for 4 years, using no-till, strip-till and disc/power harrow techniques. Looking at the picture above, you don’t really need the captions to see what’s what. I have not seen the data (should do next Friday when I visit FAR in Lincoln), but I am told there is no yield penalty from no-tilling on this site. By the way, these photos were representative, I didn’t pick specific good or bad bits.

Today’s farm visit was with Geoff Scott, who has a 300ha dairy farm about 45 minutes south of Hamilton. He milks 600 cows, soon to be 750 when his new rotary milking parlour is finished. The farm is in a micro climate, and gets 2000mm of rain annually, however, there has not been any real rain now for 2-3 months, and the whole area is DRY. There are tonnes of dairies around here, and they must be getting through some serious silage at the moment, as there is no grass to be seen. The soil here is very unusual, as it is an ash loam, with a particularly low bulk density, of about 0.5g/cm3. This is 33-50% of a normal soil, so it feels oddly light in the hand.

Top soil/sub soil horizon

Top soil/sub soil horizon

I arrived to find pastures being reseeded with a John Deere 750a. This drill had a few modifications, will will be of interest to some, and deadly boring to everyone else.

Hiab for seed bags

Hiab for seed bags

Split seed/fertiliser bin

Split seed/fertiliser bin

Weigh cells

Weigh cells

I won’t go into the details of each of these as they are pretty self explanatory. What was interesting was talking to the contractor, Greg Muller, about it, and how it compares to his main drill – a Cross Slot. First of all, he charges NZ$115/ha for drilling with the 750a, and NZ$230/ha with the CS, mainly because the work rate on the CS is about half, and also it needs a significantly bigger tractor to achieve it. Almost all the drilling he does is either grass seed, or turnips. [Edit – He actually charges NZ$155/ha with the 750a when done with seed, fertiliser and slug baiting. This compares to NZ$190/ha with the CS in the autumn, and NZ$230/ha in the spring]

For overseeding they will always use the 750a, as the CS can be too aggressive, and actually leaves strips of dead grass where the roots have been chopped up. In the autumn, when the ground tends to be drier, the 750a works very well, but Greg believes that in the spring it can have a tendency to leave slots in the damper conditions. This is a well know concern for these type of single disc drills, although maybe they would have better luck with more aggressive closing wheels, like the Guttlers? He feels that the CS is better in the spring, and  it will provide significantly better germination, especially with turnips. I got the impression that the main drawback to the 750a was really the slot closure, which is exacerbated by drilling into a thick grass root mass. Into looser or cultivated soil, Greg says that the 750a is at least as good, apart from one thing…

Greg has made one of his USPs being able to drill fertiliser, which the CS specialises in. He is a firm believer that this is really necessary. However, it again comes back to the question of establishment vs yield. He will admit, like Murray, that in the end the non-fertilised crop will catch up. So I think that there is perhaps mileage in using it for grazing covers, but I remain skeptical about grain crops – unless you care more about cosmetics than financials of course…! When I asked about yield, he quoted an example where conventional tillage yielded 6t/ha of turnips, the CS 12t/ha, and the 750a in between. Anecdotal, but some big differences. Again though, this is a dry matter yield over a few months, and so does not really bear relevance to what a grain yield may be after a full growing season.

What was really incredible to me was how much fertiliser goes onto the turnips here. 300kg/ha of DAP, and then 200kg/ha of urea top dressed. I make that about 150kg of N and 140kg/ha of P2O5!!!

IMG_2576Before I left, we dug a meter deep hole with a mini digger. Murray had been told that turnip roots go down 800mm, and he wanted to see if it was really true. Turns out it is!

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