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LAMMA 2019

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Making the most of your fertiliser input

Fertiliser prices may have come down from their historic highs of a few years ago, but may still appear expensive in our current constrained times. Peter Hollinshead talks to independent consultant Dr George Fisher about how to make best use of this valuable commodity.


We have constantly been told grass is the cheapest feed for dairy cows – to what extent does this still hold today with wheat at £110, some £25 less than a year ago, and soya down to £260/t, which is nearly £60 less than a year ago?


Regardless of those figures, we are looking at 10-11p to produce a litre of milk from proprietary concentrate compared to 3.5p for grazed grass and something like 6-7p from silage. But with some crops like fodder beet and maize we can get a litre of milk from those for below 3p a litre. So there are alternatives which can be cheaper than grazed grass depending on the system, but generally speaking grazed grass is the cheapest.


But fodder beet would require specialist machinery and maize can be very variable depending on the year, so is your figure an average one or what?


If you can grow 20t maize dry matter per hectare with over 30% starch value, and get 85% of what you grow into the cow, then you can produce milk off that maize for less than 3p per litre. In a bad year, though, you may have to double those figures.


But grazed grass is consistently around £50-60 per tonne DM to produce, first cut silage around £80 and second cut around £120, but because they tend to be more consistent they are more stable in a price comparison.


While grazed grass may be the cheapest, you do have those harvesting costs as well, don’t you?


Yes, those costs I have given you include all the field operations such as sowing, fertiliser, harvesting, storage and feeding costs, but obviously for grazed grass they tend to be a lot less than something like fodder beet or maize, so the input/output for grazed grass can be consistently the cheapest over time while these other crops may be cheaper some years but not others.


One of the drawbacks with grazing situations is the variability in the fact DM changes, weather changes and cows may be sheltering rather than grazing on wet days, and it is difficult to ensure you are getting that required input into them?


Yes, it can, but the guys who are doing it most successfully are out there measuring grass every week, they know what is left in the paddock cows come out of, what is in front of them, and they manage that intake as best as they possibly can.


We see more and more cows housed all year round – presumably that’s majorly because it allows control over intakes and offers dietary consistency?


It depends on how you want to produce milk – I don’t mind if you are producing milk from grazed grass or silage and crops, but everybody should be targeting to get at least 4000 litres from grass and forage in order to put a good profitable base into the production system because they are the cheapest inputs.


Just to clarify your position, you are an independent consultant and do a lot of work for CF which has taken over the sites at Ince and Billingham, but I should imagine even you haven’t seen crude come in at under $30/barrel – can we expect fertiliser prices to plummet?


I am an independent consultant and I’m helping CF at the moment on the technical side of their grassland business.


In terms of prices we haven’t seen anything like these oil prices for a long, long time. Compound fertilisers are significantly less than this time last year and, having said that, the main driver for prices will be demand.

So do you think prices will come down further if the urea market declines, and should people be ordering now or waiting a bit longer?


I would advise farmers to manage their risk as markets today are very volatile and they need to weigh up the pros and cons of buying just in time or planning ahead.


Are dairy fertiliser sales pretty desperate at the moment as farm incomes have been severely hit?


Fertiliser purchases have been delayed in the last six months or so for both arable and grass, partially because of the lack of cash on farms and in part the late payment of the BPS, but there are some dairy farmers on aligned contracts who are not so cash strapped so the slowdown has not been across the board.


Now everybody is currently concerned about sustainability – do these ‘artificial’ C, H and N atoms simply appear as nitrous oxide and methane further down the road?


Well, we have NVZ and Nmax in terms or slurry and manufactured fertilisers, so dairy farmers shouldn’t be putting on any more than 300kg N/ha with those regulations. Now dairy farmers are using 50% less bagged nitrogen than they were 20 years ago and 60% less phosphorus, and I think they should be congratulated as they are producing the same amount of milk for fewer inputs, and they are therefore more efficient and sustainable.


Yes, we may be making better use of home-produced P and K, but you still advocate putting more P on in particular, don’t you?


I think we need to put the right fertiliser on for the right circumstance. We know perennial ryegrass will respond to early phosphorus applications, particularly where there is not a lot of P already in the soil. So I am an advocate of using it in spring as we need to get as many tools in our kit to boost spring grass growth as much as possible as that is our opportunity to get the cheapest feed for the farm.


Just on the phosphorus element in particular, is there a question of its mobility in the soil and the need for adequate rainfall and temperature for it to be utilised?


Yes, there is, so where you put phosphorus on it will only move a matter of millimetres in the year from where you applied it. So the better the spread with phosphorus the better access the plant roots have. It’s not so much rainfall with phosphorus as temperature and placement.


We’ll come back to rainfall later. There’s also a lot of talk about field sampling – does it give a true reflection of soil status or is it not that accurate?


It is worth soil sampling, as if you don’t know what you have in the soil you don’t know what to put on in terms of manures and fertilisers to get the most out of the system. The soil sample must be representative of the field and if there are issues it is around the accuracy of sampling.


What I don’t like to see is farmers being duped into spending £100-150 on an all singing and dancing soil sample which doesn’t add anything to the system other than what they could have got by spending £10-15 per field on a basic pH, P, K, Mg soil sample.


Farmers should be sampling every field at least once every three years.

And where would they get that cut-price soil sampling from?


Well, a lot of merchants and distributors will have access to soil sampling services whereby you can either pull someone in to do it or do it yourself.


Farmers should be sampling every field on the farm at least once every three years, so every year you should be doing a third of the farm as things do change and knowing the fertility of the soil really is the basis of the system.


That £10-12 a sample is a composite sample of each field with five or six subsidiary samples, is it?


That is per field price so you need to take a number of samples around the field and mix them in one bag and that will cost £10-15.


Which brings me on to the other couple of things I wanted to ask you – the first is sulphur. This has been talked about for a good while as industrial deposition has declined – now it may work well with OSR but does it work the same magic with grassland?


Yes, it is an old story and I see a lot of farmers who should be using sulphur but aren’t.


The amount of sulphur coming out of the sky is now negligible and I am seeing farmers getting responses to sulphur now, not just on lighter soils and after cuts but on medium and heavy soils from first cuts onwards.


We can get yield responses of anything from 15%-30% and increases in grass protein content and water soluble carbohydrate content through using sulphur of around 5% in each of these cases. I am not saying every farmer should use it but we are still not using enough sulphur in dairy production in the UK.


Is it a costly thing… what’s the return there?


Actually a fertiliser with sulphur often won’t cost any more than one without, but it will have slightly less N to make room for it. In terms of fertiliser per acre it will be £10-15 per tonne more but if you produce another 2t DM/ha the return on investment would be of the order of 1:15 or 1:20.


What role does sulphur play in the plant… is it part of the protein structure?


Protein is made up of amino acids and two of the essential amino acids contain sulphur as the central element – these are methionine and cysteine.


If you don’t have enough sulphur, you don’t have enough amino acids so protein production in the plants is not efficient. And protein is not only involved in plant growth but also in energy metabolism, and if you don’t get photosynthesis working efficiently then the whole growth system suffers.


And the other thing I wanted to ask you about is urea, which is sometimes controversial, as with 46% N against ammonium nitrate at 34.5% it must be a runner for most people, must it not?


I think there is more urea being sold into the grassland market now than perhaps at any time in my whole career, and I can understand that as, on a price per kg of N basis, it is cheaper than ammonium nitrate.


The challenge with urea is that you need the right conditions for it to work agronomically. You need at least 5mm and hopefully 10mm of rain in the three days after you apply it, and for temperatures to be as low as possible, not freezing but below 5degC, so you don’t get volatilisation of N.


Where you do get that volatilisation, grass growth can be reduced significantly. It’s a balance and if you get it right it can work but about 70% of the time ammonium nitrate will outyield urea.


So maybe it is best suited to the first application in early spring?


Yes, and that’s where a lot of people are using it, but even in spring conditions ammonium nitrate can outperform urea. We looked at a lot of weather data around the west of the country and even in spring AN, in 70% of cases, will outperform urea. But I can understand, because of the price difference, why farmers use it but it worries me that systems are becoming more dependent on urea because on average those systems will be producing less grass -- our cheapest feed – than if they had used AN.


Also, I’m seeing a surprising number of farmers using urea all through the season, particularly the grazing guys who have picked this up from New Zealand where they use urea that way, and that really is a no-no because volatilisation losses will be huge.


Those volatilisation elements… what is the difference in percent terms between urea volatilisation and that of AN?


With urea we can lose on average 24% and in some cases up to as much as 50% of the N volatilised into the sky. With AN there is some loss of N into the atmosphere, not through ammonia but through nitrogen dioxide, and that could be 1-3% of the N that you put on. There can also be leaching losses with AN, but providing you are operating the system well these are only 1-3% as well.


But if we really wanted to keep costs down we could use blends rather than compounds and they would save you a bob or two, wouldn’t they?


I generally find that farmers know that a good quality compound NPK or NPKS fertiliser will outperform a blend in terms of grass growth, and I think most would be prepared to pay £10-15 more for a true granular compound compared to a blend.


Really it comes back to that phosphorus issue and, because there is phosphorus in every compound granule, you get between 10-20 more P landing sites, that gives the plant roots more opportunity to get hold of that P and you get a better yield response from the compound compared to the blend.


Remember, although blends are around £10-15/t less than compounds, if you work it back in terms of extra grass there would need to be a difference of around £60/t between a blend and compound to compare them.


Right, let’s turn to a couple of practical aspects, the first one being rotational grazing. Is it a case of the first dose in February and then following doses every three weeks as soon as the cows come off?


With rotational paddock grazing it’s as soon as you pull cows out – and that should be around 1500kg DM/ha cover from your plate meter. You need to go on with fertiliser N as soon as you can either on the day they come out or the day after. That sounds like a bit of a faff but if you want to maximise grass growth and optimise utilisation you need to be that flexible.


Should fertiliser go on throughout the season almost irrespective of whether the sun is shining or whether rain is due?


Generally, yes. The two circumstances where we should hold off are if torrential rainfall is due then hold off until the rain has gone, and likewise if you get three to four weeks without rain and into a drought situation it is another time to hold off fertiliser until the rain returns.


What would you recommend for annual grazing grass application and also for cutting grass?


On the paddock grazing I’ve seen farmers doing very well with 200-250kg N per ha per year, and for the three or four cut silage guys it might be a bit higher than that at 250–280kg. But we must make sure we take into account the slurry and manure applications we make and farmers in an NVZ must realise the Nmax is 300kgN/ha and that is manufactured fertiliser and fertiliser N from slurries and manures as well.


Just finally, it looks set to be a tough year for most milk producers and that may mean cutting back on inputs – would you be arguing not to cut back on fertiliser as it will give you a bigger return that almost any other input?


We need to look at all costs but to cut back on N fertiliser and produce less grass is a false economy as the response to N fertiliser is somewhere around £10 for every one invested, so you really don’t want to be cutting back on that sort of return on investment.

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