Here’s my final Nuffield report. Just need to do the presentation in November and I’m free.
This is roughly speaking where I’ve travelled. It’s a little abbreviated in Brazil since that got too complicated to map easily. My time in South America is almost up, but there are a few more things to say, and random pictures to insert.
I met a guy from Embrapa yesterday who is running a program near Brasilia where they are comparing conventional and Organic dairy grazing systems. It’s only been going for three years, and I haven’t seen the data (he will email it to me apparently), but they are finding hugely more efficient fertiliser use under Organic management. At the start of the trial both treatments were given the same amount of NPK fertilisers. In the conventional system these came from urea, triple super phosphate and potassium chloride. The Organic sources were animal manures and soft rock phosphate.
In each of the three years there has been a 20-30% yield penalty (measured by tonnes of dry matter produced per hectare) with the Organic management. However, the critical point is that every year the conventional fertiliser must be reapplied in the same amounts, whereas the Organic field is maintaining its yields with only what was put on at the beginning of the trial. How long will that go on for? Who knows, but already after three years it’s a very interesting result. Whether it could be more profitable to grow crops like this, even without an Organic premium, I couldn’t say; it’s going to depend a lot on the value of the land you’re farming. But it does make you wonder how much of the artificial fertiliser we apply is just being wasted.
At a previous Embrapa meeting I was given some scientific papers to take home, and have only just had a chance to read them. One is particularly worthwhile, it’s called “Integrated crop-livestock system in Brazil: Toward a sustainable production system”. The data comes from a 16 year experiment comparing these treatments,
- CS – Conventional System using disc cultivation, growing soybeans with a winter cover crop
- NTS – No-Till System, growing a soya and maize rotation with winter cover crops
- ICLS – Integrated Crop-Livestock System growing two years of soya & cover crop and two years of pasture
- PP – Permanent Pasture
Here are some of the results that I think are notable. I’ve tried to keep it slightly readable.
- “the ICLS system treatment yielded soybean production that was greater than or equal to that of CS and NTS. This higher efficiency of ICLS system may be related to availability of P in organic form” – this tallies with the experimental results found by Embrapa Cerrados
- “Systems with livestock grazing had significantly greater MWD [this is a measure of how stable the physical soil structure is] compared to other systems (ICLS: 4.12mm, PP: 4.93mm, CS: 2.19mm, NTS: 3.18mm) … Ultimately, soils with greater aggregation characteristics are considered of better quality than similar soils with weaker aggregation, mainly because TOC [Total Organic Carbon] becomes physically protected in stable aggregates.” – see the famous Slake Test
- “Concentration of TOC, TOC storage, and POC stock were increased under grazing by livestock at the following order: CS<NTS<ICLS<PP … The labile fraction of organic matter was also greater in ICLS and PP, than in NTS indicating greater energy flux in the soil system. Greater SOM lability was attributed to the presence of the forage, which adds a greater amount of organic matter to the soil than cropping alone. Moreover, there is a continuous exudation of substances from grass roots to the soil during growth which is stimulated during grazing.” – Not very surprising. But it must be noted that of all the systems, it was the NTS which actually lost the most carbon overall. CS was stable, and the other two increased.
- Total microbial activity was greater in the order you would expect, PP>ICLS>NTS>CS – I’m paraphrasing here a bit.
- “Density and taxonomic richness of the invertebrate macrofauna [i.e. worms, beetles etc] community in soil differed among management systems. Lowest values were observed in CS, while ICLS was equivalent to that of NTS and PP and greater than that of CS … Soil macroinvertebrates perform numerous essential functions, including decomposition, nutrient cycling, SOM mineralisation, soil-structure modification, atmospheric-composition regulation, and biological control of pests and diseases.” – I think it’s fairly obvious by this point what direction this paper is heading in…
- Hold on, this is a long one: “Weed community analysis showed that areas without pasture and grazing generally accumulated more weed mass than areas that were periodically or continuously grazed. The area of soil covered by weeds was 87% greater in CS compared to the average of the other treatments. Generally, areas that were continuously or periodically grazed by livestock had fewer weeds than areas where only grain crops were grown. Livestock grazing also affected seed germination: weed seedlings from treatments that included grazing took longer to germinate and emerge from from the soil surface. Regardless of the presence or absence of tillage, crop-only systems exhibited larger areas of soil covered by weeds.” – Phew. I’ve never actually seen this information in a scientific context, and the figure they come up with (87%) is huge. Very interesting.
- “Occurence of Rotylenchulus reniformis [a parasitic nematode pest] differed significantly among management systems, with a much larger population in CS [1500x more than the next highest]”
- “In years with ample rainfall, soybean production was equal in the three grain-production systems. In years with poor rainfall distribution, with water deficits, ICLS and NTS exhibited smaller productivity losses compared to CS. In 2010/11, for example, CS yielded only 60% of crop production in other systems.” – No big shock here, there’s a reason all the really dry places in the world have gone to no-till. Although it’s amazing they get droughts here when it rains perhaps 1500mm in the growing season. In the tropical heat it doesn’t take long for it all to evaporate.
I’ve found this to be a useful paper, and to me it suggests that the oft-heard fear that having animals in a system is a drain on nutrients/soil fertility is not just unfounded, but actively wrong. Now who wants to lay some water pipe?
It’s certainly been an interesting trip, but I think I’ve run out of steam. The problem is that I’ve seen enough of the details – just look at how different the first blog posts from NZ are – and it is becoming increasingly difficult to find novel concepts. Particularly here in South America, the diversity in farming methodologies seems very limited, and largely defined by what area/climate you happen to be in. There could be two explanations for this: lack of imagination, or perhaps the farmers are more switched on to the research, and unlike back at home, they are all doing the “right” things already. It’s difficult (impossible) to tell, but I haven’t found the Gabe Brown/Coin Seis sort of guy who is trying something totally different… Well I do actually know one, the problem was that he refused to let me visit! The others are probably hiding somewhere not telling anyone about it. That’s a job for a future traveller.
It’s been great fun, but this may be the last Nuffield post. Ciao.
This is going to be a short post, as once again a South American quantity of overnight rain meant that we could not get out into the field. Okara is a company which specialises in using data, both Big and small, to inform land buying decisions for its investors. The idea is to find farmland that is under-valued, or under-utilised, and snap it up for a cheap price.
The first step is to use aerial photos, satellite data, weather recording etc etc to zone the potential land into discrete areas which they think should be similar soil types. This then allows them to go and take soil samples out of these representative zones. This should give a good idea as to the land’s potential, without having to sample everywhere, which would be prohibitively expensive.
In the example picture above, the entire farm (6,000ha or so) was being used for extensive cattle grazing, and was valued accordingly: $4,000/ha. Having performed an analysis, and come up with this map, they found that over half of that ground was actually good or very good for cropping, so their investor bought it.
And the value of cropping land in that area…$7,000/ha
Today was another INIA day, but at their HQ, with a researcher called Andres Quincke. Here they have been running a trial which is now in its 52nd year, they are looking at the effect of rotations on SOM levels. There are three continuous cropping treatments. Two use the same rotation: maize – barley/sorghum – wheat/sunflower – maize. The difference is that one has been run in a conventional system, and the other without using any fertiliser at all. The third continuous cropping rotation contains soya, sunflower & wheat, with cover crops every other year. This is new though, so there are (I hate saying that) no data yet.
The remaining treatments use the same cash crops (maize, sorghum, sunflower, wheat, barley) but have differing amounts of pasture – 33%, 50% and 66%. The results are clear and interesting, but perhaps not entirely surprising. Any rotation with pasture will have significantly more SOM than continuous cropping. As you can see from the graph above, the 50 and 66% rotations are getting on for double the SOM compared to continuous cropping, and the trend is still upwards.
We’re often told that adding artificial nitrogen fertiliser destroys organic matter, and I’m sure that’s true. In a lab. But in the field it is clear in this experiment that the opposite happens. That’s because with the fertiliser there is hugely more crop residue going back into the soil. That benefits not only the SOM levels, but also massively increases resistance to soil erosion. The photo below was taken in one of the plots with no fertiliser: this happens every year, and does not happen in any of the other treatments. “We have shown now that this rotation does not work, perhaps it is time to change it to something new” says Andres. This has further repercussions too – if tillage creates crops with more biomass, it’s feasible that these systems will produce more organic matter than no-till ones. Something to think about.
The other striking thing came from a trial within the trial. They decided to look at whether the pasture phases (which all contain legumes) meant there was more available nitrogen for the following cash crops. To test this they have made small plots within the main ones, and have treated a maize crop with zero, half, normal and double nitrogen rates (0, 60, 120 and 240kg/ha). In the continuous cropping plot (with fertiliser), the difference was huge, and the plants with no fertiliser were very yellow and sick looking. In contrast, in the 50% pasture rotation, there was no visible difference between any of them! This was pretty amazing really, but of course you’ve got to wait until harvest to see what has really happened. This is definitely our situation at home; we are addicted to nitrogen.
So far so good, but I have two main problems with this trial. The first is with the pasture phases. They have no animals involved. This is an issue because they actually have to bale and remove the residues sometimes, which will obviously reduce, at least slightly, the potential to cycle carbon back in to the soil. Another problem is that grazing can possibly (so says Kris Nichols) actually have an extra beneficial effect on soil fertility, which goes beyond the simple addition of what comes out of the back end of a cow. So although the trials show a significant benefit from pasture, perhaps the effect would be even greater with grazing added in as well?
And there is the elephant in the room…money. They have measured SOC, which goes up. Hooray – but how many farmers, outside the hard core fanatics, are willing to farm just for this? Yields also go up, when taken in isolation. I.e. in the same year, a crop of maize/sorghum etc will yield more in a pasture rotation than in a continuous cropping one. However, they have not modelled overall profitability. Of course this is very hard to do, just choosing what numbers to put in for the value of the crops and beef has a massive effect. But what farmer is going to be convinced to change their system when the researcher cannot tell them if they will make more money?
I’d only ever spent 3 hours in Uruguay before this trip, but for some reason I’ve always liked it. This time there was no queue at customs, my bag was the first off the plane (that’s a new one for me) and I could buy a cheap local sim card at the airport. A great start. Unfortunately I had not been able to arrange anything constructive for the weekend, so it was tourist time. After mucking around for a couple of days I headed to Treinta y Tres (which means thirty three), and spent the night in a hotel which was perfectly comfortable, but wouldn’t have been out of place in 1964 Bulgaria.
INIA is partly funded by the government, and partly by the farmers, through levies on their sales. They perform trials in both cropping and livestock management, as well as having big labs which will test grains, forage, or whatever the farmer needs. Their building was quite new, and very smart, in stark contrast to similar government organisations over the river in Argentina.
They’ve got some of the best soil in the country over here, but it’s only 30cm deep, with a clay subsoil. That means they don’t have a huge water holding capacity, and so are normally either too dry, or totally flooded. Traditionally there has been a lot of grazing, and that continues today. It’s one of the few places in the world where it is standard practice to graze both sheep and cattle in the same field at the same time. I’ve always thought this sounded like a pretty sensible idea, but all my (super conservative) vet friends start having a fit when you mention it.
They have two research stations near Treinta y Tres, for upland and lowland systems. The upland system is dry land farming, and they are testing three rotations. All the rotations have two years where they grow soya beans – wheat – sorghum – oat cover crop. At this point they differ: one starts all over again, and the other two go into pasture, either for two years or four.
On the lowland farms, the main crop is the rice. Uruguay is the second most productive rice growing country on the planet – only the USA averages a higher yield per hectare. On the low land INIA station they also have rotation trials, ranging from intensive rice – cover crop – soya – cover crop, to the traditional rice and perennial pasture.
The cover crop they tend to use in this lowland trial is Italian ryegrass. What’s really interesting is that they put it on with an airplane, both into the soya and the rice. Uniquely, in my experience, they are happy with the results, and say it gives a good even germination. This is understandable in the rice, as they put it on just after the field is drained, so there is plenty of moisture in the soil. In the soya it goes on about a month before harvest, timed just before the leaves start to fall off. When the leaf does come off, it covers the ryegrass seed and provides humidity to help germination. In both cases, after harvest the grass is 5cm or so tall, and gets going very quickly – to be grazed before the next cash crop is planted.
The trial results are interesting – SOM is maintained in all the rotations that include pastures, and degraded in the ones that don’t. However, they have only just started using cover crops in the last couple of years, and the hope is that this may make the continuous cropping more sustainable.
In the ’50s & ’60s no-till had not been adopted, and traditional farming methods were terrible at controlling erosion. The average farm lost 20-30t/ha of soil each year, into the rivers. Since the ’90s this has improved a lot, but in the last three years the government has decided it had to do something about the country’s soils – agriculture is a big proportion of Uruguay’s GDP. What they have come up with is a system whereby the landowner (and farmer if it is a different person) must submit their long-term cropping plans for approval. Trial data from INIA is used to predict how this rotation will affect the soil erosion, taking into account topography, soil types, climate, use of cover crops, pasture phases etc. The magic number is 7t/ha. If you lose more soil than this each year, you will not get approval to go farming (or else there’s a big fine). It sounds like a pretty sensible way of protecting the country’s asset, although given what has happened in the UK with the three crop rule (no one is telling ME how to farm!) I don’t think it would be a popular move – especially because here they often stipulate at least some pasture.
Of course it does beg the question, why settle for any soil loss at all? Apparently even with low intensity farming on native grasslands they still lose ~2t/ha/yr, but in the past something must have created the soil. Maybe God? In my opinion, if they find out how to make soil, with profitability taken out of the equation, then maybe some of those techniques could be used in day-to-day farming. Sounds like a good topic for a Nuffield.