Robert Hijmans

December 9, 2014December 10, 2014

The three crops rule

The European Union’s revised Common Agricultural Policy, effective from January 2015, has introduced a measure to promote agricultural diversification. The “Greening Payment” rewards farmers for practices perceived to be ‘beneficial for the climate and the environment’. It is big pot of money: 30% of the national level agricultural subsidies. Compliant farmers get a (per hectare) payment, offenders get a fine.

These are the Greening measures that farmers can take:

‘crop diversification’: cultivate at least 2 crops when a farm’s arable land exceeds 10 hectares and at least 3 crops when it exceeds 30 hectares. The main crop may cover at most 75% of the arable land, and the two main crops at most 95% of the arable land;
maintaining an ‘ecological focus area’ of at least 5% of the arable area of the holding for farms with an area larger than 15 hectares (excluding permanent grassland) – i.e. field margins, hedges, trees, fallow land, landscape features, biotopes, buffer strips, afforested area;
maintaining permanent grassland, including traditional orchards where fruit trees are grown in low density on grassland.

This is pretty complicated.

Farms that already have ‘Greening Equivalency’, such as organic producers, do not have to meet these requirements, because, says the EU, ‘their practices provide a clear ecological benefit’. There are more exceptions. For example for:

farms that already fulfill the objectives of crop diversification as a result of being covered to a significant extent by grassland or fallowland, for specialised farms rotating their parcels each year or for farms that because of their geographical localisation would have excessive difficulties in introducing a third crop.

I suppose it is on the basis of such ‘excessive difficulties’ that rice farms (at least in Andalucía) are exempt. Who else is going to be exempt? Why not include the thousand Scottish farmers that grow only one crop — spring barley for whisky? But that still leaves them muttering into their warm ales in the arable east of England, where opponents of the measure suggest that increasing crop diversity is less efficient and leads to more greenhouse gas emissions.

If these rules are here to stay, they will likely lead to creative book-keeping and a new agricultural land market to join, for example, a wheat farm with an olive grove, perhaps in different countries.

But what about the science behind all this? Research on “ecological focus areas” suggests that these may not deliver the goods. And there is no thought given to taxonomy: it is as green to grow wheat and barley as it is to grow beans and barley, or wheat and spelt.

Some of the most intensive (and, on a per ha basis, often the most environmentally problematic production systems) have more than three crops (not to mention horticulture). In the Netherlands, for example, most arable farms grow three crops or more: potato and wheat and perhaps sugarbeet, barley, onions, or another vegetable. This is part due to legal requirements on growing potatoes in a four year rotation in most regions, to reduce nematode (and nematicide) problems. These Dutch farms will get the subsidy, but a low input wheat farm in central Spain could get a fine.

What is the current baseline, and where does the EU think it will get with these rules? I could not find any analysis this is based on, can anyone point to that (if it exists)?

Here are some estimates of the areas affected in the UK. It is hard to get farm level crop diversity data; but we have statistics about crops by region, from which that can be estimated though. There’s something fun that I could do this week.

December 7, 2014December 8, 2014

A natural experiment with Peruvian potatoes

Potatoes are generally propagated vegetatively, by planting tubers. In English, these tubers used for planting are, unfortunately, referred to as seed, which they obviously aren’t, at least not in the botanical sense. Potato breeders use sexual reproduction and the resulting real seeds (extracted from the tomato-like potato fruits) to generate new varieties. The fabled potato diversity of the Andes probably originated from seeds arising from spontaneous crosses among landraces and with their wild relatives, and alert farmers that kept some of the offspring occurring in their fields. But when and where were Andean potato varieties formed? And is this type of evolution still going on?

Marc Ghislain and colleagues ((M. Ghislain, J. D. Montenegro, H. Juarez, M. del Rosario Herrera, 2014. Ex-post analysis of landraces sympatric to a commercial variety in the center of origin of the potato failed to detect gene flow. Transgenic Research. DOI 10.1007/s11248-014-9854-4)) took advantage of a natural experiment in Peru to investigate whether new varieties have arisen from crosses between ‘Yungay’, and other varieties. Yungay ((Named after a town covered by a landslide in 1970.)) is one of the varieties of the famous Peruvian potato researcher Carlos Ochoa, produced by crossing native and exotic potatoes (from Europe, the USA, and Chiloe). Because it is genetically rather distinct from native Peruvian varieties (here is its pedigree), Ghislain and colleagues were able to use genetic markers (SSRs, in fact) to determine if a given potato variety in a farmer’s field might be an offspring of Yungay.

They looked at the DNA of 1771 leaf samples from more than 400 potato varieties growing in areas where Yungay is also grown. None of the potatoes sampled could plausibly be identified as a descendant of Yungay.

The authors’ motive was to find out whether transgenes from genetically modified potatoes might ‘pollute’ native diversity. I am more interested in the question of whether farmers are still finding, keeping and spreading new varieties from spontaneous seedlings. That would seem likely, but there appears to be no good evidence that they do so. We know that hybridization among potato cultivars, and with wild species, occurs under field conditions, but what happens to the offspring? Ghislain and his colleagues suggest that hybrids may not be adapted, and thus die off, citing research carried out in the rather unforgiving climate of Puno, and that farmers discard hybrids because they prize the quality of native varieties. But I am not convinced by that argument. Clearly, many hybrids will not make the cut, as in any breeding program, but some novelty must surely be of interest to local farmers, as it obviously has been in the past.

Is keeping new potato varieties a cultural practice that has been lost? And are most current native potato varieties therefore old, perhaps very old? Or is the process still going on, perhaps even at a similar rate as before, but the chance of detecting it is small? I wonder if there is some sort of clock that can be used to measure how old a variety is. After all, a variety is really an individual clonally propagated plant. And some potato varieties are thus of course much larger organisms than those molds that occasionally hit the headlines; each year there are about 10,000 ha of Russet Burbank in the USA alone.

Unless there is simply something wrong with Yungay’s offspring (which would make it a bad variety to use for this type of research), my guess is that there are hybrids with Yungay out there, but not many, and that they are just very hard to find. Only very few novel varieties may be good enough to spread beyond a farm to a much larger area, such that we are likely to detect them. But a transgene hybrid could have better odds than most.

November 29, 2014November 30, 2014

A meaningful date

There is a wonderful piece by the Kitchen Sisters on US National Public Radio about the history of dates in California — and about plant exploration, politics, and people.

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There are about 3400 ha of date palm in the Coachella Valley, a Southern California desert. Here is a road side view (note how you can you can estimate the growth rate by comparing with the 2007 street view photo) and here is another grove. Wikipedia says that that the Spanish introduced the date palm to lower California (Mexico) in 1765; but Walter Swingle gets the credit for bringing the plant to the USA (see this letter by David Fairchild). In 1903 he collected Deglet Noor in Biskra, Algeria, and in 1929 he collected the prized cultivar Medjool in Morocco.

Coachella date grower Patricia Laughlin has this to say about that:

When the Medjool dates came in, there were only nine offshoots that all of the present trees come from. These medjools came from the oasis of Bou Denib. It’s been wiped out by a disease in Algeria and Morocco. We have sent back good plant stock to return to those areas from which they originated. My husband and I visited. It’s over the Atlas Mountains from Marrakech — out really in the desert. When we got to Bou Denib, the mayor came out to greet us. It was a big occasion. And he said why would anyone from the United States want to come to Bou Denib? We had worked with the Medjool dates for so many years and to see where they originated was very meaningful for us.

April 20, 2012April 24, 2012

Mapping the 1970 corn blight

Here are my 2 maps ((Quick & dirty, without cross checking the numbers, but I think the maps speak for themselves.)) for this discussion. I used linear regression to predict corn yield for each county in the US, using time (year) as the independent variable. I used the years 1950 to 1969 to create the model, and to predict corn yield in 1970. This should be a reasonable estimate of the ‘expected yield’ for 1970 for each county, if it had been a ‘normal year’.

I then computed the difference between the expected yield and the yield obtained by farmers, and expressed that as the percentage of the expected yield. Negative numbers mean that yields were lower than expected in a county, positive numbers mean that they were higher than expected. Counties with data for less than 9 years were excluded.

1970 corn yields were indeed much lower than expected in the southeast. Corn blight hit very hard. But also note that yield was stable or up in the north and in the west, and look were US corn was grown in 1970. The map below expresses corn area as the percentage of the total area of a county.

Most corn is grown in the corn-belt. The southern parts of it were much affected by the disease (The Illinois Secretary of Agriculture’s estimate that, by August, 25 percent of his state’s corn crop had been lost to the blight may have been spot on). But 1970 was a normal or good year for corn yield in the northern and western parts of the corn belt, and that compensated for the losses incurred elsewhere. If you sum it all up, corn production was about 15% lower than what could have been expected. That is whole lot of corn — but perhaps not that exceptional as far as bad years go.

Here is a table of estimated corn yield by state, as percentage of the expected yield for 1970, and the corn area, as percentage of the national area (only for states with more than 1% of the national corn area in the counties data set).

State	Yield	Area	State	Yield	Area
Florida	-36	1	Minnesota	-12	8
Georgia	-33	3	Missouri	-11	5
Illinois	-31	18	Nebraska	-9	9
Indiana	-27	9	North Carolina	-5	2
Iowa	-26	18	Ohio	-1	5
Kansas	-24	2	Pennsylvania	0	2
Kentucky	-22	2	South Dakota	6	4
Michigan	-12	3	Wisconsin	15	3

February 10, 2011February 10, 2011

Food on a pedestal

tomato statue in Davis, California, USA Inspired by Jeremy’s posts on corn statues and tomato experiments in Davis, California, I offer you the “Portrait of a plump tomato”, by Gerald Heffernon. It stands in front of a Davis shop that sells heirloom tomatoes and other agricultural biodiversity (20 rice varieties!).

Tilapia statue in San Pablo, Philippines I wonder if the tomato is celebrated here for the many (industrial use) tomato fields in the Davis area. Gerald Heffernon is somewhat of a fruit specialist: he also made apricot, pear, plum and cherry statues, but food statues are rare in the USA and elsewhere.

As far as I know, and do correct me if I am wrong, the Philippines is the only country where food gets due respect, and the statues that come with that.

I believe the highest density to be in a small area, roughly forming a triangle with 10 km edges, in Laguna province. San Pablo — with its many lakes — has a big tilapia. Victoria, known for its sweet pinya, a fierce pineapple.

Laguna de Bay, the place to eat ducklings-in-the-egg known as balut (not for the faint of heart) has duck statues (here is another good one).

There are plenty of (golden and other) cow statues, in Asian temples, and elsewhere. Do you know of other statues that honor the the organisms that feed us?