Day 16

I didn't actually fly to Lincoln, I flew to Omaha and then drove from there, but Google wants to show it like this. The man at Hertz offered me an upgrade to a Mercedes E63, and although I did like the idea of spending the next three weeks driving around a 500hp car, it wasn't really worth spending a third of my scholarship on. More reasonably, I extended my normal car hire an extra day for $43, somewhat better than the £700 I was quoted in the UK earlier this week.After a leisurely lunch in Omaha (probably my last interesting meal for the next few weeks) I drove out to Lincoln to visit a University of Nebraska research farm, where I was hosted by one of their Extension Engineers, Paul Jasa, and also the farm manager Stuart Hoff.The Rogers' Memorial farm was gifted to the university in 1947 with a string of conditions, some more bizarre than others. It was originally used for grazing, and then to test out new ways of reducing water erosion through the use of novel terracing techniques. Water management is a big deal here, and rain tends to be all-or-nothing. The record in Lincoln is 11" in one hour. On the other hand, moisture conservation is critical for crop yields.The farm covers 320 acres, and is half clay loam soil, and half silty clay loam (some of which is over 8' deep). The heavier soil is farmed with a soybean->wheat->soybean->sorghum rotation, with cover crops after the wheat. The better, silty, land is farmed as maize->soybean->maize, although sometimes it will stay as soybeans for up to three years. Paul tells me that when the soybeans are farmed continuously like this, the yield actually goes up each year.This is the first farm I have seen so far that does not use Roundup Ready maize. They find it causes problems when resistant maize appears in the soybeans (which are RR), and it means that they can use seven different herbicide modes of action, reducing the chances of resistant weeds developing.As well as the commercially farmed sections, there are several long standing trial plots. I visited the Millennium trial in New Zealand, which had run tillage comparisons for 13 years, but here they have similar replicated trials that are now in their 34th year. In brief, they compare ploughing, discing and no-till, both with and without cover crops. Over this time period, no-till has come out ahead on yield by a small, but significant margin.This result is largely put down to moisture retention, both through increased organic matter (around 0.5-0.75%), and extra surface residue [I feel like I'm banging the same drum all the time now, I think I may stop talking about this in future]. They also report reduced herbicide usage, and reduced soil erosion, and massively increased water infiltration - to the point where terracing is no longer necessary. Sounds like a win all round.A different set of trial plots are working on cover crops. One experiment looks at high carbon vs high nitrogen species. When preceding maize, there is no real difference in yield between the two. With soybeans however, there is a yield benefit to using high C cover crops, but no penalty with high N. If you look at the photo below you can see that the high C covers visibly stunt the initial bean growth, but in the end they yield more. Paul believes that they are putting energy into rooting rather than leaf production, which pays off later in the season; "I like short plants" was something he often said.In contrast to David Brandt, Paul likes cover crops that die in the winter, as he finds they use too much moisture up in the spring in his hot and dry climate. Anything that is not killed by frost will be terminated in early spring. They will also spray pre-emergent herbicides onto the cover crops in early spring up to a month before drilling beans, which allow time for the chemical to be washed into the soil and activated, as well as controlling weeds in the period between the cover crop and the cash crop. This is a new one on me.Cover crops seem to have no real beneficial effect in the maize->soybean->maize rotation, as there is very little time between harvest and planting when the soil is warm enough to support significant biological activity. This is not the case when wheat is in the rotation, and large yield benefits occur with the use of cocktail blends sown in July. This positive effect is measurable throughout the four year rotation, not just in the cash crop immediately following the cover.One story Paul told me was about the severe drought in 2012. I can't remember the exact details, but it was dry. They had a field of maize which ended up yielding 10t/ha. Just a short distance away their neighbour's crop (conventionally tilled, of course) failed entirely and died before making any grain. Before I could ask the obvious question, I was given the answer. The neighbour had been happy with the outcome, as his crop insurance (a government subsidy scheme) had paid him for the crop failure, and he had been able to put his feet up at harvest time. So it isn't just the EU which makes farmers behave strangely.In Ontario, Michigan & Ohio there didn't seem to be many no-till farmers at all. Here in Nebraska 50% are using it sometimes, and 25% do nothing but. That's probably down to the warmer and drier climate; did I mention no-till is good for moisture retention?