Selected slides from May 5th Presentation

Carl will have a field day on his farm on May 5 and I have been laboring over a presentation for the day. Our intention was to present the data and not to try and moralize, but you will notice a few characters and speech bubbles that we hope to use as alter-egos that may reflect some of the conflicting thoughts in the audience. Since our last lab note, we received plant issue tests from our May 17 biomass samples so that's included. A few big take-homes from the data so far:

1. Notice the N in biomass from our Feb 12 samples - difference between (at planting) fertilized and unfertilized plots (30 lbs N vs 0) was around 1 lb N per acre - where did the 29 other lbs go? We did see a significantly increased tiller count, however, but could we have achieved that with (say) 1 or 2 lbs N? It seems obvious now, but fertilizer timing for N at least is huge and we're going "why in the world fertilize at planting when the seed hasn't even germinated? I know, of course it's about time and trips across the field etc.

2. In terms of plant tissue concentrations, there was no difference between the fertilized and unfertilized plots by Feb 12 2015 (Fertilization was mid-November, some 3 months prior).

3. In the "Strips with zero fertilizer" slide, you'll see that plant tissue N, P and K increased between Feb 12 and March 14. The working hypothesis is that this is simply the increase in soil temperatures and biological activity starting back up, since Carl didn't sneak out to fertilize while i wasn't looking.

4. After side-dressing on March 17 we see a significant difference between treatments - not unexpected BUT. Notice that on average, N in biomass for the untreated plots was 50 lb/ac N. Notice for our April 17 N in biomass. Where did the N come from?

5. We sampled the soil again on April 10 (a week before the April 17 biomass samples) and notice that organic N (actually water-extractable organic N or WEON) increased in all cases while inorganic N looks like it has more or less responded to fertilizer treatments. What is stunning is that the organic N pool is constant for all treatments, suggesting the reservoir for this pool of N (soil organic matter and breakdown of cover crop residue) is constant and also seems to have responded to the soil temperatures. You look at the notes Rick Haney puts out with his soil analyses, well, its all there, but very cool to see in real life.

6. In "Accounting for N in zero fert strips" we try to account for how the N is in the wheat based on our soil samples and cover crop samples. Isn't it convenient that the soil and biomass amples seem to add up? harvest is in the first week of June.