Wheat Harvest June 6, 2017  

We managed to get the wheat harvested on the above date with a small Gleaner GL2 plot combine. To recap, we have 40 plots with 4 treatments - this means that each treatment is replicated 10 times. In essence we have two levels of nitrogen application (roughly 33%, 66% and 100% of Rx) and two levels of potassium namely 0 and 100% of Rx.

Table 1 shows the overall result which in essence says two things namely (1) there was a significant yield response to nitrogen fertilization and (2) there was no significant yield response to the recommended potassium (K2O) fertilizer.

 

 

 

Table 1: Grouping Information for the Wheat Harvest from June 9, 2017 Using the Fisher LSD Method and 95% Confidence.

While the treatments to our first trial (Table 2) were slightly different, the conclusions (i.e., the crop responded to N, but not to K) are the same.

 

 

 

Table 2: Grouping Information from the Wheat Harvest in June 2015 Using the Fisher LSD Method and 95% Confidence

In terms of wheat yield response to N, Figure 1 shows that between the 60-0-0 and the 90-0-0 there is a lot of overlap between the data points and its a nice graphic display of why Table 1 suggests there is no statistically significant yield difference between the 60 and 90 units of N applied.

 

 

 

Figure 1: Individual Value Plot of Yield Response to Nitrogen Applied for the June 2017 Wheat Results. The Quadratic Equation in the Picture Needs to be taken with a pinch of salt and is only included to show the trends.

If we look at crop yield response to potassium (Figure 2), the same amount there is a good deal of overlap between the points. When comparing the 90-0-90 to the 90-0-0 treatments by replicate, 6 out of 10 reps showed the yield in the 90-0-90 treatment was higher, while 4 out of 10 reps showed the 90-0-0 treatment was higher.

 

 

 

Figure 2: Individual Value Plots showing Yield Response to Potassium applied. The Equation in this case merely shows how weak the relationship between Potassium applied and Yield were for these data.

We were disappointed by the yields this year - some of it had to do with the damage done by a particularly cold snap in March, but some is on me (Buz). I encouraged Carl to make as few trips across the field as possible, and one trip he saved was the post-emerge herbicide trip. Only other herbicide Carl applied was burn down of the warm season cover crop. From the vantage point of the combine, I could see that while our soils are getting healthy, we are still going to have to rely on herbicides for a while, as it was pretty visible to me how weed pressure affected yield. We live and learn.

I thought I'd include a few shots from the harvest itself. We are most grateful to our friends that rented the plot combine to Carl at a very reasonable rate - a big time saver over the regular combine a weigh wagon.

 

 

 

Figure 3: The Plot Combine in the background with a 6' swath we made through one of the plots (mid-ground). We used a standard combine to trim the edges of the plots.

 

 

 

Figure 4: The future of Soil Health Research in SC? Carl's son Caleb and my PhD student, Gabe - the instrumentation batch weighs each plot and provides a printout, but I wasn't taking any chances, so we took our own notes as well. There is no buddy seat in this combine, so you can appreciate that three hours cosied up in the cab together was quite enough!

 

 

 

Figure 5: This Image may give one an idea of the Weed Pressure that a small amount of Post-Emergent Herbicide could have fixed. We encountered mare's tail (visible here), thistle, cutleaf primrose, common vetch and the morning glory was beginning to show as it warmed up.