- Author: Mark Bolda
Below is a look at what happens to a soil following application of mustard seed meal (MSM) at 1.5 T per acre and mustard seed meal (again 1.5 T per acre) + crab meal (500# per acre) as separate treatments two weeks after fumigation with Ally 33 (67% AITC, 33% chloropicrin applied at 340# per acre on Oct 7).
Grower standard was methyl bromide/chloropicrin applied at 350# per acre. Planting took place Nov 3.
A soil sample taken on Nov 7 did not show differences in soil aspects analyzed between any of the treatments, although ammonium - N concentrations were surprisingly high (30 ppm and up) and nitrate - N numbers tended to be quite low (6 ppm and below).
Remarkably, look what has happened in the 4 weeks since that sample. Bear in mind that the grower has since sprinkled overhead several times and we had a good amount of rain as well. Commenting continues below the tables.
Unless otherwise indicated, units are in ppm of dry soil.
Table 1A. Soil analysis from December 7, 2016
|
Sample |
pH |
EC (dS/m) |
Nitrate – N |
Ammonium – N |
|
Methyl bromide grower standard |
7.4 |
0.9 |
11.3 |
4.7 |
|
Mustard Seed Meal |
7.1 |
1.7* |
34* |
20* |
|
Mustard Seed Meal + Crab Meal |
7* |
1.8* |
32* |
12* |
*Student's T-Test; different from grower standard at 5% level of significance.
Table 1B. Soil analysis from December 7, 2016
|
Sample |
(P) |
(K) |
(Ca) |
(SO4) |
(Mg) |
(Mn) |
Fe |
Na in meq/L |
Cl in meq/L |
|
Methyl bromide grower standard |
51 |
148 |
3100 |
278 |
178 |
8.9 |
18 |
1.9 |
3.2 |
|
Mustard Seed Meal |
54 |
190* |
2933 |
318 |
193 |
19.2* |
16 |
1.5 |
1.9 |
|
Mustard Seed Meal + Crab Meal |
60 |
185* |
3100 |
589 |
150 |
20.1* |
16 |
1.5 |
1.9 |
*Student's T-Test, different from grower standard at 5% level of significance.
One sees immediately that the pH has fallen, even significantly, in plots treated with mustard seed meal and mustard seed meal + crab meal. This is not surprising, since in the month's time since the initial sample on Nov 7, the ammonium has clearly nitrified (releasing 2 H+ ions per molecule, in turn acidifying the soil) creating a big pool of nitrates which have gone up significantly over the grower standard.
EC has gone up a bit due to the higher nitrates (NOT because of sodium or chloride), and interestingly levels of manganese (Mn) a mineral sensitive to acidification apparently, have soared in both MSM treated plots. Levels of available potassium (K) have gone up significantly also in MSM treated plots.
Quite interesting on the whole. By the way, a soil report like this makes for pretty good reading, and outside of the EC which is for the time being a little high in the MSM plots, all the other numbers are right where I like to see them.
Stay tuned on this one; we are following all of this trial through the season.
- Posted By: Mark Bolda
- Written by: Mark Bolda
As a postscript to last week’s post regarding salt and ammonium damage to area strawberry plantings, I will outline the results of the soil samples taken from a field demonstrating the symptoms described in that article.
Steve Koike and I collected soil samples from the affected field last Thursday, January 5. Soil samples were collected from four blocks, one of which had been overhead irrigated the day previous, and consisted of composites of at least five 5” deep samples taken from around the fertilizer band by the plant roots.
Samples were immediately taken to Soil Control Lab in Watsonville for analysis.
Results are as follows:
|
|
Nitrate (ppm) |
Ammonium (ppm) |
EC (dS/m) |
|
Sample 1 (not overhead irrigated): |
58 |
4.8 |
2.8 |
|
Sample 2 (not overhead irrigated): |
72 |
5.2 |
4.2 |
|
Sample 3 (not overhead irrigated): |
69 |
4.8 |
3.8 |
|
Sample 4 (overhead irrigated): |
24 |
5.1 |
2.2 |
The results are pretty clear in showing that the block (Sample 4 ) which had been watered by overhead irrigation had three times lower nitrate concentrations and about half the EC (which is electrical conductivity, a measure of salt) of the other three averaged as a group, but more equivocal on the reduction of ammonium.
To interpret the data in the table above, we can refer to work done some time ago which demonstrated EC’s in excess of 1.0 were related to loss in yield of strawberry, suggesting that real damage could occur at the 4x levels in the table above.
