Posts Tagged: EC
Changes to Soil Following Application of Mustard Seed Meal and Crab Meal
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.
One, one hundred, one thousand
This little mnemonic, or memory aid, in the title is helpful in remembering the critical levels of toxic constituents in irrigation water. The “one” stands for 1 part per million (ppm) of boron (B), the e” hundred” flags 100 ppm of sodium (Na) and (Cl) and the “thousand” represents the level of total soluble solids (TDS or slats) in water. Levels exceeding the critical values for any of these constituents can present problems for tree growers. The problems typically show themselves as tip-burn and defoliation. The B, Na and Cl are toxic elements at relatively low concentrations, but symptoms appear similar to the damage caused by high salinity.
Water that exceeds the critical levels mentioned in the mnemonic has a greater tendency to cause damage if sufficient leaching is not applied. It doesn't mean the water is impossible to use, only that greater attention needs to be made to ensure that these salts are adequately leached. High levels of these salts accumulate in the soil with each irrigation, and the salts are absorbed by the tree and end up in the leaves where they do their damage.
This promises to be another low rainfall year and the customary leaching we rely upon in winter rainfall is not going to be as effective as in customary years. Irrigation is a necessary evil. Every time we apply irrigation water we apply salts, and unless some technique is used to minimize salt accumulation, damage will result. This damage can be more than just leaf drop, but also the stress that induces conditions for root rot.
Irrigation water has been applied the last four years and many trees looked stressed. Even well irrigated orchards have leaf burn due to the gradual accumulation of salts from irrigation. It is probably necessary to irrigate in many winters. With the lack of rain problem, it may be necessary to irrigate even if there is rain. The wetted pattern that is created by a drip or microsprinkler emitter also creates a ring of salt in the outer band of the wetted patter. If there is less than an inch of rainfall to push this salt down, this salt tends to diffuse towards the tree where it can accumulate back in the root system. Orchards with even good water quality would find it advisable to run the irrigation system with the first rains. Growers with water quality exceeding one, hundred, or thousand should be especially alert to the need to manage water in low rainfall years.
irrigATING CITRUS
Water Terminology
I was just speaking to a group of Certified Crop Advisors and there was some confusion about the units used by different labs to report their results, so I put together this sheet to help understand the relationship between the different terms. They are usually interchangeable, but one needs to know how they convert between each other. So here is a cheat sheet.
Common ions in water: calcium (Ca2+), magnesium (Mg2+), sodium (Na1+)
sulfate (SO42-), chloride (Cl-), carbonate (CO32-), bicarbonate (HCO3-), boron (H3BO3)
Measured as parts per million (ppm) or milligrams per liter (mg/l), which are interchangeable , or milliequivalents per liter (meq/l). A milliequivalent is the ppm of that ion divided by its atomic weight per charge.
Example: Ca2+ with atomic weight of 40 and a solution concentration of possibly 200 ppm. Ca2+ has two charges per atom, so it has a weight of 20 per charge. 200 ppm divided by 20 = 10 meq of calcium for a liter of water.
Total Dissolved Solids (TDS): measure of total salts in solution in ppm or mg/L
Electrical Conductivity (EC): similar to TDS but analyzed differently.
Units: deciSiemens/meter(dS/m)=millimhos/centimeter (mmhos/cm)=
1000 micromhos/cm (umhos/cm).
ConversionTDSEC: 640 ppm=1 dS/m= 1 mmhos/cm=1000 umhos/cm
Hardness: measure of calcium and magnesium in water expressed as ppm CaCO3
pH: measure of how acid or base the solution
Alkalinity: measure of the amount of carbonate and bicarbonate controlling the pH, expressed as ppm CaCO3.
Sodium Adsorption Ratio (SAR): describes the relative sodium hazard of water
SAR= (Na)/((Ca+Mg)/2)1/2, all units in meq/l
1.5 feet of water with EC of 1.6 dS/m adds 10,000 # of salt per acre
and that same water with 20 mg/l of nutrient will supply 80# of that nutrient/acre
Sea water has ~ 50 dS/m, 20,000 ppm Cl, 10,000 ppm
Irrigation water WATCH OUT- 1,000 ppm TDS, 100 ppm Na/Cl, 1 ppm B
chemistry
Water Quality Terminology
Along with drought there are also concerns about water quality which has all kinds of weird units that area actually convertible. Here's a little guide for the principle water quality components and their conversions.
Water Terminology
Common ions in water: calcium (Ca2+), magnesium (Mg2+), sodium (Na1+)
sulfate (SO42-), chloride (Cl-), carbonate (CO32-), bicarbonate (HCO3-), boron (H3BO3)
Measured as parts per million (ppm) or milligrams per liter (mg/l), which are interchangeable , or milliequivalents per liter (meq/l). A milliequivalent is the ppm of that ion divided by its atomic weight per charge.
Example: Ca2+ with atomic weight of 40 and a solution concentration of possibly 200 ppm. Ca2+ has two charges per atom, so it has a weight of 20 per charge. 200 ppm divided by 20 = 10 meq of calcium for a liter of water.
Total Dissolved Solids (TDS): measure of total salts in solution in ppm or mg/L
Electrical Conductivity (EC): similar to TDS but analyzed differently.
Units: deciSiemens/meter(dS/m)=millimhos/centimeter (mmhos/cm)=
1000 micromhos/cm (umhos/cm).
ConversionTDSEC: 640 ppm=1 dS/m= 1 mmhos/cm=1000 umhos/cm
Hardness: measure of calcium and magnesium in water expressed as ppm CaCO3
pH: measure of how acid or base the solution
Alkalinity: measure of the amount of carbonate and bicarbonate controlling the pH, expressed as ppm CaCO3.
Sodium Adsorption Ratio (SAR): describes the relative sodium hazard of water
SAR= (Na)/((Ca+Mg)/2)1/2, all units in meq/l
1.5 feet of water with EC of 1.6 adds 10,000 # of salt per acre
and that same water with 20 mg/l of nutrient will supply 80# of that nutrient/acre
Sea water has ~ 50 dS/m, 20,000 ppm Cl, 10,000 ppm
Irrigation water WATCH OUT- 1,000 ppm TDS, 100 ppm Na/Cl, 1 ppm B
avocado water
The Postscript to Last Week’s Blog Article about Salt Damage
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.