Soil Analysis Results

[jcaldeira]

Last week I received the results of soil quality analysis performed by my Department of Agriculture.  I'm a little concerned that the electical conductivity is so low, at 0.05 compared to what the report listed as the good range of 0.40-0.80.  Are there any negative consequences of having such a low electrical conductivity?

My soil a dark volcanic clay-loam.

pH (1:5 water)                 6.5   Good  (Ideal is 5.6-6.6)
Elect. Conductivity (1:5 water; mS/cm)  0.05  Very Low   (0.40-0.80)
Total Carbon (%)                 4.7   Good  (4-10%)
Total Nitrogen (%)                0.4   Good    (0.3-0.6)
Olsen Available Phosphorus (mg/kg) 4.1  Very Low   (20-30)
               
Exchangeable Bases (me/100g)               
Calcium          17.1      High (ideal is 2-10)
Magnesium      4.3      High  (1-3)
Potassium          0.18      Low  (0.3-0.6)
Sodium         0.07      Very Low  (0.3-0.7)
               
Extractable Traces (mg/kg)               
Iron               57.5     Very High  (ideal is >4.5)
Manganese     30.6     Very High   (>1.0)
Copper          0.1     Low    (>0.2)
Zinc         0.8     Low    (>1.2)

I don't know much about soil tests, so any observations and suggestions on improving the soil for citrus, mango and avocado would be appreciated.

John

[Saltcayman]

Plants best take up water and the ions dissolved in it when the ion level is very low. This ion level is measured by either electrical conductivity (EC) or the total amount of dissolved solids (TDS). Problems arise when the TDS/EC level is low, when the plant can take up water easily. It remains hydrated, but starves because there is not a high enough concentration of ions in the soil water. If the level of TDS/EC is too high, the process of osmosis is affected, and the plant cannot efficiently take up either water OR nutrients, and the plant can starve or die of thirst in a sea of plenty. It’s up to us to supply the right mix of all the nutrients in a favorable range of TDS/EC.

This is from the gw soil-mulch forum. If you post your numbers there some experts will chime in:). Good luck.   Dave

[Mike T]

John you have a great soil, a krasnozem of basalt parent material and I presume you're getting around 2000mm/yr or so.I reckon mulch the living daylights around your plants and get those colloids sky high even if the carbon is high already.Keep it away from the trunk but grass,leaves and sticks by the barrow load is a key.You don't need to do that much with fertilizer but if you are busting to take your soil and plant health up a notch there are things you can do.

I suggest a fertlizer mix of superphosphate and potassium sulphate elevated compared to the nitrogen side of the NPK.Use the mix at less than the recommended rates.

Then there are the micronutrients.You have to be aware of antagonisms or you could cause real problems.I presume you are not usng any copper oxychloride fungicide.Don't apply individual micros unless you know about the antagonisms. Luckily manganese is high so you can apply zinc trace element on its own.A powdered micronutrient blend used in low amounts would cover the rest of the possible deficiencies.

[tabbydan]

Last week I received the results of soil quality analysis performed by my Department of Agriculture.  I'm a little concerned that the electical conductivity is so low, at 0.05 compared to what the report listed as the good range of 0.40-0.80.  Are there any negative consequences of having such a low electrical conductivity?

My soil a dark volcanic clay-loam.

pH (1:5 water)                 6.5   Good  (Ideal is 5.6-6.6)
Elect. Conductivity (1:5 water; mS/cm)  0.05  Very Low   (0.40-0.80)
Total Carbon (%)                 4.7   Good  (4-10%)
Total Nitrogen (%)                0.4   Good    (0.3-0.6)
Olsen Available Phosphorus (mg/kg) 4.1  Very Low   (20-30)
               
Exchangeable Bases (me/100g)               
Calcium          17.1      High (ideal is 2-10)
Magnesium      4.3      High  (1-3)
Potassium          0.18      Low  (0.3-0.6)
Sodium         0.07      Very Low  (0.3-0.7)
               
Extractable Traces (mg/kg)               
Iron               57.5     Very High  (ideal is >4.5)
Manganese     30.6     Very High   (>1.0)
Copper          0.1     Low    (>0.2)
Zinc         0.8     Low    (>1.2)

I don't know much about soil tests, so any observations and suggestions on improving the soil for citrus, mango and avocado would be appreciated.

John

I wouldn't worry about the electrical conductivity.  All it means is that there are a low amount of ions disolved in the water (Na+, Ca++, K+, Cl-, ...).   Your volcanic soil has a lot of minerals so it shouldn't matter too much.  Also it's not a specific test (any ions show up in conductivity, so you have benifical things like K+ not actually being "weighed" more than neutral things like SO4--).

Increasing potassium and phosphorous might be worthwhile as those are major nutrients and show up low.

[Guanabanus]

Certainly increasing Zinc will also be important.  Many trees will never bear without adequate levels of Zinc.

Spraying copper as fungicide will gradually correct the low copper.