Wednesday, February 19, 2020

Preparing To Plant? Get Your Soil pH Right Ahead Of Time.


An illustration of garden tools and white pots on brown soil next to blue-green wheelbarrow

What is soil pH? 

In simple terms, it represents the acidity or alkalinity of the soil on a scale from 0-14. Anything lower than 7 is acidic, while anything higher than 7 is alkaline. While most plants prefer slightly acidic conditions (roughly 6.5), a number of flowering plants prefer soil in the range of 4.5-5.5. You should be able to determine what your plants like with a simple internet search.

Why does it matter? 

Soil pH indirectly affects plants in many ways. Chief among them is nutrient availability as soil pH directly impacts how a nutrient gets to plants.

Truog, E. (1946). Soil reaction influence on availability of plant nutrients. Soil Science Society of America Proceedings 11, 305-308Something diagnosed as an iron deficiency based on plant symptoms may actually be a result of high pH not allowing the right iron compounds to form, leading to a lack of uptake. On the other hand, overly acidic conditions leave plants vulnerable to manganese toxicity from over-absorption (similar to metal poisoning in people). Soil pH also impacts soil life–again, slightly acidic is ideal for most soil-born organisms including earthworms and most microbes.

Why does it change?

Soil pH fluctuates based on a number of natural factors including rainwater leaching, acids formed from root respiration and acid formation from decomposition. Human inputs like chemical fertilizers can also have significant effects.

Monitoring & Adjusting:
A person crouched down and writing on a white pad next rows of green plants in black containers.

  • First things first – test your soil. There are many choices for you test-wise, we carry a variety, but there are also high-end options out there. There are even some DIY techniques out there that you could give a whirl. Once you know the status, you can plan accordingly. 
  • Need to acidify the soil? Elemental sulfur may be your best bet and it can be top dressed to soil or worked into the top 6”. Tiger 90CR® Organic Sulphur should do the trick. If you prefer using a liquid (or are growing hydroponically), SaferGro pH Down will work wonders.
  • Need to boost alkalinity? Look to lime – commonly bought as calcitic limestone or dolomitic limestone. Not only does it raise pH, lime provides the secondary macronutrients calcium and magnesium. We recommend BONIDE® Hydrated Lime
Whether the soil needs major adjustment or not, it is a good practice to test soil pH seasonally in order to maximize your growing potential. Three green plants growing from mounds of brown dirt.
Submitted by Sterling (with Pam)

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