Know What Your Soil Wants, Not What You Want

At Fifth Season Gardening, we sell pretty much every amendment your soil needs to improve its health. But many customers purchase soil amendments to add to their soil without knowing what the soil needs first.  This may be not only a waste of money, but also a waste of time.  

If plants already have enough of a particular nutrient, they either won’t absorb any extra  added to their soil (which is a waste), or, what’s worse, they’ll overdose on the nutrient to the plant’s detriment. Too much nitrogen is a good example of this effect. In excess amounts, it can make a plant grow too fast, making it weak.

Until you know what your soil needs, you shouldn’t be adding amendments, other than good compost. The best way to find out what soil needs is to get a soil test first.  The State of North Carolina provides soil test kits and analysis through county Cooperative Extension offices. We also stock the free soil sample kits at our stores for you to pick up and send in. If your state does not offer this service, you can still contact your county Cooperative Extension office for a recommendation for a local soil testing lab.

The report you get back will tell you what nutrients your soil is missing and how to remedy that. It will also tell you if you have too much of a particular nutrient.  If you don’t have time to wait for the sample to be sent off and returned from the lab, you can also get a simple testing kit from your local garden center. It’s not as comprehensive, but it’s better than not testing at all.  As you can see from the test above, if phosphorus had been added to this soil, it would have been unnecessary.

There are lots of things that affect the availability of nutrients in your soil.  

• Soil temperature – if it’s too cold or too hot, this affects the activity of the organisms in your soil that break down the minerals so that the plant can absorb them
• Soil PH – certain nutrients cannot be utilized by plants if the PH is too low or too high
  • Example: Bone Meal doesn’t work if the soil PH is above 7.  Phosphorus,  Magnesium, and Calcium won’t work if the PH is below 6.  
  • A high PH of 8 & up can result in nitrogen loss
  • Iron is more available at a PH of 7
• Levels of existing nutrients – some nutrients cancel out the availability of other nutrients
  • Example:  
  • Too much magnesium or potassium affects the availability of calcium
  • Adding lime to soil will increase the PH but also may cause an Iron deficiency
• The amount of biological activity in the soil – if you have no biological activity in your soil then there is no way for the minerals necessary for plant growth to be made available to the plant- Compost and compost teas can help with this
• Moisture – too much or too little in the soil can affect microbial activity and PH

When we talk about amending soil at Fifth Season, we’re focused on doing it organically.  Organic amendments build soil health for the long term.  This is done through the work of soil organisms which break down the minerals these amendments are comprised of into a form that plants can effectively absorb or take in.  Some call this the Soil Food Web.  These organisms include bacteria, fungi, and a variety of microorganisms.

Solutions for Building and Maintaining Good Soil Health & PH Levels Include:

• Continually adding good quality organic compost and compost teas  
• Leaving plant roots in the ground to decompose and return nutrients to the soil
• Limit tilling!  This destroys soil structure.  If you have to, do it once in clay soils, amend, and never do it again.

Before you purchase an amendment, make sure you need it, and that you’re feeding your soil what it wants, not what you want.  The only way to know this for sure is through a soil test.