Brooke’s Post: It Starts with the Soil!

It’s never too early (or too late!) to consider soil health in your garden! Here’s the basics of soil fertility and how to naturally improve it

If you are starting your own garden plot, an important first step will be evaluating the chemistry of your soil.  By testing the acidity (PH) and the nutrient content of your soil, you can determine how well the soil will support crops and what you might need to add to increase soil fertility.  You will want to purchase a soil testing kit from your local garden store.  After taking several soil samples, you will have a good sense of the makeup of your soil.  Next, you should consider what plants you wish to grow, and research what kind of soil environment these plants grow best in. Tip: UNH Cooperative Extension also operates a fee-based soil testing service

Soil pH:

PH is measured on a scale from 3.5 to 9.0, where 3.5 is the most acidic and 9.0 is the most alkaline (also known as “sweet”).  A pH of 7.0 is considered neutral.  Acidity has both positive and negative effects on plant growth.  Soil acidity determines the availability of nutrients in soil, as well as the ability of plants to take up these nutrients. Acid in soil helps to break down nutrients into plant available forms and enhances the breakdown of organic matter by microbes.  However, too much acidity will hinder uptake of macronutrients by plants.  On the other hand, alkaline soils hinder the ability of plants to absorb micronutrients.  For these reasons, most plants grow best in neutral or slightly acidic soils, with a pH between 6.0 and 7.0.  However, every plant has different needs!  For example, blueberries, peppers, and asparagus thrive in ranges from 4.5-5.0, 5.5-7.0, and 6.0-8.0, respectively.

Natural ways to control pH in soil:

To reduce acidity (increase pH) of soil, you can add lime in the form of ground limestone or wood ash.  To reduce alkalinity (decrease pH), you can add mined/elemental sulfur or coffee grounds.

Soil Nutrient Levels:

You should test your soil to determine the existing nutrient levels. Nitrogen, phosphorous and potassium are the macronutrients most important to plant growth and health.  Additionally, micronutrients such as calcium, magnesium, sulfur, iron are needed in small amounts to enable various plant functions.

Organic fertilizers:

Applying compost to the soil can make a huge difference in soil fertility. Visit to get the best fertilizer. Organic matter in compost introduces a variety of nutrients to the soil and improves water retention.  Compost should be tilled into soil two or three weeks before planting.  If you don’t already have one, start a compost pile at your home!  Plants such as peas and beans are nitrogen fixers.  This means that they are able to convert inorganic forms of nitrogen into plant-available ones.  Planting nitrogen fixers on your plot can improve nitrogen content in the soil for the following year.  Animal manure and coffee grounds will also add nitrogen to the soil. Kelp meal is a good option for increasing potassium, and phosphorous can be added with fish bone meal, chicken and pig manure, or rock phosphate.  Be careful not to over fertilize, as too much of a nutrient can also be damaging to plants.



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