Amending Clay Soil: Yes It Can Be Done

Amending Clay Soil:  Yes It Can Be Done
Amending Clay Soil:  Yes It Can Be Done

Amending Clay Soil: Yes It Can Be Done

Amending Clay Soil:  Yes It Can Be DoneAmending Clay Soil:  Yes It Can Be Done

Amending clay soil is often needed since most are not blessed with an ideal soil to work with. Since you are stuck with the hand you are dealt, you may have to work quite diligently in order to upgrade the soil. Whether you have a little or a lot of clay, you can add organic matter to create a perfect starting point.

Clay Has Potential

Before you attempt to manage your garden‘s clay soil, it helps to understand a bit about the background of soil mineralogy. The soil is made up of silt, sand and clay particles with the clay particles being the smallest, silt being the intermediate sized and the largest particles are sand. Amending clay soil is important because clay particles are stacked sort of like a sandwich then almost glued together by an electrochemical force. The horizontal arrangement of the clay particles creates a large surface area.

Individual clay particles hold a negative charge and have the ability to attract, as well as hold onto and absorb charged elements that are positive such as potassium, ammonium, magnesium, and calcium. Clay soils have a lot of potential because they are quite fertile, having the ability to absorb necessary plant nutrients.


Amending clay soil demands short-term and long-term strategies. The initial goal should be focused on adding the greatest amount of organic matter as deep as you can because applying them to the soil will improve the structure that helps to improve the health of the soil.

Your long-term strategy will be to attempt to build humus and organic carbon to promote nutrient cycling. This is done through consistent applications of manure, compost and organic matter.

Building organic matters help with amending clay soil in a couple of different ways. The organic matter separates clay particles and coats soil particles. More importantly, the microorganism that degrades the organic matter actually produces byproducts that are called glomalin. These byproducts bond the individual clay particles together. This particle aggregation in amending clay soil reduces crusting, erosion, and runoff and increases the water infiltration rate.

Organic matter, even in large amounts that are incorporated in the soil is going to break down rapidly. Any remaining organic matter will more than likely resist any further degradation for many years, even decades. However, any stable increases, called humus will occur very slowly. Therefore, any stable organic matter increase needs to be a long-term goal.

Don’t Disturb The Clay

When amending clay soil, it is advised to incorporate organic matter deeply and regularly, especially in the beginning while you are trying to whip the clay into shape. Aggregating stability, soil particle aggregation, drainage, water holding capacity, plant root growth, and nutrient retention all become increased after you incorporate organic matter.

Major losses of organic matter in the soil content can often take place if the soil is inverted by tillage. Extensive tillage will stimulate microbial activity which basically gives them an appetite so once your clay becomes friable you should reduce tillage. Since the soil is undisturbed, fertilizers will not homogenize within the tillage layer.  Therefore, plant feeder roots tend to proliferate only in the fertile top two inches of the soil.

What Is Tilth?

When amending clay soil it is helpful to understand that tilth is the soil’s physical condition related to the ease of tillage, ease of seedling emergence, seedbed quality, and deep root penetration. Soil that is well drained, takes in water rapidly, does not crust, does not make clods and facilitates aeration is referred to as having good tilth. With a proper management strategy, a good tilth is obtainable when amending clay soil.

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