When you plant a garden, you want to make sure you get the best plant growth and harvest possible. You could be growing vegetables, fruits, herbs, or flowers.
Not all soils are equal. Most of our garden soils come with some less than ideal soil properties that limit or discourage optimal plant growth. Even though you cannot change the soil type, there are materials you can add to the soil to get better results from your garden. These are called organic soil amendments to your garden soil.
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What are Soil Amendments?
A soil amendment is a material added to soil to improve its physical properties. This indirectly improves plant growth. Soil amendments are different from fertilizers because their purpose is not necessarily to add nutrients to the soil but to enhance the soil’s quality.
When these materials are added to the soil, they improve soil characteristics like the soil structure, drainage, water retention, aeration, and water infiltration. An improvement in soil properties causes a cascade of effects that cause an overall improvement in plant growth. Though most organic soil amendments have some nutrients, only a few have sufficient nutrients content to also work as a fertilizer.
Benefits of Organic Soil Amendments
Organic soil amendments improve the texture of the soil, helping it to bind together better. Soil amending materials also boost the growth of beneficial soil organisms that increase soil health by breaking down soil waste products releasing nutrients into the soil. Soil amendments improve the texture and retention of soil moisture retention.
Soil amendments adjust typical soil type characteristics like the stickiness and poor drainage of clay soil. Organic amendments loosen clay soils, making them less clumpy. This, in turn, promotes better soil aeration the soil, the growth of soil organisms, and a general increase in soil quality.
Sandy soils usually have low fertility with low nutrient levels, low organic matter content, and poor water retention. Appropriately amending sandy soils can greatly improve your garden yield.
9 Organic Soil Amendments for Growing Vegetable Garden
Compost is composed of decomposed materials mainly coming from plants such as kitchen scraps, leaves, lawn cuttings, pieces of bark, and twigs. You can prepare your own compost in your backyard by collecting the scraps of vegetation from your yard maintenance and kitchen plant waste. Compost is rich in organic matter and has some great nutrients.
Compost improves the soil structure, helps control soil pH, and increases soil organism populations. You can add compost to gardens, potted plants, and lawns.
Animal manure can act both as a solid amendment and a fertilizer because of its high nutrient content, such as ammonia (nitrogen source), potassium, phosphorus, and micronutrients necessary for plant growth. It is normally sourced from plant-eating livestock such as chickens, cows, and sheep. Other types of animal manure may not be suitable.
Animal manure is a great soil amendment. When used in home gardens, it increases the organic matter in the soils, greatly improves the soil texture and soil properties. Fresh animal manure has very high levels of ammonia. Elevated ammonia concentration is harmful to plants, so it is best to use matured or composted manure.
3. Peat Moss
Peat moss is a material formed over thousands of years and found in wetlands and bogs. It is normally composed of the moss sphagnum. Peat moss has an acid pH and is good for acid-loving plants like blueberries. Peat moss tends to be more expensive as it is usually imported from Canada.
This soil amendment has a low nutrient content but is beneficial to the soil because it holds soil nutrients in the soil, increases aeration due to its fluffy, non-compactable. It can retain these properties over several years.
Depending on your plant’s needs, you may also add lime to increase the soil’s pH if you are using peat moss.
4. Grass Clippings and Leaves
Grass clipping and leaves can be used as an amendment. They increase the soil water holding capacity and are a good source of organic matter. Fresh cuttings have more nitrogen content, while the dried cuttings are carbon-rich. The more finely chopped the cuttings, the better they integrate into the soil to enhance the soil quality.
5. Wood Products
Wood products vary in terms of size and composition. They include sawdust, wood shavings, and wood chips. As wood products decompose, they become a good source of carbon, but it’s important not to apply too much as high levels of carbon in the soil start to cause an imbalance in the soil due to soil nitrogen consumption.
6. Cottonseed Meal
Cottonseed is a by-product of the cotton manufacturing industry. This is one of the soil amendments that work as a fertilizer as well. It is an organic source of soil nutrients like nitrogen, phosphorus, and potassium. It provides a steady and slow-release of nutrients to plants as it decomposes, so you don’t have to be concerned about foliage burn.
Cottonseed has a high organic content, which aerates the soil. It also forms humus, which improves the soil texture. Together with its high nutrient content, this amendment is a great addition to a garden for plant yield and great blooms.
7. Wood Ash
Wood ash has varying amounts of nutrients depending on the type of wood that was burnt. Wood ash should be applied sparingly on the soil. It is a source of nitrogen, potassium, and micronutrients. However, there has been controversy over its safety. It is sometimes a source of heavy metals.
Wood ash is used to raise the soil alkalinity of acidic soils since it has a good proportion of calcium carbonate, which is also found in garden lime. It is best avoided for acid-loving plants because pH changes interfere with their growth.
8. Green Manure or Cover Crops
Green manure are crops from plants specifically selected to amend the soil. These can be from crops such as legumes or grasses mixed with other plants. Green manure crops are often grown out of sync with the peak planting season to prepare the soil for an upcoming peak season for a specific crop.
The EPA describes biosolids as products from the treatment of wastewater. They are composed of a nutrient-rich sludge formed when the sewage water is separated from the solids. Although biosolids are highly nutritious for soils, they can only be used if they meet federal and state requirements because of the potential health risks.
Biosolids are normally used in agricultural land applications to improve the nutrient content and soil structure. They have more limited application in vegetable gardens because they may contain heavy metals and have a high salt content.
How to Use Soil Amendments?
For soil amendments to work, they must be mixed thoroughly within the soil, unlike mulch. They are usually not a substitute for fertilizer, and although some amendments can be applied generously on the garden soils, some need to be used more sparingly.
Soil amendments have different properties and enhance the soil in different ways depending on the soil’s state. The choice of soil amendment also depends on the type of soil. Choose a soil amendment based on:
- the soil texture, determined by whether your soil is sand, clay, loam, or silt. The soil texture can be sticky, fine, coarse, compact, or loose.
- the length of time the soil amendment lasts in the soil.
- soil salinity, meaning the application of amendments with a high salt content may not be advisable.
- the pH of the soil and the amendment, e.g., peat moss has an acidic pH.
The amendments should be mixed well with the soil avoiding intrusive methods like digging in. No-tillage methods are recommended if you are adding compost for maintenance to already good soil. However, if your soil is compacted and has a poor structure, the composts need to be mixed well into the soil, and then digging the soil may be necessary.
- Wood Products Application
Although wood products serve as a good carbon source and increase water retention, it is advisable to apply wood chips or sawdust in combination with a nitrogen source such as nitrogen fertilizer to avoid nitrogen depletion in the soil.
- Cottonseed Meal Application
It is good for shrubs, vegetables, and roses. Cottonseed meal can also be applied to acid-loving garden plants and produces really good flower blooms.
It is important to observe the recommended guidelines for applying cottonseed meal as it is used differently for different plant types. There are also cases where a reapplication of the meal is needed over time. Cottonseed meal can be applied in combination with fertilizer, mulch, and plant-based manure. There may also be a need to lower the soil pH when using cottonseed meal for acid-loving plants.
There is no need to be stuck with infertile soil that is hampering your garden produce. You can find a variety of organic soil amendments that range in price from free to expensive. Soil amendments can be used to improve plant growth, crop yield, and blooms in your home garden. Each amendment has different properties and benefits to the soil and needs to be applied accordingly.