Thursday, 30th November 2023

Sweet and sour soils

By Sereba Agiobu-Kemmer
23 August 2019   |   2:59 am
How to Improve Garden Soil With Amendments Dirt by any other name will still stain your clothes, but for gardeners, that dirt becomes soil as soon as there are plants growing in it. Although garden-variety soil seems ordinary, it is actually a complex mixture of mineral particles, elemental nutrients, and organic material that combine to…

Mangoes on mango trees. Mangoes prefer acidic soils no higher than pH5.5 and no lower than 5.0 pH<br />

How to Improve Garden Soil With Amendments
Dirt by any other name will still stain your clothes, but for gardeners, that dirt becomes soil as soon as there are plants growing in it.

Although garden-variety soil seems ordinary, it is actually a complex mixture of mineral particles, elemental nutrients, and organic material that combine to form a medium that keeps plants upright, channels water and air to their roots, and offers them the nutrients they need to grow.

No gardener who has struggled with poor soil will ever again take it for granted. Taking the time to improve or preserve your garden soil can spell the difference between a vibrant, green garden and one that languishes The qualities that make for good garden soil fall into two categories: good fertility and good texture. Fertility is a combination of essential nutrients and a soil pH level that makes these nutrients readily available to the plants. Texture or Structure refers to the size of the soil particles and their cohesiveness, and the soil’s ability to transfer water and air.

Soil’s Fertility And Structure are among the most important components off a successful garden. Poor soil grows poor plants. Unless you drew the lucky card and have a garden full of black gold, you’ll need to know how to improve the soil. Improving soil is an on-going process as the plant’s leach nutrients.

How Plants Use Nutrients
Soil nutrients come from many sources, including decaying plant material, soil organisms, and fertilizer. The three primary nutrients used by plants are nitrogen, phosphorus, and potassium.

Trace elements. Besides the three primary nutrients, there are several trace elements that are necessary for good plant health, including calcium, magnesium, zinc, and molybdenum.

Why pH Matters
A lot of fuss is made over soil pH. In layman’s terms, pH is a measure of soil acidity or alkalinity. The scale goes from 1.0 to 14.0, with 7.0 being neutral. The lower the numbers go down from 7.0, the more acidic the soil. The higher they go above 7.0, the more alkaline the soil is. The reason soil pH matters are that nutrients in the soil are only available to plants if the soil pH is within a certain range. Many plants like a pH in the low acidic to a neutral range (6.2 to 6.8), but that’s not true for all plants. Gardenias, favor fairly acid soils, and Jacaranda and Oleanders will thrive in alkaline or even chalky soil. The only surefire way to know where your soil’s pH falls is to have it tested. Keep in mind that it takes time to alter soil pH and your soil will tend to revert to its old pH over time, necessitating repeated treatment.

Soils with a pH level that is higher than 7 are said to be “alkaline.” Such soils are suitable for growing plants that thrive in “sweet” soil, as opposed to a “sour” or acid soil. If soil pH needs to be raised (that is, the ground is not alkaline enough), apply garden lime. If, on the other hand, your soil has too much alkalinity, you can lower the pH by applying a fertilizer that has sulfur / ammonium-N in it (you may see “Ammonium sulfate” on the label). Do not be scared by the chemistry lingo: when you are at the garden center, just look for a fertilizer intended for acid-loving plants (it will have the ingredients that you’re seeking).

Fortunately, just as there are plants that like acidic soils, which give you planting options on the sour ground (when you can’t — or do not want to — raise the soil pH), so there are plants that like alkaline soil (or, at least, do not mind growing in it). Observe, however, that even plants within the same genus can “disagree” over what kind of ground that they like to grow in. Take the magnificent lady slipper orchid (Cypripedium), for example. There are many types. Some like their ground sweet, others like it sour, and still others prefer a soil pH that is somewhere in between.

Many plants do well in acidic, slightly acidic, neutral, near-neutral soils, alkaline soils; in other words, they will grow fairly well in some to all ranges as long as they are not extreme. Some plants prefer highly acidic soil. To make the soil more acidic, sphagnum peat, elemental sulfur, aluminum sulfate, iron sulfate, acidifying nitrogen, and organic mulches can be used.

Some plants prefer highly alkaline soil. Liming will raise the pH of acid soils. You can improve soil conditions by adding well-rotted manure (not fresh manure) and compost.

It is also easy to feed plants when they are all happy to get the same type of plant food.

All of these plants listed below have some acid soil level requirements. Some love acidic soil more than others – they range from liking slightly acidic soil to loving very acidic soil. Be careful with very acidic soil if your plants do not need a high acid soil to grow, as highly acidic soil can inhibit the numbers of flowers and fruits in some plants. Make sure you read up on the exact soil requirements for the fruit, vegetable, flower, tree or shrub you are planting so you know the exact type of soil your investment (because make no mistake about it, landscape and gardens are investments) will thrive in!

Gardenias, Begonias, Marigolds, Caladiums, Hydrangea (blue),

Vegetable Crop Soil pH Tolerances
Vegetables and other plants grow best when the soil pH is optimal for the plants being grown. It is important to match a plant to the soil pH or to adjust the soil pH to a plant’s needs.

Soil pH is important because a soil’s acidity or alkalinity determines what plant nutrients are available to plant roots. Nutrients in the soil—elements such as nitrogen, phosphorus, and potassium—become available to plants when they dissolve in water or soil moisture. Most plant nutrients will not dissolve when the soil is either too acidic or too alkaline.

Knowing the soil pH in the planting beds in your garden will allow you to group plants by their pH needs. Grow together plants with like pH needs, similar temperature tolerances, and nutritional needs.

A pH range of 6.0 to 7.0 is good for vegetables, which is neutral to slightly acidic. The growth of most vegetables will not be hindered if the soil is between 5.5 and 7.5. Below 5.5 and above 7.5, soil treatment or modification is necessary.
Vegetables that do best in slightly acidic soil include carrots cauliflower, cucumbers, celery, tomatoes, sweet peppers, garlic, onion, pumpkins, squash, sweet corn, cabbage, parsley, beans, sweet potatoes, potatoes, peanuts, thyme, oregano, okra.

Fruit Trees
Tropical fruit trees generally tolerate acidic soil better than other varieties of fruit trees. Citrus fruits from slightly acidic 6.0 pH to alkaline 8.0. Mangoes prefer pH no higher than5.5, not lower than 5.0. Guava thrives in pH between 5.0 and 7.0. Carambola, “Star Apple” equally likes 5.0 to 7.0 pH level.

Extremely low acidic soil is not ideal for a majority of fruits. While some fruit trees can thrive in slightly more acidic soil s than multi-season fruits, they cannot be planted in pH much lower than5. If the soil around your tree is too acidic to plant fruit trees, liming is one way to adjust the pH. Liming material rolled into the soil increases the availability of nutrients like calcium and magnesium and raises the pH to acceptable levels.

Crops Listed by Soil pH Requirements:
This list will allow you to group plants according to their soil pH tolerances. You will find that in the lists below, some plants may be repeated if they have a wide soil pH range tolerance; that is some plants will grow equally well in acid or alkaline soil.
Acid Soil Crops: The following crops prefer a pH of 4 to 5.5

Parsley (5.0-7.0); Peanut (5.0-7.5); Potato (4.5-6.0); Sweet potato (5.5-6.0)

Somewhat Acid Soil Crops: The following crops prefer require a somewhat acid soil; they can tolerate a pH of 5.5 to 6.5:)

Basil (5.5-6.5); Carrot (5.5-7.0); Cauliflower (5.5-7.5); Chervil (6.0-6.7); Corn (5.5-7.5.); Cucumber (5.5-7.0); Dill (5.5-6.5); Eggplant (5.5-6.5); Garlic (5.5-7.5); Melon (5.5-6.5); Parsley (5.0-7.0); Pepper (5.5-7.0); Pumpkin (6.0-6.5); Squash, 5.5-7.0);
Sweet potato (5.5-6.0) and Tomato (5.5-7.5)