There are many benefits associated with having trees on your property. They can add quite a bit of value to your property, which is beneficial if you intend to sell at some point in the future. They provide a lot of aesthetic value as well, and greater comfort in the shade they offer various spots of your property. Strategic tree planting for shade purposes can even lower the amount of energy you have to use to cool your home in the summer months.

But there are plenty of other benefits that individual types/species of trees provide as well, and many of them are capable of adding nitrogen to your soil.

Why exactly is this important, you might wonder? Well, nitrogen is one of the most essential plant nutrients. An insufficient amount of nitrogen in the soil will result in plants growing very slowly. There are some types of plants (including trees) that actually add more nitrogen into the soil, which can have benefits for plant life all around them.

Here are just a few examples of some trees that are known to have these nitrogen-producing benefits.

• Black alder: This is a tall tree found in Europe that can grow up to 30 m tall, or approximately 100 feet. It’s very resistant to cold, so it comes as no surprise that it’s frequently found in zones 2-7. It’s relatively short lived (between 30 and 70 years) and is known to thrive in damp, riparian environments. Similar to most nitrogen-producing plants, the increased nitrogen level it provide to the soil also increases phosphorous. As a result, some landscapers and gardeners will plant different species of alder as nurse crops to increase the fertility in the area for their other, more demanding and valuable trees, such as spruce, fir or beech. Black alder are capable of fixing as much as 320 kg of nitrogen per hectare per year.
• Black locust: Black locust can grow up to 52m (170 ft), but do not frequently reach those heights. They are native to North America, and are cold hardy in zones 3 to 8. It prefers a soil pH of between 6.0 and 7.0. You can expect black locus to fix up to 220 to 250 kg of nitrogen per hectare per year. The tree also doubles as a plant that is extremely resistant to rot (making it great for fence posts), and it also makes for excellent firewood because it burns long and hot.
• Empress trees (Paulownia tomentosa): The empress tree (also referred to as the princess tree) is native to China, and can grow to 10 to 25 m (33 to 82 ft). It thrives in zones 5B-9, and has the distinction of being the fastest-growing tree in the world. There are no clear studies that have been performed into the exact efficiency of this tree in its ability to produce nitrogen, but its efficiency is expected to be high, as it has nitrogen-rich leaves and very impressive growth rates even in lower-quality soils.

To learn more about some of the best nitrogen-producing trees and plants, contact one of the Soil Advocates Team at admin@soiladvocates.ca or 289-221-0164.