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September 12th, 2022
My family and I recently traveled to Zambia this last month to visit some friends in Lusaka. It was an amazing trip on many levels! While there, I saw a lot of different types of soil and soil management, both natural and manmade, and I felt such a deep sense of gratitude for the experience, the warm welcome of so many of the people we met, and the chance to see a variety of landscapes throughout the country. We were there during the dry, winter season. A lot of the soil we saw was light-colored or red and dusty (it was the dry season after all!), though there was also soil that was rich and dark, usually when it was near more consistent water, in dambos (spongy water-holding grasslands areas), or in gardens where they were watered more often or amended with manure/compost. I was fascinated to see where the soil was exposed and bare, and when it was covered. Here are some pictures that stood out to me.
Here's a dried grass seedling from a dry river bank with soil still clinging to its roots. The soil "sheath" is evidence of active soil biology where the plant leaked sugars through its roots to feed beneficial microbes in exchange for compounds it needed. These microbes also hold tiny amounts of water and can keep plants alive in very dry conditions! Neighboring grass seedlings that were a little bigger were still green and growing.
Burning back grass is one way to get nutrition or create fertilizer (from the ash) for new growth. It works and will give a new flush of growth. Small, controlled fires also can help prevent larger ones. It used to be a common land management practice in North America, too. Yet sometimes if these small fires get too hot or happen too often they can also damage the plants' roots and ultimately the soil structure over time. Notice the bright new green growth coming back through the burned old grass. Also notice the light soil color, indicating this soil is low in organic matter.
Elephants hanging out at a pool filled with a plant called "nile cabbage". The cabbage is food for many animals. It grows using nutrients from animal waste and also helps keep the water drinkable for wildlife. Notice the tree in the foreground and how its roots are above the soil level: an indicator that erosion is active here, and the soil level in that spot used to be 2-3 feet higher. I had great respect for the gardeners in the town nearby... we struggle with groundhogs and deer that eat our agricultural crops, but what do you do if an elephant visits your garden? Managing people/animal conflicts was a constant challenge from what I heard, especially near the National Parks.
A massive fig tree is fruiting near a road in South Luangwa National Park. Notice all the impalas under the tree eating the fallen figs. The tree was also filled with birds enjoying the figs. It's an example of abundance: in the midst of the dry season the tree produces fruit, and the animals come and leave waste and nutrient-rich droppings and trample it into the ground which in turn continues to feed the tree. Large trees like this anchor the soil in place, build nutrition over time, and create abundance for the entire ecosystem.
Notice how the zebras also are under a tree, both for shade and for nutrient pods. I think this was an acacia-type tree, possible winter thorn? Notice also how this landscape is covered in grass, despite the dry season. Everything but the road. Imagine what it would look like when the rains come!
At one point we were in a landscape called Mopane Woodlands named after the mopane trees that filled them. Families of elephants would go back and forth through these woods during the day and back to the river again at night. The tall trees in the background are older mopane trees, and the short, truncated shrubs in the foreground are actually also mopanes that have been pruned/eaten by elephants. It's interesting to notice how elephants maintained the grasslands by keeping forest trees small, and yet also it was interesting to consider whether or not the landscape had enough variety of ages of trees to be resilient and continue to provide enough food and fuel in the future for animals and people.
At one point we traveled to the Mutinondo Wilderness where we got to see massive granite mountains rising into the sky and "dambos" or swampy grasslands with dark, sponge-like soils. The dambos held onto water, allowing it to slowly trickle down to fill the rivers, even in the dry season! These wet areas felt incredibly peaceful, even sacred, and they hummed with life, including tiny reed frogs! There were waterfalls, rivers, and pools that were fed by a series of spongy water-holding dambos and swaths of trees.
The importance of trees was impressed on me again and again as we traveled through areas with more and some with fewer trees. When trees transpire, they breathe moisture into the atmosphere. This flow of moisture also helps pull moist air across continents from the oceans. Places like Australia which have vast deserts in their interiors have lost their plant biomass in the center of the continent. Without trees and plants, it is very difficult to pull moist air and clouds laden with rain into the center. It is both a challenge and an opportunity to increase or reduce overall tree/plant cover in a region. In the US, we are threatening to go in the direction of Australia if we are not more careful with covering our precious soil with plants for more of the year in our central Great Plains.
The trees we saw in Zambia had a mighty role - they were pulling water into the center of the continent, pulling rain that ultimately fed the rivers, including the mighty Zambezi river which is a life-giving source of the entire region. Trees here support the landscape all around them. They maintain moisture and keep the rains coming in the dry seasons. In many places, we saw trees in fields alongside agricultural crops. They functioned as windbreaks, preventing soil from drying out or blowing away, adding shade to protect crops from excessive heat, holding water in the landscapes, increasing yields, and providing both fodders for livestock and firewood for cooking.
Referring to Tree Pictures Above: Left: Baobab tree with weaver birds nests. Middle: notice the ground cover in this picture and also younger trees. Right: The amazing sausage tree has large, heavy "sausages" that hang from it and are food for many animals including baboons and elephants and it is thriving despite the bare soil in this sandy flood plain.
So many new flavors, too! One new flavor for me was ground baobab: both the roasted seeds which can be ground and used like a tasty coffee substitute, and also the fruit powder which has a citrus taste when mixed into hot or cold water. While we were there, I also tried green banana flour which has a low glycemic index, supports a healthy gut microbiome (so does baobab!), and can partially substitute wheat flour in baking for a healthier alternative that also tastes great. It made me reflect on native crops we could be growing more of here in the US, crops that also support landscape and soil health: perennials that anchor the landscape, hold water, support wildlife, and produce year after year while also growing soil at their roots. It reinspired me to also want to learn my own landscape a bit better.
Left: Notice the tiny grasses growing in the sandy soil of the riverbank. Only small amount of water is needed to bring them back to life. Middle: The remanants of dried bird beans plants. They have long thin seed pods with tiny beans that feed birds as well as fix nitrogen in the soil. Notice how the soil is a little darker here. Right: The large and heavy, almost gourd-like sausage tree fruit!
The trip to Zambia ultimately made me think more deeply about soil and landscape health. How soil health truly is a mark of resilience. How trees equal resilience. Deep roots equal resilience. Slowing water down or holding it in the landscape even at the tiny scale of microbes in the soil at a plant's roots: all that is a method or metric of landscape resilience. On a large or small scale, the need for resilience felt so essential with the challenge of the extremes of the wet and dry seasons in Zambia and yet the same concepts are also applicable and needed for building resilience in the urban soils where I live in the temperate climate of the northeast. Somehow going somewhere completely new helps see your own backyard and the local landscape in a new light.
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