Gently sloping land may be less prone to visible erosion, but soluble minerals are still carried away in runoff. The remedy for that is to minimize runoff at the source. Better yet, some of those dissolved minerals become entrapped in humus, which holds them until subsequent crop plants appropriated them. The water itself spends more time in the subsoil, within reach of plant roots.
Therefore even a gentle slope can be greatly improved by terracing, and with less effort than steeper slopes. Is it worth it? But how to go about it — and how do you terrace land that is level to begin with? Sculpting the earth into terraces involves moving soil from one part uphill to another downhill. If the land is already too flat to have any uphill or downhill, we can create some by digging deep ditches and spreading the removed soil evenly on the rest of the plot, especially on any low spots.
The combination of lowering the low point — the ditch — by, say, a foot or two, while raising the plot surface an inch or two effectively creates a terrace, a flat area where water sinks right in yet is eventually drained away slowly by the ditches.
When laying out terraces on hillsides, we want them to serve forever, so they deserve a bit of thought. The Oriental rice terraces we see in National Geographic pictures typically curve gracefully around the hillside and are often wider at some points than at others due to variations in grade.
Steeper grades require narrower terraces in order to maintain the same height. My first project Lower Garden, s was on a curved slope, so I curved the terraces see illustration. This land varied a lot in steepness — and thus width — from one end to the other, but I was determined to make the five terraces parallel — each 15 feet wide to accommodate my intensive beds, and with two foot-long beds.
On some terraces I had to move lots of earth from one end to the other. As the five terraces marched down the hill, the variance from natural contour became so extreme that I split the last terrace in two crosswise, with a cross-lynchet to separate the levels. In my so-called Back Garden, I was determined to make the terraces parallel and straight, for ease in laying out rows with a stretched string. Most of that foot slope was barely curved anyway, so it required minimal adjustment. At a fairly sharp curve at one point, I compromised and made an abrupt bend, continuing on straight for another two foot bed lengths.
But Asian countries aren't the only ones with a handle on the terrace farming system. Areas in the Mediterranean use terrace farming for vineyards and orchards of olive and cork.
Lining hillsides and the steep slopes leading down to the coast are terraced areas transformed into productive agricultural land for some of the favorite foods and wines! The Lavaux region in Switzerland also makes use of terrace farming for vineyards that line the north side of Lake Geneva. The terraces can be traced all the way back to the 11th century. Meanwhile, civilizations in South America were also tapping into the potential of terrace farming long ago to feed large populations.
Machu Picchu and surrounding ruins, pictured here, provide evidence for how the Incas mastered the agricultural practice. Smithsonian Magazine writes , "The Andes are some of the tallest, starkest mountains in the world.
Today, modern farmers are returning to the terrace farming practices used thousands of years ago as a more practical and productive way to raise the most food with the least water. Tea farmers also take advantage of terrace farming. These beautiful green crops create incredible landscapes and can often be as much a tourist destination as they are a site for growing a sought-after consumer product. Terrace farming is an ancient practice, and one that we are continually finding new evidence of in long-gone civilizations.
As recently as , researchers found that terrace farming was used near the desert city of Petra even earlier than previously thought — as long as 2, years ago. This is at the heart of terrace farming: making use of otherwise un-farmable land to create bountiful crops to support humans.
Without this practice coming of age so long ago, civilizations around the world may have had a very, very different future.
Terrace farming is also commonly used in islands such as the Canary Islands , because they have hilly terrains. When it rains, instead of rain carrying away the soil nutrients and plants down the slope, they flow to the next terrace. Every step has an outlet which channels water to the next step.
This helps in keeping some areas dry and others wet. On very high altitudes, other crops apart from rice can be grown. This is because rice does not do well at high altitudes. There are two types of terracing known as graded terracing and level terracing.
A graded terrace may have either constant or variable grades along its length. On the contrary, the level terraces follow a contour line and are best suited for permeable soil. All terracing techniques allow farmers to retain or remove water and reduce the steepness of the hill.
In fact, the purpose of terrace farming is to intercept water in a designated channel and remove it via constructed erosion-resistant ditches or subsurface pipe outlets. This proves the efficiency of terracing to stop erosion and contribute to soil conservation. Terracing helps retain soil cover and fertility since water flows do not wash off the topsoil and nutrients. Farming on a terrace is an efficient soil conservation practice.
However, it requires regular inspection and maintenance at the same time. Thus, in efficient terrace farming, it is essential to check the ridges and grass cover, improving where necessary. Another issue of the terracing practice is the sedimentation of channels, which is resolved with cleaning and planting buffer strips.
Also, the outlets and pipes should be clean and free from vegetation residue and particles that may block them. Since water comes down through designated outlets, terracing prevents the formation of soil-eroding rills. How does terrace farming prevent soil erosion? In fact, terraces break the slope, splitting one big slope into several smaller ones, making it less steep, and the force of water due to gravitation is less destructive.
However, this is not the only way of terracing to prevent soil erosion. Additionally, vegetation on front and back slopes mitigates the risk of destruction by water and wind. If a farmer sees visible signs of erosion or has decreased yields season by season, and the field elevation is uneven sloped , it is worth opting for terracing to stop erosion and boost yields.
With Crop Monitoring, farmers can get data on field elevation and how the productivity of the field has changed over time.
It shows the trend of how the vegetation was developing over a selected period. With this information, a farmer can decide on productivity zones of the field and treat each zone differently depending on the needs. In fact, the functionality of Crop Monitoring is quite comprehensive, so after implementing a terracing system, it will help monitor the state of crops with its soil moisture data, vegetation indices analytics, weather forecasts, historical insights, and more.
The choice of species depends on their productivity in highlands and sensitivity to waterlogging since terraces tend to accumulate moisture.
For example, rice grows in paddies, but its productivity drops on elevations higher than m. Nonetheless, terrace farming crops are rather diverse. These are grains, legumes, medicinal and culinary herbs, berries, nuts, fruits, vegetables, etc. In particular, examples of common crops farmed by terrace farming include:.
Prevention or reduction of soil erosion, as well as soil conservation by terracing, allow using the terraced farmlands in the long run.
It attests to the essential role of terracing in sustainable agriculture.
0コメント