The importance of Silvopastoral Systems for the recovery of forests and soils in the peruvian amazon

Written by: Miguel Erazo

PERU-Hub Communications Office

Did you know that out of the 70 million hectares of forest that used to exist in the Peruvian Amazon, 10 million hectares have already been deforested?

When we talk about the Amazon, we think of the great wealth of flora and wildlife that is abundant in this important tropical area of the Peruvian territory, but do we also think of the enormous problems it faces? Deforestation and soil degradation are clearly the main reasons that have caused an enormous loss of biodiversity in the so-called ‘green lung of the world’, which hosts a great variety of tropical forests and plays an important role in the reduction of greenhouse gases. This is well known to Julio Alegre, PhD., PERU-Hub’s Crops Coordinator and renowned professor and researcher who has dedicated more than 40 years of his life to the management and recovery of degraded soils in the Peruvian and Brazilian Amazon. His work has taken him to different countries, especially in Asia and Africa.

In view of the situation the Peruvian Amazon region faces, we talked to Dr. Alegre to learn a little more about silvopastoral systems, a strategic axis promoted by PERU-Hub that brings benefits such as reforestation, sustainable livestock production and, of course, land recovery.

Julio Alegre, PhD., is a professor and main researcher at Universidad Nacional Agraria la Molina. He belongs to the Academic Department of Soils of the Faculty of Agronomy.

What is a Silvopastoral System?

A Silvopastoral System (or simply SPS) in a very simple way, is a tree that coexists with pastures and animals. If you have a paddock (site dedicated to cattle raising) where there are fences of pure trees and pastures that are grazed with animals, you will have a Silvopastoral System in that space.

Basic Silvopastoral System (SPS) and its components. Source: Expoknews

Are there models of Silvopastoral Systems or is there only one?

There are many variants. The Silvopastoral System is an Agroforestry System (also known as SAF) and as a concept, can have a series of prototypes or variants. Within the Silvopastoral Systems can be for example: trees in rows within the paddock, scattered trees within the paddock, among many others, where the tree serves as shade or food for the animal.

Which SPS will be applied in San Martin?

Any of the above. We have studied this issue quite a bit in the area. The farmers themselves already do it. They do not know what Silvopastoral System is, but they apply it already. Farmers in San Martin commonly use live fences to prevent animals from escaping, and these live fences also serve as food for the cattle, fulfilling a double function: protection and food.

What key aspects should a producer consider before establishing an SPS on their farm?

He must know the wood producing or forestry species that he wants. If they are interested in feeding their animals, they would choose a shrub type tree that serves as fodder. And if they just want protection against the wind, they could put large windbreak trees. Now if they want it to serve both purposes (protection and food), they should use a specific species. The key is the knowledge about the plants, about the species that are going to grow in the system.

What are the benefits of a correctly applied SPS?

  • It reduces the tendency for pasture degradation. A farmer usually overgrazes the pasture without a Silvopastoral System, that is, he does not manage it properly. Whereas when he has trees, this process is regulated, and the stocking rate can be managed more efficiently.
  • At the same time, the SPS helps with soil conservation, pasture reforestation, higher pasture production, erosion prevention, animal, and farm productivity, among others.
  • It also adds value to the farmer’s farm or pasture. If we plant timber trees, we will have timber in the long term. It will generate more money than all the cattle that have been raised. In the interim the farmer can sell milk, beef, etc. In other words, while you are waiting for the tree to produce, you are building your productive system for milk, meat, etc.
San Martin is one of the regions that is continuously working on the reforestation of degraded areas in the Peruvian Amazon.

«If the farmer has a tree on his farm, this tree will also serve as a greenhouse gas sink. Environmentally it is also a benefit.»

What is the difference between Silvopastoral Systems and Agroforestry?

All the terms that we use: silvopastoral, alley cropping, row cropping, are all names of Agroforestry Systems, i.e., the general term is Agroforestry. Agroforestry includes Silvopastoral Systems, Agrosilvopastoral Systems, Row Crops, Fence Crops, and other variants. In the Agrosilvopastoral System you have: Agro=Crops, Silvo=Trees, Pastoral=Pasture and Animals. So, it is simply when you work initially with crops, then with trees (preferably protected if they are not yet grown), then with a cover (pasture) and finally with animals.

What species of trees, pasture, animals, and crops make up the Agrosilvopastoral Systems that PERU-Hub is implementing?

We are studying the following options:

  • Trees. We are going to emphasize those of fast and medium growth, which are Capirona, Bolaina, Tornillo and Shaina.
  • In the case of Grasses, we would work with those that are already known and established, such as: ‘Brachiarias’, grasses that farmers already use. We can also use leguminous plants as a protein bank with Centrosema macrocarpum, Desmodium ovalifolium, etc. We also have shrubs such as Leucaena leucocephala, Erythrina sp. among others.
  • Animals: We have Gyr (a breed of cattle) on the farm. They are 100% milk producers.
  • Crops: Cacao, guanabana, passion fruit, vanilla, etc. We are going to teach innovative things.
Trees act as a protection for the soil in the presence of water from heavy rainfall.

Regarding degraded soils, can an SPS recover the soil, or does it act only to prevent soil erosion?

It recovers it. I have recovered degraded improved pastures with hedges and trees. Crop hedges improve soil fertility, fix nitrogen, and have other properties such as providing quality organic matter that improves soil physical properties such as the ability to improve soil structure and water retention and serves as food for a great biodiversity of soil macro and microorganisms that determine good soil health.

Leguminous trees also have properties such as nitrogen uptake from the atmosphere and the leaf litter improves soil fertility. If these trees are on slopes, you put them in the contour, and they generate living barriers that protect from runoff and erosion and decrease the washing of nutrients and organic matter.

Do you know of any case of silvopastoral systems successfully applied in tropical regions of the Peruvian Amazon? What key information or data can you gather from this experience and how could it be useful for the work you are developing with PERU-Hub?

One thinks that farmers do not do agroforestry or silvopastoral systems when they have been doing it for many years. As I said before, farmers do agroforestry when they produce cocoa or coffee with shade trees.

We have found 12 different silvopastoral systems from Chachapoyas to Tarapoto, some of which are excellent and in reforestation programs the trees were left in pastures and are still grazed with animals.

On the other hand, the success of an SPS, as the farmers of Chachapoyas know, lies in the use of electric fences, because it allows the management of the animal load and grazing, thus avoiding the animal to walk alone and excessive consumption of the vegetation on the soil.

Electric fences for the Pucayacu farm plots at the Regional Development Institute (IRD) in Tarapoto, San Martin.

Finally, how do you see the development of SPSs in Peru, especially in tropical regions? Have we made significant progress, or do we still have a long way to go?

The road is always long in Peru. Other countries are already 20 years ahead of us and we had started together. For example, Colombia, Nicaragua, and Costa Rica have had SPS’s for more than 40 years. The inclusion of trees is in itself a long process.

I have the experience of having visited farmers in Colombia and they have implemented thousands of hectares of SPS for meat and milk production with the management of electric fences. It means that they have already adopted it by recognizing and understanding its importance. Those SPS designs from the Colombian experience will help to solve the problem of deforestation and soil degradation, very big problems we face in our country.

«There are only 60 million non-deforested forests left out of the 70 million we used to have.»

My hypothesis is that we should not open a single hectare of primary forest to make any kind of intervention in the Peruvian Amazon, there is already enough degraded area and we do not need to extend the agricultural frontier. Rather, we need to recover what is already degraded. Through recovery, we will improve the environment and be in line with the demands of the international community regarding the care of our forests.