In our last post, we talked about a process known as “nutrient cycling” (read here in Portuguese) and how important it is for a continuous exchange of essential substances for soil and plants.
In today’s post from the “Forest Technologies” series we will talk about processes that are often responsible for the success or failure of an agroforestry system: management and pruning.
AFS is the intercropping cultivation of agricultural crops with tree species that can be used for restoration, recovery of degraded areas and, why not, production of organic food. In this system, it is necessary to evaluate the conditions of the species, always respecting the natural succession (time) and the stratification (space) of each one of them.
And to become even more productive, with enough light and organic matter for the development of plants, it is very important to manage and prune them from time to time, respecting their cycle.
This process is important for many reasons, such as generating biomass for the purpose of building windrows that help maintain the soil moisture and prevent erosion, making it a valuable source of nutrients and energy. In addition, it helps to create closed nutrient cycles within the system, improving soil quality over time, reducing the use of external inputs and so production costs and, above all, contributing to the microclimate of the region.
The management is also carried out when some species are causing excessive shading, the so-called “ceiling effect”, that is, when the treetops close in such a way not allowing the penetration of enough sunlight to reach all the layers in the system.
In this case, when opening pruning is necessary, up to 60% of the tree height is usually cut out, leaving the stem clean, with a canopy of 30% – 40% of the total height. At this point, it is very important to consider if there is at least 50% of the original foliage to ensure a rate of photosynthesis that does not compromise the species’ resilience. The way the branches will be cut (with suitable tools and always close to the trunk), will guarantee a healthy healing and the absence of diseases, also improving the regrowth capacity and the quality of the wood.
In many of our research areas in Fazenda da Toca we use eucalyptus as the main service tree, being one of the few species capable of withstanding drastic apical pruning, regrowing and reestablishing itself in the environment.
The process of apical pruning consists in cutting completely the upper portion (canopy) of the tree, using a tower system attached to the tractor, developed in the Farm itself. In this process, considering the natural cycles and the phase of the Moon, the tree canopy will regrow vigorously, being pruned again in the following year. At this moment, there is an opening for light throughout the system, optimizing other crops and the management of the grass lines in between the trees. The shade will gradually return to the system as the trees sprout until the next pruning.
Apical pruning management guarantees a higher diametric increase (along the trunk) and a decrease in height growth, adding value and decreasing the energy cost of harvesting and log processing. In this way, wood of better quality and higher value is created, with a lower energy footprint. In addition, the pruning material (leaves and branches) are crushed and placed later along the lines, guaranteeing the ground cover and cycling macro and micro nutrients that enhance life in the soil and also return to the trees and the crops below.
Do you want to learn more about these techniques? Here at Toca we have several courses and living experiences that will share from the plantation based on agroforestry systems, to the application of techniques to improve each stage of the system implementation. We are our own laboratory and we like to disseminate everything we learn here. Do you want to know more about our work or take part in one of our courses? Access the link and come visit us.