Some considerations on pasture management in agroecosystems

Dear readers, in our blog we have addressed a great diversity of aspects related to the forage species of the grass family or poaceae focusing on pastures, because it is the main food of ruminant animals not only because of the contribution of protein that it can supply to the animals but also because of the contribution of fiber that allows there to be a pH balance in one of the compartments (Rumen) that make up the digestive system of ruminants, thus avoiding some diseases that can have an impact on production.

In the previous section, the nutritional and physiological benefits that grasses can provide when consumed by ruminants are described, but in order for these forage species to manifest their maximum potential, they must be managed in the natural ecosystems in an appropriate way by the person in charge of the productive system, starting from purely agronomic management such as organic fertilization, integrated pest control, among others, which are practices that are commonly carried out to any crop, but grasses have the ability to regrow in the short to medium term after being cut by the animal.

Taking into account the regrowth capacity that these plants have, they should be monitored on the forage surfaces and determine what frequency and cutting height should be allowed by the animals so that their gradual growth is not affected each time it is cut, that is why, regarding this variable, several publications have been made in magazines and books by specialists in the area where they indicate the possible rest days according to the rainy and rainy period as well as the cutting height.

To establish a cutting frequency in the pasture it can vary depending on the edaphoclimatic conditions (soil and climate) where they develop and the grazing pressure that is granted, that is, the animal load influences there, the days of grazing and rest that is granted to the pasture, so that its growth tissues, known in the agricultural sciences as meristematic tissues, are not affected. These tissues facilitate the growth in length of plants, there are the apical, intercalary, basal meristems, in the case of the apical ones they are located at the apices and allow the growth of stems, branches and leaves, which allows explaining why grasses regrow quickly once they are cut if their meristematic tissues are not affected by overgrazing.

In case of observing that the pastures were overgrazing as the first practice to consider is to increase the rest days because there is possibly a depletion of their reserves and allow the few active growth points to carry out their process gradually, because otherwise if we enter the animals in short periods it does not open a full recovery and in the medium or long term the plants will degrade leaving bare spaces on the surface without any type of forage plant species.

Researchers such as Bieto and Talon (2008), mention that the main function of plants is to intercept solar radiation through their foliage, in addition to absorbing water and nutrients through the roots that allows them to obtain enough energy for their growth and development, a process that forage plants perform in the same way, but apart from that, they must create mechanisms to adapt to the effect of severe defoliations.

In this regard, Chacón (2013), pointed out that the impact of defoliation is determined by the amount and type of tissue removed, remaining leaf area, harvest frequency and physiological state of the pasture, also the author mentions that the immediate effect of a defoliation is reflected in the reduction of the leaf area and therefore less amount of light intercepted which influences the accumulation of carbohydrate reserves and root growth.

In this sense, Herrera (2006), states that some symptoms have been observed such as a decrease in the accumulation of forage in species such as Megathyrsus maximus, referring to the density and growth of the stem, stating that the accumulation of biomass will depend on the height and frequency of cutting.

Dear readers, it has been possible to show that defoliation is an important disturbance factor in forage poaceae species in their growth stages, that is why it is important that height and cutting frequency standards are established in production units that adapt to the conditions of the livestock ecosystem in order to avoid affecting their growth and development, since severe defoliation results in a decrease in biomass yield.