Santiago, November 2020.- Making better use of natural resources is a key aspect that the INIA La Platina extension team promotes among small and medium farmers in the Metropolitan region, through its technology transfer efforts. This is the case of the incorporation of organic matter in the soils, to obtain greater natural fertility and, therefore, productivity. This was explained by extensionist Fabiola Sepúlveda, who for years has been developing this technique together with other INIA professionals throughout Chile.

Soil fertility is its ability to support plant life, which in turn depends on different factors such as: availability of nutrients, water retention capacity, existence of a physical space for root growth, movement of gases and the absence of destruction processes. "Consequently, the natural fertility of a soil will be determined, to a large extent, by the presence of organic matter", highlighted the INIA professional.

Specifically, Fabiola added, soil organic matter is the set of plant and animal residues of all kinds, more or less decomposed, and transformed by the action of microorganisms. While the main microorganisms that can be found in soils are: bacteria, fungi and algae, and under the action of these the residues slowly decompose and transform into varied organic compounds.

Among the main benefits that organic matter provides are:

  • It contributes to the individual mineral particles in the soil forming stable aggregates, thus improving the structure of the soil and facilitating its tillage.
  • Promotes good porosity, thus improving aeration and water penetration.
  • Increases the ability to retain water.
  • For the above reasons, it reduces the risks of erosion.
  • It provides colloidal-sized, negatively charged particles (humus) that have a high capacity to retain and exchange nutritive cations.
  • It acts as a buffering agent by reducing the tendency to a sudden change in the pH of the soil, when substances of acid or alkaline reaction are applied.
  • It enables the formation of organometallic complexes, thus stabilizing soil micronutrients that would not otherwise be usable.
  • It is a source of nutritional elements, which can be used by plants after organic matter has been decomposed by microorganisms.
  • It is possible to increase the organic matter of the soil through various practices, such as the incorporation of stubble stubble of a crop, establishment of crop rotation that consider legumes, green manures, plant covers, manufacture and application of compost, among others.

How to incorporate crop residues, pruning or stubble?

INIA La Platina extension worker, Fabiola Sepúlveda, explained that the remains of the crop that remain in the field, after harvesting or pruning, can be processed with the stubble crusher and then incorporated into the soil by means of a harrow. In this way, a decomposition occurs due to the action of soil microorganisms, with the consequent positive effects on its structure, such as increased microbiological activity and nutrient availability.

With excessive amounts of stubble, problems can be faced in soil preparation, planting and establishment of the next crop. When these residues have high carbon (C) content, compared to nitrogen (N) content, it can also promote the phenomenon called net immobilization of (N) or “N starvation”, caused by the decrease of this element in the soil , being used by microorganisms in the decomposition of waste rich in C.

Furthermore, the application of some stubble could have allelopathic effects on certain weeds or on the new crop, that is, negatively affect weeds or crops due to the action of root exudates.

How to do a correct crop rotation? 

Crop rotation is the recurring and regular succession of different crops on the same field over time. This practice has been widely used in soil conservation systems. Thus, it has been shown that it increases the availability of nutrients, improves the structure of the soil and its biological activity, and reduces the incidence of pests, diseases and weeds.

However, the success of the crop rotation will depend on the selection and sequence of the crops to be rotated. Therefore, to design the rotation, the following technical criteria should be considered:

  • Choose crops in a balanced way, those that provide nutrients and extractives.
  • Include legumes for their nitrogen contribution.
  • Include green manures.
  • Include crops with different root systems.
  • Separate in space and time the crops that are susceptible to similar diseases, pests or weeds.

It is important that the crops considered in the rotation have different nutritional requirements, but with similar pH requirements; that keep the soil covered, increase the content of organic matter and the structure of the soil, reduce the presence of pests, diseases and

weeds; and, preferably, that they have an attractive market.

Despite this, it is preferable in some cases to establish a recovery crop, as is the case with green manures, even if no harvest is obtained, since, despite not being economically profitable, they increase the production of the next crop.

About INIA 

The Instituto de Investigaciones Agropecuarias (INIA) is the main institution for agri-food research, development and innovation in Chile. Linked to the Ministry of Agriculture, it has a national presence and a work team of more than 1,000 highly qualified people. It executes an average of 400 projects per year around 5 strategic areas: Climate Change, Sustainability, Food of the Future, Emerging Technologies, and Extension and Training of Capacities. These initiatives contribute to the sustainable agri-food development of the country, creating value and proposing innovative solutions to farmers, strategic partners and society, generating a social profitability that varies between 15% and 25%, for each peso invested in each of their projects.

INIA, more than 55 years leading the sustainable agri-food development of Chile.

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Press contact: Communications Manager at INIA La Platina, María Jesús Espinoza mariajesus.espinoza@www.inia.cl