Soil is the foundation of life on planet Earth and, according to Luz et al. (2002), its fertility is what most demonstrates its agronomic value, as it defines the soil's ability to provide plants with the necessary nutrients in adequate quantities to obtain the desired productivity and can easily be modified by man to adapt to the demands of different crops.
After successive crops, it is natural that the stocks of macro and micronutrients in the soil become compromised, requiring supplementation through fertilization. According to Brazilian Legislation (Federal Law 6.894, of December 16, 1980), fertilizer is a mineral or organic substance, of natural or synthetic origin, that provides at least one nutrient to the plant.
For Malavolta (1989), fertilization is a practice that consists of adding nutrients to the soil that it can no longer provide to plants, filling the gap that exists between the plant's requirements and the soil's reserves. The exact contribution of mineral fertilizers to agricultural production is debatable, but in any case, from the millions of field experiments that have been conducted around the world, their great influence on crop productivity is clearly demonstrated (ISHERWOOD, 2000).
According to Kuyumjian (2014) (cited by SEGATTO et al., 2012), the use of organic by-products has been growing worldwide, and if well managed, it is an ecologically correct and economically viable alternative. The market today has a wide range of fertilizers, which have different formulations and nutrient sources, but the question remains: which of the products available really meets expectations, and what are the advantages and implications of each of them?
Fertilizer classification
Fertilizers are classified according to the material they are composed of, as well as their quantity of macro and micronutrients. Brazilian legislation classifies fertilizers as organic, mineral and organomineral, and all are intended to improve and increase the availability of nutrients for plants.
According to Campos (2013), mineral fertilizers (with the exception of calcium) do not improve soil structure, but enrich the soil by providing nutrients and increase the contribution of organic compounds to the soil when crops are grown according to conservation practices. These are natural or industrialized products that contain essential nutrients for crop development. However, the use of these fertilizers can have an environmental impact, from the manufacturing phase to their subsequent application to the soil, causing degradation of quality, river pollution, increased greenhouse gas emissions and increased resistance to pests and diseases.
Organomineral fertilizers are organic fertilizers enriched with mineral nutrients. According to Embrapa Swine and Poultry, the great advantage of organomineral fertilizers over mineral fertilizers is the fact that they use byproducts that are environmental liabilities from other production systems as raw materials. The current national policy on solid byproducts emphasizes the importance of reusing and adding value to solid byproducts. According to Embrapa, organomineral fertilizer technology represents a promising alternative, both for the safe disposal of animal waste and for obtaining highly efficient fertilizers.
As Müller (2012) explains, organic fertilizers are materials of animal or plant origin that are recommended for their ability to increase fertility and promote the elevation of soil biological activity. This author, citing Kiehl (1985), also says that among the many products that can be used as organic fertilizer, the following stand out: manure, poultry litter, straw, vegetable remains and compost, and agroindustrial waste.
Types of organic fertilizers
According to Reetz Jr (2016), organic fertilizers are classified into 6 categories, namely: naturally occurring material, farm waste, by-products from product processing factories and agro-industry, by-products from the animal processing industry, urban waste and soil inoculants.
Naturally occurring materials are peat, for example. They are composed of partially decomposed plant remains, mainly mosses, which occur in marshy or high-altitude (mountainous) regions. According to Embrapa, soil inoculants are biofertilizers that use living microorganisms, capable of promoting plant growth directly or indirectly, through different mechanisms, such as biological nitrogen fixation, phytohormone production, phosphate solubilization, biocontrol, among others.
Farm waste includes animal manure, poultry litter, crop residues and green manure (legumes and other fertilizers incorporated into the soil). Its main nutrient is nitrogen, but it also contains large amounts of phosphorus and potassium. According to Embrapa, even though it is rich in nutrients, the concentration of chemical elements present in fertilizer can be unbalanced, so it must be applied and supplemented with additional doses of mineral fertilizers.
Vinasse and filter cake are examples of agro-industrial by-products, generated from the processing of sugarcane. They are fertilizers rich in nitrogen, calcium, magnesium, zinc and copper. In addition, by-products from the paper and pulp industry, waste from the timber industry and seaweed extracts are also considered by-products of agro-industrial processing.
Regarding the by-products of animal processing industries, we can mention blood, horn and bone meal, and also bran and waste from the leather industry. They are characterized by their rapid action on the soil, in addition to presenting high concentrations of nitrogen. The close relationship C/N hoof and horn and blood meal can enhance the rapid mineralization of organic matter and consequently release its nutrients (KUYUMJIAN, 2014).
Advantages of organic fertilization
According to Lima et al. (2015), the principle of organic fertilization is to activate and maintain soil life. They also mention that, by replenishing nutrients and energy, natural biogeochemical cycles are activated and can be optimized. For Cavallaro Júnior (2006), organic materials can be used as sources of nutrients and as soil conditioners, improving their physical and chemical characteristics, such as increasing water retention capacity, soil aeration, pH and cation exchange capacity (CEC).
Organic fertilization also has other advantages, as it uses byproducts whose disposal would cause environmental impacts. Another highlight of this type of fertilization is its duration. The process of absorption of organic nutrients involves decomposition and mineralization, and for this reason, these compounds gradually release nutrients such as nitrogen, potassium and phosphorus, which reduces losses due to leaching and adsorption. They act on the stability of the soil structure, especially on porosity, which increases the retention of water and oxygen.
N-TIME+: An exclusive technology from ILSA Brazil
It is important to remember that soil analysis is an important factor in choosing the product to be used, as it provides all the information about the area and allows the producer to make the correct decision. High-quality organic and organomineral fertilizers should have a low C/N ratio, as this benefits the soil biota, since N serves as food for these organisms, favoring the mineralization of nutrients present in the fertilizer. They must also demonstrate significant nutrient levels and be free of seeds, pathogens and pests.
ILSA collaborates with several teaching, research and development institutions in scientific research and study of microbial activity through the use of AZOGEL, which is obtained through the FCH process. This organic matrix has shown a positive influence on soil microbial growth and activity in several scientific studies in Brazil and worldwide.
Studies conducted at the University of Padua, Italy, analyzed the number of colony-forming bacteria (CFU), that is, the number of viable cells per gram of dry weight of soil. The colonies were inoculated and incubated in Petri dishes for counting after 30, 60 and 90 days. The results show that AZOGEL increases the number of colonies present in the soil. It is also noted that there is a decreasing trend over time, since after about two months all the nitrogen of protein origin has been mineralized and absorbed by the plants.
The experiment indicated significant development of microbial populations, reaching a population of approximately 100 million viable cells per gram of dry soil, which indicates a positive response of soil microorganisms to the supply of organic nitrogen and carbon. However, CFU analyses, although a quantitative parameter, do not provide qualitative information on the microbial population, i.e., the number of cells is known, but they do not provide information on their efficiency. Thus, when the quantitative analysis of the bacterial communities present was performed using the PCR (Polymerase Chain Reaction) technique, it was evident that after 30 days of incubation, the soil that received AZOGEL application presented a greater number of nitrifying bacteria compared to the control treatment. This group of bacteria is responsible for the oxidation of ammoniacal nitrogen into nitric nitrogen. It is also possible to observe that, after 90 days of incubation, there was a considerable reduction in the number of cells in the control treatment, while the soil that received AZOGEL application continued to support communities of nitrifying bacteria.
It is important to highlight here that the quality of the rhizosphere depends on the high availability of carbon organic. The amount of carbon required is considerably higher than that of nitrogen, since microorganisms use it as a source of energy, and it is present in cellular material in a much greater quantity than nitrogen, incorporated into organic molecules that perform vital functions for cells (CANCELADO, 2014). Thus, both nitrogen and other organic components present in high concentrations in AZOGEL contribute positively to adequate microbial development in the rhizosphere. This is a very important factor because bacteria feed on organic carbon and plants feed on the elements that bacteria and fungi provide.
According to Moreira and Siqueira (2006), the C/N ratio of materials incorporated into the soil has a significant influence on all transformations of N, mainly nitrification. High C/N ratios cause the immobilization of mineral N, at least temporarily, ceasing nitrification due to lack of substrate (NH4+) and can cause nitrogen deficiency in plants, hence the importance of a fertilizer with a low C/N ratio. In addition, these authors also mention that N, because it is an open cycle in nature, is what suffers the most losses and, therefore, what most limits agricultural production. For this reason, fertilizers that gradually release this nutrient have been gaining more and more space in the agricultural sector.
THE N-TIME+ It is a highly efficient organomineral fertilizer, produced based on AZOGEL. The proven benefits of this fertilizer are numerous, such as high nitrogen fertilization efficiency, as it presents in its formulation 13 % of N, which will be released gradually and constantly throughout the plant's production cycle. In addition, it has a low C/N ratio, which, as already mentioned, is extremely important for the development of soil biota; and it promotes soil CTC, allowing balanced vegetative development. It contributes to soil microbial activity, contributing to a healthy and better structured soil, increasing crop productivity and profitability.
The value of an organic fertilizer goes beyond the simple supply of nutrients, as its use provides many beneficial effects to the soil. organic matter It acts as an energy source for beneficial microorganisms (which fix nitrogen from the air in the rhizosphere and fungi that associate with the roots), improves structure and aeration, and has the ability to store moisture. It has a regulating effect on soil temperature, slows down phosphorus fixation and increases cation exchange capacity (CEC), and helps to hold potassium, calcium, magnesium, and other nutrients in forms available to the roots, protecting them from leaching by rainwater or irrigation practices. In addition, some of its decomposition products have a stimulating effect on root development (MALAVOLTA et al., 2000).
References
CAMPOS, ARF Organic and mineral fertilization on productive characteristics of tomato cultivar Santa Cruz in a protected environment. Federal University of Paraíba, Areia, 2013. 44p. (Course Completion Work)
CANCELADO, SV Evaluation of the microbiological quality of a compost produced from animal and vegetable waste. São Paulo State University “Julio de Mesquita Filho”, Jaboticabal, 2014. 82 p. (Master's dissertation)
CAVALLARO JÚNIOR, ML Organic and mineral fertilizers as sources of N and P for arugula and tomato production. Agronomic Institute of Campinas, Campinas, 2006. 39 p. (Master's Dissertation)
ISHERWOOD, KF Mineral Fertilizer Use and the Environment. International Fertilizer Industry Association, Revised Edition. Paris, 2000. 63 p.
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LUZ, MJS; FERREIRA, GB; BEZERRA, JRC Fertilization and Soil Correction: Procedures to be Adopted Based on Soil Analysis Results. Technical Circular, Embrapa Cotton, Campina Grande, n. 63, 2002. 32 p.
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MOREIRA, FMS; SIQUEIRA, JO Soil microbiology and biochemistry, UFLA Publishing House, Lavras, 2006. 729 p.
MÜLLER, DH Characteristics of organic fertilizers, effects on soil and banana tree performance. Federal University of Mato Grosso, Cuiabá, 2012. 83 p. (Master's Dissertation)
Presidency of the Republic – Civil House: Check it out.
Embrapa Swine and Poultry Electronic Portal (Available at: Embrapa)
REETZ JR, HF Fertilizers and their efficient use. International Fertilizer Industry Association, France, 1st ed. 2016, 179 p. Translation: LOPES, AS; ANDA, São Paulo, 2017.
SEGATTO, MP; ANDREAZZA, R.; BORTOLON, L.; SANTOS, VP; GIANELLO, C.; CAMARGO, FAO Decomposition of industrial waste in soil. Science and Nature, UFSM, v. 34, p. 49-62, 2012.
Authors
- Agricultural Eng. Msc. Aline Tramontini dos Santos
- Agricultural Eng. Msc. Carolina Custodio Pinto
- Agricultural Eng. Msc. Thiago Stella de Freitas
