Soybeans (Glycine max [(L.) Merrill]), is the country's main agricultural crop destined for export, which makes Brazil occupy a prominent place in the global agricultural scenario as the world's largest producer of this commodity in 2022. The National Supply Company (CONAB) published, in July 2022, its 10th Harvest Survey, stating that in this harvest, 40,950.6 thousand hectares were sown, 4.5 % higher than the 2020/21 harvest. Also in this survey, the production obtained was 124,05 thousand tons, 10.2 % lower than the 2020/21 harvest, and the average productivity achieved was 3,029 kg ha-1. This reduction in relation to the last harvest is most likely due to the influence of the phenomenon La Niña, especially in the South and Mato Grosso do Sul regions, with a drastic drop in rainfall. The State of Mato Grosso has consolidated itself as the largest national producer, followed by the States of Goiás, Minas Gerais, São Paulo, Paraná and MATOPIBA – an important region for the expansion of the country's agricultural frontier, which includes the states of Maranhão, Tocantins, Piauí and Bahia, according to data released by IBGE (2022).
Soybeans, according to Sfredo et al. (1986), are annual crops that are very demanding in terms of all essential macronutrients. In order for the nutrients to be efficiently used by the crop, they must be present in the soil in sufficient quantities and in balanced ratios. Insufficiency or imbalance between nutrients can result in poor absorption of some nutrients and excessive absorption of others. In order to achieve and maintain this balance, certain practices such as liming and fertilization must be employed rationally, always based on soil analysis.
Soil liming
Most Brazilian soils are considered acidic. When not corrected, acidity can become a serious problem. This acidity is basically due to the presence of two components: H ions+ and Al+3, and is caused by the intense washing and leaching of soil nutrients, by the removal of cationic nutrients by the crop without proper replacement, and also by the use of acidic fertilizers. When acidity is high, the most advisable measure for its correction is liming. Soil liming is the recommended technique to reduce this acidity, where limestone (CaCO3) – a rock with low solubility, with the aim of correcting the soil pH, increasing calcium and magnesium levels, neutralizing aluminum and preparing the environment for the roots to grow in a way that provides the best crop development.
In addition to the benefits mentioned, Santiago and Rossetto also highlight the increased availability of phosphorus, since it reduces the sites where this element is fixed in the soil; reduced toxicity of aluminum and manganese through the formation of hydroxides, which are not absorbed; increased mineralization of organic matter and, consequently, greater availability of nutrients. Liming also favors nodulation and consequent biological fixation of nitrogen – extremely important in soybean farming. Therefore, liming is essential to improve the physical, chemical and biological properties of the soil, representing one of the most cost-effective investments for rural producers.
According to Sfredo (2008), liming should be done at least 90 days before sowing soybeans, to allow the limestone to react and increase the pH. According to this author, in regions with a rainy season and a dry season (6 months for each), liming should be done before the end of the rainy season, prior to the next crop season, in order to provide enough time for the limestone to be incorporated into the soil. Sfredo (2008) also states that the limestone should be incorporated to a minimum depth of 20 cm.
ILSA Brazil soybean fertilization plan
Figure 1. Phenological phases of soybean crops and fertilization recommendations ILSA BRASIL.
Soybean plants prefer soils with clay contents ranging from 15 to 35 %. Soils should have good structure, adequate drainage, and good water retention capacity and nutrient availability for plants. According to Borkert et al. (1994), nutrient absorption by soybeans is influenced by several factors, including climatic conditions such as rainfall and temperature, genetic differences between varieties, nutrient content in the soil, and different crop treatments. Nutrient absorption is measured by the amount accumulated in the leaves and stems of the plant and increases until reaching the point of maximum accumulation, which is 75 days (Sfredo, 2008b). From this point on, accumulation decreases due to the translocation of nutrients to the grains in formation (Cordeiro et al., 1979).
The element most required by soybeans is nitrogen (N). According to Sfredo (2008b), it is estimated that 83 kg of N are needed to produce 1,000 kg of grains. The sources of N required for soybean crops are: 1. soil, mainly through the decomposition of organic matter; 2. non-biological fixation, resulting from electrical discharges, combustion and volcanism; 3. biological fixation of atmospheric N; and 4. nitrogen fertilizers, as mentioned by Crispino et al. (2001). N plays a fundamental role in the plant, being directly linked to the composition of amino acids and proteins, constituting macromolecules and enzymes, in addition to being responsible for the dark green color of vegetables and, as it promotes the development of the root system, improving the absorption of other nutrients from the soil. According to Faquin (2005), nitrogen is one of the nutrients required in greatest quantity by plants, constituting 2 to 5 % of the plant's dry matter. ILSA Brasil offers organomineral nitrogen fertilizers recommended for soybean crops, produced based on AZOGEL® and GELAMIN® – hydrolyzed gelatins for agricultural use, which provide N throughout the production cycle. AZOGEL® is the matrix used to manufacture fertilizers for soil application, and GELAMIN® for fertilizers for foliar application and/or fertigation.
The Gradual MIX® line of fertilizers is produced from the AZOGEL® matrix, with formulations for use throughout the production cycle. For soybean crops, ILSA Brasil recommends the following formulations as base fertilization: 06-15-10 (for in-line potassium application) or 06-24-00 (when the farmer chooses to apply potassium via KCl in broadcast form). Among the many benefits of using the Gradual MIX® line are: longer-lasting assimilable N – gradual release mediated by soil microorganisms, allowing balanced vegetative development; lower losses of mineral nutrients due to the protective action of high CTC organic matter; and it also prevents deficiencies of nitrogen, phosphorus, potassium and calcium, macronutrients that are essential for balanced plant growth. In addition, Gradual MIX® promotes increased soil biological activity, showing affinity with atmospheric N-fixing microorganisms.
For foliar application of soybean nutritional supplements, ILSA Brasil® offers the following fertilizers: ILSAMIN Potente®, ILSAMIN Physio®, ILSAMIN Ágile® and ETIXAMIN Kally®, all derived from the GELAMIN® matrix. ILSAMIN Potente® is a fertilizer that should be used in the planting furrow and contains, in addition to the amino acids characteristic of the matrix, humic and fulvic acids and auxin inducers. The presence of these elements stimulates plant rooting, since certain amino acids are converted into indoleacetic acid (auxin) through several metabolic pathways, as cited by Goulart et al. (2011). This conversion is important for the initiation of development and establishment of the root-shoot axis of plants (TAIZ; ZEIGER, 2004). In addition, these organic acids increase the water retention capacity of the soil and are directly associated with increased stability of soil aggregates – improving their structure, and also with increased cation exchange capacity (CEC). They stimulate micro and macrofauna and promote better absorption of nutrients by plants, also acting on hormonal metabolism.
ILSAMIN Physio®, in turn, can be used from the VC stage to the V4 stage, normally associated with the application of glyphosate, as it contains manganese (Mn) in its composition. Mn helps reduce damage caused by herbicides, by promoting, together with the amino acids present in the fertilizer, resistance and/or overcoming abiotic stresses. In a trial published by Albrecht et al. (2018), the application of bioregulators enriched with Mn was successful in attenuating visual symptoms of glyphosate phytotoxicity, increasing plant dry matter mass and chlorophyll index, evidencing attenuation of symptoms in soybean plants. The authors also show that low phytotoxicity did not significantly interfere with the agronomic characteristics and production components evaluated.
Another excellent fertilizer that ILSA Brasil® has available, also derived from the GELAMIN® matrix, is ILSAMIN Ágile®, which can be used throughout the soybean production cycle. This product has 16 essential amino acids in its formulation that act directly on plant metabolism, promoting resistance to stress – especially related to environmental factors such as frost, water deficit and heat stress. In addition, it stimulates healthy root growth and enhances photosynthesis, since amino acids increase the speed of recovery from damage. Furthermore, Castro et al. (2011) mention that the use of amino acids promotes grain filling, generates an increase in plant height and also in the number of pods, increasing crop profitability.
For the reproductive phase of soybeans, especially between stages R4 and R8, the use of ETIXAMIN Kally® fertilizer is recommended, which has a major advantage over similar fertilizers: it provides potassium (K) and amino acids simultaneously. K plays a fundamental role in grain filling, as it is associated with the process of translocation of sugars and organic acids from photosynthesis. In addition to K, amino acids also play a fundamental role in the activation of enzymes and phytohormones, which enhances both the photosynthetic process and the metabolism of sugar transport in the plant. Fertilization with ETIXAMIN Kally® accelerates and promotes rooting, increases grain quality and also favors resistance against biotic and abiotic stresses, since potassium is directly related to enzyme activation, promoting crop protection, in addition to increasing the thickness of the leaf cuticle and cell wall, which hinders the entry of phytopathogens and the progress of infections. It is important to mention that K also acts in the osmotic regulation of the plant, which ensures the health of the plants in the face of adverse climatic conditions.
The amino acids present in ILSA Brasil fertilizer formulations increase the plants’ ability to withstand adverse conditions, whether abiotic or biotic – such as increased resistance to diseases and pest attacks. This is because N is not released in a single step, but rather throughout the cycle, avoiding competitive inhibition of the absorption of other nutrients responsible for the rigidity of plant tissues. In addition, all of our fertilizers have a low environmental impact throughout the production chain, contributing to sustainable agriculture and high profitability for the producer.
It is important to mention that fertilization to be carried out on crops must be rational, which presupposes the appropriate use of fertilizers, avoiding insufficient or excessive applications, in order to provide the plants with the nutrients that are actually needed, in the appropriate quantities and at the appropriate times, while simultaneously preserving the environment. To this end, it is necessary not only to know the state of soil fertility, but also to know whether the nutrients present there are being effectively used by the crop. Therefore, the doses to be used are not described in the text because they should be based on soil and/or leaf analysis and on the recommendation of an agricultural engineer.
Bibliographic references
Brazilian Crop Monitoring – Grains. 10th Survey, National Supply Company (CONAB), July 2022. Available at: https://www.conab.gov.br/
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Brazilian Soybean Producers Association (APROSOJA Brazil) – Available at: https://aprosojabrasil.com.br/a-soja/
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CORDEIRO, DS; SFREDO, GJ; BORKERT, CM; SARRUGE, JR; PALHANO, JB; CAMPO, RJ Liming, fertilization and mineral nutrition. In: EMBRAPA. National Soybean Research Center. Ecology, management and fertilization of soybean. Londrina, 1979. p.19-49. (EMBRAPA-CNPSo. Technical Circular, 2).
CRISPINO, CC; FRANCHINI, JC; MORAES, JM; SIBALDELLE, RNR; LOUREIRO, MF; SANTOS, EN; CAMPO, RJ; HUNGRIA, M. nitrogen fertilization in soybean crops. Technical Communication, Embrapa Soja, Londrina, n. 75, 2001. 6 p.
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IBGE Indicators: Systematic Survey of Agricultural Production – Agricultural Production Statistics, 2022. Available at: https://biblioteca.ibge.gov.br/visualizacao/periodicos/2415/epag_2022_maio.pdf
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SFREDO, GJ Liming and fertilization of soybeans. Technical Circular, Embrapa Soja, Londrina, n. 61, 2008. 12 p.
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SFREDO, GJ; LANTMANN, AF; CAMPO, RJ; BORKERT, CM Soybean: mineral nutrition, fertilization and liming. Embrapa Soja, Londrina, Documents, n. 17, 1986. 51 p.
TAIZ, L.; ZEIGER, E. Plant physiology. Porto Alegre: Artmed, 2004. 719p. (Translation).
Authors
- Agricultural Eng. Msc. Aline Tramontini dos Santos
- Agricultural Eng. Msc. Carolina Custodio Pinto
- Agricultural Eng. Msc. Thiago Stella de Freitas
