Copper and Zn distribution in humic substances of soil after 10 years of pig manure application in south of Santa Catarina, Brazil

Use of Swine Manure in Agriculture in Southern Brazil: Fertility or Potential Contamination?

“…With the increase in Cu and Zn saturation and availability in the soil promoted by SM, consequently, there is an increase in the concentration of these metals in the soil solution, which potentiates their toxic effects on plants and organisms and their movement in the soil profile [7,16,17,20,63,64]. The increase in the concentration of these metals in the soil solution after continuous applications of PS was demonstrated by De Conti et al [65] in soil samples obtained in Santa Maria, RS.…”

“…Although the use of SM contributes considerably to the improvement of soil fertility, its continuous use has been rising concern in academic and environmental society, especially with the use of high doses [22,45]. Greater attention is paid to P and heavy metals accumulation in soils, which can cause water eutrophication and plant toxicity, respectively, representing risks to the quality and functionality of soils and nearby water resources [7,14,15,17,24,25]. For this reason, many studies continue to evaluate the total contents and availability of these elements in different types of soil, applied SM, and management.…”

“…Cu and Zn when added to the soil via SM are distributed in pre-existing forms in the soil, such as mineral and organic, being adsorbed by the most avid adsorption sites. This ability of soils to adsorb Cu and Zn will depend on the nature of the soil source material, the content, and composition of the clay fraction, the content and composition of the MOS, and the geochemical conditions of the soils, such as pH and ionic strength [17,53,62]. However, the continuous addition of Cu and Zn to the soil by SM applications promotes bonds with less adsorption energy and precipitates with greater solubility [53].…”

“…However, SM also has factors limiting its use, such as its variable concentration of nutrients and unbalanced to the needs of the plants, which can compromise the quality and functionality of the environment when excessive and/or continuous fertilization is carried out in the same areas [13][14][15][16][17]. The main concerns raised by researchers, and according to the publications of international academic society, are related to the phosphorus (P) and heavy metals, such as copper (Cu) and zinc (Zn), accumulation, availability, and losses in areas submitted a long history of applications [3,[18][19][20][21][22][23].…”

“…The main concerns raised by researchers, and according to the publications of international academic society, are related to the phosphorus (P) and heavy metals, such as copper (Cu) and zinc (Zn), accumulation, availability, and losses in areas submitted a long history of applications [3,[18][19][20][21][22][23]. The results of the studies developed to emphasize the importance of adopting technical criteria for the use of SM in agricultural areas, proposing limits of doses used, applications based on soil attributes and composition of manure, the recommendation for crops, determination of limiting elements for the applied dose (mainly P), supplementation of the application of SM with chemical fertilizers and adequate treatments for the storage and stabilization of waste, for example [10,17,24,25].…”