Formas de fósforo no solo após sucessivas adições de dejeto líquido de suínos em pastagem natural

Effects of Pig Slurry Application and Crops on Phosphorus Content in Soil and the Chemical Species in Solution

“…Approximately 38,000 m 3 of pig slurry (PS) is generated daily (Fepam, 2008), which is applied repeatedly in the same areas of cultivation, especially because the land distribution in the main producing regions in the North and Northwest of the State consists of mostly small farms. The PS is applied as organic nutrient source, including P for plants (Guardini et al, 2012;Lourenzi et al, 2014), which is one of the most limiting macronutrients for crop productivity in the weathered soils of tropical and subtropical regions (Gatiboni et al, 2008).…”

“…However, when P is added successively and at high rates to the soil, for example by PS application in crop conservation systems such as no-tillage (NT), where the soil is not tilled, the total P content may increase (Berwanger et al, 2008;Lourenzi et al, 2014), and especially the content available to plants, which can be diagnosed by the method of Mehlich-1 (Gatiboni et al, 2008;Guardini et al, 2012). Thus, the saturation of the most avid adsorption sites and a reduction in adsorption energy between phosphate oxygen and functional groups of the surface of oxides and clay minerals are expected, increasing the P concentration in the solution (Guardini et al, 2012;Schmitt et al, 2014); consequently, the P transfer in surface runoff solution to surface waters increases, but also migration in the soil profile by water flow, raising the risk of contamination of subsurface waters, especially in soils with sandy surface texture (Berwanger et al, 2008;Ceretta et al, 2010b;Wang et al, 2013).…”

Changes in soil acidity and organic carbon in a sandy typic hapludalf after medium-term pig-slurry and deep-litter application

“…However, since the volume of manure produced on swine farms is usually great and crop fields are small, farmers frequently repeat applications of swine fertilizer on the same areas. Thus, nutrient contents in the soil are expected to increase over the years (Mcdowell et al, 2001;Basso et al, 2005;Gatiboni et al, 2008;Ceretta et al, 2010a,b;Girotto et al, 2010). The chemical properties related to soil acidity are also expected to change, e.g., with increases in soil pH and base saturation, as well as a decrease in aluminum saturation (Ceretta et al, 2003;Lourenzi et al, 2011).…”

Available content, surface runoff and leaching of phosphorus forms in a typic hapludalf treated with organic and mineral nutrient sources

“…That is because P is predominantly found in inorganic form in the manure, readily available to plants. This may be seen in figure 1, where the greatest available P contents were observed in the first days of soil incubation, which indicates that a large part of the P present in the manure is found in the inorganic form, which is the predominant form of accumulation in soils treated with manure (Chardon et al, 2007;Gatiboni et al, 2008;Ceretta et al, 2010a;Guardini et al, 2012a;Lourenzi et al, 2013). Furthermore, the absence of tilling in the no-tillage system favors P accumulation in the soil surface layers because, in the soil, the P may be adsorbed to the surface of functional groups of reactive particles, normally forming inner sphere complexes (specific adsorption) (Barrow, 1999).…”

“…Furthermore, the addition of high P quantities to the soil, especially in areas treated with successive manure applications, may reduce the binding energy between the ion and the functional group involved, due to saturation of the adsorption sites. There is thus P accumulation in inorganic labile fractions, especially in the soil surface layers, but also in deeper layers (Gatiboni et al, 2008;Ceretta et al, 2010a;Guardini et al, 2012a;Lourenzi et al, 2013). Among the methods used for evaluating P availability in the soil is the anion exchange resin (AER) method (Bolland et al, 1996;Berwanger et al, 2008;Guardini et al, 2012b), used for determining P availability to plants (CQFS-RS/SC, 2004) and also as an indicator of the contamination potential in soils with sequential application of animal manure (Guardini et al, 2012b).…”