Field‐Scale Evaluation of Phosphorus Leaching in Acid Sandy Soils Receiving Swine Waste

Abstract

Accurate descriptions of P leaching are important because excess P applied to soils can enter surface water via leaching and subsurface transport, thereby negatively impacting water quality. The objectives of this study were to monitor P leaching in soils with a long-term history of waste application, relate soil solution P concentrations to soil P status, and quantify P leaching losses. Soil solution was monitored for 20 mo with samplers installed at 45-, 90-, and 135-cm depths in two pits (1 X 3 X L5 m) in Autryville (loamy, siliceous, thermic Arenic Paleudults) and Blanton (loamy, siliceous, semiactive, thermic Grossarenic Paleudults) soils located in a grazed pasture in Sampson County, NC, which had received swine waste for >20 yr. Maximum soil solution P concentrations at 45 cm exceeded 18 mg L' in both soils. Soil solution P concentrations at 90 cm in the Blanton soil were similar to that at 45 cm indicating low P sorption. Soil solution P concentrations at 90 cm in the Autryville soil averaged 0.05 mg L-' compared to 10 mg L' at 45 cm. A split-line model related soil solution P concentration to the degree of phosphorus saturation (DPS), identifying a change point at 45% DPS. Phosphorus movement past 45 cm equaled or exceeded surplus P additions for both soils. Longterm waste applications resulted in DPS > 90%, high soil solution P concentrations, and substantial vertical P movement. Phosphorus leaching should be considered when assessing long-term risk of P loss from waste-amended soils.

The Role of Subsoil as a Source or Sink for Phosphorus Leaching

“…Similarly, Sinaj et al (2002) concluded from a study with intact silty loam columns that P was sorbed in the subsoil and that P leaching could not be assessed based on P mobility in the topsoil. The importance of subsoil properties for P leaching was further stressed by Nelson et al (2005), who pointed out that P content and P sorption capacity of the subsoil must be considered. More recently, Liu et al (2012b) observed 5-to 9-fold higher total P leaching in a laboratory rain simulation experiment with topsoil lysimeters than in a field study on the same soil (Liu et al, 2012a), leading those authors to conclude that the subsoil is important for P sorption in that soil.…”

Numerical Application to Monitor Diffusion Pressure on the Deposition of Fungi in Slight Heterogeneous Phreatic Deposition

“…This can have serious negative implications. Daniel et al (1998) found that concentrations of P critical for terrestrial plant growth were an order of magnitude larger than concentrations at which lake eutrophication may occur Subsurface P transport is a less studied and understood transport mechanism compared to transport by overland flow, although abundant studies have reported its occurrence [1][2][3][4][5]. For example, Andersen and Krovang (2006) modified a P Index to integrate potential P transport pathways of tile drains and leaching in Denmark.…”

“…Hively et al [2] considered transport of total dissolved P (TDP) for both base flow and surface runoff. Nelson et al [5] indicated that phosphorus leaching and subsurface transport should be considered when assessing long-term risk of P loss from waste amended soils. Kleinman et al [4] noted that the P leaching is a significant, but temporally and spatially variable transport pathway.…”

Evaluating Fertilizer Application Strategy for Improving Crop Yields and Reducing Mineral Nitrogen Leaching in High Rainfall Areas of Taiwan

“…Therefore, from environmental perspectives, repeated and/or heavy application of manure and manure compost in agriculture is questioned (Sharpley et al 1996, Nelson et al 2005. This ultimately requires lower levels of compost application and use of supplemental fertilizer to meet crop requirement while avoiding costly surplus of N and reducing P buildup in the soil (Sikora & Enkiri 2001).…”