Phosphorus in Surface Runoff from Calcareous Arable Soils of the Semiarid Western United States

Abstract

Management strategies that minimize P transfer from agricultural land to water bodies are based on relationships between P concentrations in soil and runoff. This study evaluated such relationships for surface runoff generated by simulated sprinkler irrigation onto calcareous arable soils of the semiarid western United States. Irrigation was applied at 70 mm h' to plots on four soils containing a wide range of extractable P concentrations. Two irrigation events were conducted on each plot, first onto dry soil and then after 24 h onto wet soil. Particulate P (>0.45 !Lin) was the dominant fraction in surface runoff from all soils and was strongly correlated with suspended sediment concentration. For individual soil types, filterable reactive P (<0.45 !Lin) concentrations were strongly correlated with all soil-test P methods, including environmental tests involving extraction with water (1:10 and 1:200 soil to solution ratio), 0.01 M CaCl 2, and iron strips. However, only the Olsen-P agronomic soil-test procedure gave models that were not significantly different among soils. Soil chemical differences, including lower CaCO3 and water-extractable Ca, higher water-extractable Fe, and higher pH, appeared to account for differences in filterable reactive P concentrations in runoff from soils with similar extractable P concentrations. It may therefore be possible to use a single agronomic test to predict filterable reactive P concentrations in surface runoff from calcareous soils, but inherent dangers exist in assuming a consistent response, even for one soil within a single field. P HOSPHORUS TRANSFER in runoff from agricultural soils to water bodies can contribute to blooms of toxin-producing cyanobacteria (blue-green algae) and other water quality problems associated with eutrophication (Foy and Withers, 1995;Leinweber et al., 2002). Accumulation of P in soils occurs following long-term application of manure or mineral fertilizer in excess of crop requirements, and a growing number of studies show strong correlations between concentrations of extractable soil P and filterable reactive P in runoff (for recent reviews see Haygarth and Jarvis, 1999;Sims et al., 2000). Linear relationships were observed in surface runoff (Pote et al., 1996(Pote et al., , 1999, while studies of subsurface drainage under natural rainfall can display nonlinear relationships, whereby filterable reactive P concentrations increase markedly after exceeding a threshold or "change point" in extractable soil P (e.g., Hesketh and Brookes, 2000). Understanding these relationships will contribute to the development of models and man-

Evaluating phosphorus loading from repeated manure applications to two Saskatchewansoils

“…The Plenty soil had lower organic matter content compared with Dixon. Soil organic carbon is positively correlated with soil organic P and microbial P concentrations (Richardson 1994;Hountin et al 2000;Aarons et al 2004), and total soil organic P is in turn positively correlated with Olsen extractable organic P (Turner and Haygarth 2004). Liquid hog manure has relatively low organic matter compared with SCM, but the enhanced crop growth and subsequent straw incorporation back into the surface soil may stimulate microbial growth and promote higher organic P concentrations over time.…”

Phosphorus Availability to Barley From Manures and Fertilizers on a Calcareous Soil

“…1). Turner et al (2004) conducted containing 0.5 M NaOH and 0.05 M EDTA for 4 h at 20 °C. Extracts were centrifuged at 10,000g for 30 min and aliquots analyzed for total P by ICP-OES.…”

Assessing edge-of-field nutrient runoff from agricultural lands in the United States: How clean is clean enough?

“…The most widely used indirect method of assessing P runoff potential is to test for soil test P levels, and this alternative could be proposed to indirectly evaluate nutrient runoff. Many states use this method to determine P application thresholds with the assumption that soil P concentrations below a critical level will produce acceptable levels of P runoff (Sharpley et al 2001;Turner et al 2004;Regan et al 2014). Dissolved P concentrations in runoff have been shown to be correlated to soil test P levels; however, these same studies also noted that additional factors (e.g., runoff and erosion variability) need to be considered for accurate prediction of P runoff losses (Sharpley et al 1996;DeLaune et al 2004;Harmel et al 2009).…”