Relationship between Phosphorus Levels in Three Ultisols and Phosphorus Concentrations in Runoff

Abstract

Soils that contain high P levels can become a primary source of dissolved reactive P (DRP) in runoff, and thus contribute to accelerated eutrophication of surface waters. In a previous study on Captina soil, several soil test P (STP) methods gave results that were significantly correlated to DRP levels in runoff, but distilled H20 and NH4-o x a l a t e m e t h o d s gave the best correlations. Because results might differ on other soils, runoff studies were conducted on three additional Ultisols to identify the most consistent STP method for predicting runoff DRP levels, and determine effects of site hydrology on correlations between STP and runoff DRP concentrations. Surface soil (0-2 cm depth) of pasture plots was analyzed by Mehlich HI, Olsen, Morgan, Bray-Kurtz P1, NH4-oxalate, and distilled H 20 methods. Also, P saturation of each soil was determined by three different methods. Simulated rain (75 mm h) produced 30 min of runoff from each plot. All correlations of STP to runoff DRP were significant (P < 0.01) regardless of soil series or STP method, with most STP methods giving high correlations (r > 0.90) on all three soils. For a given level of H 20-extractable STP, low runoff volumes coincided with low DRP concentrations. Therefore, when each DRP Concentration was divided by volume of plot runoff, correlations to H 20-extractable STP had the same (P < 0.05) regression line for every soil. This suggests the importance of site hydrology in determining P loss in runoff, and may provide a means of developing a single relationship for a range of soil series. E UTROPHICATION of streams and lakes can be greatly accelerated by the influx of nutrients in surface runoff from agricultural land. Since P has been identified as the nutrient in runoff that is usually the most limiting to algal growth, control of P levels in runoff is often recommended as the best way to minimize the eutrophication of surface waters (Rohlich and O'Connor, 1980; Little, 1988; Breeuwsma and Silva, 1992; Sharpley et al., 1994). Phosphorus is often perceived to be so immobile in soil that losses from agricultural land are not usually considered to be agronomically important, but even small agronomic losses can have serious environmental consequences. In fact, soils that contain high levels of P from excessive fertilization can become a primary source of dissolved reactive P (DRP) in runoff (Edwards et al., 1993). Other investigators have found direct correlations between soil P levels and P concentrations in runoff.

Controlling Sprinkler Irrigation Runoff, Erosion, and Phosphorus Loss With Straw and Polyacrylamide

“…Average time before runoff began during the first irrigation on bare, untreated soil was 4.5 min compared to 10 min on strawcovered soil. The increased infiltration on straw-covered soil probably caused the readily desorbed phosphorus on the straw and surface soil to leach into the soil profile (Baker and Laflen, 1982;Mostaghimi et al, 1988;Pote et al, 1999), removing it from the primary mixing zone where phosphorus is transferred to runoff water (Zhang et al, 1999).…”

Matrix based fertilizers reduce nitrogen and phosphorus leaching in three soils

“…The problem is made more severe because some turfgrass operators and homeowners often apply nutrients in quantities exceeding plant requirements (Hart et al, 2003). Several studies indicated that sediment bound P concentrations in runoff generally increase as soil P concentrations increase (Sharpley et al, 1993;Pote et al, 1999;Cox and Hendricks, 2000). Long-term overfertilization of soils is recognized as potentially contributing to eutrophication of surface waters (Sims, 1993;Frossard et al, 2000).…”

Pig effluent-P application can increase the risk of P transport: two case studies

“…For example, Baker and Eldershaw (1993) recommend that crop responses to fertiliser applications would be expected in soils in the range from deficiency to about 40 mg P B /kg for the surface 0.10 m. It is likely that increases in P B levels in a soil will be indicative of increased algal-available P should runoff reach surface water bodies. Pote et al (1999) found that a wide range of published soil test determinations of P were significantly (P < 0.01) related to runoff dissolved molybdatereactive P, with most relationships exhibiting correlation coefficients in excess of 0.90 (r). Pote et al (1999) investigated 3 Ultisols in their trial, and included the Olsen et al (1954) bicarbonate extract amongst the soil tests studied.…”

“…Pote et al (1999) found that a wide range of published soil test determinations of P were significantly (P < 0.01) related to runoff dissolved molybdatereactive P, with most relationships exhibiting correlation coefficients in excess of 0.90 (r). Pote et al (1999) investigated 3 Ultisols in their trial, and included the Olsen et al (1954) bicarbonate extract amongst the soil tests studied. Other researchers have also indicated that soils that contain high levels of P from excessive fertiliser application can become an important source of dissolved molybdate-reactive P in runoff .…”