Tillage and Fertilizer Management Effects on Phosphorus Runoff from Minimal Slope Fields

Abstract

Phosphorus fertilization can increase P losses in surface runoff, but limited information is available for fields with <2% slopes in the US Midwest. Our objectives were to determine the effects of tillage-fertilizer placement (no-till-broadcast, strip till-broadcast; or strip till-deep placement, -15-cm subsurface band) and fertilizer rate applied in the fall (0, 52, or 90 kg PO ha yr) on runoff P concentrations and loads in fields with <2% slopes near Pesotum, IL, during fall and spring simulation runoff events, and to measure corn ( L.) and soybean [ (L.) Merr.] grain yield. Across four simulated runoff events, deep placement reduced dissolved reactive P (DRP) loads by 69 to 72% compared with the broadcast treatments. A tillage-fertilizer placement × P rate interaction showed that DRP and total P (TP) concentrations remained low when P was deep placed, regardless of P rate, whereas concentrations increased with increasing P rate for the broadcast treatments, but no differences existed for bioavailable P (BAP) (α = 0.05). At one site, rainfall simulation in the spring versus fall increased runoff volumes but sharply decreased BAP concentrations. During fall runoff simulations, deep placement reduced TP loads, and greater TP loads occurred with the 90- than the 52-kg PO ha yr rate. Similarly, when P was broadcast in the fall, DRP and TP concentrations were greater than deep-placed P, but no treatment differences occurred in the spring. Deep banding P and K did not reduce crop yield but reduced runoff losses of P from flat fields compared with broadcast P applications, particularly at high rates of P application.

Soil and crop response to phosphorus and potassium management under conservation tillage

“…In contrast, subsurface banding of fertilizers caused a substantial increase in P and K test levels in the location of the band instead of in the surface layer, without raising STP levels at soil surface even with the buildup rates. These trends were reported by other studies (Dodd & Mallarino, 2005; Farmaha et al., 2011, 2012a; Fernández & White, 2012; Hansel et al., 2017), indicating that deep placement of P fertilizer is beneficial to reduce the potential of surface P runoff (Yuan et al., 2018).…”

“…As additional work is done to re‐evaluate recommendations, emphasis should be given also to environmental stewardship to ensure an adequate balance between production and environmental protection goals. As highlighted in this study, P rate and placement could have important roles in reducing soil P concentrations in surface layers, and, as mentioned in a related study (Yuan et al., 2018), reduce the potential for P runoff.…”

“…The adoption of deep banding of P and K fertilizers for conservation tillage systems has been hypothesized to increase nutrient availability and thus to enhance crop productivity and fertilizer use efficiency (Mallarino & Murrell, 1998; Yin & Vyn, 2002). From an environmental perspective, deep banding is considered to be ideal in terms of eliminating nutrient stratification and reducing the potential for surface runoff of fertilizer P (Kimmell, Pierzynski, Janssen, & Barnes, 2001; Randall & Vetsch, 2008; Yuan, Fernández, Pittelkow, Greer, & Schaefer, 2018). However, because many studies on fertilizer placement have reported conflicting results regarding crop performance in comparison to broadcast fertilizer, requirements for effective fertilizer placement remain unclear.…”

Managing Phosphorus Loss from Agroecosystems of the Midwestern United States: A Review

“…Research studies have been reported on 4R's of P management and the impact of tillage systems on crop production and runoff P loss in the central U.S. [28,29,31,32,34,41,[59][60][61]. Many researchers have reported dissolved reactive phosphorus (DRP) to be greater in surface water runoff under no-till systems compared to other tillage systems [41,59,62].…”

“…Algoazany et al [60] reported that soluble P concentration of surface water runoff ranged between 270 to 572 µg L −1 in a watershed under corn-soybean production. Yuan et al [61] reported that strip till-deep placement of P fertilizer reduced DRP loads 69% to 72% compared with a no-till-broadcast application of P, while showing no differences in grain yield due to application method. Fall broadcast P fertilizer application increased DRP and total P concentrations compared to deep banding P, but there were no differences between P fertilizer placement treatments for a spring application [61].…”