Nitrate leaching to shallow groundwater systems from agricultural fields with different management practices

Abstract

Monitoring the concentration of NO(3)-N from agricultural fields to the subsurface and shallow ground water resources have received considerable interest worldwide, since agriculture has been identified as a major source of nitrate-nitrogen (NO(3)-N) pollution of groundwater systems in intensively farmed watersheds. A study was conducted to quantify the impact of two tillage practices viz. chisel plow (CP) and no till (NT) with liquid swine manure application on nitrate leaching to the shallow ground water system under corn-soybean production system. This study is part of the long-term field experiments conducted at Iowa State University using completely randomized block design. The NO(3)-N concentrations in the shallow ground water were monitored at three depths viz., a network of subsurface drains at a depth of 1.2 m and piezometers at depths of 1.8 m and 2.4 m. Results of this study showed that the average NO(3)-N concentration during the study period was 16.1 mg l(-1), 14.4 mg l(-1) and 11.8 mg l(-1) at 1.2 m, 1.8 m and 2.4 m depths, respectively implying significant amount of NO(3)-N leaching past the subsurface drain depth of 1.2 m into the shallow groundwater but the NO(3)-N concentration decreases with the depth. The NO(3)-N concentrations in shallow groundwater were significantly higher under the chisel plow system in comparison with the no till method of tillage. Fall application of liquid swine manure caused more leaching in comparison with the spring application. Higher NO(3)-N concentration was observed under corn in comparison with the soybean plots. An in-depth analysis of the data showed a definite relationship between the NO(3)-N concentration in subsurface drain water at a depth of 1.2 m and shallow groundwater at depths of 1.8 m and 2.4 m depths.

Stream Nitrogen, Phosphorus, and Sediment Concentrations Show Contrasting Long‐term Trends Associated with Agricultural Change

“…A more likely explanation for decreased NO 3 concentrations is increased denitrification in soils under reduced tillage (Mkhabela et al, 2008;Melero et al, 2011;Tatti et al, 2015;García et al, 2016). This is perhaps due to increased organic matter, increased moisture, and decreased O 2 availability in soils, conditions that enhance denitrification rates and thus reduce leaching of NO 3 to shallow groundwater (Rekha et al, 2011). Whatever the mechanism(s) accounting for the acceleration of NO 3 declines in our streams, they agree generally with trends in the Maumee River in the Lake Erie watershed, where NO 3 concentrations actually increased between 1980 and 1990, when conservation tillage increased, but then declined rapidly over the next ~20 yr when the use of conservation tillage was common but stable (Stow et al, 2015).…”

Midwestern cropping system effects on drainage water quality and crop yields

“…Some studies comparing chisel plowing to no-till (NT) found little to no difference in NO 3 -N leaching (Fox, Zhu, Toth, Jemison, & Jabro, 2001;Logan, Eckert, & Beak, 1994). Other research found lower NO 3 -N concentrations in subsurface drainage from NT compared with other tillage systems with similar cropping rotations (Angle, Gross, Hill, & McIntosh, 1993;Kanwar, Colvin, & Karlen, 1997;Rekha, Kanwar, Nayak, Hoang, & Pederson, 2011). A central Iowa study showed significantly lower seasonal and annual NO 3 -N concentrations and overall N losses with NT compared with a chisel plowed treatment (Waring, 2016).…”

The effects of pig manure type and application timing and frequency on nitrate leaching from a seven‐course arable rotation on a retentive alluvial soil

“…In terms of leaching, the risk period for slurry application was autumn, which is well documented (e.g. Nila Rekha et al ., ). However, there was little risk from FYM applications made in this period, probably related to its relatively low NH 4 –N content (Table ); Sørensen & Rubæk () noted that FYM could present a leaching risk when applied in autumn if the NH 4 –N content was high.…”

“…A number of studies have identified best management practices for decreasing N leaching from manure applications. Timing of application seems to be critical, with N leaching losses greater from autumn than from spring applications of liquid pig manure (Nila Rekha et al ., ). Beckwith et al .…”