Impact of Long‐Term Tillage Systems for Continuous Corn on Nitrate Leaching to Tile Drainage

Abstract

Information is lacking on the long-term impact of tillage systems on NO3 losses to surface and groundwater. An ll-yr (1982An ll-yr ( -1992 study was conducted to assess NO3 losses to subsurface, tile drainage for corn (Zea mays L.) grown with continuous conventional tillage (CT) and no tillage (NT) on a poorly drained Webster clay loam soil (fine-loamy, mixed, mesic Typic Haplaquoll) at Waseca, MN. Nitrogen was applied at an annual application rate of 200 kg ha-1. Mean annual subsurface drain flow during the ll-yr period was 35 mm higher for NT (315 ram) compared with CT (280 ram). Flow-weighted nitratenitrogen (NO~-N) concentrations increased dramatically in the wet years (1990 and 1991) following the dry period of 1987 to 1989. Flow-weighted NO~-N concentrations during the 11-yr period averaged 13.4 and 12.0 mg L -1 for CT and NT, respectively. Although subsurface drain flow was 12% higher with NT, NO3-N losses were about 5% higher with CT mainly due to higher NO3-N concentrations with CT in the last 2 yr. Corn grain yields and N removal were significantly higher in 6 out of 11 yr with CT compared with NT with no difference between tillage systems in the other 5 yr. Grain yields averaged 8.6 Mg ha -~ with CT and 7.3 Mg ha -~ with NT during the ll-yr period. Multiple regression equations showed that annual flow-weighted NO~-N concentration is best predicted from residual soil NOs in the 0-to 1.2-m profile and spring rainfall while NO3-N flux can be predicted well from May and June rainfall. Results from this long-term study indicate that on this poorly drained soil, CT had a positive effect on corn grain yield and N removal compared with NT, but tillage systems had minimal impact on NO~ losses to subsurface drain flow. Higher drain flow with NT does not necessarily result in higher NO~-N fluxes lost via subsurface drainage.

RZWQM simulated effects of crop rotation, tillage, and controlled drainage on crop yield and nitrate-N loss in drain flow

“…They also showed no difference in drain flow in years when ET was similar for corn and soybean. The NT system had higher drain flow than MP (7-14%) or CP (2-5%) (Table 3), which is in agreement with Randall and Iragavarapu (1995), and Bjorneberg et al (1996). Again, tillage effects Although N losses were higher under CC than under CS, N losses could be comparable to those under CS under certain circumstances (Figs.…”

“…Many field studies have been conducted under subsurface drainage conditions with various management practices to reduce N loss in subsurface drainage flow (Randall and Iragavarapu, 1995;Fisher et al, 1999;Huggins et al, 2001;Randall, 2002, 2004;Kladivko et al, 2004). Computer models were also developed and used to evaluate these management effects on drain flow and N loss in drain flow, such as DRAINMOD , ADAPT (Davis et al, 2000), CERES-Maize (Garrison et al, 1999), and RZWQM (Bakhsh et al, 2004a,b).…”

Adubação nitrogenada na cultura do milho

“…ns Não-significativo. efeito do N proveniente da leguminosa (Randall & Iragavarapu, 1995). Dados climáticos da área experimental indicam uma temperatura média de 24°C e precipitação de 1.491 mm durante o período experimental (outubro de 2000 a abril de 2001) e uma temperatura média de 20°C e precipitação pluvial de 790 mm no período de maio a outubro de 2000, anterior à instalação do experimento.…”

“…Em virtude das condições climáticas durante o período experimental, era esperado que a lixiviação do NO 3 -ocorresse nas parcelas que receberam as maiores doses de N, mas os dados indicam uma elevada capacidade de mineralização deste solo em condições de alternância de períodos secos e úmidos. As reduções, nos valores de NO 3 -, são semelhantes às encontradas por Randall & Iragavarapu (1995). Segundo esses autores, em anos secos, as perdas foram inferiores a 3% do N aplicado e, nos chuvosos, variaram de 25% a 70%.…”

“…O cultivo de milho em rotação com a soja produz até 30% mais do que se cultivado em monocultura, por causa do aporte de N da leguminosa para a cultura subseqüente (Peterson & Varvel, 1989;Crookston et al, 1991;Bundy et al, 1993;Omay et al, 1998). Resultados semelhantes, principalmente em anos secos ou em condições de estresse, foram obtidos por Raimbault & Vyn (1991) e Randall & Iragavarapu (1995).…”