Balancing Nitrogen Sinks and Sources Using Cover Crops On Manured Fields

Balancing Nitrogen Sinks and Sources Using Cover Crops On Manured Fields

Summary

The purpose of this project is to assess the magnitude of nitrogen fluxes on heavily manured fields. Additionally, this project aims to assess the potential benefits of specific cover crops and their mitigatory effects on nitrogen losses. To these aims, both rye and oats, two popular cover crops used in the northeastern US, were planted at the earliest date after maize harvesting. At the onset of winter, plots were harvested to assess both N uptake and residual N, presumably available for loss during the subsequent months. The measurements are thus far preliminary as the majority of N losses are assumed to come through the spring and early summer months.

Objectives/Performance Targets

• 1) Assess the nitrogen dynamics associated with the addition of winter forage cover crops (winter rye and oats) on manured soils. This study will assess the effect of these cover crops with respect to leaching losses and denitrification as compared to a control plot. 2) Analyze the partial nitrogen budget (uptake, leaching, mineralization and denitrification) of the maize-nitrogen system. The aim is to provide an account of the nitrogen-use efficiency (NUE) from these cover crop treatments over a benchmark NUE (fallow plots).

Accomplishments/Milestones

A replicated (4) planting of both winter rye (Secale cereale) and oats (Avena sativa) as cover crops occurred on September 24th, 2010 at recommended agronomic rates with control-fallow plots in a spatially balanced randomized design. Field sampling for N analysis took place on December 3rd, 2010 to assess N content through plant uptake as well as residual N (NH4 and NO3) remaining in the soil at the start of the winter period. This was accomplished by coring in triplicate from each plot and compositing the samples.

Additionally, tension lysimeters were installed at a depth of 50 cm in each plot and sampled at the same time (December 3rd, 2010). Nitrate and ammonium analysis were conducted.

Impacts and Contributions/Outcomes

None yet to report

Collaborators: