Related Experiment Videos
Quantifying the impact of regular cutting on vegetative buffer efficacy for nitrogen-15 sequestration.
A Bedard-Haughn1, K W Tate, C van Kessel
1Department of Plant Sciences, University of California, Davis, CA 95616, USA. bedard.haughn@usask.ca
Journal of Environmental Quality
|August 11, 2005
Summary
Regularly cutting vegetation in buffer strips significantly enhances nitrogen (N) uptake and reduces nitrate-N loss from pastures. This management practice increases plant N demand and sequestration, improving water quality over the irrigation season.
Area of Science:
- Environmental Science
- Soil Science
- Agricultural Science
Background:
- Vegetative buffer strips are crucial for mitigating nutrient runoff from agricultural lands.
- Understanding nitrogen (N) dynamics in these systems is vital for water quality protection.
- The impact of vegetation management, specifically cutting, on N sequestration requires further investigation.
Purpose of the Study:
- To quantitatively assess the effect of regular cutting on nitrate-N (NO3(-)-N) uptake by vegetative buffers using stable 15N isotope tracing.
- To determine how cutting influences N demand and sequestration in flood-irrigated pasture buffer plots.
- To evaluate the temporal dynamics of N sequestration in response to cutting.
Main Methods:
- Established 10 buffer plots in a flood-irrigated pasture.
- Applied 15N-labeled potassium nitrate (KNO3) at 5 kg N ha(-1) with 99.7 atom % 15N.
- Monthly cutting of vegetation in half of the buffer plots.
- Quantified 15N sequestration in aboveground biomass and assessed water quality impacts.
Main Results:
- Cutting did not significantly impact initial 15N sequestration in the first few weeks.
- Over the irrigation season, cut buffers sequestered 2.3 times more 15N than uncut buffers, linked to increased aboveground biomass.
- Cutting enhanced 15N attenuation from surface and subsurface water, with significant effects observed 21-42 days post-application.
- Irrigation rate was the dominant factor, with a 75% reduction decreasing runoff losses by 50% and 15N concentration sevenfold.
Conclusions:
- Regular cutting of pasture buffer strips significantly enhances N sequestration and improves water quality by stimulating plant growth and N demand.
- The positive effects of cutting on N attenuation are temporally dependent, becoming significant after several weeks.
- Optimizing irrigation rates remains a primary strategy for mitigating nutrient losses from irrigated pastures, complementing vegetation management practices.