Combining δ13C Measurements and ERT Imaging: Improving our Understanding of Competition at the Crop-Soil-Hedge Interface

Publication Type

Journal contribution (peer reviewed)

Authors

Khalid Hussain, Chalermchart Wongleecharoen, Thomas Hilger, Jan Vanderborght, Sarah Garré, Wattanai Onsamrarn, Marc-André Sparke, Jan Diels, Thanuchai Kongkaew and Georg Cadisch

Year of publication

2015

Published in

Plant and Soil (available online first)

Keywords

Agroforestry, erosion control, Konkurrenz, Thailand

Background and aims

Hedgerow cropping decreases erosion in hillside agriculture but also competes for water and nutrients with crops. This study combined two methods for an improved understanding of water and nutrient competition at the crop-soil-hedge interface.

Methods

δ¹³C isotopic discrimination in plants and soil electrical resistivity tomography (ERT) imaging were used in a field trial with maize monocropping (MM) vs. leucaena hedgerow intercropping with and without fertilizer (MHF⁺ and MHF^-) in Thailand.

Results

Hedges significantly reduced maize grain yield and aboveground biomass in rows close to hedgerows. ERT revealed water depletion was stronger in MM than in MHF⁺ and MHF^‑ confirming time domain reflectometry and leaf area data. In MHF⁺, water depletion was higher in maize rows close to the hedge compared to rows distant to hedges and maize grain δ¹³C was significantly less negative in rows close to hedge (‑10.33‰) compared to distant ones (‑10.64‰). Lack of N increased grain δ¹³C in MHF^‑ (‑9.32‰, p≤0.001). Both methods were correlated with each other (r= 0.66, p≤0.001). Combining ERT with grain δ¹³C and %N allowed identifying that maize growth close to hedges was limited by N and not by water supply.

Conclusion

Combining ERT imaging and ¹³C isotopic discrimination approaches improved the understanding of spatial-temporal patterns of competition at the hedge-soil-crop interface and allowed distinguishing between water and N competition in maize based hedgerow systems.