Drought increases root and rhizodeposition carbon inputs into soils.

Area of Science:

• Agricultural Science
• Soil Science
• Plant Biology

Background:

• Drought stress significantly impacts crop yield and plant health.
• Plants adapt to drought by altering root systems and rhizodeposition for better resource acquisition.
• Agricultural management practices influence root and rhizodeposition responses, but their interaction with drought is understudied.

Purpose of the Study:

• To investigate how different agricultural management systems affect plant root and rhizodeposition responses to drought.
• To assess the impact of biodynamic, mixed conventional, and mineral conventional cropping systems on belowground carbon dynamics under drought conditions.

Main Methods:

• A semi-continuous 13CO2 isotope labeling experiment was conducted in a long-term field study.
• Drought was induced using rainout shelters in wheat fields across different cropping systems.
• Root biomass, net rhizodeposition, and rhizosphere microbiome were analyzed.

Main Results:

• Drought increased total root carbon, primarily through fine root biomass, especially in systems with farmyard manure (biodynamic and mixed conventional).
• Net rhizodeposition carbon increased under drought across all systems, particularly in the topsoil (0.25m).
• Drought altered the rhizosphere microbiome, increasing some plant-growth-promoting genera while decreasing others involved in nitrogen fixation.

Conclusions:

• Drought enhances belowground carbon input via fine roots and rhizodeposition.
• Farmyard manure application in cropping systems can amplify drought-induced increases in fine root carbon, potentially improving soil carbon sequestration and nutrient foraging.
• Management strategies incorporating organic amendments may be crucial for enhancing crop resilience to drought.