The right amount of biochar keeps fertilizer nitrogen in soil, not groundwater
Iamsaard K, Ninlaphong P, Soilueang P, Kullachonphuri S, Nakdee M
Soil Health
If you garden in sandy soil that drains fast and eats through fertilizer, this research shows exactly how much biochar to mix in to actually keep nutrients around for your plants instead of watching them wash away after the next watering.
Sandy soil is like a leaky bucket for nutrients, water and fertilizer just run straight through it. Scientists tested mixing charcoal made from corncobs into sandy soil along with regular fertilizer, and found that adding about 3% of this biochar did the best job of holding onto ammonium (a form of nitrogen plants need). But adding even more biochar, at 4%, backfired and actually let more nitrate (another nitrogen form) leak away, showing that with soil amendments, more isn't always better.
Key Findings
3% biochar application rate maximized ammonium (NH4+) stabilization in subsoil layers by improving cation exchange capacity
4% biochar treatment produced the highest nitrate (NO3-) concentrations in the soil profile but also increased nitrate leaching
Biochar significantly altered soil pH, cation exchange capacity, and water retention, with these changes strongly correlated to nitrogen mobility patterns
chevron_right Technical Summary
Adding corncob biochar to sandy soil at the right amount helps hold onto nitrogen fertilizer instead of letting it wash away into groundwater, but too much biochar can backfire and increase nitrate runoff.
Abstract Preview
Original paper
Biochar-amended and fertilized conditions influences nitrogen retention and loss dynamics: insights from a sandy loam soil column study.
Nitrogen (N) leaching from coarse-textured soils poses a significant environmental threat due to high permeability and inherently low nutrient exchange capacity, leading to groundwater degradation ...
open_in_new Read full abstractAbstract copyright held by the original publisher.
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