Effects of Leucaena biochar addition on crop productivity in degraded tropical soils.
Elias, D. M. O., . 2020.
Abstract
Biochar has the potential to increase crop yields on degraded, tropical soils. It can be readily produced in rural
community settings using low-cost technology and is most economically feasible if produced from local biomass
or waste residues. Biochar was produced from Leucaena biomass using low-cost pyrolysis and sequential pot
experiments were then conducted in Malaysia on three degraded soils. We first evaluated the effect of Leucaena
biochar on yields of Amaranthus, a leafy vegetable crop and measured changes to soil pH and nutrient availability
over two growth cycles. We then tested whether any yield response to biochar was dependent upon the rate of
biochar or fertilizer application. We found that biochar application at 30 t ha%u22121 with maximal fertilizer increased
yields between 17 and 53% on very strongly acidic soil. Biochar added at 15 t ha%u22121 with maximal fertilizer
increased yield by 54% on strongly acidic soil whilst there was no significant yield response on fertilized, slightly
acidic soil. Unfertilized biochar treatments showed small yield responses across all soils over 2 growth cycles
(9%u201311%), but yields were much lower than in fertilized treatments. Biochar also decreased short-term N avail-
ability when applied with fertilizers, which may improve nitrogen retention and substantially increased soil pH.
This may reduce mobility of Fe, Mn and Al ions, which were negatively associated with yield. Our results suggest
that Leucaena biochar can elicit a positive crop yield response but only when combined with fertilizer additions
on very strongly to strongly acidic tropical soils.
Key Words
Biochar Malaysia Yield Degraded tropical soils Soil pH Food security
