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Combining compost and biochar facilitates moisture improvements and plant growth under field conditions
Author(s)
Date Issued
March 1, 2026
Type
Article
Abstract
Aims: Using vegetation on degraded soils often faces difficulties due to poor nutrients and limited water retention. Soil amendments such as compost and biochar are therefore required. However, their combined effects on soil and plant development are complex, as intense rainfall and high temperatures in tropical conditions may accelerate amendment degradation and alter soil properties over time. Methods: A two-year field experiment was conducted to monitor soil moisture dynamics, microstructure, vetiver grass (Chrysopogon zizanioides) growth, including shoot height, root depth, and root biomass. Four treatments were compared: unamended soil (S), soil + compost (C), soil + compost + raw biochar (C + RB), and soil + compost + pre-treated biochar (C + PB). Results: S and C treatments exhibited relatively low water retention, associated with smaller proportions of sub-micropores and super-nanopores. C contained more large pores, promoting drainage but causing greater moisture fluctuations. In contrast, C + RB enhanced water retention by increasing fine-pore volumes, while C + PB achieved the highest and most stable soil water content. The improved moisture conditions in C + PB corresponded with deeper rooting and greater root biomass compared with other treatments. Conclusion: Pure compost promoted early plant growth but was less effective over multiple wet–dry seasons, as its organic matter decomposed rapidly under tropical conditions. Combining compost and biochar, particularly pre-treated biochar, offers a practical, field-ready approach to improve soil structure and moisture retention, thereby supporting sustained plant growth in degraded soils.
Citation
Plant and Soil, 520(1), 793-810, 2026