Abstract
Previous studies have shown that biochar fertilization has profound effects on plant and fine root growth, but there is a lack of studies on how changes in plant and soil stoichiometry by biochar fertilization influence plant growth and root morphology. We investigated the effects of biochar fertilization on biomass, root morphology, plant nutrient concentrations, and the stoichiometry of plants and soil in a greenhouse experiment with Pinus massoniana (Lamb.) (PM) and Cunninghamia lanceolata (Lamb.) Hook. (CL) throughout the 2017 growing season immediately following biochar fertilization application. Four levels of biochar treatment were used, i.e., addition rates of 0 (control), 5 (low biochar), 10 (medium biochar), and 20 t ha−1 (high biochar). Biochar fertilization had no effect on biomass, fine root length, or fine root surface area. Biochar treatment, however, had significant effects on nutrient levels and their stoichiometry in both plants and soil. Detrended correspondence analysis suggested that increases in soil C:N, soil C:P, and soil N:P were associated with increases in plant nutrient levels, especially P concentration. Our results indicate that biochar fertilization prioritizes enhancing plant and soil nutrients over increasing height and diameter in the first growing season. A higher biochar fertilization dosage has a major influence on root morphology for PM and on P concentrations in the plant and soil for CL, probably through different growth characteristics and nutrient resorption rates. Further studies, particularly those considering long-term effects, are necessary before general recommendations regarding biochar application should be given.
Highlights
Biochar application to soil is receiving increasing attention as a potential way to promote nutrient cycling, reduce soil CO2 emissions, and enhance carbon (C) sequestration [1,2]
Biochar fertilization did not significantly alter plant biomass fine root length and fine root surface area, but higher fertilization rates significantly increased soil organic C and total N and P, which directly led to an increase in soil C:N and C:P
The enhancement of plant net height and net diameter by biochar addition could be attributed to an increase in the N and P concentrations in leaves or shoots, or to greater absorption of available nutrients via changed root morphology (1.0–2.0 mm for P. massoniana (PM) and 0–0.5 mm for Cunninghamia lanceolata (Lamb.) Hook. (CL))
Summary
Biochar application to soil is receiving increasing attention as a potential way to promote nutrient cycling, reduce soil CO2 emissions, and enhance carbon (C) sequestration [1,2]. It has been reported that biochar application to forest soil could change the soil environment and thereby benefit plant. Forests 2019, 10, 612 growth by increasing cation exchange capacity (CEC), water retention, soil aggregation, and microbial increased functions [3]. These improved forest soil environment features may have an immediate positive effect on plant and fine root growth, root morphology, and nutrients by the sufficient contact of roots with biochar [4,5]. Previous studies showed that the effects of biochar application on plant growth vary with the dosage applied and with species [7,8]. Results from some studies suggested that biochar application can improve the growth and productivity of plantations in nutrient deficient conditions [10,11]
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