Search

Straw return has been strongly recommended in China, whereas applying biochar into soil is considered to provide more benefits for agriculture as well as the environment. In this study, a five-year (2011–2015) field experiment was conducted to evaluate the effects of uncharred maize straw amendment (MS) and charred maize straw amendment (charred MS) on organic carbon (C) contents in bulk soil and in various soil aggregate-size and density fractions. Compared to no amendment (CK), the bulk soil organic C content significantly improved by 9.30% for MS and by 23.4% for charred MS. Uncharred and charred maize straw applied annually at a consistent equal-C dosage resulted in 19.7 and 58.2% organic C sequestration efficiency in soil, respectively, after the five years of the field experiment. The percentages of macroaggregates (>0.25 mm) and occluded microaggregates (0.25–0.053 mm) obviously increased by 7.73 and 18.1% for MS and by 10.7 and 19.6% for charred MS, respectively. Moreover, significant incremental increases of 19.4 and 35.0% in macroaggregate-associated organic C occurred in MS and charred MS, respectively. The occluded microaggregates associated organic C significantly increased by 21.7% for MS and 25.1% for charred MS. Mineral-associated organic C (

In agricultural ecosystems, one optimized crop residue management practice, i.e., incorporating biochar produced from crop residues via pyrolysis to the soil, is considered a promising technology for mitigating climate change and improving soil quality. However, the potential mechanisms are still not well known. In this study, a five-year (2011–2015) field experiment in a Mollisol of Northeast China that included four treatments, i.e., CK (no fertilizer), NPK (mineral nitrogen, phosphorus and potassium fertilizers), NPKS (NPK plus maize straw) and NPKB (NPK plus maize straw-derived biochar), was conducted to evaluate the effects of maize straw and its derived biochar application on the following: 1) the size distribution and water stability of soil aggregates; 2) the concentrations of organic and humic carbon (C) in bulk soil and water-stable aggregate fractions; and 3) the chemical compositions of organic and humic C in water-stable aggregate fractions. Compared with the CK and NPK treatments, the proportion of macroaggregates (>0.25 mm) [mainly large macroaggregates (>2 mm)] increased whereas the proportions of microaggregates (0.25–0.053 mm) and silt + clay fractions (

Application of organic amendments, such as maize straw and its derived biochar and compost are considered as effective strategies for sustaining soil productivity. However, limited information available on the variation of soil carbon sequestration, soil quality and crop yield responses to these amendments, especially in the highly rich organic matter soils. The field experiment was conducted in a Mollisol since the fall of 2011 to evaluate the impact of chemical fertilizer plus maize residue driven materials amendments on continuous maize yield, soil carbon sequestration and soil quality parameters. The experiment consisted of five treatments: CK (no fertilizer), NPK (chemical fertilizer), NPK+ST (NPK plus maize straw), NPK+CP (NPK plus straw compost), and NPK+BR (NPK plus straw biochar). The organic materials were applied on an equal carbon input basis (3.2 Mg ha−1 per year). Soil samples were collected from 0 to 10 cm and 10–20 cm soil depths in 2017, and analyzed for contents of soil organic carbon (SOC), readily oxidizable organic carbon (ROC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), nutrients and aggregates-size distribution. The NPK+BR and NPK+CP significantly increased SOC stock at the topsoil (0–20 cm) relative to CK and NPK treatments. The amount of soil carbon sequestration (relative to SOC baseline in 2011) associated with different treatments was as follow: NPK+BR (13.1 Mg ha−1) > NPK+CP (5.60 Mg ha−1) > NPK+ST (2.90 Mg ha−1) > NPK (0.50 Mg ha−1) > CK (−1.90 Mg ha−1). However, the greatest concentrations of ROC, DOC and MBC at the topsoil were observed in NPK+CP treatment, with greater supply of available nutrients than other treatments. The NPK+BR reduced the fraction percentage of microaggregates significantly (

A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen (N), phosphorus (P), and potassium (K) uptake, and grain yield of spring maize. The results indicated that subsoil tillage promoted root development, increased nutrient accumulation, and increased yield. Compared with conventional soil management (CK), root length, root surface area, and root dry weight at 0–80 cm soil depth under subsoil tillage to 30 cm (T1) and subsoil tillage to 50 cm (T2) were significantly increased, especially the proportions of roots in deeper soil. Root length, surface area, and dry weight differed significantly among three treatments in the order of T2 > T1 > CK at the 12-leaf and early filling stages. The range of variation of root diameter in different soil layers in T2 treatment was the smallest, suggesting that roots were more likely to grow downwards with deeper subsoil tillage in soil. The accumulation of N, P, and K in subsoil tillage treatment was significantly increased, but the proportions of kernel and straw were different. In a comparison of T1 with T2, the grain accumulated more N and P, while K accumulation in kernel and straw varied in different years. Grain yield and biomass were increased by 12.8% and 14.6% on average in subsoil tillage treatments compared to conventional soil treatment. Although no significant differences between different subsoil tillage depths were observed for nutrient accumulation and grain yield, lodging resistance of plants was significantly improved in subsoil tillage to 50 cm, a characteristic that favors a high and stable yield under extreme environments.