Albic soils are often compact, acidic, and low in organic matter, making them difficult to cultivate and limiting their ability to store carbon. A new field study suggests that combining no-tillage management, retained crop straw, and microbial organic fertilizer may provide an effective way to improve these soils while increasing their soil organic carbon reserves.
“Our results show that improving carbon storage in albic soil requires both physical protection of the soil and sufficient organic inputs to support biological processes,” said corresponding author Hongguang Cai. “No-tillage combined with a high rate of microbial organic fertilizer produced the most consistent increase in soil organic carbon across the full 40-centimeter soil profile.”
Researchers conducted a one-year field experiment from 2023 to 2024 in Shulan City, Jilin Province, China. They compared three common tillage systems: no-tillage, plough tillage, and rotary tillage. Each system was combined with microbial organic fertilizer applied at rates of 600, 1,200, or 2,400 kilograms per hectare. The fertilizer was produced from composted livestock and poultry manure and contained beneficial microorganisms, including Bacillus subtilis, Bacillus amyloliquefaciens, and Trichoderma harzianum.
What they found
The research team measured soil organic carbon, bulk density, porosity, nutrient levels, microbial biomass carbon, soil aggregate stability, and the activities of four enzymes involved in carbon cycling. Measurements were taken from the topsoil at 0 to 20 centimeters and the subsoil at 20 to 40 centimeters.
The strongest overall carbon response occurred under no-tillage with the highest microbial organic fertilizer rate. Compared with the no-tillage control without straw return, this treatment increased soil organic carbon by 22 percent in the topsoil and 93.2 percent in the subsoil. Soil organic carbon reached 14.57 grams per kilogram in the topsoil and 8.75 grams per kilogram in the subsoil.
No-tillage also generally maintained a larger proportion of macroaggregates and greater aggregate stability. These larger soil aggregates can physically enclose organic matter, reducing its exposure to microorganisms and slowing decomposition. This process may help newly added carbon remain in the soil for longer periods.
Key trade-off
However, the study also revealed an important trade-off. Plough tillage improved soil conditions at depth and produced relatively high subsoil carbon concentrations, but it reduced macroaggregate stability. Mechanical loosening can relieve compaction and improve aeration, root growth, and nutrient movement, yet greater disturbance may weaken the soil structures that protect organic carbon.
Rotary tillage produced strong responses in several carbon-cycling enzymes, but higher enzyme activity did not always lead to greater carbon accumulation. The researchers found that enzymes associated with the breakdown of sugars, cellulose, and hemicellulose were linked differently with soil carbon and aggregates depending on soil depth and tillage method. In some cases, greater decomposition activity may have accelerated carbon turnover without producing equivalent gains in stabilized carbon.
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“The findings highlight that soil carbon storage is controlled not simply by how much organic material is added, but also by how effectively the soil protects that carbon from rapid decomposition,” said Cai.
The researchers conclude that conservation tillage, particularly no-tillage combined with adequate microbial organic fertilizer, has promising short-term potential for restoring albic soils and increasing carbon storage from the surface to 40 centimeters deep. Because the experiment lasted only one year, longer-term monitoring will be needed to determine whether these improvements persist and how they affect crop productivity and greenhouse gas emissions over time.
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