When microorganisms break down crop residue, many farmers believe that if they apply a lot of nitrogen fertilizer, the nutrient will be deposited in the soil along with carbon.
The University of Illinois' latest study, however, raised the possibility that given initiatives could be ineffective for poor soils.
Research reveal poor soils lose carbon despite crop residue and nitrogen addition
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According to Tanjila Jesmin, a doctoral researcher in the Department of Natural Resources and Environmental Sciences (NRES), a division of the College of Agricultural, Consumer, and Environmental Sciences (ACES), it had been a surprise due to their earlier research which showed high-nitrogen corn residue broke down faster, as per Phys.org.
The study's co-author and professor of NRES, Richard Mulvaney, outlined how impoverished soils have less aggregate particles-tiny, craggy chunks that contain soil bacteria and provide soil its structure.
Reduced aggregates allow soil's free-roaming bacteria to more easily contact carbon, consume it, and produce carbon dioxide as a byproduct.
Jesmin carried out soil incubation research in the laboratory to find out how soils with different fertility levels mineralized carbon in the form of corn residue.
In Central Illinois, she collected two soils of similar kind, one with high natural nitrogen concentration and the other with low nitrogen content due to 70 years of continuous cropping.
She also gathered maize residue from a single field; this time, the amount of nitrogen of the corn tissue was the same.
Following the application of several mixtures of maize residues and either potassium nitrate or ammonium sulfate fertilizers, Jesmin incubated the soils in jars.
She tracked microbial carbon mineralization over a two-month period by observing intermittent variations in microbial activity and continual carbon dioxide emissions from the incubation jars.
For both soil types, fertilizer accelerated the breakdown of residue, but the types of fertilizer responded differently depending on the fertility of the soil, explained Jesmin.
In low-nitrogen soil, potassium nitrate had a bigger impact on the rate of residue breakdown than ammonium sulfate did in high-nitrogen soil.
Jesmin also brought up the issue of the low-nitrogen soil becoming more acidic as a result of fertilizer use, which can restrict roots' access to vital nutrients and exacerbate the problem for poor soils.
In low-fertility soils, nitrogen management could be able to help; for instance, providing fertilizer when crops need it during the growing season.
Mulvaney also recommended reducing the amount of tilling.
Measured in terms of soil organic carbon, soil organic matter contains carbon.
Through mineralization, soil carbon serves as a source of nutrients, as per Agriculture Victoria.
It also helps to combine soil particles structure, which enhances resistance to physical deterioration.
Microbial activity also rises, which raises water storage and availability to plants.
Aggregate stabilize carbon
Physically preventing soil organic carbon from decomposing by encasing it in narrower pores, aggregates can stabilize soil organic carbon, as per ScienceDirect.
When soil particles combine, they create holes of various sizes and shapes that store and preserve carbon.
Carbon farming could save Crops
Measured in terms of soil organic carbon, soil organic matter contains carbon.
Through mineralization, soil carbon serves as a source of nutrients.
It also helps to combine soil particles structure, which enhances resistance to physical deterioration.
Microbial activity also rises, which raises water storage and availability to plants.
In order to improve Soil organic carbon focus and achieve a positive C budget, optimal management techniques must be adopted.
