In a crop like maize under conventional mono culture the carbon food printi is the heavy energy dependence for chemical fixation of atmospsheric nitrogen which can account over half of the total carbon footprint.

The carbon footprint can exceed 300 kg carbon per hectare over half from the nitrogen fertilizer.

By using soybean crop before the maize crop the need for nitrogen fertilizer immediated is cut in half as no supplemental nitrogenis needed on soybean.

If on the maize crop manure was used instead of nitrogen the manure woud lead to over 300 kg per ha of sequestration and elimination the nitrogen fertilizer foot print giving a carbon positive rather than negative footprint improving the soil rather than degranding it.

The use a legume cover crop would allow stablegrain and also increase carbon sequestration in the soil double the manure effect.

When quantifying the effect of the agriculture system the reduction of inputs is important but of greater importance is managing the system to improve carbon sequestration ability.

Whatever we measure can be improved so baseline of our soils and planning to improve them is of critical importance and to monitor and adapt according to the gained information.

Dear Paulo,

Could you please provide the references?

Thanks

A substantial reduction in the usage of synthetic fertilizers can significantly contribute to soil carbon sequestration. Synthetic fertilizers are typically produced from fossil fuels, releasing greenhouse gases during their manufacturing process. These gases contribute to climate change. By reducing synthetic fertilizer use, we can mitigate these harmful emissions.

Additionally, excessive synthetic fertilizer application leads to nutrient imbalance in the soil. This imbalance can inhibit the growth of certain microorganisms that play crucial roles in carbon sequestration. These microorganisms, such as mycorrhizal fungi, form symbiotic relationships with plant roots, enhancing nutrient uptake and promoting the conversion of atmospheric carbon dioxide into organic carbon stored in the soil.

Furthermore, synthetic fertilizers can accelerate the decomposition of organic matter in the soil due to their high nutrient concentrations. This rapid decomposition releases carbon dioxide into the atmosphere, counteracting the sequestration potential. By reducing fertilizer use, organic matter decomposition can be slowed down, allowing for the accumulation of carbon in the soil.

To maximize soil carbon sequestration, alternative agricultural practices such as organic farming, agroforestry, and crop rotation can be employed. These practices focus on building soil health through the use of organic matter amendments, cover crops, and diversified crop systems. By restoring soil fertility and boosting microbial activity, these practices enhance the potential for carbon sequestration in agricultural lands.

In summary, a substantial reduction in synthetic fertilizer usage contributes to soil carbon sequestration by minimizing greenhouse gas emissions, promoting microbial interactions, and minimizing carbon dioxide release through organic matter decomposition. Implementing sustainable agriculture practices further enhances the potential for soil carbon sequestration, leading to improved soil health and environmental sustainability.

The answer is agroecology, avoid chemical fertilizers and add organic matter to the soil, this way you'll be imitating nature and causing soil fertility to increase naturally thereby sequestering more carbon.

Based on Wiesmeier et al. 2020,an increase of SOM by 1.7% requires 3 t of dry biomass 213 kg N/ha, 21 kg P/ha and 9 kg S/ha. If the grower omits the application of nutrients, i.e. through mineral sources as requested in organic farming schemes, the primary effect ist that he forgoes about 70% of the biomass production (average yield loss when converting conventional to organic production), producing only 2.1 t of dry matter. So in the first place omission of nutrient supply leads to a net loss in CO2 fixed in the biomass as source for the built-up of SOM. Secondly, plant biomass remaining on the field, e.g. cereal straw, have a wide C : N ratio, unsuitable to form stable humus complexes with narrow C : N ratios during the sequestration process. This is why increased sequestration requires in additon to the nutrients for high biomass production nutrients for the sequestration. From which source these nutrients originate, whether organic or mineral sources, does not matter for the process of carbon sequestration. In case mineral fertilizers are used, CO2 emitted during production of these sources and transport can be easily assessed from respective publications related to the subject and can be deducted from the total C sequestration to calculate the net amount. If organic nutrient sources (from plant or animal production) are used, the life cycle of these products and the CO2 emissions during production and transport need also to be taken into account. Important for an effective, climate relevant sequestration is that the addition of these products do not constitute a migration, e.g. soybean/fodder is imported from other countries or other fields, fed to animals of which the manures are taken to feed the crops meant for carbon sequestration. Another important feature in that respect is that both high supply of mineral and organic nitrogen may lead to gaseous N-losses, especially N2O with a high GHG-potential. Planting cover crops between main crops or planting trees between the main crops is regarded as a possibility to reduce humus loss or even increase humus accumulation without external (organic or mineral) inputs. The principle effect is that these crops are able to make use of nutrients and moisture from soil compartments not used by the main crops, their biomass and the nutrients are not harvested and generally fully returned to the field. Employing such systems, however, need to be checked regarding their competing effect, restricting the production of the main crops, with the effect that food production migrates to new areas (non-cultivated natural, ecologically often sensitive areas) with a potential to increasing instead of decreasing emissions.

Это один из самых дискуссионных вопросов. На фоне высокой биологической активности почва способна функционировать не снижая содержание углерода, даже при повышенных дозах минеральных удобрений.

Yes search pimentel hepperly crop systems rodale energy analysis. Also check on publications on researchgate

Microbial Activity: Synthetic fertilizers can inhibit the activity of soil microorganisms responsible for decomposing organic matter. Reducing their usage promotes microbial diversity and activity, enhancing organic matter decomposition and carbon sequestration

Increased Plant Residues:Synthetic fertilizers may stimulate rapid plant growth, leading to increased biomass production. However, this often results in a higher ratio of labile to recalcitrant organic matter, making it more susceptible to decomposition. Root Exudates and Mycorrhizal Associations: Synthetic fertilizers can alter plant root exudation patterns and disrupt mycorrhizal associations. These changes influence soil microbial communities and reduce carbon inputs to the soil. Limiting synthetic fertilizer usage promotes healthier plant-microbe interactions, enhancing the flow of carbon-rich root exudates into the soil. Improved Soil Structure: Excessive synthetic fertilizer application may lead to soil acidification and degradation of soil structure. Improved soil structure resulting from reduced fertilizer usage enhances water retention, aeration, and microbial activity, supporting the accumulation of soil organic carbon. Nitrogen Saturation and Leaching: Overuse of synthetic nitrogen fertilizers can lead to nitrogen saturation in soils, increasing nitrate leaching and promoting the release of greenhouse gases. Reducing synthetic fertilizer application helps mitigate nitrogen-related environmental issues, supporting a more stable carbon balance in the soil. Agroecological Practices: Practices associated with reduced synthetic fertilizer use, such as agroecological and organic farming, often involve cover cropping, crop rotation, and the incorporation of organic amendments. These activities enhance carbon inputs to the soil and create a more favorable environment for carbon sequestration.

Promoting Carbon-Rich Crops: Certain crops, such as legumes, have the ability to fix atmospheric nitrogen, reducing the need for synthetic nitrogen fertilizers. Additionally, these crops often contribute more carbon to the soil through root exudates and residues, promoting carbon sequestration.