Physiochemical and soil biota response to biochar in agricultural soils

Physiochemical and soil biota response to biochar in agricultural soils

Summary

This project is looking at the complex issue of soil quality and health in agricultural soils using chemical, physical and biological assessments as a means of generating an integrated evaluation of soil health changes. Biochar was applied at 5 rates to a alluvial silt loam soil in July of 2012. Since then, soils have been sampled and evaluated for pH, nitrate concentration, micronutrient content as well as agronomic yields using sweet corn as the cash crop. Overall, pH and micronutrient content of soils increases with higher application rates of biochar. Yield has not been significantly affected in any of the growing seasons thus far. This information is very useful in determining the soil quality for crop growth. However, for full soil health evaluation, soil biology must also be included in the evaluation. Soil nematode and microbial community shift evaluation are currently underway as a key indicator of soil biological health and those results will elucidate the effect that the biochar amendment has had on the soil’s food web and greater ecosystem.

Objectives/Performance Targets

The objectives of this research study are to

• • Characterize changes in physiochemical properties of soils amended with biochar.
    • • Soil nitrate and soil pH changes have been characterized and are currently being statistically evaluated for significance.
    • • Soil extractions for macro- and micronutrient data are underway.
    • • Calcium, magnesium, potatssium, manganese, sulfur, copper, nickel and iron will be measured using microwave plasma atomic emission spectroscopy.

• • Calculate and analyze nematode community indices and the bacteriovores to fungivores ratio in biochar amended field plots.
    • • Initial samples have been taken and a few sample nematode counts have been performed illustrating that there are differences amongst biochar treatment levels.
    • • Separated from soil using a sugar flotation methods commonly used in the literature.
    • • Further counting and identification is underway.

• • Evaluate changes in native soil bacteria as a result of biochar application.
    • • Bacterial samples have been taken and frozen.
    • • I have identified the appropriate DNA extraction kit and am currently being trained on the Illumina systems in order to complete the 16S rRNA extraction and analysis myself.
    • • Awaiting the UMass genomics lab to become fully functional in early Spring.

Accomplishments/Milestones

August 2014: Began soil sample nutrient data collection and collected final soil sample for nematode analysis.

September-November 2014: Continued characterization of soil physical properties. Completed soil pH and nitrate data collection.

November 2014: Presented soil physiochemical characteristic results at CSSA, SSSA, ASA annual meeting in Long Beach, CA.

December 2014: Continued micronutrient extraction. Attended Illumina DNA sequencing platform training. Initial nematode extraction and counts performed. Continued work on nematode counts.

Progress has moved forward mostly as expected. However, the DNA analysis process will likely take longer than I originally allotted. I will likely finish the DNA extractions in January and then complete the qPCR metagenomics in February.   No other large change of plans, just a delay in the DNA analysis of the bacterial composition.

Impacts and Contributions/Outcomes

This past season of growing on my biochar plots has shown a significant rebound in the nitrogen immobilization that occurred initially. Even though the amount of biochar applied at the highest rate was extreme, there is evidence showing that the corn grown without added nitrogen was no less than the corn grown without biochar but with nitrogen. This may aid in the adjustment of nitrogen fertilizer applications to soils amended with biochar. As biochar is a one-time amendment, this can lower the inputs necessary to have a successful sweet corn crop in the New England region.

The pH changes over time in the biochar field have presented interesting results. The biochar has a liming effect on the soils and the increase in pH has stabilized after 10 months and has remained constant. The cationic nutrient (Mg, Ca, K,) content of the soils has increased with higher biochar rates as well, however, more investigation is needed to determine the source of the increased nutrient retention. The biochar itself has a significant ash content which is likely the source of the added Ca, Mg, and K. Nutrient analysis of the biochar is currently underway.

The greatest potential for new knowledge lies in the soil biology research, which is just underway. There is only one published paper regarding biochar’s effects on soil nematodes so the potential for increasing the knowledge base around biochar and it’s effects on soils health are great. 

I presented this work at both out local Field Day at the UMass Center for Agriculture as well as the annual meetings of the Agronomy, Soil Science and Crop Science Societies in Long Beach, California.

Collaborators: