By Sally Brown, University of Washington
Abstracts of these resources are available in the searchable Information Portal offered to Northwest Biosolids members.
- Soil power! The dirty way to a green planet, https://nwbiosolids.org/resource/soil-power-dirty-way-green-planet
- Effects of organic matter amendments on net primary productivity and greenhouse gas emissions in annual grasslands, https://nwbiosolids.org/resource/effects-organic-matter-amendments-net-primary-productivity-and-greenhouse-gas-emissions
- Soil carbon and nitrogen fraction accumulation with long-term biosolids applications, https://nwbiosolids.org/resource/soil-carbon-and-nitrogen-fraction-accumulation-long-term-biosolids-applications
- Biosolids amendment dramatically increases sequestration of crop residue-carbon in agricultural soils in western Illinois, https://nwbiosolids.org/resource/biosolids-amendment-dramatically-increases-sequestration-crop-residue-carbon-agricultural
- Degradation rate model formulation to estimate soil carbon sequestration from repeated biosolids application, https://nwbiosolids.org/resource/degradation-rate-model-formulation-estimate-soil-carbon-sequestration-repeated-biosolids
Many of us who are passionate about biosolids in the good way are so because we have seen what they can do for plants. Supersize, luxurious growth, incredible vigor - name your superlative; plants respond to biosolids applications by growing like crazy. It turns out that one of the reasons that the plants like the biosolids so much is because the biosolids do wonders for the soil. The primary way that one can improve soils is to feed them a well balanced diet rich in carbon and other nutrients. This helps soil provide nutrients, hold water, and grow plants. It also helps soils to store carbon. Understanding how to increase soil carbon storage through the use of amendments like composts and biosolids is becoming a critical tool in the fight against climate change and for increased resilience to the changes that are already occurring. As we continue on this path, more and more people are seeing the light and the mechanisms for the brightness are becoming better understood. This library focuses on both this increased recognition and the mechanisms that support the magic. Welcome to the first Biosolids eBulletin library of 2018.
The first article in the library is an editorial from the New York Times. In it the author, a writer for the LA Times talks about how increasing soil carbon storage is a way to both reduce carbon emissions and keep eating- not quite having your cake and eating it too but pretty close. This is a short, well written piece that details what most of you reading this blurb likely already know: soil is a critical part of the solution and we are part of the toolbox that makes it so. It is here because it is from the NYT and it provides a short and succinct summary of why land application is terrific. In addition to a discussion on how to hurt soil, synthetic fertilizer, and the resurgence of regenerative agriculture, he also talks about compost addition. He sites the California soil health initiative and the Marin Carbon Project. The Marin Carbon Project is the focus of the second article in the library.
What happened in Marin is that a rancher partnered with a professor at UC Berkeley and looked at whether compost made from animal manure could help restore productivity and increase soil carbon in a degraded rangeland. Short answer is yes. A single application increased soil carbon, water holding capacity and net primary productivity. That is the research presented in the second paper. This is stuff you already know if you have worked with biosolids. Point is, they hadn’t and they have a great website (http://www.marincarbonproject.org/about), are great at getting attention paid to what they have done, and are working to expand the research. This paper was written by Rebecca Ryals and Whendee Silver. Whendee is the professor at UC Berkeley and Rebecca, now at UC Merced, was her graduate student. Rebecca has started working with SOIL Haiti (https://www.oursoil.org/who-we-are/about-soil/) and attended the W- 3170 meeting last year. Hopefully soon with the appropriate partners (hear that CASA?) she will start working more with biosolids amended soils.
From here the 3rd and 4th papers in the library delve into the mechanisms behind the observed increase in soil carbon storage- see previous libraries on this topic- February 2009 for example. The 3rd paper describes work done on the WSU long- term dryland wheat plots. Here the authors have analyzed the soil carbon and nitrogen to divide them into the heavy and light weight fractions. Biosolids increased both fractions in comparison to both the control and the fertilizer amended plots. The largest increase was seen in the light weight fraction with 91% of the carbon added in the biosolids application staying in the soil. That is a remarkably high percentage. Thirty five percent of the added N was also retained. Yields between the fertilizer and biosolids plots were about the same but in the fertilizer plots none of the added N was retained. The 4th paper looked at fields in Illinois that had biosolids applied for 13 years, from 1972-1984. Here the authors looked at how much of the crop residue stayed in the soil. They measured this over 34 years, from 1972- 2006. They found that with the balanced nutrition provided by the biosolids, the soil microbes were able to assimilate more of the crop residue carbon, retaining 32.5%. In comparison, the fertilized plots only retained 11.8% of the crop residues. Both studies show that biosolids, by providing a balanced diet helps soils to add carbon over time and simultaneously hold onto nitrogen.
The final paper in the library is also based on data from the long term biosolids plots in Illinois. Here the authors look at both mine sites and degraded farmland and attempt to develop degradation/ soil carbon accumulation rate constants. They note that the CENTURY model is the gold standard for soil carbon in traditional agriculture. Here they are building an equivalent model for biosolids. The model includes both the added C from the biosolids and the added C from increased biomass. All slopes show a high rate of initial accumulation followed by a stabilization at the higher level of soil C. The stabile phase is the result of a combination of biosolids C breaking down and increased crop residue staying put. While this is based on conditions in IL, the 2nd and 3rd papers in the study suggest that similar models are possible for different organic amendments in different parts of the country and different land management scenarios.
The take home here is that more and more scientific studies are confirming and explaining the biosolids magic. Adding organics to soil increases soil organic matter and improves soil for the long term. This is a powerful tool to combat climate change and still have supper. SYLVIS, a long time member of NW Biosolids is developing a new easy to use model to calculate how much carbon your biosolids can sequester. If you don’t have the patience to read the papers- soon you can just use this calculator.