Modern Soil Health

Outline Modern Soil Health Carbon Cycle Nitrogen Cycle

Carbon Cycle The series of processes by which carbon compounds are interconverted in the environment, involving the incorporation of carbon dioxide into living tissue by photosynthesis and its return to the atmosphere through respiration, the decay of dead organisms, and the burning of fossil fuels. Think of carbon as the energy source of all life! Remember C6H12O6? This is Glucose! The sweet, yummy fuel of life! Processing of carbon from inorganic (locked up in biomass) to organic (usable forms by microbes, flora and fauna).

Where is Carbon? Carbon is stored in biomass of living organisms, soil and water Plant tissue Muscle fiber Cell liquids Terrestrial carbon (land) Oceanic carbon (dissolved) Carbon is respired by microbes, animals and plants in the form of CO2 (Carbon Dioxide) Carbon Dioxide can be taken up by plants (photosynthesis), dissolved in liquids (the ocean), stored in the atmosphere and taken up by microbes in the soils.

How is Carbon Released from Storage? Fossil fuel burning releases CO2 Photosynthesis takes up CO2 and it can be released from root respiration in the rhizosphere Respiration of organisms that use oxygen that release CO2 Release of other C sources: Animal waste (Methane, CH4), enteric methane producers (ruminants) and microbes in anaerobic conditions. Decomposition of biomass! Plant roots, plant leaves and stems, microbes, animals, crop residues, manure, eggshells, nutshells, tree bark, etc.

Forms of Carbon important to Agriculture Carbon Dioxide Fossil Fuel burning (tractors, trucking, harvesting, transporting, etc.) Livestock respiration (confined production and free-range) Root and microbe respiration Methane Ruminants respire methane Rice paddy production Manure lagoons or manure areas in fields Soil Microbes under anaerobic production

Who Cares? Loss of carbon is important to climate change and our warming environment! Climate Change Climate change refers to a broad range of global phenomena created predominantly by burning fossil fuels, which add heat- trapping gases to Earth’s atmosphere.

Agricultural practices can effect the release of carbon that promotes climate change. Who Cares?

The Heating Index of Carbon Containing Molecules Global Warming: A hot topic for science, politics and the general public. Global warming: o the long-term warming of the planet since the early 20th century, and most notably since the late 1970s, due to the increase in fossil fuel emissions since the Industrial Revolution. Worldwide since 1880, the average surface temperature has gone up by about 1 °C (about 2 °F), relative to the mid-20th-century baseline (of 1951-1980). This is on top of about an additional 0.15 °C of warming from between 1750 and 1880.~NASA

The Heating Index of Carbon Containing Molecules The global warming potential (GWP) is the process of comparing greenhouse gases like CO2 and CH4 on an equal scale. The GWP of a molecule of CO2-CO2, by definition, has a GWP of 1 regardless of the time period used, because it is the gas being used as the reference. CO2 remains in the climate system for a very long time: CO2 emissions cause increases in atmospheric concentrations of CO2 that will last thousands of years. (Some sources consider this GHG negligible in agricultural production as plants take it up). The GWP of methane- 21 over 100 years. CH4 emitted today lasts about a decade on average, which is much less time than CO2. But CH4 also absorbs much more energy than CO2. The net effect of the shorter lifetime and higher energy absorption is reflected in the GWP. The CH4 GWP also accounts for some indirect effects, such as the fact that CH4 is a precursor to ozone, and ozone is itself a GHG. Or 21 kg of CO2.

Practices that Release Carbon In Agriculture Soil Disturbance: Tillage, driving over soil, etc. Decomposition of biomass. Fossil fuel use. Transition from perennial soils to annual soils. Burning of plant residues, forests to open crop or rangeland, or weed control.

How do we Store Carbon? Grow crops Grow trees Reduce fossil fuel use Reduce mechanical tillage of soils Reduce burning of residues Optimize uptake and decomposition of residues to reduce GHG release. Modernizing production/manageme nt practices Precision agriculture Less fuel use Optimized tillage and chemical use Proper seed use for region Reduce soil ponding Reduce emissions from lagoons Increase soil organic matter Reduce irrigation

Nitrogen Cycle Nitrogen-most abundant element in atmosphere and an essential building block of all life: DNA, amino acids, etc. Nitrogen Cycle: a biogeochemical cycle in which nitrogen is converted from its inert atmosphere form, N2, into forms that are used in biological processes Ammonia-Ammonium Ammonium to Nitrite Nitrite to Nitrate Nitrate or Nitrite to Nox, Nitrous oxide Nitrate or Nitrite back to ammonium

Nitrogen Cycle

Nitrogen fixation Nitrogen Fixation-removal of nitrogen from the atmosphere the chemical processes by which atmospheric nitrogen is assimilated into organic compounds, especially by certain microorganisms as part of the nitrogen cycle. Either by lightning or biological or industrial Biological mediated by Nitrifiying bacteria associated with roots on a plant like legumes (symbiotic) or in soils.

Biologic Nitrogen fixation

Symbiotic Nitrogen Fixation

Where is Nitrogen? Nitrogen is stored in biomass of living organisms, soil and water Plant tissue Muscle fiber Cell liquids Terrestrial Nitrogen (land) Oceanic Nitrogen (dissolved) Nitrogen is respired by microbes in the form of N2O (Nitrous Oxide) or NO (Nitric Oxide) Nitrogen can be taken up by plants in the form of nitrate (NO3-), ammonium (NH4+) for biomass, dissolved in liquids (the ocean), stored in the atmosphere and taken up by microbes in the soils.

How is Nitrogen Released from Storage? Fossil fuel burning NOX Processing of nitrogen constituents Release of other N sources: Animal waste and microbes. Decomposition of soil organic matter nPlant roots, plant leaves and stems, microbes, animals, crop residues, manure, eggshells, nutshells, tree bark, etc.

Forms of Nitrogen important to Agriculture Nitrous Oxide Fossil Fuel burning (tractors, trucking, harvesting, transporting, etc.) Livestock waste after microbial decomposition Microbial processing of organic matter Microbial processing of chemical fertilizer Chemical fertilizer volatization Nitrate Fertilizer Ammonium

Who Cares? Loss of nitrogen is important to climate change and our warming environment!

Agricultural practices can effect the release of carbon that promotes climate change. Who Cares?

The Heating Index of Nitrous Oxide The GWP of Nitrous Oxide (N2O) has a GWP 298 times that of CO2 for a 100-year timescale. N2O emitted today remains in the atmosphere for more than 100 years, on average. Or similar to releasing 298 kg of CO2.

Practices that Release Nitrogen In Agriculture Soil Disturbance: Tillage, driving over soil, etc. Decomposition of biomass. Fossil fuel use. Transition from perennial soils to annual soils. Over fertilization. THESE PRACTICES INCREASE N2O IN ATMOSPHERE OR NITROGEN IS RELEASED IN WATER AND FLOWS DOWN STREAM CAUSING UETRIFICAITON.

How do we Store Nitrogen? Grow crops Grow trees Reduce fossil fuel use Reduce mechanical tillage of soils Optimize uptake and decomposition of residues to reduce GHG release. Modernizing production/manageme nt practices Precision agriculture Less fuel use Optimized tillage and chemical use Proper seed use for region Reduce emissions from lagoons Increase soil organic matter Reduce irrigation