Picking up Phosphorus Grenades

It has been shown that the microcystis aeruginosa bacteria that is associated with algal blooms occurring in Lake Lariat (among many other lakes in the U.S.) is responsive to reductions in phosphorus, but not to efforts targeted at nitrogen reduction. Since dog and cat feces contain more than the usual amount of phosphorus (compared to cow manure, for example), and dogs and cats produce manure close to their own body weight every month, there is probably about 20,000 lbs of manure and about 300 lbs of phosphorus being spread by dogs and cats around the "critical area" of Lake Lariat every month, assuming owners are already sending half of their pets' manure to the landfill. That comes close to 2 tons of phosphorus every year. Unlike nitrogen, phosphorus gets consumed slowly in the soil, so it is more likely to end up in the Lake, where it may accumulate to trigger algal blooms.

Photo by Minnesota Pollution Control Agency

One thing to note about picking up dog crap in one's yard is that it should be done frequently, but at least prior to rain events. Letting it dry for a day or so is OK, if no rain is forecast. I like to time my pile pick-up rounds to coincide with rain-barrel draining when a storm is due the next day. As for dog walking, I've learned to take a couple of poop pickup bags and to have a plastic grocery bag to drop those into. The bigger bag gets tied on my belt until I can dump the contents in a trash can. I would consider composting these, but dog poop bags on the market aren't made for compost piles. Even the vegetable-based bags don't break down quickly or thoroughly enough. (Exceptions exist, e.g. Bio Bag)

For cat owners, the eco-opportunity is greater since cats are often given to going in a litter box. The key is finding a compostable litter. The late Gene Logsdon addressed this idea in chapter 3 of Holy Shit: Managing Manure to Save Mankind. A great odor absorbing material to mix into the litter is ground up biochar. It is not going to break down much in the composting process, but it should enhance composting temperature and time. I'm thinking about hosting an Amazon giveaway with Logsdon's book as the prize. It could be a way to get agriculturally oriented people in my community thinking about manure composting.

Clean Yard, Clean Lake

While septic systems are the major contributor to water pollution in this area, we humanure machines also have dogs that contribute in a more distributed fashion. Normally considered an urban problem due to runoff often being quickly shunted to stormwater drains rather than directed onto the landscape for infiltration, it also warrants attention in suburban settings with less impervious surface.

Taking the Maryland fertilizer law single application limit for lawns as a reference point, a dog contributes about 0.75 pounds per day, so every 25 days or so will drop enough manure to exceed the 1,000 square feet nitrogen and phosphorus limits in the fertilizer law. Nobody fertilizes that frequently, so leaving dog waste to decompose in one's yard violates the principle of the fertilizer law (aside from the fact that it makes a mess out of your lawn). However, when a person walks their dog instead of leaving it in a yard all the time, a lot of their pet's droppings get distributed over an area much greater than 1,000 square feet, so it's probably not excessive and needn't be collected, except in urban areas, or where it is clearly destined to be washed into a storm drain, or when required by rules.

If the fertilizer law is valid, nowhere is it more so than in the critical area, to include around inland lakes and streams. I traced out a line 1,000 feet from Lake Lariat on a topographic map and found that my house is inside that self-imposed buffer. Fortunately, I already collect and compost my dog's waste. Using that compost in a project that can demonstrate its efficacy is going to be one way that I gradually accustom others in my area to the idea of humanure compost. I think the project will be a conservation landscape in front of my house.

Part of my campaign could be spent encouraging dog owners in the target area to pick up the dog shit in their yards, especially from November 15th to March 1st when no fertilization of lawns is allowed. Dog poop will tend to wash into runoff more during those months because the ground is less pervious due to freezing.

The #1 Source of Pollution in Our Watershed

The 7 million or so gallons of sewage that spilled from wastewater treatment plants into a couple of the Chesapeake Bay's tributaries two weeks ago turned my head in a new direction. It redirected me on my capstone project for the Watershed Stewards Academy to focus on humanure in my neighborhood. Septic tanks are the current locus of the problem. Particularly problematic are failed septic systems in which sewage resurfaces and then gets washed by storm runoff into surface water.

The environmental impact of failed septic systems can be estimated using a figure from Purdue University stating that one failed system will discharge 76,650 gallons of sewage to the surface in one year. Extending that to an estimate of the number of homes in the critical area of the Chesapeake Ranch Estates, and applying a factor of 10%, which is the EPA's estimate of the proportion of septic system failures, and the annual amount of sewage flowing overland from this 1,000 foot wide zone stretching about 1 mile along the Chesapeake Bay comes to 3.8 million gallons. It could be double or triple that, depending on the actual failure rate, which has be estimated at over 30% in some states. Project that kind of problem all along the coastline of the bay and its tributaries and the wastewater treatment plants end up smelling like a rose.

Maryland's laws pertaining to poop aren't all that stringent. Farmers are allowed to dump manure on their fields. Homeowners are allowed to spread it on their lawns. If the fertilizer limits on nitrogen are applied to manure (phosphorus is actually the more limiting element), you could legally put 40 pounds of horse manure on a 1,000 sq. ft. lawn in a single application. Not that anyone would, but you could instead apply 20 pounds of humanure to the same lawn and remain under the nitrogen limits. A failed septic system used by a family of four would expel roughly 700 pounds of excrement (assuming toilets outside the home are used 50% of the time) to the land. That amounts to over 35 times the nitrogen limit for lawn fertilization (humanure contains 5% - 7% N). And that's just the poo! There is also a lot of urine and other nasty liquids in the mix with a whole lot more nitrogen.

It is hard to say whether the nutrient-laden runoff or the 100 or so pathogens in the sewage are a greater problem. Research published in 2015 from leading experts in the field of water sustainability shows that pathogens from septic systems make it into surface water much more than what authorities had believed. The pathogens are pretty scary, but to fish and other marine life, nutrient overload can quickly become deadly.

Keep in mind that all septic systems, working or not, tend to pollute the environment. The total amount of nitrogen loading to the Chesapeake Bay watershed from septic systems in Calvert County exceeds that from every other category,

Photo by Jim Barter

which includes agriculture, urban runoff, forests, and wastewater treatment plants. On average, the amount of nitrogen entering the watershed from a septic system is 19 pounds per year, based on calculations using figures from the Calvert County Watershed Implementation Plan. That is equivalent to dumping lawn fertilizer for over twenty 1,000 sq. ft. applications straight into the bay.  Every house.  Every year. The pathogens (including certain bacteria, viruses, protozoa, and other parasites)  in the effluent from working septic systems also make it into groundwater to one degree or another. In areas where septic systems are greatly concentrated, such as the Chesapeake Ranch Estates, both pollutant types will make the surrounding waters inhospitable to man or beast.

Anti-Septic Solutions

Clivus (pronounced "cleevus") Multrum toilets are a brand of composting toilets that have received the "best available technology" (BAT) designation in Maryland, which means they could be used as alternatives to septic tanks if combined with greywater systems on new construction. They could also allow reduction of septic tank sizes by 30% when installed without a greywater system. If folks want to bypass the 5-year recurring requirement for a groundwater discharge permit, they might try using the composted urine from the toilet as a nitrogen booster to compost high carbon material in a separate long-term, thermogenic compost pile. One drawback to this and other types of waterless toilets that require a vent fan is that you might want to include a backup source of power to keep the fan running during power outages. Another is that it may cost you more to heat and/or cool your home due to the continuous venting through the toilet.

All of this is particularly relevant to someone who has a home in the critical area (within 1,000 feet of a tidal waterbody or wetland) in Maryland. Structures outside the critical area will probably not be subjected to the expense of a change to their septic system, now that Gov. Hogan has announced a turnabout on the mandate for denitrifying septic systems. Homeowners who must still upgrade could take the Multrum toilet/greywater route, though it is not clear whether regulations would still require them to own a septic system and if it would still need to be upgraded. The new tack being taken by the Hogan administration may favor the composting toilet/greywater system option in lieu of costly septic system upgrades. One person I know with a house in the critical area told me his septic system would cost him $20K to upgrade due to the very deep leach field it requires.

The Maryland Department of the Environment (MDE) does not condone the use of compost that is harvested from composting toilets and says that it should be bagged and sent to landfills. There are no laws that specifically prohibit use of this compost on one's own property, though the low composting temperature of Clivus Multrum toilets means that owners should limit the compost use to ornamentals (roundworms being a possibility, and all).

What MDE and the general public need to wrap their minds around is that we must get comfortable with humanure composting. Once you get into compost gardening, you start to realize how valuable and scarce compost is. Compost is also valuable outside of gardening. We are not going to be able to continue the highly polluting practice of synthetic fertilizer production from natural gas if we want to keep from burning up the planet. Christophe Pelletier lays it out for us in economic terms,

In the future, we are going to see a new look at fertilization. The economics of agriculture will change. This is inevitable, because the cost of inputs will increase. This will be a direct consequence of the increase of the price of oil, and of the depletion of phosphates reserves. This change of economics will drive renewed interest for manure, and for sewage. These sources will become attractive and competitive, as they contain large amounts of minerals directly available. Because of their nature, they have a high content of organic matter. One of the most efficient ways to remove nitrates from water is to grow plants with it. One of the main sources of phosphates will be manure.

Now, if manure is going to be so important to growing food in the future, let's not rule out humanure until after a thorough investigation of its appropriateness.

Pelletier weighs the value of manure against the future cost of synthetic fertilizer, but the carbon cost could also be factored in. Compost, in general, can be helpful in reducing greenhouse gasses. The points made by the U.S. Composting Council could be easily extended to include humanure compost.

If the least expensive and most effective method (using a bucket and manually adding your scat to a compost pile) seems too undignified or time-consuming, composting toilets are another option better than sticking with the sewer or septic systems that are currently harming our environment. In Maryland, we are fortunate to have an authorized distributor of Clivus Multrum toilets with plentiful experience.

Compost Fit for a Prince

Making Biochar, Rain or Shine

My small scale biochar production cycle is weather-driven. When rain is infrequent, I make char while the sun shines and pour out the new biochar into a framed area dubbed my "biochar patch." Quite a bit can accumulate before rain comes to rinse the biochar and fill up its macropores, making it ready for the next step. I like to allow no more than a day to pass after a good rain before I crush the moistened biochar with a tamper and screen it through a salvaged patio tabletop into a bin. Dry biochar makes too much hazardous dust when crushing and sifting, so rain is welcome, though a couple of dry days are then needed for my feedstock to dry again. This gives me time to split more wood in preparation for the next round. 

My biochar patch with screening tools

Screened biochar

The admittedly tedious process of sifting biochar by hand has the advantage that any remaining torrefied pieces can be culled and sent back for more charring. Torrefied wood, i.e. pieces not charred completely through, inhibits plant growth, and does not belong in the final product. A less laborious (but more polluting) method of granulation is pouring damp biochar into a chipper/shredder. Occassionaly, I do this and then purge the machine by shredding leaves or sticks to prevent the residual biochar from corroding the metal and to avoid having a black dust cloud emerge when the machine is started up the next time. I've seen others use gas powered portable blower vacs to grind up biochar. (My electric blower may do the trick with dry biochar - something to try out.) The output from my shredder is a gelatinous concentration of biochar particles that needs to be mixed well with the soil or compost so that it becomes aerobic once again.

My biochar patch serves as a unique area of water retention for the garden that I am working to turn into something of a tropical paradise. Aside from getting free water to rinse and moisten the biochar, staying in rhythm with nature this way includes the benefit of a nitrogen charge whenever a new storm comes through. During lightning storms, some of the diatomic nitrogen (N2) that predominates in the atmosphere is ionized. These nitrogen-rich ions become entrained by raindrops that deposit it on the soil where it is mineralized into a form that plants can use and biochar can store as a slow-release fertilizer. If enough rain falls on biochar, I suppose it accumulates a sufficient charge of nitrogen to make it garden-ready.

Particles needn't be so fine as from a shredder when biochar is added to the soil. It helps earthworms to ingest them, but the larger (< 2 cm) particles that drop through the expanded metal screen used in a manual approach will break down from freeze-thaw cycles over time and the larger size doesn't reduce biochar's effectiveness in the meanwhile. Some situations are well suited to top-dressing with raw biochar in bulk form. Weathering eventually breaks up these unground particles, so they leach into the soil beneath. In the interim, they acquire nitrogen from above and pioneering microbes from below that make this labor-saving method of biochar application most economical. In my next post, I want to talk about one more reason top-dressing could be preferable to burying biochar.

Char Your Lawn

Of the nutrients that pollute the Chesapeake Bay lately, phosphorus has been the worst. "Why, of course, with all those chicken factory farms on the eastern shore," might be one's reaction to this statement. In fact, the major phosphorus inputs are coming from tributaries on the western shore of the Chesapeake. The cause has not been identified, but it could well be leaching from residential yards. Maryland soils are generally high in phosphorus, so soil disturbances by developers could also play a role.

In 2012, Maryland passed a law that prohibits the use of phosphorus on lawns except for one-time applications in cases of repairing patches, establishing a new lawn, renovating an entire lawn, or if a soil test shows a deficiency. As the phosphorus gets used up over the years, lawns will then suffer, more soil testing will be needed, and more phosphorus. Biochar can help here. Along with its many other soil enhancing benefits, biochar is very good at adsorbing phosphorus and feeding it to plants, including turfgrass. Most biochars, e.g. those made from wood, also produce a temporary liming effect in the soil, raising high acid soils' pH to one more suitable for turf (6.0 to 6.8). By applying biochar to turf, you can avoid frequent repeat applications of phosphorus and help to reduce pollution of your watershed.

Photo by Mr Thinktank (CC BY 2.0)

The steps to take when renovating a lawn include dethatching with a thatch rake or machine, and then using an aerating machine to remove small plugs throughout. After aeration, apply fertilizer-charged biochar with particle sizes small enough to drop into the newly created holes. (If phosphorus is adequate per soil test results, fertilizing with biochar will still help preserve other nutrients added, as well as the extant soil phosphorus). Spray with water to wash the char into (but not off) the lawn, then seed and water again. The biochar will also help keep the lawn moist while the seed germinates. Check the pH semi-annually to see if lime is needed and don't mow it less than 3 inches.

Permasoil

Weeds like cypress spurge can establish themselves where nutrients are scarce, but most horticultural plants require more care and feeding in order to grow to their full potential. Nitrogen is the macronutrient in highest demand by vegetables, requiring most gardeners to supplement their soils with fertilizer at certain times in a plant's lifecycle. Farmers typically use aged manure as a nitrogen source, which may put their customers at slight risk of pathogens in their produce. Synthetic fertilizers are used by most non-organic farmers and gardeners, leaving a large carbon footprint and upsetting soil microbial communities. Compost adds some nutrients, but the nitrogen is typically consumed within six weeks.

Healthy soil has the ability to cycle nitrogen to plants from the activity of microbes with no outside supplementation. Healthy soil requires the presence of live plant roots throughout the year, e.g. cover crops, with no more than three weeks dead space. If one added compost at a high rate every year, the soil could become nutrient sufficient after many decades. In the meantime, a grower needs to fertilize in addition to using compost.

The missing piece from this discussion is biochar. Biochar raises the cation exchange capacity (CEC) of soil better and more permanently than compost, meaning more nutrients will be available to plants for a longer period. If small portions of biochar are added annually to a plot of land, poor soil health can improve to a self-sustaining level in only a decade or two because it harbors a plethora of soil biota. Once soil reaches that state, it becomes a treasured renewable resource rather than a recurring receptacle. Biochar that is pre-charged with nutrients and inoculated with microbes can bring soil to a regenerative state most quickly.

Photo by Willi Heidelbach (CC BY 2.0)

You can be a successful grower by relying on synthetic fertilizers, or you can be even more successful by following organic practices, including natural fertilizers and compost, but unless you grow on prime farmland already, you can only be fully successful in your lifetime if you use biochar. Until your soil gets to that point, keep the fertilizer handy (but please hot compost the manure).

Beyond Chemicals

While I see a need to have soil restoration promoted in the next version of the Calvert County Comprehensive Plan, there are already many elements of the plan and ongoing institutions promoting soil conservation. The Comprehensive Plan includes "Sediment flows from development and farming" as a threat to the vision that

Our wetlands, streams, and forests support thriving plant and animal communities.

The corresponding action is "Develop soil conservation and water quality plans for farms."

When you look into the Best Management Practices of the Soil Conservation District, it appears that they have this whole issue pretty well in hand (at least among the farms on the list of cooperators). Many of these best practices lead to soil restoration in addition to soil conservation. At least one of the BMPs, however, is potentially counterproductive - that is, perpetuation of chemical fertilizers.

Photo by Paul Riismandel (CC BY-NC-SA 2.0)

The problem with chemical fertilizers is that they can reduce the soil biota population below a critical level where the microorganisms make the soil ecosystem work in the plants' favor. This results in the need to use more fertilizer to achieve the same results as in previous years and the soil undergoes a death spiral until it is no longer economical to farm.  Many of the trace nutrients used by plants are generated by the proliferation of soil microorganisms and could be uneconomical to add directly as we do commonly applied macronutrients like Nitrogen, Phosphorus, and Potassium (N, P, K).

It may be possible to restore soil humus by intensive farming methods while still using chemical fertilizers, but a surer method is to farm organically using biochar, compost, and organic fertilizer, as necessary. The goal should be to eliminate fertilizers altogether in favor of creating humus which is self-regenerating as long as crops are grown successively and rotated from year to year. Our farmers, large and small, need to learn to do this if for no other reason than that chemical fertilizers are a nonrenewable resource. A better option, still, is to grow perennial food crops. While we're at it, let's take advantage of soil carbon restoration for its role in cooling the planet.

Please Don't Feed the Algae

Global warming isn't the primary cause of all environmental problems, but it still plays a hand in most.  Take the Upper Middle River outside of Baltimore where, last month, 200,000 fish were suffocated by an algae bloom that led to anaerobic conditions in the water.  The algae bloomed from a combination of warm temperature and an over-abundance of nutrients in the water.  When the weather cooled, the algae died, decaying through a chain of microbial feeding frenzies that consumed dissolved oxygen and released toxins damaging fishes' gills.  Dead fish compounded the effect of dead algae. Not to say that we will suffocate from all of the die-offs occurring around us (though the oxygen concentration in our air is falling), but this is an example of how the fate of a lesser ecosystem occupant can dramatically affect higher species.

The Maryland Department of the Environment has not identified any single pollution source as the trigger for the algae bloom, but leaves open the possibility that an accumulation of nutrients (read "fertilizer") could be to blame. It will be poetic justice when, in the coming decades, the rising seas reclaim the land surrounding this Chesapeake Bay tributary away from homeowners who prized their lawns while poisoning more sentient creatures.

Yet, if cumulative small trespasses can lead to ecological disasters, abundantly small acts of stewardship may also mitigate others.  If you have forested land anywhere in the Chesapeake Bay watershed, Forests for the Bay is a resource treasure trove that can help you care for it.  It takes only a 1 minute free sign up process to open up the treasure house.