How to Maintain a Lawn Without Herbicides or Synthetic Fertilizer, Version 2

Although I can appreciate the benefits of grass around the home, I am not a big fan of big lawns. They demand lots of energy and water, and in return, our family, which consists entirely of humans, cannot eat grass. For this reason, we have devoted most of our backyard to a vegetable garden, shrubs, berries and fruit trees. Unfortunately, a borough by-law prevents us from growing tomatoes or other produce in front of our home, so I maintain a small lawn.

Here’s what it looks like today, in early September.

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Although not “impeccable” by conventional standards, it’s quite green, and yet it has not ever received any herbicide or pesticide in its entire 21-year existence. For the last 15 years or so, it has not received any synthetic fertilizer either. So how do I keep it green?

I add used coffee grounds to my lawn throughout the summer. In the spring I also spread a few composted chicken manure pellets with my backyard’s compost in areas that have mostly grass. It also gets some urea(a nitrogen-source) from dogs who pee on my front yard during the winter. What’s wrong with synthetic fertilizer? Aside from being expensive, it inevitably spreads beyond the lawns’ borders, eats away at sidewalks, and runs off into our storm drains and river.

Next we come to the subject of “weeds”. Using such a term demonstrates ignorance of botany, which is a beautiful but underappreciated science. By not using herbicide, I save money, don’t risk health effects and allow plants like bird’s foot trefoil (Lotus corniculatus) to survive. Before flowering it looks like this patch from my lawn:

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It is a legume so it provides some of its own fertilizer thanks to a bacteria in its roots. If I don’t mow the lawn for a while, the trefoil produces attractive flowers that look these:

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Other non-grass plants worth tolerating are herbs like oregano, which spread to the lawn from the rock garden. If you look carefully, there is also parsley at the bottom center of the picture.  P1170382.JPG

There are three plants that I treat as “weeds” because they would otherwise grow at the expense of the grass, oregano and trefoil. They are dandelions, plantain and crab grass. To remove dandelions and their entire root, I use a tool. But trefoil does compete with them nicely. The other two have shallow root systems and are easy to pluck out with my thumb and index:P1170378.JPG

These were removed a little late. They have flowered and could have already spread their seeds. It’s best to learn to recognize them and pull them out earlier and donate them to the compost pile.

To encourage a deeper root network, I rely on rain, and even during dry spells, I water grass only every second day.  To conserve more water I use some water from a rain bucket positioned below the roof gutter. Since the patch of grass is only about 300 square feet, it takes me less than 15 minutes to hose it down.

Hopefully, if you haven’t already adopted similar practices, you will now be willing to save money, learn some botany and spend a little more time outdoors.

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Hot Chili Pepper Chemistry

The English word pepper is ambiguous. Botanically it could be refer to plants that produce black powdered pepper. The angiosperms (flowering plants) who serve as a source of that spice belong to the order Piperales and to the 3600-member family Piperaceae. (Kings play chess only for goodness’ sake is a mnemonic for remembering the order of biological classification: kingdom, a group of related phyla, which in turn, at least in singular form, phylum, is a group of related classes, and so on with orders, families, genera and species. ) Piperine is the compound mainly responsible for black pepper’s pungency, but as expected it does not appear in unrelated plants also dubbed as peppers.

1280px-Ripe_jalapeno_pepper
In jalapeños,  dihydrocapsaicin and capsaicin, are the two  amides mainly responsible for their hotness.

Pepper can also refer to Capsicum chinense, the Red Savino haanero chili, a member of the tomato family, Solanacea.  That fruit scores in the hundreds of thousands of units on the Scoville scale of “hotness”.  Other hot  peppers and milder ones are found among the many varieties of another Capsicum species, known as annum, which includes sweet peppers, jalapeños, and New Mexico chili.

 

There are four different amides (specifically, capsaicioids) found in hot peppers of the Capsicum genus. A Brazilian study revealed that in these fruits capsaicin makes up anywhere from 24% (in jalapeños) to 95% (pimenta preta) of capsaicioids present. These in turn combine to account anywhere from 0.2 mg to 7 mg per gram of fresh pepper, in other words, less than 1%. The percentage of course soars when the pepper is dried. Except in jalapeños and fatalis, the equally potent compound, dihydrocapsaicin, is the second most abundant amide. The greatest concentration (9.2%) of nordihydrocapsaicin, a substance about half as hot, was found in pimenta de mesa. Finally another related compound, homocapsaicin, the least potent of the quartet, is entirely absent from most spicy peppers, but it makes up 12% of dedo-de-moça pequena’s capsaicioids.

Nordihydrocapsaicin
nnordihydrocapsaicin 9 100 000
Dihydrocapsaicin
dihydrocapsaicin 16 000 000
Homocapsaicin
homocapsaicin 8 600 000
capsaicin
capsaicin 16 000 000
pimenta de mesa
The hot amides in pimenta de mesa consist of about 53% capsaicin, 37% dihydrocapsaicin, 1% homocapsaicin and about 9% nordihydrocapsaicin . The latter’s concentration is not surpassed in 20 other species of Capsicum.

From examining the above structural diagrams notice that in comparison to capsaicin,  homocapsaicin’s double bond is slightly further away from the tail end of the molecule. On the other hand, nordihydrocapsaicin’s strength is compromised by being one CH2 shorter than its hotter counterpart, dihydrocapsaicin.

How do these compounds exert such a powerful reaction in our mouths? In all mammals they cause tingling and burning sensations by activating  a non-selective cation channel, called VR1, on nerve endings. It’s not a coincidence that the same channel also interacts with compounds released by inflammation from actual intense heat sources or acidic protons. Birds, however, have a variant of VR1, which is still sensitive to heat and acid but which does not interact with capsaicin or its analogues.  It’s likely an example of co-evolution between Capsicum plants and animals who can eat their fruits without suffering deterring consequences. They then fly to other destinations to spread ingested seed.
We get more evidence of coevolution thanks to Jordi Altimiras of  Linköping University who made me aware of a study revealing that chilli seed germination is decreased in the gastrointestinal tract of mammals but not by the passage through the tract of birds.

Finally why are peppers producing capsaicioids in the first place? Any biosynthesis is catabolic and thus consumes energy. But making capsaicinoids in fruits is a worthwhile investment; it reduces fungal infection and seed mortality. From that narrow perspective we mammals have more in common with fungi than birds.

Sources:

  • Molecular basis for species-specific sensitivity to “hot” chili peppers.  2002 Feb 8;108(3):421-30.
  • Comparative Study of Capsaicinoid Composition in Capsicum Peppers Grown in Brazil
    http://www.tandfonline.com/doi/full/10.1080/10942912.2015.1072210
  • Directed deterrence by capsaicin in chillies. Nature 412: 403-404 and Tewksbury JJ, Reagan KM, Machnicki NJ, Carlo TA, Haak DC, et al. (2008)
  • Evolutionary ecology of pungency in wild chilies. ProcNatAcadSciUSA 105: 11808-11811 .

Green Grass Without Synthetics

There are benefits to having grass in parks and residential properties. When taken care of, grass becomes a natural carpet on which one can easily rest, play or walk. But to keep Poa pratensis green and thus in a juvenile state requires an investment of energy, an amount that is exaggerated by our questionable habits.

The typical high maintenance option involves buying synthetic fertilizer for spring and autumn applications, herbicide for weeds and pesticides for grubs. Some hire a company to drive around the neighbourhood to periodically spray lawns with the necessary concoction. To avoid the nuisance of a long electrical wire, people buy  gas-powered mowers.  And to prevent leaves and tree seeds from accumulating on lawn, blowers come to the rescue.

Even if people with such habits are aware that making fertilizer is an expensive  process partly because nitrogen does not spontaneously react with molecular hydrogen; even if they know that some fertilizer-pellets inevitably get sprayed onto sidewalks where they damage concrete, induce diarrhea in dogs and end up in storm drains and eventually into waterways and contribute to eutrophication; even if they suspect that the use of pesticides has ecological consequences;  even if they are aware of  the carbon footprint of synthetics and mowers and of the noise pollution of blowers, there is a possibility that they persist with their habits because they believe there is no alternative.

But when there is a will to change, there are always other options. One reason people turn to mass-maintenance techniques is that they plant more grass they can handle. City parks or residents can instead plant more trees, shrubs and cultivate gardens, which is what we did with 2/3 of the lawn we originally had in our backyard. I never spray any of our fruit trees or apply any pesticides to our garden. Instead of synthetic fertilizer, we rely on  a combination of household compost and composted chicken manure.  Grass cannot be eaten, but from July to October we have not needed to buy any tomatoes, garlic, parsley, basil, thyme or Swiss chard. We still have frozen cherries from our tree and we’ve also enjoyed arugula, fresh beans, onions and Mexican peppers, most of which were grown from seed.

P1150783.JPGA city bylaw prevents us from cultivating the front yard, but I manage to sneak in some oregano and bird’s-foot trefoil. They require less water and nitrogen than Kentucky bluegrass and displace  weeds. Since our city does not use pesticides on the grass between our sidewalk and road, dandelions, crabgrass and plantains find their way into our property. But I just pull them out with a hand tool. As an alternative to synthetic fertilizer, mulch from the electric mower is left on the lawn so that essential elements like nitrogen, phosphorus and potassium can be recycled. To supplement the lawn with more natural fertilizer, we let the dog pee on it and then immediately add collected rainwater to prevent “burning”. Due to their carnivorous diets, dogs’ urea is highly concentrated so it easily creates a hypertonic solution that needs to be diluted. In the spring the melting ice and snow takes care of that. Spots that don’t receive their share of dog pee get coffee grounds, which also keep the lawn green.

Abating the effects global warming involves more than reducing the use of fossil fuels for transportation and electricity-generation. They only account for a combined 45% of greenhouse gases(see pie chart below). Just about everything else ranging from reproduction to growing grass and food also impacts climate change. To solve the problem, regardless of the field of human activity, green or technical, we have to conserve and act more benignly towards ourselves and our surroundings.

image
AFOLU is an acronym for agriculture, forestry(deforestation) and other land uses. Its large contribution to greenhouse gases is often ignored in media reports about climate change. Source: www.ipcc.ch/report/ar5/wg3/

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