Hacker News Reader

Are you sure you aren't over-fertilizing? Or are you doing something else silly that causes you to lose all your N? That's a crazy amount of nutrient for even a very large garden.

>That's a crazy amount of nutrient for even a very large garden.

Its really not. Cattle manure is around 2% nitrogen. If we call a yard of composted manure 450 kg, that's around 9 kg of nitrogen. Say I'm going through 5 yards annually, which is about right, so 45kg. I'd say some where between 1/2- 1/4th of that actually reaches the plants (22kg). I've got substantial gardens, and I garden them very intensively. I've got about 1000m2 of gardens. In my climate I can crop continuously. High fertility for corn would be around 280 kg/ha. If I'm at 220kg/ha on my 1000m2, that seems about right.

Where are you located. I am in south Florida, treasure coast. I am hoping to step up my farming on 5 acres over the next few years.

I'd rather not be too specific, but somewhere that is tropical by lat, but sub-tropical by climate. We would have very similar climates.

5 acres is a huge amount of area. Good luck! I've found a lack of resources for the issues you'll likely face around farming in tropical and sub-tropical climates. It was a big transition for me from being able to rely on long periods of intense cold to kill of most of the pests. I'm still trying to figure out big parts of how to do gardening here.

Are you actually farming corn though? Over the whole thing? And at the density of commercial operations?

Sure, industrial corn operations use a lot of nitrogen (though they have indeed been shown to be over fertilizing, and a lot of the N from my state ends up in the Gulf), but gardens worked by human hands can be much, much, much more resource efficient at the cost of time and difficulty of automation.

With integrated nitrogen fixing plants, better use of mulch (which yes, ties up N at the surface temporarily, but can pay dividends overall), management of water flow etc, I cannot imagine needing that much fertilizer. I garden intensively in Iowa, and I do add a lot of compost when starting new beds (soil is clay) and I top up in the spring, but the older my beds get the fewer inputs they need.

> Cool. And which of those can I generate using excess electrical energy from my solar panels?

Perhaps use the excess energy to power an electric wood chipper to process your garden's waste? Wood chips made from small branches are quite rich in nitrogen.

> Over the last 3 years I've imported almost 5000kg of animal manures into my gardens.

What size garden do you have? The recommended dosage of manure is 30-50T per hectare, so 3-5T per 1000m2, but this is for the most exigent vegetables.

> Its more important for me to have the independence and control over my food-supply than it is to hold to a particular relgiosity around where my N comes from.

When you use a chemical fertilizer you depend on the manufacturer and distributor. How can this be called independence?

There are important differences at the soil biology level between the N coming from a chemical fertiliser or assimilated by soil bacteria. The former induces plants to use more water, necessitating more frequent watering. It also infiltrates ground water and pollutes aquifers. Another externality is greenhouse gas emissions in the process of manufacturing it.

> When that fails, I'll use a pesticide.

I'm not passing judgement but I think it's important to understand the consequences of our choices. At this point it is common knowledge that chemical fertilizers and pesticides are harmful to the environment and to people's health. I think it's important to be aware of the externalities implicated in all those choices. They might be easier, faster, cheaper in the short term, but in the long term they may prove to be introducing problems that are much harder, slower, much more expensive to solve in the long term.

I'm not going to bother responding to most of your points because most of them are poorly thought out and not worth my time, however this one stands out to me and I think captures the thrust of it..

>I'm not passing judgement

Oh I think you are. For many people in the world the decision around using synthetic fertilizers or pesticides is a decision between having a crop or not. This choice you want to make is a privilege that can only be made in the context of additional resources not accounted for, like having sufficient area to do crop rotation, additional land for the cultivation of fertilizers, or additional time and resources to dedicate to cultural practices.

Have you done the math on what are you would need to grow an acre of corn using only animal fertilizers? What about the carbon cost of moving that fertilizer around? What about the cost to the soil for tilling it in? How much additional land would need to be dedicated to animals to do? What about the methane and water quality issues for raising those animals? What if you live in an urban or sub-urban area?

There are real issues around over fertilization, intensified crop rotations, and pesticide use. Rejecting these tools outright, and more specifically, the attitude that we have the privilege to reject them outright is deeply problematic. If what you actually want is for people to grow into being more food self-sufficient, this attitude creates more barriers than it resolves.

If we could run the Haber-bosch process on what is effectively waste electricity, this would be a huge deal. Home gardeners could have something not too dissimilar to a battery bank that kicks on when there is surplus electricity, and fix nitrogen for storage into a tank for later use. Farmers could dedicate small sections of their farms to solar panels which can optimize between grid usage or the filling of fertilizer tanks depending on the economics. It would reduce the cost of producing and moving around that fertilizer. It would be a really good thing.

> What size garden do you have? The recommended dosage of manure is 30-50T per hectare, so 3-5T per 1000m2, but this is for the most exigent vegetables.

Reading their other comments, they have about 1000m2 of garden. So using 5t over 3 years is 1/2 to 1/3 of the dosage you listed. They don't appear to be over using.

"I try to use IPM"

What is IPM?

Also, how big is your land, if you need 5000 kg in 3 years?

edit: your profile says: "remote sensing of forests"

Can you explain, what that is?

IPM is a method for determining when and how to control pests;

https://www.epa.gov/safepestcontrol/integrated-pest-manageme...

IPM is integrated pest management, or an approach to pest management that generally avoids chemical pesticides, often taking a life-cycle approach to trying to deal with problematic insects, slugs, snails, etc. For me, this means mostly trying to manage three issues: aphids, powdery mildew, and tropical fruit flies.

I have around 1000m2 of planted area in a mix of vegetable crops and tree crops. 5000kg of cattle manure works out to around ~220kg/ha/yr of N, which is comparable with fertility rates for nitrogen intense crops like corn. Consider how deep a layer of compost would be spread that thin. Thats about 5kg/m2 over a couple of years, say some rounding for easy math, about 1.7kg of cattle manure/ m2/ yr. Maybe 2-4 good shovels of compost or 0.5-1.5 good cow shits per meter sq/year. Its really not that much. I also live in the subtropics and can crop more or less continuously. Its a ton of work, but I hope to have enough production to feed my family, and to run a small stand at a farmers market this summer.

My day job is the satellite remote sensing of forests and forested ecosystems. I use various different remote sensing platforms like landsat, sentinel, GEDI, and others, to consider questions around the carbon cycle, and biogeochemical processes in general. If you think you know me, the fact I'm particularly interested the impacts of disturbance of long term forest growth rates and carbon cycling would be an immediate tell as to my identity.

Thanks for the explanations.

When I was heavy into gardening and self sufficency, my main problem with pest management were slugs (I live in a quite humid area) and if I get into it again, I will probably use a physical barrier all around the planted area. (Last time I tried it very ecological and biodiverse and it was exhausting and regarding slugs, not working at all.)

If you manage, to make your own nitrogen with solar, I would like to read about it. Sounds promising to me as well, but I am not sure if it is worth the effort for small gardening.

"My day job is the satellite remote sensing of forests and forested ecosystems."

And I was asking, because it sounded a bit esoterical a la remote viewing and that seemed odd, with your otherwise very pragmatic approach ... so thanks for clarifying, sounds interesting. And good luck for the next harvest!