How Big Of An Offender Are You?

[MGRox]

We all know or have read about agricultural crops causing problems from leaching excess salts from fields into rivers and streams. We know that there is an increasing focus to not over-apply fertilizers or apply fertilizers across multiple instances to attempt a reduction in pollution.

We all sit on the sidelines in our hobby and, as well, look down on this pollution as bad. However, do we really have the ability to do this; or are we worse offenders? If we progress legality to the point where large field crops of cannabis are grown - how do we stack up in this case?

Here's a nice comprehensive document that covers the pounds per acre of NPK (or PK) for various field crops. It is from the agricultural and environmental services laboratories.
http://aesl.ces.uga.edu/publications/soil/CropSheets.pdf

Of interest to us here are the P and K recommendations for the "Low" soil test. Here we can see the maximal amount of an element that is to be added, relative to each crop.

Looking at all of the crop types we can see an approximate average for P at around 80-120 lbs per acre. For K we can see an approximate average in the 120-180 lbs per acre range.

One well known offender is Corn crops. The average yield for corn crops is around 150 bushels per acre. If we look at the low soil tests for this level we find. 110 lbs per acre of P and 130 lbs per acre of K. These levels are heavily contributing to pollution, but they are not the highest.

One of the highest values shown in the paper is for corn at 300 bushels per acre (double average!). Here with a low soil test we see a whopping 200 lbs per acre of P and 280 lbs of K!!!

There are only a few other crops with P or K values close to being as high as above; Dioecious trees and shrubs (pre-plant), Cabbage, Cauliflower, Collards, Broccoli, Kale, Mustard, Potatoes, Spinach, Turnips and Tomatoes are all at 200 lbs of P and K. Wine grapes at 200lbs of P and 165lbs of K.

Note that the vegetables are primarily short leafy plants with small root mass, or are tubers. The exceptions being pre-plant trees and shubs, along with Tomatoes.
----------------------------

These figures are all in pounds per acre and we often use figures in PPM's, so how does it correlate?
We can easily calculate the expected PPMs in the soil based on pounds per acre.
From info here: https://edis.ifas.ufl.edu/hs1229
"Pounds of phosphorus pentoxide applied per acre × 0.5 × 0.4364 = increment of phosphorus in soil (ppm)
Pounds of potassium oxide applied per acre × 0.5× 0.8302 = increment of potassium in soil (ppm)"

Let's take a look at the number one offender for pollution, which is Corn at 150 bushels per acre.
110 lbs of P = 24 ppm and 130 lbs of K = 54 ppm.

Now lets look at the highest for the small root mass, leafy veg or tuber application rates.
200 lbs of P = 44ppm and 200 lbs of K = 83 ppm

Finally lets look at the highest application rate of all crops in the 500 page booklet. Corn @ 300 bushels.
200lbs of P = 44ppm and 280 lbs of K = 116 ppm

**These are the starting levels, applied once through the entire growing season and are considered to be "highly excessive" when it comes to run-off and pollution.


So, How big of offenders are we; if we were to be growing acre based crops. Well let's look at a commonly used profile. The Lucas Ratio.
Lucas ratio has 100 ppm of P and 200 ppm of K. That works out to 458 lbs per acre of P and 480 lbs per acre of K. This is more than double the highest P level of even corn at 300 bushels!!!!
We would be by orders of magnitude as the worst offenders in the world for pollution, if we ran lucas ratio in an acreage setting.

The recommended levels for Hemp are; "80-120N, 80-120P2O5, and 160-200 K2O kg/ha"
http://www.collectionscanada.gc.ca/obj/s4/f2/dsk3/ftp04/mq24965.pdf
This works out to a maximum of 107 N - 107 P - 179 K , In lbs per acre.
Which is; 107 ppm of N 23 ppm of P and 74 ppm of K

So how big of offender are you? How much P or K are you adding in pounds per acre?

Guess To start: I'm at 107 lbs of P and 217 lbs of K for veg. In flower I'm at 230 lbs of P and 500lbs of K.

 

[X.rm]

We all know or have read about agricultural crops causing problems from leaching excess salts from fields into rivers and streams. We know that there is an increasing focus to not over-apply fertilizers or apply fertilizers across multiple instances to attempt a reduction in pollution.

We all sit on the sidelines in our hobby and, as well, look down on this pollution as bad. However, do we really have the ability to do this; or are we worse offenders? If we progress legality to the point where large field crops of cannabis are grown - how do we stack up in this case?

Here's a nice comprehensive document that covers the pounds per acre of NPK (or PK) for various field crops. It is from the agricultural and environmental services laboratories.
http://aesl.ces.uga.edu/publications/soil/CropSheets.pdf

Of interest to us here are the P and K recommendations for the "Low" soil test. Here we can see the maximal amount of an element that is to be added, relative to each crop.

Looking at all of the crop types we can see an approximate average for P at around 80-120 lbs per acre. For K we can see an approximate average in the 120-180 lbs per acre range.

One well known offender is Corn crops. The average yield for corn crops is around 150 bushels per acre. If we look at the low soil tests for this level we find. 110 lbs per acre of P and 130 lbs per acre of K. These levels are heavily contributing to pollution, but they are not the highest.

One of the highest values shown in the paper is for corn at 300 bushels per acre (double average!). Here with a low soil test we see a whopping 200 lbs per acre of P and 280 lbs of K!!!

There are only a few other crops with P or K values close to being as high as above; Dioecious trees and shrubs (pre-plant), Cabbage, Cauliflower, Collards, Broccoli, Kale, Mustard, Potatoes, Spinach, Turnips and Tomatoes are all at 200 lbs of P and K. Wine grapes at 200lbs of P and 165lbs of K.

Note that the vegetables are primarily short leafy plants with small root mass, or are tubers. The exceptions being pre-plant trees and shubs, along with Tomatoes.
----------------------------

These figures are all in pounds per acre and we often use figures in PPM's, so how does it correlate?
We can easily calculate the expected PPMs in the soil based on pounds per acre.
From info here: https://edis.ifas.ufl.edu/hs1229
"Pounds of phosphorus pentoxide applied per acre × 0.5 × 0.4364 = increment of phosphorus in soil (ppm)
Pounds of potassium oxide applied per acre × 0.5× 0.8302 = increment of potassium in soil (ppm)"

Let's take a look at the number one offender for pollution, which is Corn at 150 bushels per acre.
110 lbs of P = 24 ppm and 130 lbs of K = 54 ppm.

Now lets look at the highest for the small root mass, leafy veg or tuber application rates.
200 lbs of P = 44ppm and 200 lbs of K = 83 ppm

Finally lets look at the highest application rate of all crops in the 500 page booklet. Corn @ 300 bushels.
200lbs of P = 44ppm and 280 lbs of K = 116 ppm

**These are the starting levels, applied once through the entire growing season and are considered to be "highly excessive" when it comes to run-off and pollution.


So, How big of offenders are we; if we were to be growing acre based crops. Well let's look at a commonly used profile. The Lucas Ratio.
Lucas ratio has 100 ppm of P and 200 ppm of K. That works out to 458 lbs per acre of P and 480 lbs per acre of K. This is more than double the highest P level of even corn at 300 bushels!!!!
We would be by orders of magnitude as the worst offenders in the world for pollution, if we ran lucas ratio in an acreage setting.

The recommended levels for Hemp are; "80-120N, 80-120P2O5, and 160-200 K2O kg/ha"
http://www.collectionscanada.gc.ca/obj/s4/f2/dsk3/ftp04/mq24965.pdf
This works out to a maximum of 107 N - 107 P - 179 K , In lbs per acre.
Which is; 107 ppm of N 23 ppm of P and 74 ppm of K

So how big of offender are you? How much P or K are you adding in pounds per acre?

Guess To start: I'm at 107 lbs of P and 217 lbs of K for veg. In flower I'm at 230 lbs of P and 500lbs of K.

 

[X.rm]

Those are important questions, i wonder what your thoughts are on drain to waste ?

 

[Seamaiden]

You didn't read that paper about ammonium pollution being worse than fossil fuels, didja?

Agricultural ammonia emissions disrupt Earth's delicate nitrogen balance
New research indicates that nitrogen cycle disturbance from emissions of agriculture-related ammonia now exceeds the effects of fossil fuel combustion emissions
Date: May 9, 2016
Source: Colorado State University
Summary: New research indicates that nitrogen cycle disturbance from emissions of agriculture-related ammonia now exceeds the effects of fossil fuel combustion emissions.

When considering human impacts on earth systems, disturbance to the carbon cycle grabs the headlines. But another critically important earth process, the nitrogen cycle, has also seen major disruption from human activity.

It turns out the nature of that disruption in the U.S. has changed over the last several decades. New Colorado State University research indicates that nitrogen cycle disturbance from emissions of agriculture-related ammonia now exceeds the effects of fossil fuel combustion emissions.

And no matter what the source, excess nitrogen in the atmosphere, as it cycles through terrestrial and aquatic ecosystems in both wet and dry processes, has debilitating environmental impacts. These include increased soil acidification, decreased biodiversity, and changes to the chemistry of lakes and streams.

The research team was led by Jeffrey Collett, professor and head of CSU's Department of Atmospheric Science, and includes collaborators from the Environmental Protection Agency, the National Park Service and the National Atmospheric Deposition Program.

Publishing May 9 in Proceedings of the National Academy of Sciences, the researchers describe a slow, measurable shift in sources of nitrogen deposition -- the input of reactive nitrogen from the atmosphere to the biosphere -- that continue to wreak havoc on ecosystems. The paper's first author is Yi Li, a recent CSU Ph.D. graduate who now works for the state of Arizona.

Starting in the 20th century, human-made nitrogen deposition has come from two main sources: nitrogen oxides from fossil fuel emissions, which become nitrates in the atmosphere; and ammonia, which derives mostly from livestock waste and from nitrogen fertilizers, and which cycles through ecosystems as ammonium.

Over recent decades, most attention has been focused on the fossil fuel side of the equation. In that time, major strides have been made to stem those emissions, through technological improvements and government regulations. Tailpipe emissions are cleaner than ever today, and power plants are tightly regulated for nitrogen oxide pollutants.

In contrast, ammonia from agricultural processes has received little attention, and ammonia is not a regulated pollutant. The CSU researchers have found that ammonium has now surpassed nitrates as the dominant source of nitrogen deposition and subsequent disruption to the nitrogen cycle.

"We are used to thinking of nitrates as driving a lot of the nitrogen deposition, and that was true in the 1980s," Collett said. "But largely because we've reduced nitrates so much while ammonium deposition has increased, the balance is now shifted, and ammonium is now a bigger contributor to nitrogen deposition."

Ammonia emissions, while not toxic to humans at current atmospheric levels, also have secondary effects, the researchers say. Ammonia is a chemical precursor to many particulate matter pollutants that are harmful to humans, including ammonium nitrate and ammonium sulfate.

In the paper, the researchers analyzed the shift in nitrogen deposition sources from nitrates to ammonia in the context of what's called wet deposition, which is nitrogen that enters the nitrogen cycle in the form of rain or snow.

Nitrogen can also undergo dry deposition, which is when a gas molecule or particle in the atmosphere is directly deposited to the earth's surface. Quantification of dry deposition is more challenging, Collett said, and less data is available to analyze those effects. A recent expansion in U.S. ammonia measurements allowed the team to more fully quantify nitrogen dry deposition inputs. These findings further emphasize the importance of ammonia as a main contributor to ecosystem inputs of nitrogen.

The takeaway? "Policymakers need to be thinking about ammonia, not just nitrates," Collett said. "We've worked hard at decreasing nitrates by reducing emissions of nitrogen oxides from fossil fuel combustion, but if we want to continue to make progress on reducing nitrogen deposition, we need to think about ammonia as well."

 

[Blaze]

A good topic, I have not seen to many people consider this topic. In preparation to eventually have to deal with the North Coast Regional Water Board I calculated what I used in my outdoor garden last year. Cannabis is a heavy feeder, which is expected from something that can go from a single seed or small 3" cutting to a 10' tall 10' wide (or more) plant in 7-8 months. However I think the ratios outlined by the Lucas formula are pretty darn high and most growers do tend to over feed. I feed a lot less than most other growers I've met and my numbers are still pretty high compared to most crops.

Based on my notes of what was used and the total square footage of my garden I came up with this:

For a 6-moth season I use:

210-245 lbs/acre N
193-225 lbs/acre P
144-167 lbs/acre K

I would be curious to see what other people's numbers are.

 

[X.rm]

You didn't read that paper about ammonium pollution being worse than fossil fuels, didja?

The question is, what is one to do ? I hand water with a subpump and retrieve excess with a wet/dry shopvac and throw the solution down the drain. Im sure theres some negative effect Eventhough theres some sort of a recycling plant somewhere along the line. But what alternative is there ?

 

[Savage Henry]

I'm curious what large vegetable producers do with their runoff. I've read about tomato growers in Australia and Mexico running coir DTW.

 

[Blaze]

Not using synthetic nitrogen produced by the Harber-Bosch process would be a good start. Between 50% and 90% of synthetic nitrogen is never used by the plant anyway and ends up as a pollutant in the environment.

 

[Seamaiden]

I'm curious what large vegetable producers do with their runoff. I've read about tomato growers in Australia and Mexico running coir DTW.

They don't do anything, they let it go into the soil and water tables. That is part and parcel of the problem.