Ecology
Bird Seed, Fertilizer, Biomass, and Habitats
Dr. Jay Maron
jaymaron.com

Biomass
Biomass production
Energy
Fertilizer
Nutrients
Food
Bird seed

Volcano cooling
Climate engineering
Tree carbon capture
Habitat
City cats
Hydroponics


Food chain

Biomass is dominated by trees.

Plants are 10% of ocean biomass and 98% of land biomass.

On land, most plants are not eaten, and in oceans, most plants are eaten. Oceans have 5 times as much consumer biomass as producer biomass.


Mammals and birds

For mammals and birds, biomass is dominated by domestic animals.

Mammal biomass is dominated by humans and cattle.

The larger the organism, the more accurate the population data. Populations for many small species are unknown.


Wild birds


Mammal biomass

Mammal biomass is approximately constant over the range of animal sizes.

Data from pantheria.org.


Metabolism

Metabolic power/mass scales as Mass-1/4.

The biomass distribution scales as Mass0, hence most mammal metabolic power is expended by small organisms, not large organisms.

Data from pantheria.org.


Brains

A human brain is 1.6 kg and uses 20 Watts.


Biomass

Land               Bkg             Ocean        Bkg

Plants         3300000             Crustasian  4800
Plants, trees  2600000             Fish        4200
Bacteria        420000             Mollusk     1140
Fungi            72000             Plant       1000
Archaea          42000             Jellyfish    620
Protist          24000             Mammal       120
Crops            14000             Virus        100
Worm              1320
Virus             1100
Insect            1050
Amphibian          600
Arachnid           150
Mammal, wild        30
Reptile             18
Bird, wild          12

Mammal, human      360
Mammal, domestic  1000
Bird, domestic      30

Indicator species

Ocean mammals

              World biomass   Population   Mass
                   Bkg         millions     kg

Whale, total            40       1.5
Dolphin, total           7      50
Seal, total              6      25

Whale, sperm            16        .40    40000
Whale, fin               6        .10    60000
Whale, S Bottlenose      3        .5      6000
Whale, blue              2.5      .02   125000
Whale, humpback          2.4      .080   30000
Whale, bowhead           2.2      .030   75000
Whale, bryde             1.4      .095   15000
Whale, sei               1.1      .057   20000
Whale, right              .6      .01    60000
Whale, gray               .6      .026   25000
Whale, orca               .4      .1      4500

Dolphin, white-sided     4.9    41         120
Dolphin, orca             .45     .1      4500
Dolphin, spotted          .3     3         113
Dolphin, bottlenose       .24     .6       400
Dolphin, striped          .2     2         100

Seal, crabeater          1.6     8         204
Seal, harp               1.4     8         180
Seal, elephant            .7      .5      1400
Seal, brown fur           .4     2.1       185

Land predators

           World biomass   Mass   Population
               Bkg          kg

Dog, wild       3
Fox, red        1.2          8
Cat, wild        .5
Bear, black      .15       154
Bear, brown      .06       278
Bear, polar      .018      475
Jaguar           .005       81
Leopard          .004       54
Wolf, grey       .002       40

Land foragers
         World biomass (Bkg)

Squirrel      7
Raccoon       3.8
Elephant      2.4
Rat           1.9
Kangaroo      1.2
Rabbit        1.1
Deer          1.0
Fox            .8
Moose          .58
Hippo          .45

Waterfowl

           World biomass   Population   Mass
                Bkg         millions     kg

Duck total       .10         100         1.0
Goose total      .07          20         3.75
Swan total       .02           2        10

Duck, mallard    .021         19         1.08
Duck, pintail    .004          5.35       .8
Duck, long-tail  .004          5          .74

Goose, Canadian  .022          6         3.75
Goose, snow      .019          6         3.2

Swan, mute       .0072          .605    11.9
Swan, whooper    .0021          .18     11.4
Swan, tundra     .0018          .3       6.1
Swan, black      .0017          .3       5.8
Swan, trumpeter  .0005          .046    11.6

Birds of prey

              World biomass   Population   Mass
                   Bkg         millions     kg

Hawk, red-tailed     .0028       2.6      1.06
Goshawk              .0019       2         .956
Buzzard              .0017       4         .43
Peregrine falcon     .0012       1.2      1.0
Kestrel              .0009       5         .184
Falcon, laughing     .0009       1.6       .57
Hen Harrier          .0005       1.3       .40
Hawk, roadside       .0004       1.6       .275
Hawk, Eurasian       .0003       1.5       .22
Merlin               .0003       1.3       .195
Gyrfalcon            .0002        .11     2.1

Eagle, golden        .0007        .17     4.18
Eagle, snake         .0002        .1      1.68
Eagle, bald          .0001        .02     4.85
Eagle, hawk          .0001        .1       .85

Heron, grey          .0014       1.0      1.4
Egret, cattle        .0012       5.4       .22
Heron, boat-billed   .0003       1.6       .2

City biomass

For Manhattan,

           Mass  Number per  Number per   Mass/area
                   person     hectare
            kg                            (Humans=1)

Human       65      1          300        1
Cat, wild    3.9     .143       43         .0086
Pigeon        .27   1.5        450         .0062
Rat           .32   1.0        300         .0049
Squirrel      .5     .03         7.5       .00023

Biomass production

Land carrying capacity

   Year

 -11000     Livestock
  -9500     Crops
  -6000     Crop rotation. 2-field system
  -4000     Ox power
  -3500     Horse
      0     Trade network
    900     3-field system
   1492     Columbian exchange. Guano fertilizer introduced
   1700     4-field system. Nitrogen-fixing plants
   1800     Fertilizer becomes widespread
   1850     Mechanization
   1895     Refrigeration
   1950     Pesticides
   1980     Genetic engineering

English wheat yield:

Year    Wheat yield (kg/hectare/year)

1500       .018
1550       .022
1600       .029
1650       .031
1700       .038
1750       .047
1800       .063
1850       .073
2020       .8

Arable land

Crop locations are decided by rain, rivers, lakes, reservoirs, aquifers, and aqueducts. Prime farmland is for crops and subprime land is for grazing. There is 2.2 times as much grazing land as cropland, and agriculture is 38% of world land.

The plot shows the center of mass for crops.

Farm fraction
Ogallala aquifer
Central valley aquifer
Spokane Valley aquifer


Carrying capacity

Land can support more people with wheat than with beef, by a factor of 16. Sugar cane is more efficient than wheat by a factor of 16.

Farm productivity is expressed as kg/meter2/year of food. If we factor in the calorie content of the food, we can express this as food production power in Watts/meter2. The value for wheat is 16 times larger than for beef.

The table shows the production power for various foods, with a comparison to solar cells and wind turbines.

              Production   Energy/Mass    Power    Type of energy
             kg/meter2/yr   MJoule/kg  Watt/meter2

Solar cell           -         -        40         Electricity
Wind turbine         -         -        15         Electricity

Algae               10        16         5.1       Biomass
Bamboo               2        16         1.0       Biomass
Grass                1        16          .50      Biomass
Typical tree          .5      16          .25      Biomass

Sugar cane           8        16         4.1       Food
Wheat                 .5      14          .22      Food
Milk                  .6       2.1        .040     Food
Fish                  .1       9          .028     Food
Goose (grazing)       .1       9          .028     Food
Beef (grazing)        .05      9          .014     Food
Tomato               8        .8          .20      Food
Tomato, hydroponic 150        .8         3.8       Food

For most crops, 50% of the plant biomass is edible produce.

In 1850, a family of 4 could be supported by 40 acres, and this is the origin of the phrase "40 acres and a mule". This corresponds to 25 people/km2. At the time, world population was 8 people/km2 and today it's 50 people/km2.

It takes 120 Watts of food energy to support a human. If the calories come from cane sugar, then land can support 30000 people/km2.

Wild mammal biomass is 30 Bkg and human biomass is 360 Bkg.


Farming cost inputs

Land is far cheaper in Brazil than Iowa. Land is 1/5 of the cost in Brazil and 1/2 the cost in Iowa.

Iowa pays less for fertilizer than Brazil, but they pay more for seeds.

Labor is only 1/15 the cost, for both Iowa and Brazil.

Costs are in $/acre/year.

               Iowa    Iowa    Iowa   Brazil  Iowa
               cows    corn    soy     soy    grass

Land            56     256    256      60      55
Labor           22.9    42.7   33.6    20      33
Seed             -     114.4   49.2    25       -
Machinery        5.2    70.2   64.5    40      20
Other            5.2    31.9   26.9    16       -

Nitrogen        27.2    71.7    -       -      58
Phosphorus      11.7    29.6   19.5    25      19
Potassium       12.0    18.3   27.9    35       -
Lime             -      15.7   15.7    15       -

Herbicide        4.6    39.6   48.7    40       5
Insecticide      -      18.4    -      10       -
Fungicide        -       -      -      25       -
Other pesticide  -       -      -       4       -

Total          137.9   770.8  542.0   315      181

Source


Fertilizer


Elements

A simple and cheap fertilizer recipe is:

                   Relative mass

Urea                    4
Potassium chloride      4
Monoammonium phosphate  1
Calcium chloride        1
Magnesium chloride      1
Ammonium sulfate        1

Growing 1 kg of biomass requires the following elements:

        Element  Cheapest form          Molecule    Cost   Fertilizer   Element frac   Element cost
         gram                                        $        gram      in fertilizer     gram/$

Nitrogen    15   Urea                   CO(NH2)2    .025      26            .467          482
Potassium   15   Potassium chloride     KCl         .044      29            .524          340
Phosphorus   2   Monoammonium phosphate (NH4)2HPO4  .011       7            .269          185
Calcium      2   Calcium chloride       CaCl2       .011       6            .361          182
Magnesium    2   Magnesium chloride     MgCl2       .036       8            .255           55
Sulfur       2   Ammonium sulfate       (NH4)2SO4   .025       8            .243           79

Total                                               .152      84

Well-irrigated crops produce 1 kg of biomass per meter2 per year. Typical crops are 1/2 edible matter and 1/2 inedible matter. Trees can produce wood at a rate of 2 kg/meter2/year.

As an example, for nitrogen fertilizer,

Nitrogen requirement    = n =       =   15  grams           to produce 1 kg of biomass
Urea nitrogen fraction  = u =       = .456
Urea requirement        = U = n / u =   33  grams
Nitrogen cost per kg    = c =       =  482  gram/$
Nitrogen cost           = C = n/c   = .029  $

The appendix has a table with all possible fertilizer molecules.


Nutrients

Almost all vitamins fit into one pill, with the exception of calcium, potassium, phosphorus, and magnesium, which can be supplemented separately. The nutrient requirement for animals and plants is:

            Human       Bird         Crop         Supplement
           gram/day   gram/day      gram/kg

Calories     2200      165           0
Protein        50        9           0
Potassium       3.5       .4        14            Potassium phosphate
Phosphorus      1.0       .4         1.5          Potassium phosphate
Calcium         1.0       .8         2            Calcium chloride
Magnesium        .35      .4         1.5          Magnesium chloride
Iron             .27      .2          .14
Zinc             .075     .05         .038
Manganese        .075     .05         .038
Copper           .022     .02         .011
Nitrogen        0        0          15            Ammonium nitrate
Sulfur          0        0           1.5          Ammonium sulfate

We assume a 75 kg human and a 1 kg bird. For other masses, scale accordingly. For crops, the nutrient requirement is in grams of nutrient required to produce 1 kg of biomass. Crop biomass is typically 1/2 edible food.

For young birds, calcium and phosphorus are especially important, for bones. For egg-laying birds, calcium is important for egg shells.


Bones

Bones are made of calcium and phosphorus, in a 2:1 ratio. For a 1 kg bird,

Calcium    = 14.0  grams
Phosphorus =  6.5  grams
Potassium  =  4    grams
Magnesium  =  1    grams

For bones,

Calcium fraction         = .279
Phosphorus fraction      = .130
Calcium/phosphorus ratio =  2.1

The best bone supplements are calcium chloride (CaCl2) and monopotassium phosphate (KH2PO4).


Eggs

For a chicken egg,

            Mass     Calcium
            grams     grams

Egg total    60       1.95
White        36.6      .0023
Yolk         18.3      .028
Shell         5.1     1.92

Almost all the calcium is in the shell. Eggs are 3.2% calcium. Shells are 94% calcium carbonate (CaCO3) and calcium carbonate is 40% calcium.

An egg is typically 3% of the mass of the adult bird.


Growth

It takes 50 days for a bird to grow to adult size.


Nutrient content of food

Sesame
Poppy
Chia


Calories and protein

The left plot shows the protein and calorie content of food. Foods with high protein and low fat are in the lower right. Nuts are heavy in protein, especially peanuts.

The right plot shows how much calories and protein you get per dollar. The cheapest meats are pork, chicken, and turkey.


Potassium, phosphorus, and calcium

The plot shows the potassium, phosphorus, and calcium content of food. Calcium is abundant in cheese and milk and rare in other foods. Sesame is rich in calcium.


Bone nutrients: calcium and phosphorus


Potassium and phosphorus

The plot shows the phosphorus and potassium content of food. Most nuts are rich in these elements.


Bird seed: calories and calcium

For bird seed, what matters is calories and calcium, and the best seeds are sesame and nyger.


Water


Rivers


Aquifers

                               Water (km3)

Nebraska     Ogallala              3608
California   Central Valley        2000
New Jersey   Kirkwood Cohansey       67
Washington   Spokane Valley          38
Illinois     Mahomet                 15

Germany      Upper Rhine         450000
Libya        Nubian Standstone   150000
Australia    Artesian Basin       64900
Brazil       Guarani              40000

The Mississippi river is 531 km3/year.


Climate

Temperature

Earth mean temperature       = 288   Kelvin
Current rate of increase     =   1.7 Kelvin/century
Temperature in 1800          =   -.9 Kelvin compared to present
Temperature in 1000          =   -.5 Kelvin compared to present

Carbon dioxide

Atmosphere CO2 fraction    =  .00041
CO2 fraction in 1700       =  .00027
CO2 fraction last ice age  =  .00018             (1 million years ago)
CO2 fraction increase rate =  .000002 per year
Atmospheric carbon         =880000⋅109 kg       = 121000   tons/person

Greenhouse gases

Gas        Year      Year     Contribution  Radiation  Half life
           1750      2015     to warming     change     (years)
           (ppm)     (ppm)                  (Watts/m2)
H2O                             36-72%
CO2       280       395          9-26%        1.88        60
CH4          .7       1.79       4-9%          .49        12
O3           .237      .337      3-7%          .4           .05
N2O          .270      .325                    .17       114
CCl2F2       0         .000527                 .169      100
CCl3F        0         .000235                 .061       60
CHClF2       0         .00022                  .046       12
"ppm" stands for parts per million.
"Radiation change" is the change in power absorbed by the Earth due to the molecule, with the change tabulated from 1750 to the present.
"Half life" is the half life in the atmosphere. The sun regenerates 12% of the ozone layer each day.
A halocarbon is a molecule composed of carbon and halogens (fluorine, chlorine, bromine, iodine). There are no natural sources of halocarbons and so the pre-industrial level is zero.
Sea level

6 meter rise in sea level

Sea level rise since 1870          =   225 mm
Sea level rise if Greenland melts  =  7200 mm
Sea level rise if Antarctica melts = 61100 mm

Total rate of sea level rise       =  2.8 mm/year     3.3
Greenland melting rate             =   .6 mm/year      .049
Antarctica melting rate            =   .2 mm/year      .026
Glacier melting rate               =   .3 mm/year     1.2
Thermal expansion rate             =   .8 mm/year     1.4

Acceleration of sea level rise     = .013 mm/year/year
Ocean heat gain                    =    5 ZJoules/year

Water:

             Volume     Change
              kkm3      km3/yr

Ocean           1338000      1200
Groundwater       23400
Ground ice          300
Lake                176.4
Mountains            40.6
Atmosphere           12.9
Swamp                11.5
River                 2.12
Biomass               1.12

Ice, Antarctica   21600      -191
Ice, Greenland     2340      -247
Ice, Canada islands  83.5     -60
Ice, Alaska          44.6     -50
Ice, Russia, NE      33.8      -2
Ice, Himalayas       23.7     -26
Ice, Svalbard        13.3      -5
Ice, Andes, South    11.7     -29
Ice, Iceland          8.7     -10
Ice, Canada, West     2.6     -14
Ice, Scandinavia       .8      -2
Ice, Swiss Alps        .3      -2
Ice, New Zealand       .3       0
Ice, Caucuses          .2      -1
Ice, Russian islands          -11
Ice, Andes, North              -4

Ocean heat


World climate summary

Atmosphere temperature rise=   .017 Kelvin/year      (.9 Kelvin since 1800)
Sea level rise             =  2.8   mm/year          (225 mm since 1800)
Atmosphere CO2 frac        =   .0035                 (.0027 in 1800)
Atmosphere carbon          =720     Gtons
Photosynthesis of carbon   =120     Gtons/year
Human carbon emissions     =  9     Gtons/year   = 1240   kg/person/year
Energy produced            =   .57  ZJoules/year =   78.6 GJ/person/year = 2490 Watts/person
Electricity produced       =   .067 ZJoules/year =    9.2 GJ/person/year =  292 Watts/person
Food                       =   .027 ZJoules/year =    3.7 GJ/person/year =  117 Watts/person  =  2500 Cal/person/day
Sunlight energy            =3850    ZJoules/year
Wind energy                =  2.25  ZJoules/year
Photosynthesis of biomass  =  3.00  ZJoules/year
Ocean heat gain            =  7.5   ZJoules/year
World power                = 18     TWatts       = 4500   Watts/person
Energy cost                = 16     T$/year      = 2210   $/person/year   (27.8 $/GJoule)
Population                 =  7.254 billion
Food                       =  1.58  Tkg/year     =  218   kg/person/year  (As carbs)
Earth land area            =148.9   Mkm2         =    2.0 Hectares/person
Rainfall over land         =107000  km3/year     =14800   tons/person/year
River flow                 = 37300  km3/year     = 5140   tons/person/year
Water total use            =  9700  km3/year     = 1390   tons/person/year
Water for agriculture      =  1526  km3/year     =  218   tons/person/year
Water for home use         =   776  km3/year     =  111   tons/person/year
Water desalinated          =    36  km3/year     =    5   tons/person/year
Rainfall increase per year =   .20  mm/year          (Rainfall is increasing with time)
The above table can be used to convert various quantities, such as:
Energy of hydrocarbon food                      17  MJoules/kg
Agricultural water required to produce food   1000  litres/kg       (in the form of carbohydrates)
Electricity cost                               100  $/MWh           =  2.78⋅10-8 $/Joule
Agricultural water required to produce food   1000  litres/kg       (in the form of carbohydrates)
World average                               722000  people per kg3 of water used

The Sun

Sunspot number correlates with solar intensity.

Solar intensity has long-term variations and these impact climate. The sun is presently dimming.

Carbon-14 is a proxy for solar intensity.

Sunspots impact cosmic rays, and cosmic rays have an impact on climate by forming clouds.

Sun intensity average             =  1366.0 Watts/meter2
Sun intensity at sunspot maximum  =  1367.0 Watts/meter2
Sun intensity at sunspot minimum  =  1365.1 Watts/meter2


Volcano cooling

Volcanoes often cause global cooling, and the table shows all major volcanic cooling events.

Region        Volcano     Magma    Index   Year  Temperature change
                          (km3)                       Celcius

Philippines   Pinatubo        25     6     1991     -.2
Alaska        Novarupta       28     6     1912     +.2
Guatemala     Santa Maria     20     6     1902     -.1
Indonesia     Krakatoa        20     6     1883     -.4
Indonesia     Tambora        160     7     1815     -.5   Caused the "Year without a summer"
Iceland       Laki            14     6     1783     -1
Peru          Huenaputina     30     6     1600      ?
Vanuatu                      108     7     1452      ?
New Zealand   Tarawera               5     1315      ?    Famine of 1315-1317
Indonesia     Rinjani         10     7     1258      ?    Caused the Little Ice Age that ended the Viking era
Iceland       Hekla 3          1     5     1159      ?
North Korea   Paektu         110     7      946      ?
Unknown                              7      535     -2
Indonesia     Lake Toba     2800     8   -72000     -1

Energy


Energy/Carbon

For heat energy,

         Energy/Carbon  Energy/mass
           MJoule/kg    MJoules/kg

Natural gas   73           55
Oil           53           46
Coal          38           32

Fertilizer

The chief fertilizer elements are nitrogen, phosphorus, and potassium, and they draw substantial mining energy.

World metal mining is dominated by iron, aluminum, copper, and gold.

World production and reserves for fertilizer elements are:

          World    Fertilizer  Reserves  Carbon  Carbon   Element  Usual form
         Bkg/year   Bkg/year     Bkg     kg/kg   Bkg/year  $/kg

Nitrogen     38      30.0    Infinite     1.09    32.7     5.66    Urea                     CO(NH2)2
Phosphorus   22      11.0         260     1.30    14.3    56       Monoammonium phosphate   NH4H2PO4
Potassium    34      11.0        3240     2.64    29.0    11.8     Potassium chloride       KCl

"Carbon kg/kg" is the carbon emitted to produce 1 kg of element.
"Carbon Bkg/year" is the carbon emitted by the world due to the fertilizer element.
"Element $/kg" is the price of the element per kg.


Primary materials

The plot shows how much energy the world expends per year for primary materials. The materials that consume the most energy are are steel, plastic, hydrogen, wood, and food.

Hydrogen is a primary chemical, and it's produced from methane by steam reforming. 45% of hydrogen becomes ammonia (Haber process) and 80% of ammonia becomes fertilizer.

Methane CH4  →  Hydrogen H2  →  Ammonia NH3  →  Urea CO(NH2)2


Climate engineering


Carbon capture

Adding 1 kg carbon to the atmosphere increases greenhouse heating by 4.1 Watts.

There are 2 classes of geoengineering: Carbon management (usually trees) and greenhouse warming management (usually cloud seeding and aerosols). The above number allows you to compare costs.

A tree captures carbon at a rate of .5 kg/meter2/year, which decreases greenhouse heating by 2.0 Watts/meter2.


Albedo

"Albedo" is reflectivity.

                 Albedo

Water             .07
Forest, conifer   .10
Forest, deciduous .16
Grass             .20
Crop              .20
Snow              .62

The difference in reflected flux between trees and grass was measured to be 8 Watts/meter2 at 40° latitude, where solar flux is 190 Watts/meter2, and this corresponds to an albedo difference of .04. Williams, Gu, & Jiao (2021).

If you replace an arctic conifer tree with snow, the albedo change is ".52". The average solar power at 60° latitude is 110 Watts/meter2, so the change in power is 57 Watts/meter2. This the most extreme case. The realistic change is less, because there isn't always snow on the ground, and because trees are sometimes covered in snow.

Latitude     Power at Earth surface, averaged over the year, in Watts/meter2.

    0          230
   15          250
   30          210
   45          180
   60          110

Forests

2011

The density of a typical forest is:

Wood density           =   11  kg/meter2
Wood energy/mass       =   20  MJoule/kg
Wood energy/meter2     =  220  MJoule/meter2
Wood value/kg          = .036  $/kg
Wood value/meter2      = .4    $/meter2

The growth rate of a typical forest is:

Wood production rate   =  1.0  kg/meter2/year
Energy production rate = 20    MJoule/meter2/year  =  .6 Watts/meter2

Wood is 1/2 carbon and 1% nitrogen.

The fertilizer requirement for nitrogen is:

Wood nitrogen mass fraction     = n       =  .01
Price of nitrogen in fertilizer = p       = 5.7   $/kg
Nitrogen price / kg wood        = P = p n =  .057 $/kg

Trees also need potassium, phosphorus, calcium, magnesium, and sulfur, and their total cost is similar to that of the nitrogen. The total fertilizer cost is double the nitrogen cost.


Tree strategy

Sequoia
Redwood
Douglas Fir
Redwood

Bamboo is a fast-growing tree and it's easily harvested, because it's light on side branches. A new bamboo forest achieves full leaf coverage early, whereas an oak forest takes longer.

The largest trees are sequoias, redwoods, douglas firs, and eucalyptus. Douglas firs can grow in the arctic.

Trees should be planted close to water. For existing trees, fertilizer should go to large trees that are close to water.

If possible, plant trees so that their shadows are cast over water, because trees have a larger albedo than water.

Plant trees that produce nuts, because birds are more likely to get the nuts than insects. Also, the more birds, the fewer insects.

An old forest is carbon-neutral and a young forest captures carbon. Replace old forests with young forests, or harness the deadwood in old forest.


World forests

          World fraction  Forest  Deforestation  Fires
                %          Bkg       Bkg/yr      Bkg/yr

South America   22        96000        400         50
Russia          21        92000          ?        100
Africa          17        73000        240         50
Canada          12.6      55000          0         50
USA              7.9      34800          0         15
S.E. Asia        5.9      26000       -120         10
China            5.3      23300       -170         20
E.U.             4.1      18000        -40          3
Asian Islands    3.6      15800         30         10
Australia + NZ   3.2      14100          ?         20
C. America       2.7      11900         60          5

World            1000    440000        350        250

World forest carbon:

Carbon in atmosphere               = 880  trillion kg
Carbon in plants                   = 550  trillion kg
Carbon in trees                    = 500  trillion kg
Total human-generated carbon       = 300  trillion kg

Forest carbon capture rate         =  45  trillion kg/year
Atmospheric carbon increase rate   =   4  trillion kg/year

World forest area                  =  39  million km2
New forest neeeded to offset carbon=   4  million km2

Deforestation rate                 = .35  trillion kg/year

Total wood carbon harvested        =4.56  trillion kg/year     Wood for power + wood for industry
Wood carbon for biomass power      =1.59  trillion kg/year
Wood carbon for industry           =2.97  trillion kg/year

Using trees to offset atmospheric carbon gain requires 4 Mkm2 of forest, and world forests total 39 Mkm2. Forests capture carbon at a rate of .5 kg/meter2/year.


Forest fires


Dams

Hoover Dam
Grand Coulee Dam
Shasta Dam
Dworshak Dam
Oroville Dam

              Height    Year     Power  Capacity
              meter   completed   MW      MW

Grand Coulee    170     1942    2235    7079
Glen Canyon      93     1966     521    1320
Hoover          221     1936     360    2080
Oahe             75     1963     289     786
Garrison         64     1954     248     583
Shasta          184     1945     214     676

Niagara Adams           1895              37
Buffalo Bill    110     1910
Roosevelt       109     1911
Arrowrock       110     1915
Elephant Butte   92     1916
O'Shaughnessy   130     1923
Gorge            91     1924
Horse Mesa       93     1927              15
Canyon          109     1927              18
Pacoima         111     1929
Diablo          119     1930      76     129
Owyhee          127     1932
San Luis         93     1967             424
Oroville Dam    187     1968     170     819
New Bullards    197     1969     123     340
Dworshak Dam    219     1973     187     400

Solar cells

A typical solar farm costs 5 $/Watt and produces 30 MWatts/km2. The largest solar farms are:

                                       GWatts  km2  MWatts/km2  B$  $/Watt

California   Solar Star                   .58   13    45
California   Topaz                        .55   25    22      2.5   4.5    Thin film CdTe
California   Desert Sunlight              .55   16    34                   Thin film CdTe
China        Longyangxia Dam              .32    9    36
California   Cal. Valley Solar Ranch      .29    8    36      1.6   5.5    Silicon crystal
Arizona      Agua Caliente Solar Project  .29   10    29      1.8   6.2    Thin film CdTe

American solar farms tend to be in California or Arizona where sunlight is abundant and clouds are scarse. We calculate the payback time for a typical 1 meter2 solar cell in Arizona.

Solar cell efficiency         =  e             =  .20               Converting solar to electric energy
Arizona solar intensity, peak =  Ipeak          = 1000 Watts         Noon in mid-summer
Arizona solar intensity, ave. =  Iave           =  250 Watts         Averaged over day and night
Solar cell peak power         =  Ppeak =  e Ipeak=  200 Watts
Solar cell average power      =  Pave  =  e Iave =   50 Watts

Silver is the most reflective metal

The types of solar cells are:

Technology         Efficiency  $/Watt  Market frac   Key element   Element cost ($/kWatt)

Multi junction            .41                        Gallium
Thin film Ga As           .29                        Gallium
Crystalline Si (mono)     .25     .50     .36        Silver        48
Crystalline Si (poly)     .20     .50     .55        Silver       100
Thin film Cu In Ga Se     .20             .02        Indium
Thin film Cd Te           .16             .051       Tellurium      5
Thin film Amorphous Si    .11             .02        -
World record              .44

Inverter

A solar cell system requires an inverter to convert DC to AC power. For a 1 meter2 cell,

Solar cell efficiency               =  e
Peak power                          =  Ppeak =  e Ipeak    =  200 Watts
Cost of inverter per peak Watt      =  Qinv  =  .15 $/Watt
Cost of inverter                    =  Cinv  =  Qinv Ppeak  =  15 $
Cost of solar cell                  =  Ccell               = 100 $
Total system cost                   =  Ctotal              = 200 $
The the inverter costs less than the solar cell.
Wind turbines

A typical wind farm costs 1.5 $/Watt and produces 10 MWatts/km2. The largest wind farms are:

                                    Peak    Avg    km2   B$   $/Watt
                                   GWatts  GWatts

China       Gansu Wind Farm           6.0                   5.2    .9
India       Muppandal Wind Farm       1.5
California  Alta                      1.55    .31    36
India       Jaisalmer Wind Park       1.06
Oregon      Shepherds Flat Wind Farm   .84    .23    78     1.4   1.7
Texas       Roscoe Wind Farm           .78          400
Texas       Horse Hollow Wind Center   .74          190

The larger the turbine, the more efficient it is. Commercial wind turbines include:

               MWatts    M$  Watts/$  Blade diam  Height
                                         (m)       (m)
Bergey XL-1      .001    .004   .25      2.5
Bergey Excel-S   .010    .024   .42      7.0
GE 1.5 MW       1.5     2       .75     60          80
Vesta V164      8      10       .8     164         220

The power generated depends on wind speed cubed. For the Vesta V164,

Air density                 =  D          =  1.22 kg/meter3
Blade radius                =  R          =    82 meter
Wind turbine cross section  =  A  =  πR2  = 21000 meter2
Wind speed                  =  V          =    10 meter/second    (Typical for a good site)
Efficiency factor           =  Q          =   .75                 (Cannot be larger than 1)
Power generated             =  P  = .59 QDAV3 =  11 MWatts

For a typical wind turbine,

Cost per Watt               =    1  $/Watt
Peak power                  =  1.5  MWatts
Total cost                  =  1.5  M$
Height                      =   80  meters
Rotor mass                  =   22  tons
Rotor diameter              =   60  meters
Tower mass                  =   52  tons
Steel in foundation         =   26  tons
Concrete in foundation      =  456  tons
Base diameter               =   15  meters
Blade lift-to-drag ratio    =  120
Rotor cost fraction         =  .20
Generator cost fraction     =  .34
Tower cost fraction         =  .15
Geared generator Neodymium  =  .025 kg/kWatt  =  .62 $/kWatt
Gearless generator Neodymium=  .25  kg/kWatt  = 6.2  $/KWatt
Neodymium total cost        = 9300  $            (Gearless generator, 1.5 MWatts)
Neodymium fraction of magnet=  .31               (By mass)
Neodymium price/kg          =   20  $/kg

Nuclear fission reactors

Fission reactors are used primarily for electricity and heat, and they can also generate valuable elements. Neutron transmutation can turn cheap tungsten into valuable rhenium, osmium, iridium, platinum, and gold. Radioactive waste is abundant in the valuable catalysts rhodium and palladium.

Fission reactors can generate transuranic elements, which are necessary for nuclear rockets and space engineering.

Neutron transmutation moves an element one spot to the right in the periodic table.


Burnt fission fuel

Burnt fission fuel contains the valuable catalyists rhodium and palladium. One kg of uranium costs $100 and produces $13000 of rhodium and $1600 of palladium. The elements produced by the fission of one kg of U-238 are:

               Mass   Value of   Value of element  Half life
                      element     in burnt fuel
               gram     $/kg          $/kg           year

Rhodium-103     26.1   500000      13000            Stable
Palladium-106   22.4    72000       1600            Stable
Xenon           44.6     1800         80            Stable       A mix of Xenon-131 and Xenon-132
Technetium-99   51.4        ?          ?            211000
Strontium-90    11.8        ?          ?                28.8

Technetium is important because there are no stable isotopes and it doesn't occur in nature. Strontium-90 is important because it can be used as a radioisotope battery. Technetium-99 and Strontium-90 don't have well-established market prices because they only come from fission reactors. Xenon is easy to extract because it's a noble gas.

The numbers are for fission by fast neutrons. Fission by slow neutrons produces similar numbers.


Antarctic wind power
Cape Denison, Antarctica
Katabatic wind
Douglas Mawson collecting ice in a 45 m/s wind

The windiest place on the planet is Cape Denison, Antarctica, with a year-round average wind speed of 25 m/s. Wind turbine power scales as windspeed cubed.

Katabatic winds continuously blow from the Antarctic center to the coast, gaining energy as they flow downward. The wind at Cape Denison always blows in the same direction, simplifying construction.

A 10 km array of wind turbines at Cape Denison can generate 5 GWatts.

Wind turbine height  =  H  =  100 meters
Coastline length     =  L  =   10 km
Wind speed           =  V  =   25 meters/second
Efficiency           =  f  =  1/4
Air density          =  D  =  1.22 km/meter3
Power                =  P  =  f D H L V3  =  4.8 GWatts

The power can be used to produce metals. Ore is brought to Antarctica and extracted with electricity. Suitable candidates include titanium, magnesium, and aluminum.


Biochar

Cellulose
Lignin

Wood consists of a mix of cellulose and lignin, with a typical mass composition of

Carbon       .44
Oxygen       .44
Hydrogen     .06
Nitrogen     .01
Potassium    .01
In the process of "pyrolysis", biomass is heated in a zero oxygen environent, producing carbon (biochar). Energy is extracted from the biomass without producing CO2. When biochar is added to soil it improves the water retention and nutrient content.

One can control the amount of carbon sequestered by varying the pyrolysis temperature.


                                 Celsius    Char     Energy yield
                                          fraction      (MJ/kg)

Bamboo cold pyrolysis (no oxygen)   400      .4           4
Bamboo hot pyrolysis  (no oxygen)   700      .2          10
Bamboo (burn in O2)               >2000      .02         18

Land vs. ocean

              Gain       Loss
              km2        km2

World         25000     53375
China         13500
Netherlands    7000
South Korea    1550
USA            1000
Japan           500      2190
Ecuador                 28500
Vietnam                 14700
Sweden                   3290
Iraq                     3070
Bulgaria                 2030

Cooling the Earth with aerosols and cloud seeding

Clouds can be formed with sulfuric acid cloud seeding. Sulfur can be put into the atmosphere in the form of H2SO4, H2S, or SO2. Sulfur lasts 4 years in the atmosphere and has to be replenished. Power from the jet stream can be used to launch sulfur.


Ocean iron fertilizer

Antarctica, Ross Ice Shelf

Fertilizing the ocean with iron causes large-scale biomass growth, and when it dies it takes the carbon to the bottom of the ocean.

In the ocean the microbe nutrient requirement is:

Element     Relative mass

Carbon        1
Nitrogen       .18
Phosphorus     .024
Iron           .000044

Iron is insoluble in the ocean and is usually the limiting nutrient. Between nitrogen and phosphorus, nitrogen is usually the limiting nutrient. A small amount of iron fertilizer can capture a large amount of carbon.

Diatoms are microbes with silicon walls as opposed to conventional lipid membranes. If silicon is present then silicon microbes outcompete lipid microbes because silicon walls cost 8% as much energy to make as lipid membranes.

Diatoms are good carbon fixers because when they die they sink to the bottom of the ocean, and the carbon stays there.

The best place to fertilize the ocean with iron is the Antarctic Atlantic, where iron is scarce and silicon, nitrogen, and phosphorus are abundant. This is also the region where the ocean currents flow downward.

Ocean concentrations of phosphorus, nitrogen, and silicon:


Iceberg freshwater

Iceberg B15

Antarctic icebergs can be moved to places in the tropics where sun is abundant but water is scarce. The energy required to move the iceberg costs far less than the value of the freshwater delivered.

Ocean currents can help save energy. The South Indian Current brings icebergs to Australia, The South Pacific current brings icebergs to Chile, and the South Atlantic current brings icebergs to Africa.

We calculate the energy required to move an iceberg for a typical iceberg.

Energy required to move an iceberg  =  Constant  *  Distance moved  *  Velocity2

Iceberg height           =  Z               =    .5 km
Iceberg sice length      =  X               =    10 km
Density of ice           =  d               =   917 kg/m3
Density of seawater      =  D               =  1025 kg/m3
Iceberg mass             =  M  = d X2 Z     =    46 trillion kg

Iceberg distance traveled=  L               =  1000 km     (Assume ocean currents help)
Iceberg travel time      =  T               =     1 year
Iceberg speed            =  V  =  L/T       =   .03 m/s

Drag force               =  F = ½ D X Z V2  =   2.3 million Newtons
Drag energy              =  E  =  F L       =  2300 GJoules
Drag power               =  P  =  F V       =    69 kWatts
Energy cost              =  e               =    36 MJoules/$
Freshwater value per kg  =  z               = .0001 $/kg
Iceberg freshwater value =  Z  =  M z       =     5 billion $

The iceberg should move as slow as possible but it should move fast enough to reach its destination before melting. We assume a travel time of 1 year, and this determines the velocity. Presumably, measures can be taken to slow melting such as covering the iceberg with a white tarp.


Hydroponics

Hydroponics is the technique of growing plants in water rather than soil, where the water is fertilized with nutrients. Hydroponics can yield 100 times as much food as soil-based agriculture, and a person can be sustained with only 200 square meters of hydroponics.

Hydroponics is easy. One can buy a system that takes care of everything and one need only supply the system with water and fertilizer. One can further improve yield with greenhouses, lighting, and mirrors.


Hydroponic system

Grow kit
Nutrient solution
Mirror foil
LED light
Sturdy greenhouse
Unsturdy greenhouse

A "grow kit" takes care of supplying the plants with water. One need only supply the kit with water and fertilizer. Fertilizer comes in powder form and dissolves in the water. Kits cost $2 per plant site.

Putting a greenhouse around the kit amplifies the yield by allowing one to control temperature and humidity. A greenhouse also allows plants to be grown during the winter.

Mirrors can amplify the sunlight reaching the planet, and mirror film is cheap.

Lights can improve the growth rate and make it possible to grow plants 24 hours.


Nutrient solution

1 kg of nutrient powder is mixed with ton of water. The composition of a typical nutrient solution is

        Parts per million

Potassium       160
Nitrogen        150
Calcium         100
Phosphorus       40
Sulfur           40
Magnesium        30
Iron              2
Manganese          .5
Zinc               .3
Boron              .2
Copper             .1
Molybdenum         .075
Source
Hydroponic yield vs. field yield

Hydroponics offers gains over field agriculture in many categories. The following table shows the amplification for each category in terms of hydroponic yield over field yield. The total amplification is the product of the amplification from each category.

                  Amplification factor

Plant density               8          In terms of plants/meter2
Crops per year              4
Crop variety                2
Temperature contro l        2
LED lighting                2
Carbon dioxide enhancement  1.5

Habitat

Bird populations can be increased with plants that produce nuts or berries.


Nut trees

Hickory
Walnut
Oak
Almond

Cashew
Pistachio
Hazel


Nut plants

Sesame
Poppy
Flax
Chia

Lotus
Sunflower
Safflower


Berries

Blackberry
Blueberry
Raspberry
Strawberry
Apple

Juniper
Mulberry
Cranberry
Holly
Cedar

Winterberry
Dogwood
Elderberry
Firethorn
Burning bush

Serviceberry
Sumac
Pokeweed
Chokeberry


Lunar ice

Ice at the moon's south pole (left) and north pole (right)

Climate engineering can be done from space, but it requires lunar ice. Lunar ice can be used for rocket fuel, life support, and radiation shielding. The moon's low gravity makes it easy to launch ice into space. Lunar ice is converted into hydrogen + oxygen rocket fuel, moved to low-Earth-orbit, and used to help rockets go from there to other destinations.

The moon has metal asteroid craters.


Asteroid mining

In a metal asteroid, the most valuable metals are osmium, rhodium, nickel, platinum, and palladium.

A cubic metal asteroid 100 meters in size has a mass of 1 billion kg, and the value of the metals is:

         Concentration   Value    Value in asteroid
             ppm         $/kg         Billion $

Osmium         7.6     1600000      12
Rhodium        4.1      500000       2.0
Nickel     67000            16       1.1
Platinum      19         35000        .7
Palladium      3.8       72000        .3
Cobalt      6300            33        .2
Iron      910000              .15     .1

Space mirror

Jet Propulsion Laboratory designed a space mirror with the goal of minimizing the mass per area. It consists of mylar coated with aluminum.

Mirror surface density =     6  grams/meter2
Mirror thickness       = .0043  mm       (Mylar coated with aluminum)
Mylar density          =  1.39  g/cm3
Aluminum density       =  2.70  g/cm3

Space mirror

A space mirror can cool the Earth. Greenhouse gases generated by humans have increased the sun's effective brightness by 1.5 Watts/meter2. The size of a mirror required to cancel this is 560000 km2, which costs 3.4 trillion dollars to launch.

Greenhouse gas forcing preindustrial          =   1.5 Watts/meter2
Greenhouse gas forcing now                    =   3.0 Watts/meter2
Solar forcing change                = I       =   1.5 Watts/meter2
Solar forcing increase rate                   =  .031 Watts/meter2/year
Earth surface area                  = A       =   510 Million km2
Solar power change                  = P = IA  =   765 TWatts
Solar intensity                     = I       =  1361 Watts/meter2
Mirror area                         = A = P/I =560000 km2   =   (750 km)2
Mirror mass/area                    = D       =  .006 kg/meter2
Mirror mass                         = M = DA  =   3.4 billion kg
Launch cost per kg                            =  1000 $/kg
Mirror launch cost                            =   3.4 trillion $

Appendix

Wild city animals

Cities often encourage wild cats to stay wild, and many have a "catch, sterilize, and release" program. Many also do censuses of cat colonies and have a network of colony caretakers.

The plague has closed down most of New York City's animal shelters.

New York City has the same number of wild cats as house cats.

Pet dogs in homes  300000
Pet cats in homes  600000
Wild cats          400000
Given to shelters   20000 per year
Adoptions           14000 per year
Euthanized           4000 per year
NYC area              784 km2
NYC humans        8300000
Wild cats/area          5 cats/hectare

Rats

Wild cats kill on average .12 rats/day. The calorie intake is:

Cat mass             = 4.5   kg
Rat mass             =  .265 kg
Cat food requirement = 218   Calories/day
Rat kills/day        =   .12 Rats/day
Calories in a rat    = 800   Calories
Calories from rats   =  96   Calories/day

Ocean nutrients

Mass fraction of elements in parts per million. For the ocean, "oxygen" means dissolved gaseous oxygen.


          Human   Wood   Cane   Ocean   Ocean    Ocean   Deep     Deep     Soil   Soil    River  Ocean     Ocean
                         plant  (avg)  surface  surface  Pacific  Atlantic       (avail)        halflife   molecule
                         (dry)          polar   equator                                          (Myr)
Oxygen    650000 420000           10                        5       8                                      O2      Dissolved oxygen
Carbon    180000 400000 400000    28                                                      58      .11      HCO3-   Bicarbonate
Hydrogen  100000  60000                   .0072    .0072                                                   H+      Acid pH=8.14
Nitrogen   30000  20000  31000      .5    .50      .05       .56     .28                    .23            NO3-    Nitrate
Calcium    14000   2000          410                                        10000  10000  15      1.0      Ca++
Phosphorus 11000  13000  11500      .07   .005     .0005     .009    .003    1000     10    .02            HPO4--  Phosphate
Potassium   2500  44000  33700   390                                         1500      3   2.3   12        K+
Sulfur      2500   1000    900   910                                           40          8     11        SO4--   Sulfate
Sodium      1500               10800                                                       6.3   68        Na+
Chlorine    1500               19400                                                       8    100        Cl-     Chloride
Magnesium    500   1300         1290                                                       4.1   13        Mg++
Iron          60    165     75      .0034  .000006 .00002    .00028  .00034                 .7     .0002
Fluorine      37                   1.3                                                                     F-      Fluoride
Zinc          32                    .0049                    .0007   .00013
Silicon       20                   2.2   1.69      .140     4.2     1.4                    1.3     .02     H4SiO4  Orthosilicic acid
Bromine        2.9                67                                                                       Br-
Strontium      4.6                 8.1
Strontium                          8                                                                       Sr++
Rubidium       4.6                  .12
Nickel                              .0066
Vanadium                            .0019
Titanium                            .001
Aluminum                            .001                                                           .0006
Copper         1     190    13      .0009
Cobalt                              .0004
Manganese                           .0004                                                          .0013
Chromium                            .0002
Lead           1.7                  .00003
Boron                  3     2     4.4                                                                     BO3---  Borate
Lithium                             .17

The deep ocean is richer in nutrients than the surface.

For polar oceans, iron is the limiting nutrient for bacteria.
For equatoral oceans, nitrogen is the limiting nutrient.

The "Redfield ratio" for ocean carbon fixation by algae and diatoms is

(Carbon, Nitrogen, Phosphorus, Iron)  =  (106:16:1:.001)
For the ocean, all elements with a mass fraction larger than 1e-6 are included.

The Pacific and Indian oceans both have upward flows in the global thermohaline flow and are hence richer in nutrients than the Atlantic ocean. In the Atlantic ocean water sinks at both poles.

The Indian ocean has a similar composition as the Atlantic ocean.

Atmospheric CO2 dissolves in the ocean and seizes an OH- ion to become bicarbonate (HCO3-).

Silicic acid is produced non-biologically by the dissolving of quartz.

The halflife of water in the ocean is 4100 years.


Supercomputers
Expanded article

Supercomputers are critical to climate modeling.

The farther ahead we can predict weather, the greater the economic payoff.

Supercomputing is driven by speed/$ and mobile computing is driven by speed/power.

Speed per dollar        =    2  GFlop/$      (CPU)
Speed per dollar        =   40  GFlop/$      (GPU)
Memory, RAM             =   .2  GByte/$
Memory, solid state     =    7  GByte/$
Memory, disk            =   33  GByte/$
Speed per power         =  200  GFlop/Watt   (GPU)

Battery energy per mass = 1000  MJoule/kg
Battery power  per mass = 1000  Watt/kg

Fertilizer

Fertilizer molecules

We list the full set of fertilizer molecules.

Element     Molecule     Common name          Element  Fertilizer  Element   Solubility   Human
                                               cost       cost     fraction               edible
                                                g/$       g/$        ppt      g/Litre

Calcium     CaCl2        Calcium chloride        182       504       361        745         *
Calcium     Ca(NO3)2     Calcium nitrate          35       142       244       1212
Calcium     Ca(H2PO4)2   Monocalcium phosphate                       171         20         *
Calcium     CaHPO4       Dicalcium phosphate                         295           .2       *
Calcium     Ca3(PO4)2    Tricalcium phosphate                        388           .02      *
Calcium     Ca(C2H3O2)2  Calcium acetate                             253        347         *
Calcium     CaC6H10O6    Calcium lactate                             184         58         *
Calcium     Ca3(C6H5O7)2 Calcium citrate                             241           .85      *
Calcium     CaCO3        Calcium carbonate                           400           .013     *
Calcium     CaC12H22O14  Calcium gluconate                            93        low         *

Potassium   KCl          Potassium chloride      340       649       524        254         *
Potassium   K2SO4        Potassium sulfate       136       303       449
Potassium   KH2PO4       Monopotassium phosphate  44       153       287        226         *
Potassium   K2HPO4       Dipotassium phosphate              13                 1492         *
Potassium   K3PO4        Tripotassium phosphate                                 900         *
Potassium   KNO3         Potassium nitrate                 126       387

Phosphorus  (NH4)H2PO4   Monoammonium phosphate  185       689       269        360
Phosphorus  (NH4)2HPO4   Diammonium phosphate     38       161       235        600
Phosphorus  KH2PO4       Monopotassium phosphate  35       153       228        226         *
Phosphorus  Mg(H2PO4)2   Monomagnesium phosphate                                            *
Phosphorus  MgHPO4       Dimagnesium phosphate                                              *
Phosphorus  Mg3(PO4)2    Trimagnesium phosphate                                             *

Magnesium   MgCl2        Magnesium chloride       55       217       255                    *
Magnesium   MgSO4(H2O)7  Magnesium sulfate        33       336        99
Magnesium   Mg(H2PO4)2   Monomagnesium phosphate                                            *
Magnesium   MgHPO4       Dimagnesium phosphate                                              *
Magnesium   Mg3(PO4)2    Trimagnesium phosphate                                             *
magnesium   Mg(NO3)2     Magnesium nitrate                           164        710
Magnesium   MgS          Magnesium sulfide                                      351

Nitrogen    CO(NH2)2     Urea                    482      1032       467       1079
Nitrogen    (NH4)H2PO4   Monoammonium phosphate   84       689       122        360
Nitrogen    (NH4)2HPO4   Diammonium phosphate     34       161       212        600
Nitrogen    (NH4)2SO4    Ammonium sulfate         69       324       212        744
Nitrogen    (NH4)NO3     Ammonium nitrate                            350        150
Nitrogen    KNO3         Potassium nitrate                           139
Nitrogen    Mg(NO3)2     Magnesium nitrate                           189        710

Sulfur      (NH4)2SO4    Ammonium sulfate         79       324       243
Sulfur      K2SO4        Potassium sulfate        56       303       184
Sulfur      MgSO4(H2O)7  Magnesium sulfate        44       336       130

Fertilizer cost

                 Chloride   Phosphate   Sulfate   Nitrate
                    Cl         PO4        SO4      NO3
                   g/$         g/$        g/$      g/$

Potassium   K       649        153        303*     126
Calcium     Ca      504*         -        114      142*        Calcium sulfate = Gypsum
Magnesium   Mg      217          -        336*     113*
Nitrogoen   NH3     283        698        163*       -         Ammonium nitrate is an explosive

For example, 1 dollar buys 649 grams of potassium chloride.

Urea = CO(NH2)2 = 1032 gram/$.