Table of Contents

APPENDIX C

AGRICULTURE

The agricultural system is derived from standard nutritional requirements for adult men and women and for children. The space colony population is used to normalize these requirements to that of a "typical" person weighing 60 kg as shown in table 5-16.

TABLE 5-16 (gif format)

TABLE 5-16.- HUMAN NUTRITIONAL REQUIREMENTS

Daily requirement per
person (ref. 1)
Body weight
kg
Colony
population
CaloriesProtein, g
Adult men 70 4853 2900 70*
Adult women 58 4633 2100 58*
Children** 32 864 2150 54
Weighted
average
61 - 2479 63.3

*Colony workers may require higher protein intake due to
strenuous workloads.
**Assumes a normal age and sex distribution of children under
18 years old.

These requirements are met by an average daily diet which is shown in table 5-17 (a) which also includes the caloric and nutritional values calculated for this diet. The nutritional requirements are met and an excess of protein is provided by a substantial margin.

TABLE 5-17 (a) (gif format)

TABLE 5-17.- (a) AVERAGE DAILY SPACE COLONY DIET (g/PERSON)

Source Amt,
g
Calories,
kcal
Carbo-
hydrates,
g
Fats,
g
Protein,
g
(Meat) Trout
Rabbit
Beef
Chicken
40
40
40
40
78
64
142
49
0
0
0
0
4.6
3.2
12.8
1.3
8.6
8.4
6.3
8.8
(Produce) Eggs
Milk
24
500
39
330
0.2
24.5
2.8
19.0
3.1
17.5
(Dry plant produce) Wheat
Rice
Sugar
180
100
100
608
363
385
130.1
80.4
99.5
3.6
.4
0
24.3
6.7
0
(Vegetables and Fruit) Carrots
Lettuce
Peas
Apple
Potato
Tomato
Orange
100
100
100
100
100
100
100
42
14
126
56
76
22
51
9.7
2.5
21.6
14.1
17.1
4.7
12.7
0.2
.2
.6
.6
.1
.2
.1
1.1
1.2
9.5
.2
2.1
1.1
1.3
Totals 1814 2445 417.1 49.7 100.2

Note: Calculated from reference 2.


Vitamins and trace minerals are also available in excess quantities as shown in table 5-17 (b).

TABLE 5-17 (b) (gif format)

TABLE 5-17.- (b) VITAMIN AND MINERAL COMPOSITION OF AVERAGE DIET

Nutrient Space Colony
average diet*
Recommended
daily
allowances**
Vitamin A (iu) 14,399 4915
Vitamin C (mg) 144 56
Niacin (mg equiv) 33 15
Riboflavin (mg) 2.1 1.6
Thiamin (mg) 2.2 1.2
Calcium (g) 0.88 0.82
Phosphorus (g) 1.57 0.82
Iron (mg) 17.0 13.6
Potassium (mg) 3,549 Not listed
Sodium (mg) 1,680 Not listed
Linoleic acid (g) 1 Not listed
Cholesterol (mg) 319 Not listed

*Average diet evaluated in cooked form. Source: Watt, B.K., and Merrill, A. L. Composition of Food. Agricultural Handbook, No. 8, Washington, D.C. Revised 1963.
**Each value is weighted to reflect the population composition of 8 percent children (weighing 28 kg), 47 percent adult males (70 kg), and 45 percent adult females (58 kg). Source: Recommended Dietary Allowances, 7th edition, National Academy of Sciences, 1968.


A more careful analysis of the colony's protein requirement could provide savings in meat requirements and, in turn, provide substantial savings in the required land area for plants.

The diet is treated as a daily average of all components as if each colonist ate a small portion of each foodstuff each day. In reality, of course, the colonists would eat a varied selection that over time averages to this diet. The individual components of the diet are chosen to provide adequate variety for both-nutritional and psychological purposes. These components are meant to be representative of classes of foods and not specifically limited to these items. For example, pork could be considered as a feasible diet component with feed and area requirements intermediate between beef and rabbits. In addition, it should be explicitly stated that this diet represents typical American preferences and does not recognize ethnic or religious dietary preferences. It is reasonable to expect, however, that such preferences could be adopted if desired.

The meat in this diet dictates the requirement for a stable herd of animals for which the rates of birth and slaughter are equal. In effect, each colonist has 26 fish, 6.2 chickens, 2.8 rabbits and about 1/7 of a cow (see table 5-5). The plant diet for these animals plus that for humans then forms a total requirement for all plants as given in table 5-18.

TABLE 5-18 (gif format)

TABLE 5-18.- TOTAL PLANT REQUIREMENTS, g/PERSON/DAY

Sorghum* Soybean* Wheat* Rice* Fruits and
vegetables
Corn* Other Totals
Man - - 225 125 - 937 125a 1412
Cattle
Chickens
Rabbits
Fish
217
-
100
-
100
170
100
100
-
-
-
-
-
-
-
-
-
30
20
-
-
-
-
-
633 b
37 c
-
81 d
Totals 317 470 225 125 50 937 758 2882

Notes:
*Dried grain.
a Man also utilizes 125 g/person/day of sugar extracted from sorghum.
b Cattle also utilize 633 g/person/day roughage from sorghum and soybean.
c Chickens also utilize 37 g/person/day fish meal.
d Fish also utilize 81 g/person/day animal meal from meat processing byproducts.
(c and d are not included in totals)


Food processing byproducts and silage are extensively used in satisfying the animal diet. Implicit in this derivation is allowance for yields in meat dressing and food processing, for moisture and silage content of the grains, and for the metabolic requirements of the various animals. These factors are given in table 5-19, parts A-J, along with the carbon, nitrogen, hydrogen, and oxygen elemental balance for each step in the food chain (refer to fig. 5-16).

TABLES 5-19 A-J listed in gif format

TABLE 5-19.- FACTORS OF METABOLIC REQUIREMENTS

A. diet requirements for man (from table 5-17 (a)), g/day
Total C H O N
(Meat) Trout
Rabbit
Beef
Chicken
40
40
40
40
7.6
6.4
12.8
5.3
4.2
4.2
4.4
4.2
27.0
28.2
21.9
29.3
1.2
1.2
.9
1.2
160 32.1 17.0 106.4 4.5
(Produce) Egg
Milk
24
5000
3.7
32.5
2.6
54.0
17.3
411.0
.4
2.5
524 36.2 56.6 428.3 2.9
(Dry plant products) Wheat
Rice
Sugar
180
100
100
67.5
35.8
40.0
13.9
7.6
7.0
95.2
55.7
53.0
3.4
.9
-
380 143.3 28.5 203.9 4.3
(Vegetables, fruit) Carrot
Lettuce
Pea
Apple
Potato
Tomato
Orange
100
100
150
100
100
100
100
4.6
1.7
13.6
6.2
8.0
2.5
5.8
10.6
10.9
15.3
10.4
10.2
10.8
10.5
84.6
87.2
119.7
83.3
81.4
86.5
83.5
.2
.2
1.4
.1
.3
.3
.2
750 42.4 78.7 626.2 2.7
(Total food intake) above
H2O
1814
750
254
-
181
83
1365
667
14
-
2564 254 264 2032 14

C/H/O/N ratios for food calculated from data of reference 2.


TABLE 5-19.- B

Mass balance on one person
Total C H O N
(In) Food
O2
H2O
2564
686
400
254
-
-
264
-
44
2032
686
356
14
-
-
(Out) CO2
H2O
Wastes
857
857
1936
231
-
23
-
94
214
626
763
1685
-
-
14


TABLE 5-19.- C

Mass balance on food processing
Total C H O N
(In) Meat and produce
Plant
H2O
724
1412
750
84
233
-
77
134
83
556
1037
667
7
8
-
(Out) Food
Kitchen waste
2564
322
254
63
264
30
2032
228
14
1

Based on: 20% of meat and plant materials are lost to waste.


TABLE 5-19.- D

Mass balance on animal harvesting
Total C H O N
(In) Meat and produce 1168 138 126 890 14
(Out) To nonhuman
To food processing
444
724
54
84
49
77
334
556
7
7

Based on: 33% of milk to nonhuman food processing. Efficiencies of meat harvest (dressed/animal)
fish = 35%
steers = 55%
rabbits = 65%
chickens = 60%


TABLE 5-19.- E

Mass balance on nonhuman food processing
Total C H O N
(In) Fish
Beef
Chicken
Rabbit
Milk
93
41
33
27
250
18
13
4
3
16
10
5
4
3
27
62
22
24
20
206
3
1
1
1
1
(Out) Meal
H2O
118
326
54
-
13
36
44
290
7
-

Based on: Animal meal has 15% moisture.


TABLE 5-19.- F

Mass balance on animals
Total C H O N
(In) H2O
Nonhuman veg
Meal
O2
3853
1470
118
747
-
575
54
-
424
121
13
-
3429
736
44
747
-
38
7
-
(Out) H2O
CO2
Meat, milk,eggs
waste
1494
939
1168
2587
-
254
138
237
164
-
126
268
1330
685
890
2051
-
-
14
31


TABLE 5-19.- F.1.

Animal food requirements
Beef steer: 1 steer for 11 persons
Harvested at 400kg after 16 months
Metabolic requirements for 1/11 250 kg steer
300 g sorghum mix/day
200 g soybean mix/day
Roasting chicken: 5.6 chickens/person
Harvested at 2.6 kg after 25 weeks
Metabolic requirements for 5.6 chickens at 1.1 kg each
37 g fish meal/day
150 g soybean/day
Rabbits
Harvested at 3.4 kg after 125 days
Metabolic requirements for 2.8 rabbits at 1.8 kg each
100 g sorghum/day
100 g soybean/day
20 g corn/day
Dairy cattle
400 kg cow produces 12.45 kg milk/day
Metabolic requirements for 1/16.6 cow at 400 kg
350 g sorghum mix/day
100 g soybean mix/day
Laying hens
1.5 kg hen lays 5 eggs/week, 54 g/egg
Metabolic requirements for 6/10 hen at 1.5 kg
20 g soybean/day
30 g corn/day
Fish
Harvested at 2 kg in 1 yr
Metabolic requirements for 26 fish at 1 kg each
100 g soybean/day
81 g animal meal/day

Summary

Plant Matter Total C H O N
Beef steer
Roasting chicken
Rabbits
Dairy cow
Laying hen
Fish
500
150
220
450
50
100
187
67
89
167
20
45
40
13
19
36
4
9
263
62
105
240
25
41
10
8
7
7
1
5
Total 1470 575 121 736 38
(Animal meal) Roasting chicken
Fish
37
81
17
37
4
9
13
31
3
4
Total 118 54 13 44 7


TABLE 5-19.- F.2.

Animal metabolic requirements, g/day [Based on animal biomass of F.1. above.]
InOut
AnimalO2H2O CO2H2OMeat
produce
Waste
Beef steer 180 910 230 450 91 819
Roasting chicken 168 616 210 146 83 532
Rabbit 88 302 110 189 77 235
Dairy cow 220 1840 275 690 750 795
Laying hen 23 85 29 19 24 86
Fish 68 100 85 - 143 121
Total 747 3853 939 1494 1168 2588

Data based on the following: Food requirements (ref. 22). For caloric and nitrogen
requirements - diets calculated
Metabolism (ref. 22) CO2 calculated by O2/0.8
Chicken egg production (ref. 23). Fish Food and metabolism; personal communication, Chris Brittleson, Wisconsin Dept. of Natural Resources, Nevin Fish Hatchery, Madison, Wisconsin


TABLE 5-19.- G

Mass balance on non-human food processing
Total C H O N
(In)Sorghum
Sorghum roughage
Soybean
Soybean hay
Corn
1406
1829
2103
883
220
119
152
211
75
18
144
188
222
91
23
1138
1485
1646
713
178
5
4
24
4
1
Total 6441 575 668 5160 38
(Out) to animals
Water
1470
4971
575
-
121
547
736
4424
38
-

Based on:
Sorghum roughage 14.5% moisture after drying
Soybean hay 10.8% moisture after drying
Two times dry roughage or hay as seed.


TABLE 5-19.- H

Mass balance on plant harvest
Total C H O N
(In) From fields 16,273 1,347 1682 13,172 72
(Out) To food processing
To nonhuman food
H2O
Waste
1,412
6,441
1,205
7,215
233
575

539
134
668
133
747
1,037
5,160
1,072
5,903
8
38

26


TABLE 5-19.- H.1

Plants from field
Material Total C H O N
Sorghum
Soybean
Corn
Wheat
Rice
Fruits and vegetables
4080
4620
1034
3018
1647
1874
341
425
86
254
135
106
419
481
107
309
168
198
3309
3678
838
2442
1341
1564
11
36
3
13
3
6
Total 16,273 1,347 1,682 13,172 72


TABLE 5-19.- H.2

To food processing
Material Total C H O N
Wheat
Rice
Vegetables
Sugar
225
125
937
125
85
45
53
50
17
9
99
9
119
70
782
66
4
1
3
Total 1412 233 134 1037 8


TABLE 5-19.- H.3

Drying Human food - wheat materials balance
Material Total C H O N
(In) From field 3018 254 309 2442 13
(Out) To food processing
H2O
Waste
225
781
2012
85

169
17
86
206
119
695
1628
4

9

Based on:
1/3 dry weight is grain, Harvested at 80% moisture.


TABLE 5-19.- H.4

Drying Human food - rice materials balance
Material Total C H O N
(In) From field 1647 135 168 1341 3
(Out)To food processing
H2O
Waste
125
424
1098
45
-
90
9
47
112
70
377
894
1
-
2

Based on:
1/3 dry weight is grain, Harvested at 80% moisture.


TABLE 5-19.- H.5

Harvest waste
Material Total C H O N
Fruit and vegetable
Sorghum roughage
Soybean roughage
Corn roughage
Wheat roughage
Rice roughage
937
845
1634
814
2012
1098
53
70
139
68
169
90
99
87
168
84
206
112
782
686
1319
660
1628
894
3
2
8
2
9
2
Total 7340 589 756 5969 26
Less extracted
from sorghum
125 50 9 66 -
Harvest waste 7215 539 747 5903 26

Based on: Soybean and grain roughage 80% moisture.
Fruit and vegetable waste 50% of harvest and same composition. Corn is 1/5 of dry corn plant.


TABLE 5-19.- I

Mass balance on plants
Total C H O N
(In)Irrigation water
Recycle water
Nutrients
CO2
168,750
61,250
93
235,082
-
-
-
1347
18,563
6,737
21
-
150,187
54,513
-
3,642


72
-
(Out) Plants
Irrigation return
Evapotranspiration
O2
16,273
50,000
164,900
3,909
1,347
-
-
-
1,682
5,500
18,139
-
13,172
44,500
146,761
3,909
72
-
-
-

Based on: 30.5 cm water on 45 m^2 in 60-day season, 50,000 g irrigation return.


TABLE 5-19.- J

Mass balance waste processing
Total C H O N
(In) Wastes
O2
62,060
2,476
862
-
6759
-
54,367
2,476
72
-
(Out) CO2
NH4
H2O
3,193
93
61,250
862
-
-
-
21
6738
2,331
-
54,512
-
72
-


Sorghum is chosen as a principal component of the animal diet because it can be produced in excellent yield and because it provides a source of protein (11 percent) while also providing silage and sugar. Protein make-up for the animal diet is provided from soybean (34 percent) and from meat processing byproducts.

From the quantitative requirements for each plant component, total plant growing area requirements can be obtained based upon estimates of crop yields as presented in table 5-4.

The success of the colony's agricultural systems rests entirely upon the photosynthetic productivity. Crops were estimated assuming a yield double that of the world record for that crop, as shown in table 5-20.

TABLE 5-20 (gif format)

TABLE 5-20.- CROP YIELDS

Terrestrial Yields Colony yields
Crop Record yield Reference g/m^2/seasonSeason, day g/m^2/seasonSeason, dayg/m^2/day
Wheat
Rice
Soybean
Corn
Sorghum
14 tons/ha
266 bu/ha
9000 kg/ha
26500 kg/ha
675 bu/acre
24
25
26
25
25
1400
1596
900
2650
3780
100
100
100
100
100
2800
3192
1800
5300
7560
90
90
90
90
90
31
35
20
58
83
Tomatoes
Lettuce
67 tons/ha
24 tons/ha
5
5
6700
2400
~70
~70
70 as veg. 132

Unit weights:
Rice 60lb/bu
Sorghum 56lb/bu
Soybean 60 lb/bu
Corn 56 lb/bu

Conversion factors
1 ha = 100 X 100 = 10^4 m^2

1 bu = 35.24 liters
1 ton = .0906 tonnes (t)


In addition, a factor of 1.1 improvement is obtained by shortening the growing season from 100 to 90 days. The record yield data come from harvests under good but not ideal or controlled growing conditions. Comparison of typical terrestrial and space colony growing conditions is presented in table 5-21.

TABLE 5-21 (gif format)

TABLE 5-21.- PHOTOSYNTHETIC PRODUCTIVITY ENHANCEMENT

Factor Terrestrial Space Colony
Light intensity Reduced by atmosphere and clouds Greater by 7.5
Photo period ~12 hr Can be 24 hr
pCO2 17 Pa (0.13 mm Hg) 400 Pa (3 mm Hg) greater
in growing area
Water Sometimes dependent on rainfall Irrigated regularly
Temperature No control Optimized for species
Season 1 per year in many areas 4 per year
Crop damage
from weather
Hail, rain, wind None
from pests and insects 5-15 percent loss of crop None*
from weeds 2.5 to 5 percent loss of crop None*
from disease 10 to 60 percent loss of yield None*

*Controlled by quarantine.


Including the shortened season, the net improvement is a factor of 2.2 which is further enhanced by harvesting 4 crops per year. Thus the farmer in a typical American Midwestern farm who produces 100 bushels of corn per acre in a single season year would look with astonishment on the space colony farmer who produces 4164 bushels of corn from a single acre in his 4-season year. While this factor of 40 is substantial, it is believed to be credible since a portion of it is derived from year-round growing. Substantiation of crop yields is required and can be obtained through careful study under controlled conditions (and most of the research could be performed on Earth). The improvement that has already been achieved for certain vegetables in Abu Dhabi (ref. 5) is shown in table 5-22.

TABLE 5-22 (gif format)

TABLE 5-22.- INCREASED PRODUCTIVITY FACTORS*
IN VEGETABLES (ref. 24)

Cabbage 2.59
Cucumber 8.48
Eggplant 12.63
Lettuce 2.33
Okra 4.73
Tomato 2.37
Turnip 7.14

*Under greenhouse conditions.


The summer study did not pursue the issue of food reserves, design margins and safety factors with respect to agriculture. Due to the importance and fragility of the agricultural system further study should consider this issue. In general, it was felt desirable to produce some excess food continuously, store some of the excess as reserve, and recycle the remainder. In fact, it would seem wise to design the system such that the colony could survive on the output of two of the three agricultural units for a period of several months if some disaster ruined production in one of the areas. Also, the study did not pursue microbial and insect ecology but did assume that these important areas could be resolved upon further study.


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