APPENDIX C

AGRICULTURE

The agricultural system is derived from standard nutritionalrequirements 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)

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 (b) (gif format)

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 table5-18.

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

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 A
• Table 5-19 B
• Table 5-19 C
• Table 5-19 D
• Table 5-19 E
• Table 5-19 F
• Table 5-19 G
• Table 5-19 H
• Table 5-19 I
• Table 5-19 J

TABLE 5-19.- FACTORS OF METABOLIC REQUIREMENTS

A. diet requirementsfor 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

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/season	Season, day	g/m^2/season	Season, day	g/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

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)

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)

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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Curator: Al Globus If you find any errors on this page contact Al Globus.

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