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Greenhouse Operation

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manny kung edited this page Sep 22, 2020 · 30 revisions

Greenhouse Operation

Revised 21 Sep 2020

Crop Model

In mars-sim, Farming is the class responsible for defining the greenhouse operation (which is one of the Building Functions) of an Inflatable Greenhouse, Inground Greenhouse or Large Greenhouse.

On the other hand, CropType is the class that model all the crucial steps running through the full growing cycle of a crop.

In terms of modeling how a food crop grows, we develop an in-house Crop Model in terms of the following inputs, outputs and environmental conditions :

All food crops :

  • Inputs - Requirements in terms of crop tissue culture, crop seed, nutrients, water, co2, amount of light, etc..
  • Outputs - Products in terms of crop seeds, O2, food resources, item resources, etc..
  • Condition 1 - Favorable environmental factors such as temperature, fertilizers, soil condition, etc..
  • Condition 2 - Work Time from a settler or a bot, as modified by stress, skill, etc..
  • Condition 3 - Specialized building to offer protection and control.

We also define the following 6 characteristics in crops.xml for each individual crop :

Param Name Description
growing-time # of sols
crop-category crop type
edible-biomass in tonnes per hectare (or gram per square meter) per day
edible-water-content in proportion of 1 (1.0 means 100%)
inedible-biomass in tonnes per hectare
daily-PAR in mole per square meter per day

Growth Phases

We classify the food crops into a total of 14 crop categories as follows :

Crop Categories
bulbs
corms
flowers*
fruits
fungi*
grains
grasses
leaves
legumes
roots
seeds*
spices*
stems
tubers

The crop categories with (*) above does NOT have 'unique' growth phases and have the 'standard' phases only :

Standard Phases
Incubation
Planting
Germination
Growing
Harvesting
Finished

Beginning v3.1.0, we began to implement alternative Phenological Growth Phases for each crop category.

Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors (such as elevation).

These artificially distinctive phases mimic the fidelity of the life-cycle of a food crop in mars-sim.

In case of Tubers, instead of using the standard growth phases, we have the following 9 phases uniquely defined :

  • INCUBATION
  • PLANTING
  • SPROUTING
  • LEAF_DEVELOPMENT
  • TUBER_INITIATION
  • TUBER_FILLING
  • MATURING
  • HARVESTING
  • FINISHED

The code snippet below is from CropConfig class, where we define the phases that a Tubers crop (such as "Sweet Potato" and "Yam") has to go through by percentages of growth.

  if (cat == CropCategoryType.TUBERS) {
  	
  	phases.put(0, new Phase(PhaseType.INCUBATION, INCUBATION_PERIOD, 0D));
  	phases.put(1, new Phase(PhaseType.PLANTING, 0.5D, 1D));
  	phases.put(2, new Phase(PhaseType.SPROUTING, 1D, 10D));
  	phases.put(3, new Phase(PhaseType.LEAF_DEVELOPMENT, 1D, 10D));
  	phases.put(4, new Phase(PhaseType.TUBER_INITIATION, 1D, 15D));
  	phases.put(5, new Phase(PhaseType.TUBER_FILLING, 1D, 39D));
  	phases.put(6, new Phase(PhaseType.MATURATION, 1D, 24D));
  	phases.put(7, new Phase(PhaseType.HARVESTING, 0.5, 1D));
  	phases.put(8, new Phase(PhaseType.FINISHED, 0.5, 0));
  }

As you can see, the SPROUTING phase is from 0 to 14 % (i.e. 14D above), LEAF_DEVELOPMENT phase is from 15% to 20% (i.e. 5D above).

One may also compute the MATURING phase to be from 73% to 100%.

Thus, at 100%, the crop is good for harvest.

Edible Biomass

Let's use Taro as the example to illustrate how we derive the edible-biomass,

<crop name="Taro" growing-time="200.0" crop-category="tubers" edible-biomass="4.7" edible-water-content=".706" inedible-biomass=".05" daily-PAR="34.56" />

First, we obtain the yield from https://en.wikipedia.org/wiki/Taro.

"The global average yield is 6.2 tones/hectare but varies according to the region. In Asia, average yields reach 12.6 tones/hectare."

We obtain the average tonnages per hectare as follows :

(12.6+6.2)/2 T/ha = 9.4 T/ha

If we convert Tonnes/hectare to gram/square meter.

9.4 T/ha = 9400 kg/ha or 940 g/sqm

For Taro, the average growing-time is 200 days.

To obtain the daily harvest mass [g/sqm/day], we divide it by 200 days

940/200 = 4.7 g/sqm/day

Thus, we arrive at the edible-biomass of 4.7 g/m2/d for Taro

Future Modeling

The Multivariate Polynomial Regression (MPR) Model is a crop model that consists of a set of nonlinear polynomial equations, six for each crop.

The dependent variables for three of the six MPR equations are the relative growth rates of (a) total dry mass prior to formation of yield bearing organs, (b) total dry mass after the formation of yield bearing organs, (c) yield dry mass.

See pdf

The independent variables used in each equation include the average PPF, T, and CO2 values (averaged from planting date up to the current time increment t), and the total or yield dry mass at t-1.

The model-based predictive controller adjusts light intensity, atmospheric/elevated atmospheric carbon dioxide concentration, photosynthetic photon flux (PPF), average daily air temperature (T).

Reference :

  1. Crop Production for Advanced Life Support Systems, P.18 Table 6, 8-11-2006

  2. NASA Advanced Life Support Baseline Values and Assumptions CR-2004-208941 http://ston.jsc.nasa.gov/collections/trs/_techrep/CR-2004-208941.pdf

  3. Space Settlements: A Design Study 1975. http://settlement.arc.nasa.gov/75SummerStudy/5appendC.html

  4. For Roots and tubers, see http://www.fao.org/es/faodef/fdef02e.htm

  5. http://healthyeating.sfgate.com/list-fruits-vegetable-high-water-content-8958.html a. Vegetables that contain 92 percent water include cauliflower, eggplant, red cabbage, peppers and spinach. b. Broccoli is 91 percent water by weight. c. Additional healthy hydrating foods include carrots with 87 percent water andgr een peas and white potatoes with 79 percent water. d. Water content. http://www2.ca.uky.edu/enri/pubs/enri129.pdf

  6. Typical expected yield for food crop. http://www.kzndae.gov.za/Portals/0/Horticulture/Veg%20prod/expected_yields.pdf

  7. 01ICES-307 Design Parameters for Mars Deployable Greenhouses. http://www.marshome.org/files2/Bucklin1.pdf

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