Micro Farms Project 7. Corn Field Design
Figure 8. Corn Field for the Micro Farm.
In Mexico corn is the most important staple food. It is used in tortillas, which is served with every meal. A sierra farmer with 3 teenaged children claimed he buys 12 kilograms of corn a week for his family at a cost of $2.50.
Traditional corn growing in the sierra is by using milpas or shifting agriculture. An area of tropical forest is cleared and corn is planted, often this is on steepslopes, at risk of erosion.
The land is cleared, corn planted by hand and harvested. The yield for this effort is very low, 600kg hectare or less. The remaining stock is also used for animal food.
The micro farm has 1200mē corn field which is fertigated. It is expected to produce 1200 kg of corn in a year (1 kg/mē). It should also produce 3600kg of animal forrage.
The corn field requires nitrogen and it should receive all it needs from the fish pond waste water. It should use about 8 liters water day per mē, or 9600 liters fo water a day.
The corn variety to be grown is probably in the first year a variety to determine which is most appropiate for the family.
Human and animal power are widely used for corn production, especially in developing countries, and are very energy-consuming. For example, in Mexico, corn production by a single person using swidden or cut/burn agricultural technology requires about 1,140 hours (143 days) of labor, the total energy input from human labor being 17,245 kJ per day. When animal power is used, such as ox power in Mexico, the human labor investment is reduced from 1,140 hours to 380 hours. Under these farming conditions, 1 hour of oxen power replaces nearly 4 hours of human power. Assuming that an ox consumes 83,710 kJ per day in forage and grain and that a human still consumes 17,245 kJ per day at hard work, growing corn using animal power requires more energy input than growing corn by hand, but gives more free time to the farmer to pursue other activities.
Yields of corn produced by hand or with animal power in Mexico are significantly lower than yields produced by mechanization in Canada, for example, but the reason is not related to the type of power used. The lower yields can be attributed to reduced use of pesticides and fertilizers, to the lack of hybrid (high-yielding) varieties and to poorer soils on which crops are grown.
The energy analysis in mechanized agriculture is different from labor-intensive agriculture. Of course, the total input of human power is very low, but this is balanced by the significant use of fossil fuel energy required to run the machines. In the US, in 1990, fossil fuel energy inputs averaged about 43.9 million kJ/ha of corn, the equivalent of about 1,050 liters of gasoline, resulting in an output/input ratio of 2.5:1. Compared with the output/input ratio of 11:1 for corn hand produced in Mexico, it can be observed that the former is actually more efficient in terms of energy consumed.
15 December 2007
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