Integrated Farming Systems at Different Scales 427Cultivation–breeding–processing–energy integration
This is the most complex system at household level. Residents, homestead gardens,
domestic animals and biogas generating facilities are well integrated into a system.
It is not possible to give detailed descriptions of all the varieties and we present a
case study to show how farmers manage their small homestead with full use of
resources and to optimal effect.
A case study – Zhangxi’s household ecosystem
Structure of the household ecosystem
Zhangxi is a farmer of Shilihe village, Sujiatun district of Shenyang City, Liaoning
Province. There are three people including workers in his family, with a total area of
605m^2 , of which the house area is 91m^2 and the garden area is 220m^2. In the spring
of 1990, with the guidance and help of scientists, Zhangxi rearranged his household
system. The optimized household ecosystem is divided into a number of basic sub-
systems: plastic shed, biogas digester, pig sty and toilet, garden and residents.
- A plastic shed with an area of 136.5m^2 was built in front of the house. Oyster
mushrooms were planted twice within a year, first in summer (from August to
the next November) and then winter (from November to the next June). - A biogas digester with a volume of 7.5m^3 is set underground in the west of the
shed, and a pig sty and toilet are constructed on the biogas digester. The human
and animal faeces and urine are put into the digester automatically, to produce
biogas for illumination and fuel. - A 19.5m^2 pig pen and toilet was arranged above the biogas digester.
- The area of fields for the household is 220m^2.
- There are three persons in the family encompassing the resident subsystem.
Energy analysis and nutrient balance of the household ecosystem
The energy flow of household ecosystems is divided into three categories: energy
input from outside of the ecosystem (Table 18.1), between components within the
ecosystem, and the energy flow from the system to outside. Tables 18.2, 18.3, 18.4
and 18.5 describe the nutrient balances in the plastic shed subsystem, biogas
digester subsystem, pigpen subsystem and garden subsystem, respectively.
Benefits analysis
It is evident that the household ecosystem is an efficient, highly productive system
with considerable, comprehensive benefits. The subsystems closely interact with each
other. With accumulation of productive experience and improvements in techniques,
the yield of crops increased from June 1994 to May 1995. The total material was
9250kg, and 8000kg of oyster mushrooms were produced, the increase in benefit
was nearly doubled. In general, the biogas pond can produce about 150m^3 of biogas
used by the family and 1400kg/yr of biogas sediment which is used in the garden
(roughly 150kg) and the fields outside of the household (roughly 1250kg). In