Energy flow through an organic agroecosystem in China

Abstract

The energy flow in a traditional organic agroecosystem located in Hailun county of Northeastern China was analyzed for the years 1952–1954. For this energy analysis of the Hailun agroecosystem and human society, energy production was divided into 3 systems: crops, livestock and forestry. In terms of energy, this agroecosystem was self-sustaining. Human and horse power provided the major energy inputs. In the crop system, the energy input/output ratio was about 1:2. Fossil energy input into the total agroecosystem was less than 2% of the total. Based on only fossil energy inputs and crop outputs, the ratio was 1:107. The sources of food and household energy for human society came from the crop, livestock and forestry systems. The crop system provided more than 80% of the energy for this society. In addition to natural additions of N and P, legumes, other crop rotations and the application of human and livestock wastes to the land provided the nutrients for crop production. However, the agroecosystem was not self-sustaining in terms of some soil nutrients. Quantities of both nitrogen and phosphorus were calculated to be declining because of losses due to composting, storage, burning crop residues, exporting some harvests and soil erosion.