According to the principles of ecolomics, taking Guyuan Ranch of Hebei province as a study site, the method for realizing profitable ecolomic recycling of the Bashang region has been investigated through modeling of systems engineering. The system dynamic model was applied as the main model which expressed the general feedback relations of the whole system structure. Monte Carlo method was used to simulate the impact of erosion on soil fertility. A comprehensive integration of qualitative and quantitative analysis, coefficient simulation, and grey system model was used for prediction. An "Ecolomic Laboratory" has been established to reflect the trand of ecolomic development of that region and its regularity of variation. Several programs have been formulated based on the practical experiences and qualitative analysis. A comprehensive evalution was carried out according to the results of computer emulation to seek for strategy and measures of continual development and mutual promotion of agriculture and animal production consistent with natural environmental conditions.

In this paper, a concrete measure dealing with the problem of agricultural environmental conservation and the construction of an ecological agriculture experimental district in the south and north mountainous region of Dazu County has been proposed. It was regarded that planting fruit trees and increasing forest covering areas were permament solutions. Grass planting and developing herbivorous stocks may enable the production of agroecosystems to achieve a even higher leve of productivity,make its structure more stable, and its function more complete.Controlling agricultural environmental pollution was considered the fundamental measure for improving the quality of the environment and promoting its healthy and sound development. To develop the township enterprises and to change the rural economic structure could effectively reduce the burden on limited land resources and to implement its rehabilitation. Birth control and raising the quality of population assures the protection and reformation of the whole agricultural environment. 

Two methods, principal components analysis and cluster analysis, were applied in this experiment to study the factore affecting the background values of soil elements for 22 kinds of soil samples developed from 11 types of parent materials. The results obtained were as follows: 1. The figures of background values of soil elements were comprehensively affected by the five soil-formation factors, and then by the parent material.2. Several effected soil patterns could be classified according to the composition of influential factors. 8. Using the principal component equations and the pattern figures of the background values of soil elements, the unknown patterns of background values of soil elements could be identified. 

A leaching experiment has been carried out on some typical soils in Southern China using simulated acid rain. The leaching characteristics of different types of soil were investigated to provide scientific basis for preventing, environmental damage due to acid rain.

The ecological classification of animal husbandry regions was a determined by a combination of the structure of species or kinds of livestocks and the feeding methods and management practices which possessed significant regional ecological characterisics.Complicated topography existed within Daoyuan County consisting ol different geomorphological types including mountains,hills and plains. The land elevation gradually decreased from south-west toward the east that caused apparent regional differences between the animal husbandry enterprises in each of the regions. The authors used cluster analysis by selecting five factor groups(topo-graphy , feed resources, carrying capacity, structure of stocks and poultry kinds)and 20 other factors. The regional ecological types of animal husbandry of Daoyuan County could be classified into three groups and eight subgroups according to these calculations. The first group consisted of swine, chicken, duck and rabbit production for the high plain regions; the second consisted of cattle,swine, rabbit, chicken and duck for the hilly region; the third consisted of cattle, sheep, rabbit, swine, chicken for the mountainous region. On the basis of such classification, the method of equal-effect coefficients Was used to make a comprehensive evalution of exploitation potential of each type of region. The results of evaluation indicated that the second group had the highest exploitation potential. It was determined from these results that animal husbandry should be further strengthened and developed for the hilly reglon and the structure of animal husbandry of the entire county should be readjusted.The proportion of herbivorous stocks should be raised and the pasture and feed resources of plant proteins should be fully exploited and utilized. 

The Loess plateau region is one of the important agricultural region in China. Soil erosion is the main cause of the degradation of local environment and backwardness in agricultural production. In the paper, the relationships between soil erosion and human activities as well as the succession of habitation have been analysed. Certain patterns of different ecological agriculture, criteria of evaluation, and control measures Were propose for the purpose of soil conservation. 

An ecological household with integrated development in cropping, animal husbandry edible fungus production has been taken as a basic study unit. The situation of its energy flow was analysed from an ecological view point after making a detailed investigation on this farming household. The results showed that this houldhold has made great achievements in their multiple enterprise management, material recycling and comprehensive utilization of organic wastes. This reflected the characteristics of energy flow of a man made.ecosystem.The experimant proved at the establishment of ecological agricultural systems is approprate for the current situation in a large number of Chinese rural regions. This approach also provides a very useful direction for agricultural developmeat and rural construction. 

An investigation has been carried out on the problem of contributing factors and control measures for iron-containing ground water in the primitive environment of the second Songhua river valley based on a large amount of data obtained from recent redearch. It has been proven, through an analysis of the collected data , that the iron content of underground water was closely related to the conditions for oxidation and reduction potential, acidity and alkalinity and surface runoff of water flows. 

A 36% emulsion oil of Illoxan is currently an ideal herbacide for sugar beet, both domestically andabroad. The purpose of studying the degradation and residue dynamics under field condition was to providenecessary residue data of this herbacide for its reglstered from and at the same time to make a scientificbasis for its "standard of safe usage" . From 1984 to 1985, the authors used three dosages for Illoxan onexperimental fields on Zhejiang province, Beijing municipality and Helongjiang province at: 83 ml/mu, 125ml/mu and 16T ml/mu. After 92-106 days of application, no residue of Illoxan could be detected in thebeet tubers, nor in the soil.It was suggested that the interval for safe application of Illoxan should be 106days, the permissible residual amount eas 0.1 mg/kg and the application rate should be one per growingseason at the rate of 83 ml/mu. 

A study on nitrogen dynamics in soil under grain-cotton double cropping system has been carried out by using isotope ¹⁵N from 1981 to 1984. The results showed that too much nitrogen fertilizer has been used for cotton fields in Hubei province. The amount of nitrogen fertilizers applied in the cotton fields in Hubei province was excessive and it should be controlled. Broadcasting or shallow dressing, methods should be changed to deep layer dressind in order to increase the utilization ratio of N fertilizers and to reduce pollution to the environment. Increasing the proportion of legume crops in the rotation systems could decrease the amount of N fertilizers required and at the same time, could serve as an important method of preventing nitrogen pollution within the field ecosystem. 

The ecological distrobution of Aspergillus flavus on field crops and grains, the control of the mould and measures of detoxication have been comprehensively reviewed in this paper. It was believed that a clear understanding of the distribution dynamics of Aspergillus t’lavus and a strengthening of control measures are important work for the agricultural environmental sciences.

The basic principles for waste water exploitation in township enterprises were discussed from an ecolomic perspective. They are: food chain theory and the principles of additional links for increasing production and limitless recycling. Three ecolomic models of waste water reuse were suggested: 1.Pretreatment of waste water-oxidation ponds-raising aquatic products, stocks and poultry-field ecosystem; 2.Pretreatment of waste water-oxidation ponds-aquatic products, stocks and poultry-bio-gas-earthworm-stocks and poultry-field; 3.Integrated utilization and multi-purpose management. 

Compared with the natural ecosystems, agroecosystems possess their own special characteristics. Based on this point, some relationships in the eco-agricaltare establishment were discussed. For example:the relationship between "self-sustained" and "high input/output" System, between diversity of Structure and roles of dominent components, between small-scale management and large-scale development, and between ecological improvement and economic development. in addition the author put forward his own point of view on these problems.