Based on the investigation of the biomass,productivity,and production structure of poplar in the farmland shelterbelt forest,the growth relationship of Populus to-mentosa and Populus daquansis has been established. The results of analysis were as follows: The biomass was 26.09 t/ha, net biotic productivity, 2.609 t/ha · a, net increased output value, 109.38 yuan/ha · a. The yield structure varied greatly depending on the situations of different trees in the shelterbelt. The relative growth equation of the two kinds of poplar, W= aDb, was fit at close correlation and high precision. It could be used to estimate the biomass of the tress in the farmland shelterbelt forest where poplar was dominant at present.

The biogas system is the kernel component of Guquan Experimental Farm of Ecological Engineering. The wastes of the farm are used by the biogas digestors to produce biogas, liquid and solid slurry, which are used respectively as fuel, feed and fertilizer in the farm. Through using integratedly them, the intensity of the farm’s being dependent on the input from external system is lightened and the cost of the farm is decreased so that the production of the farm is more sustainable and stalable and that the economic, ecological and social efficiences have been gotten more highly. The authors point out that the development of biogas is one of important projects to rural ecological construction. 

A comparative study on fish culture fed only with slurry digested and with chicken manure had been done in this paper. The results showed that the net fish yeilds for the ponds fed only with slurry digested and with chicken manure were 12,120 kg/ha and 3,412.5 kg/ha respectively. The net profit of the former has increased by 2.5 times as compared with that of the latter.The reasons why fish culture with slurry digested can increase fish yield so obviously had been examined by authors through analysis of input-output of energy, N, P and biomass of plankton as well as the changes of DO in fish poud.And they suggested that it is an effective way to raise utilization rate of waste resources and to promote the further development of biogas digester system in rural areas by means of liquid slurry digested to culture fish.

In this paper, the salt meadow of the Yellow River Delta has been classified and the characteristics of each type have been described,the production potentialities of main types of the grassland studied, and the development and protection of the grassland discussed.

This paper deals with the effects of hydrological transfers, i.e., precipitation, irrigation, leaching and surface runoff, on the balance of nitrogen, phosphorus, potassium, calcium, magnesium and sulphur in the rice field ecosystm, cropped with wheat-rice rotation, in the Tai Lake region of Jiangsu Province. The results show-edi a. the sequence of the quantities of the nutrients transfered by hydrological pathway was in the order of Ca, Mg, S,K,N, and P.b.the capacities of calcium and magnesium in the soil nutrient pool were very significantly influenced by hydrological transfers, which resulted in the negative balance for these two elements, w-hile the effect on the capacities of nitrogen and potassium was rather small, the least effect was found in that of phosphorus, c. the contributions of hydrological input to the total input of calcium, magnesium and sulphur ranged from 50% to 88%) on the other hand, the.output contributions were from 73% to 94%. It could be concluded that hydrological transfers played a predominant role in the cycling of these three elements.

According to the comprehensive control measures of soil erosion in west Liaoning province, an effective approach for abjusting the ecological structure of the small watershed of Tarpiugguo-horizontal, vertical and material cycling structures of plants in the watershed, coordinated with appropriate engineering practices has been described.Some means were suggested to greatly reduce the loss of water and soil, to improve the conditions of supply and demand of forage fertilizer and fuel; to increase the soil fertility the grain output and the people’s income and to improve the ecological functions.Finally the overall control has been realized. 

The experiments of fumigation of soybean were carried out in 4 sets of open top field chamber.The HF concentrations within the four cambers, A, B, C and D ( CK ) 0.0036, 0.011, were 0.038 and 0.0007 mg/m³ respectively.The results showed that the changes in the leave electric conductivity were closely correlated with the environmental condition in which the leaves grew and absorbed fluoride and with the developing stages of soybean plant.It was found that the fluoride content and absorbtive rate of leaves were increased aynchronously with the increment of time and concetration of fumigation,the maximum value appeared in the treatment of C group which had higher HF concentration.Much more fluoride was accumulated in leaves than in other parts of the plant, the differences in fluoride content of leaves among all treatments were significant, but that between root, pod-skin and bean was not obvious.Fumigation with higher concentrations caused obvious varietions in the number ot pod, bean as well as in the bean weight, When the concentration exceeded 0.0039 nig/m8, the yield of soybean would probably decrease to n large extent.

The results of typical application tests showed that the oriental housefly ( Dom-estica vicina ) in the northern suburb of Tianjin city has developed resistance to DD-VP. In 1983, the LD₅₀ value of the housefly was 0.473 μg, 35 times larger than that of the susceptible strain. In 1986, the resistance rate, compared with that in 1983, dereased by 14 times. As to pyrethroid phenothrin no resistance has yet been found in that housefly.The bimolecular rate constant ( Ki ) for the reaction of DDVP with the housefly head AchE has been determined as 0.7×10⁵ mol^-1 min^-1. The resistance capacity of oriental housefly to DDVP was probably due to an altered form of AchE which showed a greatly reduced rate of reaction with inhibitor. 

Chlorinated benzens in the environment could not be readily degraded anaerobi-cally. The residual amount of this compound in the environment chiefly depended on the rate of bio-degradation. In this paper, an experiment has been conducted on the bio-degradation of that compound for the flooded soil under anaerobic condition and moist soil under aerobic condition collected from the irrigated area of Datong river in Changzhou city of Jiangsu province. Based on these experiments, the cause of high content of chlorinated benzen compounds has been investigated and its coun-termeasures prorosed.

The simulated laboratory experiments showed that the soil microorganisms in rice soil were effective in degrading the pesticide to some extent, but the degradation of carbofuran in soil could not be accelerated when applied repeatedly. The number of bacteria, actinoniycetes and fungi in the treated soil incresed 2.3 to 4.4 times as compared with untreated soil.

Based on the investigation of the ecological, environmental effects, regional balance, purifying rate of pollutants and their regional differentiation, the principles and methods of formulating the quality standard of irrigation water have been discussed in this paper, the Cd and As quality standard for three types of soil in China proposed. 

Youyu county is located in the northern part of Shanxi province, belonging to the semi-arid region. This paper described the achievements of practising comprehensive agricultural production system in that county. The development of animal husbandry, raising wild animals and plants, establishing processing system of agricultural and stock products have been emphasized in this paper in order to further promote the development of agriculture and forestry. 

Using the theory of grey system, an analytical model of dynamic tendency has been established in this,paper, based on the 30-year historical data of the development of animal husbandry of Qinghai Province.Qualitative and quantitative system analysis have been made and some constructive suggestions for the development strategies of animal husbandry for that province prpposed. The models showed: i. The maximun carrying capacity was 38 793 444 sheep units according to the present primary productivity of the grassland. 2. The number of cattle, camel and pig had an increasing tendency in different degrees, while that of sheep,, horse, mule, and donky decreased. 

The concept of benignant circulation of agricultural ecolomic system is a perplexed theoretical problem. By analyzing this concept, the authors found that a transition circulation existed between the benignant and the vicious circulations. The transition circulation played an important role in the overall circulation of the agricultural ecolomic system. Ten important characteristics of benignant circulation have been discussed and main conditions for achieving benignant circulation analyzed.