The paper describes scientifically the characters of soil fertility, its process of formation, direct and indirect component of soil fertility. And also, it describes, with several research and analyzing data, the measurement for increasing fertility of paddy field which has low yield

Method of calculation for the good organization of practices of spraying pesticides, was indicated. Primary calculating method able to spray quickly pesticides, such as calculation of pesticide quantity, necessary duration of spraying, calculation of necessary water quantity, return times of spraying with once filling pesticides in tank were shown

The combine harvester consists of rubbing thrashing part, air-iron net selecting part, ear-inputting part, and grain receiving part. Action principle of some action bodies as likes; thrashing drum, blower, rotating vibrating net, are new. Total weight of the harvester is 280 kg, power 7 kw, rotating times of the drum 760 (r/min), and the rate of grain is little

The maximum life of piston was prolonged by improving the old with wedge-shaped rings, on the base of deciding abrasion character of the rings, and cracks of gas loss. The compressed pressure was increased to average 0.2 Mpa, and also, fuel consumption was fairly reduced

Life habit and damage symptom of pink borer, and method of its prevention, and control, were studied. To prevent first damage, the chemicals should be applied to larvae which are beginning to move. Chemicals should be applied in the period of maximum occurrence of pink borer F1, F2, and of its eggs. Organic phosphorus should be sprayed as to 1000 l/ha, mixing rate of water, 800-1000 times

To obtain high yield in paddy field, the standard value of some morphological index was decided. The high yield was related with ploughing layer depth, soil thickness, surface gley thickness and peal thickness. When the ploughing layer depth is 25 cm, and the soil thickness 70-80 cm, highest yield can be obtained

The method and principle on rapid humification for humus soil by industrial method was studied. For making rapid humus soil, the condition of air, temperature, hydrated lime and nutrients should be provided. The width of humification place is 3-4 m, length 4-6 and depth 2-2.2 m

About 150 kinds of weeds emerge on the field of Ongjin reed. Especially, annual weeds are superior to others. The longer the age of reed field is, the more perennial weeds are superior. It is better to sprinkle P.C.P. 15 kg/ha and 2.4 D 0.5 kg/ha dissolved in 800 liters of water, from the end of April, more than 2 times every 15 days

"Hyongsan duck" is an improved female breed from "Dudan duck". The number of laying eggs/year is 250 pcs, body weight at 45 days 2657 g, and body weight at 49 days 2936 g. "Jasan duck" is an improved variety by the method of complex line. It grows rapidly and the rate of reproduction is high. Laying eggs at 40 days is 226 (275 pcs a year), body weight at 45 days 3051 g, 3426 g at 49 days, and ...

The method of cultivation for the mixing of first crop and second crop was experimented in field from 1980-1988. Barley planted in ridge as first crop ripened at around June 5, and the rice as second crop was cultivated from around June 15. The yield of rice increased to 150% more than single cropping of rice