Research on Fertilization Techniques and Their Effect in Eight Cunninghamia lanceolata Seed Or chard

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Research on Fertilization Techniques and Their Effect in Eight Cunninghamia lanceolata Seed Orchards in Four Provinces

According to the experimental results of fertilizing in eight seed orchards in four provinces from 1983 to 1992,the best results occurred using unfertile soil.The sort of fertilizer and its make-up should match with the soils in local sites,that is,mainly PK mixtures should be added to mid-fertile soil and nitric mixtures should be added into this basic fertilizer for poor soil. The time of fertilizing should match the development of rhythm and the differentiation of flower buds.(The best tirne for fertilizing is likely to be June, followed by April and autumn--generally in August, but also November for phosphatic types. )It is suitable to fertilize the trees twice per year, and it is better to use not only chemical fertilizers but also muck or green manure. The amount of fertilizer used should be matched with the age of trees and the fertility of the soil,that is generally 10--170gN, 100--250g P2O5and/or 50--100g K20 per tree per time. The amount of seeds can be increased by 20%--100%with the best mixture of fertilizer and the seed output rate the of the cone. The weight of 1000 seeds and germination percentage may also be increased. This research also shows :the response of fertilizing is dilferent for various clones. Suitable fertil- ization can increase the clilorophyll content in needles and the quantity of strobiles. Reasonable fertilization can slightly increase B.H.D. and crown growth but not make it uncontrolable.