Effect of Combined Application of Fertilizers on Gain-loss Distribution of Soil Nitrogen
Ma Chengze He Fang( Anhui Agricultural University)
Field trial results showed that exhaustion of loosely combined nitrogen caused an apparentdecrease of the potential capacity of soil nitrogen supply in a successively unfertilized soil; freecombined--nitrogen substantially accumulated while N in N- complexes obviously depleted in thecase of the simple use of commercial fertilizer. This reveals that the residue of chemical nitrogenis not helpful in the building up of soil nitrogen reservoir and will damage the surroundings. Thegained nitrogen in soil usually presented itself in loose form in the combined trials of commercialfertilizer and organic manure. Better results were obtained from the trials of fertilizer-rice strawcombinations or from those of fertilizer--straw and farm manure combinations as compared withthe trials of jest fertilizer and manure. The former two treatments apperared to be beneficial notonly to maintain soil nitrogen but also to strengthen the potential capacity of soil nitrogen supply.Since the gain and loss of total soil nitrogen as well as various combined nitrogen are positivelycorrelated to total soil O. C., heavy soil O. C. and its loose parts, soil N storage and supply canbe coordinated through the manipulation of soil O. M. decomposition and accumulation.