Study On Dynamic Relationship Between Labile Soil Organic C, N And Crop Growth Under Straw Incorporation

The objectives of this study were to investigate the dynamic relationship between labile soil organic C, N and different crop growth under straw incorporation in Yucheng (Shandong) Station, Institute of Geographic Sciences and Natural Resources Research, CAS. The 0-20 cm soil layer with the winter wheat (Jimai 22) - summer corn rotation system was taken as the experimental material, and the different nitrogen levels also used to this experiment. The soil organic carbon(SOC), total nitrogen(TN), dissolved organic carbon (DOC), hot water-extractable carbon (HWSOC), easy oxidation carbon (EOC), pariculate organic carbon (POC), particulate organic nitrogen (PON), nitrate nitrogen (NO3—N), ammonium nitrogen (NH4—N) in the soil, the aboveground biomass and yield of the two crops were determined, respectively, so as to reveal the law of the diversification of labile soil organic C, N under straw incorporation. The results were as follows:The effects of different fertilizers on the labile SOC, TN and C/N had no significant (P>0.05), however, the effect of fertilizer level on the SOC had higher significant (P<0.01). There were higher significant for the SOC, N in the different stage of crop growth (P<0.01). Because of the different fertilizer, the DOC content under urea treatment had obviously decline after fertilize in April, then it kept in the steady state. The HWSOC content increased after fertilized in April with two fertilizers, but the long-term ammonium bicarbonate group decreased after fertilize in August. Same change between different fertilizations on the EOC content increased after fertilize, decreased after straw incorporation. The effect of the various fertilizers and fertilizer level on the POC was not significant (P>0.05).The NO3—N in soil under different fertilizer after straw incorporation increased. The effect of the interaction between different fertilizer level and the period of crop growth on wheat yield was higher significant (P<0.01), and the effect of the interaction between different fertilizer level and various fertilizers on the above-ground biomass and the stem biomass of the wheat yield was higher significant (P<0.01); the effect of the different fertilizer level on the above-ground biomass and the stem biomass of the wheat yield was not significant (P>0.05). The effect of various fertilizers on the above-ground biomass and the stem biomass of the com was not significant (P<0.05) and on the leaf biomass of the com was not significant (P>0.05). The effect of the interaction between different fertilizer level and the period of com growth on the three indices including the above-ground biomass, stem biomass and leaf biomass of the com biomass was higher significant (P<0.01). Compared with long-term ammonium bicarbonate treatments, the urea treatments to the crop improvement was better. The effect of different fertilization on the 1000-seed weight of the crops was not significant, but there was significant difference with the control (non-fertilizer).