Effects Of Long-term Fertilization On The Organic Carbon And Nitrogen Pools And Soybean Rhizosphere Organic Carbon Stability In Black Soil

The four major black soil zones in the world have become important agricultural production soils due to their natural advantages of fertile black soil resources and high organic matter content,which has developed the biggest grain bases.Heilongjiang Province is located in the black soil zone of the Northeast Plain,accounting for 74.77%of the total area of black soil,Heilongjiang Province as a vital crop area plays a key role in guaranteeing Chinese crop safety.With rapid decreasing of soil organic carbon content,Studying inorganic fertilizers and livestock manure applying to the field is of great significance to crop yield,soil fertility and sustainable soil cultivation in this area.Study on the characteristics of input of different fertilizers on carbon and nitrogen pools and rhizosphere organic carbon stability has become key issues.This study mainly focus on soil carbon and nitrogen pools and rhizosphere organic carbon stability mechanism by history data statistic,DayCent model and combined with soybean rhizosphere soil experiment analysis using methods of fourier transform infrared,¹³C nuclear magnetic resonance and Illumina Miseq methods based on 38-year long-term fertilizer experiment of Heilongjiang Mollisols Scientific Observation Station of Cultivated Land Conservation and Agricultural Environment of the Ministry of Agriculture and Rural Affairs.Nine treatments were included in our research,such as no fertilization?CK?,nitrogen?N?,nitrogen plus phosphorus plus potassium?NPK?,Manure?M?,manure plus nitrogen?MN?,manure plus NPK?MNPK?,2 time nitrogen?N2?,2 time Manure?M2?,2 time manure plus nitrogen?M2N2?.Main results showed as follow.1.The annual average carbon input was 1030.1 kg/hm² in long-term fertilization experiment,which could balance soil organic carbon?SOC?.NPK treatment maintained SOC level.CK,N and N2treatments significantly reduced SOC and carbon storage,M2,MNPK,MN and M2N2 significantly increased SOC and carbon storage,the annual increasing of carbon storage was 0.052?0.222 t/hm².2.The annual average 86.1 kg N/hm² of soil nitrogen surplus can maintain the balance of soil nitrogen,the soil nitrogen remained stable in MN and MNPK treatments.M2N2 treatment significantly increased TN and soil nitrogen pool with applying fertilizer years,other fertilization treatments showed a decreasing trend year by year.3.SOC concentrations were generally higher in rhizosphere soil than in bulk soil.CK and N treatments significantly decreased SOC.The C/N ratio significantly decreased,the total C in different soil particle sizes of rhizosphere soils was lower than that of bulk soil in N-treated rhizosphere soil.The total C in different soil particle sizes of rhizosphere soil was lower than that of bulk soil in M2 and M2N2 treatments.4.Fertilization treatment reduced O-alkyl C in rhizosphere soil,increased the ratios of alkyl C to O-alkyl C and hydrophobic C to hydrophilic C,these founding indicated that soil C tended to be highly recalcitrant and stable.The ratios of alkyl C to O-alkyl C and hydrophobic C to hydrophilic C were higher in M2 and MNPK treatments.5.Higher OTU?Chao and Shannon index were observed in rhizosphere soil compared with the bulk soil.Inorganic fertilizers significantly decreased microbial diversity.Long-term application of manure plus NPK?MNPK?and 2 time Manure?M2?increased the abundance of genera which was positively correlated with aromatics and aliphatic,but decreased the abundance of genera which was negatively correlated with aliphatic and carbohydrate in rhizosphere soil.Organic manure significantly increased the abundance of Haliangium?MND1?Variovorax?Anaerolineaceae?uncultured?env.OPS 17?norank?Microscillaceae?uncultured?Subgroup 6?norank?RB41?Chloroplast?norank and Nitrospira genera which were significantly positive correlated with relative content of aliphatic,aliphatic/carbohydrate ratio,SOC and>0.25mm C in bulk soil.Inorganic fertilizers had lower abundance of Haliangium?MND1?Variovorax?Anaerolineaceae?uncultured?env.OPS 17?norank?Microscillaceae?uncultured?Subgroup 6?norank?RB41?Chloroplast?norank and Nitrospira genera,and higher abundance of WD2101 soil group?norank?Acidobacteriales?norank?Pseudolabrys?Micropepsaceae?uncultured?Burkholderia-Caballeronia-Paraburkholderia?Rhodanobacter?Gaiellales?norank?Bryobacter?Granulicella?Mucilaginibacterk?SC-I-84?norank genera which were remarkably negative correlated with relative content of aliphatic,aliphatic/carbohydrate ratio,some of genera such as Acidobacteriales?norank?Bryobacter?SC-I-84?norank were remarkably negative correlated with>0.25mm C in bulk soil.