Fertilization Effects On Active Organic Carbons And Soil Structure In Black Soil Farmland With Different Soil Organic Matter Contents

Based on a long-term soil spatial shift field experiment in Hailun Agroecology ExperimentalStation, CAS, the content of the main dissolved organic carbons and water-stable aggregatedistribution of Black soil under two fertilization levels were examined from the growing seasons of2011to2012. The soil in the facility had five levels of organic matter content (SOM), they wereHeilongjiang Bei-an (SOM11) Heilongjiang Nen-jiang,(SOM6);Heilongjiang Hai-lun (SOM5),Jilin De-hui (SOM3), Jilin Li-shu (SOM1.7)]. The results showed that:1. After the application of chemical fertilizer, the content of soil water-stable aggregates(>0.25mm) and aggregate-associated C were higher than those in no fertilizer treatment. With thedecrease of soil organic matter content in chemical fertilizer treatments, the content of soilwater-stable aggregated and aggregate-associated C decreased (p>0.05). The highest contentappeared in SOM11,while the lowest appeared in SOM1.7. In no fertilizer treatment, the content ofsoil water-stable aggregated and aggregate-associated C decreased dramatically(p<0.05.;Aggregates greater than1mm aggregated decreased more than other size of them, and thelowest appeared in SOM1.7. There was a significant positive relationship between>1mmaggregates content and soil organic carbon (SOC)(p<0.05) under the chemical fertilizer treatments.However, no fertilizer treatment had no significant influence on total organic carbon in the>1mmaggregate. Chemical fertilizer significantly increased the content of macro aggregate-associated Cand total organic carbon, indicating that>1mm macro aggregate played a major role in the changeof soil total organic carbon.2. Compared with the no fertilizer treatment, long-term application of chemical fertilizersincreased the contents of soil organic carbon, soil readily oxidizable organic carbon, microbialbiomass carbon, particulate organic carbon, and light fraction organic carbon except the dissolvedorganic carbon in the Black soil farmlands with5different soil matter levels.. The effect oflong-term fertilization on soil SOM11was the most significant, followed by SOM6, SOM5, SOM3,SOM1.7. The distribution ratios of soil active organic carbons in the chemical NPK fertilizertreatment were overall lower than those in no fertilizer treatment. Fertilization had no effect on thecorrelativity between active organic carbons and organic carbon in the Black soil farmlands with5different soil matter levels.