135-3 Distribution Of Nitrogen In Aggregates Of Black Mollisols and Red Typic Hapludults Soils Under Long-Term Fertilization.

See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
See more from this Session: Nitrogen Management for Corn and Wheat

Monday, November 4, 2013: 1:35 PM
Tampa Convention Center, Room 13

Yinghua Duan, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agri. Sci,, Beijing, China, Minggang Xu, CAAS Institute of Agricultural Resources and Regional Planning, Beijing, China and Zhen Liu, Institute of Agricultural Resources and Regional Planning,Chinese Academy of Agri. Sci,, Beijing, China
Abstract:
Soil aggregates with various degree of stability has important implications in nutrient storage and supply for plant growth. This study evaluated the effect of long-term fertilization on N distribution in aggregates. The total N (TN)and accumulation in four size fractions (250−2000 µm, 250−53 µm, 53−2 µm and <2 µm) were analyzed in two soils: black (high OM) soil (Mollisols) from northeast China and red (acidic) soil (Typic Hapludults) from south China, from a 22-year fertilization experiment. The treatments included unfertilized control, chemical fertilization (NPK), manure application (70% N supply) with NPK (NPKM), and NPK with corn-stover returned (NPKS). The portion of N in a specific aggregate relative to the total N amount in all aggregates and differences under various fertilizations were estimated. The results showed that the TN content decreased at 0.015 g/kg/yr for both control and NPK treatments, but increased at 0.025 g/kg/yr for the NPKM treatment in black soil (P < 0.05). The TN content of red soil, however, did not change significantly for all treatments over the fertilization period. The highest TN concentrations were detected in the 53−2 µm microaggregates in the black soil (0.73−1.21 g/kg), and <2 µm microaggregates in red soil (0.46−0.98 g/kg) among the four size fractions of aggregates. There was significant decrease of N portion in the 53−2 µm aggregates of the red soil by 6% and 10% under NPKM and NPKS treatment, respectively, compared to the NPK treatment. However, there was no significant change for the N portion in the 53−2 µm aggregates in the black soil. This data may suggest that soil property change from long-term fertilization further impacted soil N storage or availability.

See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
See more from this Session: Nitrogen Management for Corn and Wheat