Effect of soil fertility on the allocation of nitrogen derived from different maize residue parts in the soil-plant system

Abstract

Crop residue incorporation is an effective agricultural management to enhance soil organic carbon and nitrogen (N) sequestration, which inevitably affects the crop N uptake, and consequently the allocation of N in the soil-plant system. However, to what extent the crop residue type and soil fertility moderate the contribution and recovery of maize (Zea mays. L) residue-derived N (residue-N) in the soil-plant system is poorly understood. Therefore, a 2-year in situ experiment was conducted on an Alfisol with high fertility (HF) and low fertility (LF), along with the application of 15N-labeled maize root or straw (both stem and leaf) residues. The results showed that the HF treatment had a smaller proportion of residue-N in total N uptake compared with the LF treatment (on average of 2.0% vs. 3.6%), but with a larger recovery rate (on average of 23.5% vs. 12.8%). The application of straw residues increased the proportion of residue-N in plant total N compared with that from the application of root residues in the HF treatment. The percentage of residue-N in total soil N (TSN) and the residue-N recovery in the LF soil were 60.7–108.5% and 9.6–25.8% higher than those in the HF soil, respectively. The proportion of root-derived N (root-N) in TSN was significantly higher than that of straw-derived N (straw-N) in the LF soil. In addition, total residue-N recovery rates were similar among all residue-amended treatments. The results indicated that the soil with high fertility could increase residue-N utilization by plant, especially the straw-N, while the soil with low fertility favored the accumulation of the residue-N in soil, especially the root-N, and its low fertility was more likely to be improved. Overall, soil fertility and residue type could significantly affect the allocation of maize residue-N in the soil-plant system.