Nitrogen Fertilization and Cropping Systems Effects on Soil Carbon Pool in an Argiudolls in Westcentral Illinois PDF Download

Author: Sindhu Jagadamma
Publisher:
ISBN:
Category : Cropping systems
Languages : en
Pages : 282

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Book Description
Abstract: The adoption of recommended management practices (RMPs) such as nitrogen (N) fertilization and cropping systems play important role in increasing crop residue production, with attendant increase in soil organic carbon (SOC) sequestration, agronomic productivity, and soil quality. This study was conducted with the objectives to evaluate the effect of long term N fertilization and cropping systems on: (i) SOC and soil organic nitrogen (SON) concentrations and pools, (ii) SOC sequestration rate (iii) soil quality determinants such as aggregation, total porosity and soil pH, and (iv) agronomic productivity and its relation with SOC pool. Replicated soil samples were obtained from a long-term experiment (23-yrs) at the Northwestern Illinois Agricultural Research and Demonstration Center, Monmouth, IL during Spring, 2004 up to a depth of 90 cm. The soil type is Muscatune silt loam (Fine-silty, mixed, superactive, mesic Aquic Argiudolls). The experimental design was split-split plot within a randomized complete block with three cropping systems [continuous corn (Zea mays) (CCC), and two rotation plots with corn and soybean (Glycine max) grown in alternate years (CSB and SBC respectively)] as the main plot, presence or absence of cover crop [oats (Avena sativa)] as sub plot and five N rates [0 (N0), 70 (N1), 140 (N2), 210 (N3) and 280 (N4) kg N ha−1] in the split-split plot arrangement. Results showed significant increase in both SOC and SON concentrations and pools by the addition of N fertilizers, with SOC pool ranging from 68.4 Mg ha−1 (N0) to 75.8 Mg ha−1 (N4), and SON pool ranging from 6.5 Mg ha−1 (N0) to 6.9 Mg ha−1 (N3) for 0-30 cm depth. The SOC sequestration rate over 23 years of N application ranged from 158 kg ha−1 yr−1 (N2) to 324 kg ha−1 yr−1 (N4) for 0-30 cm depth. Both soil bulk density (Pb) and C:N ratio significantly decreased with increase in the rates of N fertilizer for 0-30 cm depth. Continuous corn system, across all N treatments, sequestered 6 Mg ha−1 more SOC for 0-30 cm depth compared to corn-soybean rotation. Both water stable aggregates (WSA) and mean weight diameter (MWD) increased with increase in the rates of N, with mean WSA values ranging from 47 to 54% and MWD from 0.44 to 0.71 mm. The soils under CCC had more WSA (52.1%), which is 3% higher than that under corn-soybean rotation. The MWD values of cropping system treatments ranged from 0.5 to 0.65 mm, with the highest value corresponding to CCC. Both WSA (R2=0.23) and MWD (R2=0.32) were positively correlated with SOC concentration. The CCC system and increased rates of N fertilization increased corn residue (stover) yield, and thus the amount of biomass returned to the soil. However, N fertilization had no significant influence on soybean residue production. Regression analysis indicated a significant positive relationship between stover yield and SOC pool, but not between soybean residue yield and SOC pool. This study indicated that long-term continuous corn cultivation and judicious N fertilization are desirable management strategies for increasing SOC sequestration, enhancing soil physical quality , and improving sustainability of production systems.