Organic matter fractions and N mineralization in vegetable‐cropped sandy soils. (18th March 2013)

• Record Type: Journal Article
• Authors: Jegajeevagan, K.; Sleutel, S.; Ameloot, N.; Kader, M. A.; De Neve, S.
• Is Part Of: Soil use and management. Volume 29:Number 3(2013:Sep.)
• Page Start: 333
• Page End: 343
• Publication Date: 2013-03-18
• Subjects: Nitrogen mineralization -- soil organic matter -- intensive vegetable production -- soil fractionation -- sandy soils; Soil management -- Periodicals; 631.4
• DOI: 10.1111/sum.12044
• Languages: English
• ISSNs: 0266-0032

Abstract

Abstract: Soil organic nitrogen mineralization rates and possible predictors thereof were investigated for vegetable‐growing soils in Belgium. Soil organic matter (SOM) was fractionated into sand (> 53 μm) and silt+clay (< 53 μm) fractions. The latter fraction was further separated into 6%NaOCl‐oxidation labile (6%NaOCl‐ox) and resistant N and C and subsequently into 10%HF‐extractable (mineral bound) and resistant (recalcitrant) N and C. The N mineralization turnover rate (% of soil N/year) correlated with several of the investigated N or C fractions and stepwise linear regression confirmed that the 6%NaOCl‐ox N was the best predictor. However, the small R² (0.42) of the regression model suggests that soil parameters other than the soil fractions isolated here would be required to explain the significant residual variation in N mineralization rate. A next step could be to look for alternative SOM fractionations capable of isolating bioavailable N. However, it would appear that the observed relationships between N fractions and N mineralization may not be causal but indirect. The number of vegetable crops per rotation did not influence N mineralization, but it did influence 6%NaOCl‐ox N, probably as an effect of differences in crop residues returned and organic manure supply. However, the nature of this relation between management, SOM quality and N mineralization is not clear. Explanation of correlations between N mineralization and presumed bioavailable N fractions, like the 6%NaOCl‐ox N, requires further mechanistic elucidation of the N mineralization process.