Organic matter fractions and N mineralization in vegetable‐cropped sandy soils

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.

Visible and near infrared spectroscopy for predicting soil nitrogen mineralization rate: Effect of incubation period and ancillary soil properties

“…Moderate but negative correlations are observable between SNMR and TN for Kroky and Langs. Logically, soil TN and TC were moderately to highly correlated, supporting previous reports (Elrys et al, 2021;Jegajeevagan et al, 2013). Soil EC often achieved moderate correlations with TN and TC, and the correlation with TC was observed particularly in fields that have different soil type i.e, Cambisols (Kroky, Langs and VDD).…”

“…Both processes always occur simultaneously in soil and the result is the net N mineralisation, crucially determining crop N availability in soil. The magnitude and Soil N Mineralisation Rate (SNMR) is governed by a large range of soil properties [(soil organic C (SOC) and soil organic N (SON) content, soil texture, pH, soil moisture content (MC) and aeration) and environmental factors (temperature)] ( Dalias et al, 2002;Dessureault-Rompré et al, 2010;Guntiñas et al, 2012;Jegajeevagan et al, 2013). Soil N mineralisation is widely recognized as a critical aspect of soil fertility, essential for providing and evaluating readily available N to agricultural crops.…”

Effects of Two Types of Straw Biochar on the Mineralization of Soil Organic Carbon in Farmland

“…Biochar can seriously affect soil carbon dioxide emissions [35]. Ameloot et al [36]. reported, biochar was prepared from willow wood (Salix dasyclados) and swine manure digestion material at 350 and 700 • C, respectively; when the four treatments of blank, DS350, DS700, WS350, and WS700 were applied to agricultural soil, the C mineralization in all treatments increased rapidly in the early stage, and then the CO 2 emission continued to increase at a much slower rate, which is similar to our results.…”