Labile organic matter fractions as early‐season nitrogen supply indicators in manure‐amended soils |
| |
| Authors: | Ben W Thomas Joann K Whalen Mehdi Sharifi Martin Chantigny Bernie J Zebarth |
| |
| Institution: | 1. Department of Natural Resource Sciences, Macdonald Campus, McGill University, 21,111?Lakeshore?Road, Sainte‐Anne‐de‐Bellevue, Quebec, H9X 3V9, Canada.;2. Environmental and Resource Studies Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario, K9J 7B8, Canada.;3. Agriculture and Agri‐Food Canada, Soils and Crops Research and Development Centre, 2560 Hochelaga Boulevard, Québec, Québec, G1V 2J3, Canada.;4. Agriculture and Agri‐Food Canada, Potato Research Centre, 850 Lincoln Road, P.O. Box 20280, Fredericton, New Brunswick, E3B 4Z7, Canada. |
| |
| Abstract: | Soil test indicators are needed to predict the contribution of soil organic N to crop N requirements. Labile organic matter (OM) fractions containing C and N are readily metabolized by soil microorganisms, which leads to N mineralization and contributes to the soil N supply to crops. The objective of this study was to identify labile OM fractions that could be indicators of the soil N supply by evaluating the relationship between the soil N supply, the C and N concentrations, and C/N ratios of water extractable OM, hot‐water extractable OM, particulate OM, microbial biomass, and salt extractable OM. Labile OM fractions were measured before planting spring wheat (Triticum aestivum L.) in fertilized soils and the soil N supply was determined from the wheat N uptake and soil mineral N concentration after 6 weeks. Prior to the study, fertilized sandy loam and silty clay soils received three annual applications of 90 kg available N (ha · y)?1 from mineral fertilizer, liquid dairy cattle manure, liquid swine manure or solid poultry litter, and there was a zero‐N control. Water extractable organic N was the only labile OM fraction to be affected by fertilization in both soil types (P < 0.01). Across both test soils, the soil N supply was significantly correlated with the particulate OM N (r = 0.87, P < 0.001), the particulate OM C (r = 0.83, P < 0.001), and hot‐water extractable organic N (r = 0.81, P < 0.001). We conclude that pre‐planting concentrations of particulate OM and hot‐water extractable organic N could be early season indicators of the soil N supply in fertilized soils of the Saint Lawrence River Lowlands in Quebec, Canada. The suitability of these pre‐planting indicators to predict the soil N supply under field conditions and in fertilized soils from other regions remains to be determined. |
| |
| Keywords: | dairy manure nitrogen mineralization poultry litter organic amendment swine manure water extractable organic matter |
|
|
