Manipulating Nitrogen Release from Nitrogen-Rich Crop Residues using Organic Wastes under Field Conditions

• Published in: Soil Science Society of America journal Vol. 71; no. 4; pp. 1240 - 1250
• Main Authors: Chaves, B, Neve, S. de, Boeckx, P, Cleemput, O. van, Hofman, G
• Format: Journal Article
• Language: English
• Published: Madison Soil Science Society 01.07.2007; Soil Science Society of America; American Society of Agronomy
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Botrytis; Brassica; Brassica oleracea; carbon nitrogen ratio; Composting; composts; Crop residues; Earth sciences; Earth, ocean, space; equations; Exact sciences and technology; field experimentation; Fundamental and applied biological sciences. Psychology; immobilization in soil; immobilizer wastes; leaching; mineralization; nitrates; nitrogen; organic wastes; Pulp & paper mills; remineralizing wastes; silt loam soils; soil nutrient dynamics; Soil science; Soils; Surficial geology; Belgium; Soil science; Earth science
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj2005.0379

Following mineralization of N-rich crop residues, large amounts of mineral N can be released into the soil. Manipulating N mineralization of crop residues may be an option to reduce NO3(-) in soil. The potential to manipulate the N release from vegetable crop residues by using organic wastes was tested under field conditions. At the start of the experiment, cauliflower (Brassica oleracea L. var. botrytis L.) residues (73 Mg fresh matter ha-1) together with an immobilizer waste (approximately 5 Mg C ha-1 of straw, green waste compost, sawdust, or paper sludge) were incorporated into a silt loam soil. After 154 d, a remineralizing waste (approximately 1 Mg C ha-1 of vinasse or dairy sludge) was incorporated. During the field experiment, the mineral N content in the soil was measured at regular time intervals, and net N release, NO3(-) leaching, and denitrification were simulated using a N mineralization-immobilization model coupled to a NO3(-) leaching model. Straw, green waste compost, and sawdust were able to immobilize between 54 and 68% of the N released by the cauliflower residues and reduced NO3(-) leaching by 56 to 68%. Paper sludge released an extra amount of N due to its low C/N ratio. No consistent remineralization of N could be found in any of the treatments, probably due to an unsuitable composition of the remineralizer wastes. Manipulating N release of N-rich crop residues by using organic wastes may be a suitable method to reduce NO3(-) leaching; however, stimulating remineralization of immobilized N by the start of the following spring may not be easy to achieve.