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Mineral Fertilizer and Manure Effects on Leached Inorganic Nitrogen, Nitrate Isotopic Composition, Phosphorus, and Dissolved Organic Carbon under Furrow Irrigation
Author(s) -
Lentz R. D.,
Lehrsch G. A.
Publication year - 2018
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2017.09.0384
Subject(s) - leaching (pedology) , fertilizer , chemistry , nitrate , dissolved organic carbon , manure , phosphorus , nutrient , irrigation , nitrogen , environmental chemistry , agronomy , soil water , environmental science , soil science , organic chemistry , biology
A better understanding of nutrient leaching in furrow irrigated agriculture is needed to optimize fertilizer use and avoid contamination of water supplies. In this field study (2003–2006), we measured deep percolation fluxes at 1.2‐m depth and associated nutrient concentrations and mass losses from dairy manure nitrogen (N) or mineral N (urea, sodium nitrate [NaNO 3 ])–amended soils (372 kg available N ha −1 in 4 yr) and nonamended controls and determined the δ 15 N‐NO 3 and δ 18 O‐NO 3 isotope ratios in the leached nitrate. Flow‐weighted concentration means for individual irrigations varied widely, from near zero to as much as 250 mg L −1 for NO 3 –N, 480 μg L −1 for dissolved reactive phosphorus (DRP), 43 mg L −1 for dissolved organic C (DOC), and 390 mg L −1 for chloride (Cl). Relative to other treatments, mineral fertilizer increased NO 3 –N concentrations 2.6‐ to 3‐fold and Cl concentrations 2.6‐ to 3.6‐fold in deep leachate, particularly when NaNO 3 was applied in 2004 and 2006, and produced maximum mean season‐long NO 3 –N and Cl losses. Manure and control treatments produced similar leachate nutrient mass losses, and for some irrigation periods, mineral fertilizer produced 85 and 97% lesser DRP losses and two times greater Cl losses compared with manure and control treatments. Four‐year cumulative losses among treatments differed only for Cl. Isotopic composition of deep‐leached nitrate indicates that both transformation and biologic cycling of mineral and manure N are rapid in these soils, which, with percolation volume, influence the amounts of NO 3 –N and DOC leached. In light of the potential negative effects associated with either fertilizer type, and because even nonamended soils produced substantial amounts of leached NO 3 –N (69.5 kg ha −1 yr −1 ), management must minimize percolation water losses to limit nutrient losses from these fertilized, furrow‐irrigated soils. Core Ideas Nutrient losses were more correlated with percolation water volume than nutrient concentration. Adsorption, precipitation, and cycling of manure nutrients limit their losses below 1.2‐m depth. To limit nutrient losses in furrow irrigated soils, percolation water losses must be reduced.