Excessive Nitrate Limits the Sustainability of Deep Compost Mulch in Organic Market Gardening

Benjamin Ruch, Margita Hefner () and André Sradnick
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Benjamin Ruch: Organic Farming and Cropping Systems, University of Kassel, Nordbahnhofstr. 1 a, 37213 Witzenhausen, Germany
Margita Hefner: Organic Farming and Cropping Systems, University of Kassel, Nordbahnhofstr. 1 a, 37213 Witzenhausen, Germany
André Sradnick: Leibniz Institute of Vegetable and Ornamental Crops (IGZ) e.V., Theodor-Echtermeyer-Weg 1, 14979 Großbeeren, Germany

Agriculture, 2023, vol. 13, issue 5, 1-13

Abstract: Market gardening is a widespread practice of bio-intensive vegetable production characterized by direct marketing, small-scale farming structures, high crop densities, and innovative cultivation approaches. Currently, deep compost mulch (DCM) is a popular trend among related growing techniques. The combination of no-till and a permanent mulch of compost aims to improve soil fertility, regulate soil temperature, retain soil moisture, and control weeds. To address the problem of perennial weeds in organic no-till, deep mulch layers of typically 150 mm are used. The amount of compost required and the associated N inputs are immense and carry the risk of environmentally harmful N surpluses that can be lost through nitrate leaching or denitrification. The aim of this study is to evaluate the use of compost as mulch and to investigate N dynamics under DCM. For this purpose, a literature review was conducted, and soil inorganic nitrogen (N min -N) was measured under on-farm conditions up to a soil depth of 900 mm in a market garden with DCM in Germany for one year. Furthermore, based on the collected data, the different N pathways were calculated using the N-Expert and NDICEA models and simulated for two additional scenarios. Results from field measurements showed a strongly increased N-surplus not taken up by the crops and a shift of N min -N to deeper soil layers for municipal organic waste compost (MW), with an average accumulation of 466 kg N min -N ha −1 at 600–900 mm depth. N inputs from DCM can be significantly reduced by the use of green waste compost (GW) with low bulk density or wood waste compost (WW) with an additional high C/N ratio.

Keywords: organic vegetables; organic mulch; no-dig; no-till; soil mineral N; nitrate leaching; denitrification (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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