Nitrate (NO3 -) leaching from grassland can be kept at acceptable levels, but is often high after ploughing for grassland renewal or for silage maize/grain production. In on-farm research with several organic farmers, management options are being explored to save scarce organic manure and to reduce N-losses

de Wit, J.

van der Burgt, G. J.

van Eekeren, N.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings XX International Grassland Congress Management Options to Reduce N-Losses from Ploughed Grass-Clover J. de Wit Louis Bolk Institute, The Netherlands G. J. van der Burgt Louis Bolk Institute, The Netherlands N. van Eekeren Louis Bolk Institute, The Netherlands Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/20/satellightsymposium1/52 The XX International Grassland Congress took place in Ireland and the UK in June-July 2005. The main congress took place in Dublin from 26 June to 1 July and was followed by post congress satellite workshops in Aberystwyth, Belfast, Cork, Glasgow and Oxford. The meeting was hosted by the Irish Grassland Association and the British Grassland Society. Proceedings Editor: D. A. McGilloway Publisher: Wageningen Academic Publishers, The Netherlands © Wageningen Academic Publishers, The Netherlands, 2005 The copyright holder has granted the permission for posting the proceedings here. This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. Optimisation of nutrient cycling and soil quality for sustainable grasslands 10723-4 7-5 6-6 21-6 3-9 25-11A 25 23 83 107 65 58B 20 18 89 110 26 46C 13 15 71 88 24 37D 10 66 121 143 77 49Table 2 Recorded mineral N-availabity (0-30 cm, kg/ha) for different treatments at different datesMineral N (kg/ha) at:21-6 25-11Treatment (ton DM/ha) (0-60 cm) ( 0-90 cm)A 16.8 136 135B 15.8 133 100C 15.3 113 58D 16.1 175 103Table 1 Maize production and mineral availability for different management optionsMaize productionManagement options to reduce N-losses from ploughed grass-clover J. de Wit, G.J. van der Burgt and N. van Eekeren Louis Bolk Institute, Hoofdstraat 24, 3972 LA Driebergen, The Netherlands, Email: j.dewit@louisbolk.nl  Keywords: nitrate leaching, N-losses, grass-clover, silage maize  Introduction  Nitrate (NO3-) leaching from grassland can be kept at acceptable levels, but is often high after ploughing for grassland renewal or for silage maize/grain production. In on-farm research with several organic farmers, management options are being explored to save scarce organic manure and to reduce N-losses.   Materials and methods  A trial was conducted on a loamy löss (2.6% OM in 0-30 cm) with four treatments: A) ‘standard’ farmer practice, i.e. application of 20m3 of slurry in early spring (21 April), mowing grass (26 May), soil ripping, application of 18m3 slurry, ploughing and sowing of maize (1 June); B) and C) were similar to A, but with no slurry application before ploughing, or no slurry at all, respectively. D) as C), but with early soil ripping (27 April) to enhance N-availability. Field history included three years of arable crops followed by one-year grass-clover (> 50% clover). Mineral N-availability was measured 9 times at regular intervals, maize production was assessed by harvesting three rows of 3 m/plot. Mineral N-availability in the layer of 0-30 cm was modelled by the soil-N flow model NDICEA (Koopmans & Bokhorst, 2002).  Results  The recorded mineral N-availability was lower than standard Dutch advice (185 kg N/ha), while recorded residual N was higher than the maximum Dutch advice to attain NO3 leaching <50 mg/l, i.e. 90 kg N (Table 1). The recorded production follows mineral N-availability reasonably closely except for the early soil ripping treatment. Figure 1 shows the NDICEA-results, matching the recorded mineral N-levels closely (Table 2) except for the late growing period, possibly due to underestimation of the capillary capacity resulting in a predicted decomposition rate being lower than reality (2003 was an extremely dry year). Figure 1 also shows NDICEA-results of “treatment E”, being similar to D but with silage maize following three-year-old grass-clover. Mineral N-availability is predicted to be much higher due to the decomposition of a much higher amount of easily available soil OM (roots and living soil organisms).   Conclusion  Silage maize production following grass-clover was increased by manure application but N-losses, both residual- N and denitrification losses (not shown), increased much more. This is particularly true for grass-clover leys older than 2 years. Early soil ripping enhances mineral N-availability and silage maize production without applying scarce organic manure, but also reduces grass production and increases potential N-losses. Therefore, future experiments will be concentrated on maize production without destroying the grass-clover to facilitate a more direct transfer of fixated N from clover to maize and possibly lower inherent N-losses.  Figure 1 Simulated mineral N availability (kg/ha, 0,30cm) References Koopmans, C. J. & J. Bokhorst, 2002. Nitrogen mineralisation in organic farming systems: a test of the NDICEA model. Agronomie 22, 855-862 05010015020025019-2 19-3 16-4 14-5 11-6 9-7 6-8 3-9 1-10 29-10 26-11A B C D E= as D but after 3-years grassclover

Management Options to Reduce N-Losses from Ploughed Grass-Clover

Nitrate (NO3-) leaching from grassland can be kept at acceptable levels, but is often high after ploughing for grassland renewal or for silage maize/grain production. In on-farm research with several organic farmers, management options are being explored to save scarce organic manure and to reduce N-losses

Offered papers 74923-4 7-5 6-6 21-6 3-9 25-11A 25 23 83 107 65 58B 20 18 89 110 26 46C 13 15 71 88 24 37D 10 66 121 143 77 49Table 2 Recorded mineral N-availabity (0-30 cm, kg/ha) for different treatments at different datesMineral N (kg/ha) at:21-6 25-11Treatment (ton DM/ha) (0-60 cm) ( 0-90 cm)A 16.8 136 135B 15.8 133 100C 15.3 113 58D 16.1 175 103Table 1 Maize production and mineral availability for different management optionsMaize productionManagement options to reduce N-losses from ploughed grass-clover J. de Wit, G.J. van der Burgt and N. van EekerenLouis Bolk Institute, Hoofdstraat 24, 3972 LA Driebergen, The Netherlands, Email: j.dewit@louisbolk.nlKeywords: nitrate leaching, N-losses, grass-clover, silage maize Introduction  Nitrate (NO3-) leaching from grassland can be kept at acceptable levels, but is often high after ploughing for grassland renewal or for silage maize/grain production. In on-farm research with several organic farmers, management options are being explored to save scarce organic manure and to reduce N-losses.  Materials and methods  A trial was conducted on a loamy löss (2.6% OM in 0-30 cm) with four treatments: A) standard farmer practice, i.e. application of 20m3 of slurry in early spring (21 April), mowing grass (26 May), soil ripping, application of 18m3 slurry, ploughing and sowing of maize (1 June); B) and C) were similar to A, but with no slurry application before ploughing, or no slurry at all, respectively. D) as C), but with early soil ripping (27 April) to enhance N-availability. Field history included three years of arable crops followed by one-year grass-clover (> 50% clover). Mineral N-availability was measured 9 times at regular intervals, maize production was assessed by harvesting three rows of 3 m/plot. Mineral N-availability in the layer of 0-30 cm was modelled by the soil-N flow model NDICEA (Koopmans & Bokhorst, 2002). Results  The recorded mineral N-availability was lower than standard Dutch advice (185 kg N/ha), while recorded residual N was higher than the maximum Dutch advice to attain NO3 leaching <50 mg/l, i.e. 90 kg N (Table 1). The recorded production follows mineral N-availability reasonably closely except for the early soil ripping treatment. Figure 1 shows the NDICEA-results, matching the recorded mineral N-levels closely (Table 2) except for the late growing period, possibly due to underestimation of the capillary capacity resulting in a predicted decomposition rate being lower than reality (2003 was an extremely dry year). Figure 1 also shows NDICEA-results of treatment E, being similar to D but with silage maize following three-year-old grass-clover. Mineral N-availability is predicted to be much higher due to the decomposition of a much higher amount of easily available soil OM (roots and living soil organisms).  Conclusion  Silage maize production following grass-clover was increased by manure application but N-losses, both residual- N and denitrification losses (not shown), increased much more. This is particularly true for grass-clover leys older than 2 years. Early soil ripping enhances mineral N-availability and silage maize production without applying scarce organic manure, but also reduces grass production and increases potential N-losses. Therefore, future experiments will be concentrated on maize production without destroying the grass-clover to facilitate a more direct transfer of fixated N from clover to maize and possibly lower inherent N-losses. References Koopmans, C. J. & J. Bokhorst, 2002. Nitrogen mineralisation in organic farming systems: a test of the NDICEA model. Agronomie 22, 855-862 Figure 1 Simulated mineral N availability (kg/ha, 0-30cm) 05010015020025019-2 19-3 16-4 14-5 11-6 9-7 6-8 3-9 1-10 29-10 26-11A B C D E= as D but after 3-years grassclover

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Management Options to Reduce N-Losses from Ploughed Grass-Clover

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