Seasonality of nitrogen uptake, apparent recovery of fertilizer nitrogen and background nitrogen supply in two Irish grassland soils
Keyword
Apparent recovery of fertilizer nitrogenFertilizer nitrogen for grass
Nitrogen mineralisation
Nitrogen uptake
Seasonality of nitrogen uptake
Date
2013
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P.N.C. Murphy, K. O’Connell, S. Watson, C.J. Watson, J. Humphreys. Seasonality of nitrogen uptake, apparent recovery of fertilizer nitrogen and background nitrogen supply in two Irish grassland soils. Irish Journal of Agricultural and Food Research, 2013, 52, 17–38Abstract
Improving fertilizer nitrogen (N) use efficiency is central to sustainable and profitable grassland agriculture. A plot experiment with a control and fertilizer N (calcium ammonium nitrate, 25–50 kg/ha N) applied on nine occasions from February to September 2002 was conducted at two sites in southwest Ireland to assess N uptake and apparent recovery of fertilizer N (ARFN). Apparent recovery of fertilizer N after eight weeks varied from low in February (21%) and March (46%) to high from April to August (69–98%), indicating that high N use efficiency can be achieved in Irish grasslands at these times. Low recovery in spring suggested that N was applied in excess of immediate crop requirements. Note that N uptake and ARFN values from this study are likely to be somewhat conservative, particularly for spring applications. Over the 8 weeks during which growth was monitored, most (70%) of the grass yield and N uptake response to fertilizer N were in weeks 1 to 4 after application; however, a significant (30%) response occurred in weeks 5–8. This suggested that residual N availability following grazing at 4 weeks can be significant and that there may be scope to decrease N application rates in a grazing rotation. This can potentially improve N use efficiency and decrease N surpluses, with associated economic and environmental benefits. Apparent recovery of fertilizer N was closely related to soil temperature, with a 5.8% increase in ARFN with a 1 °C increase in temperature. Background (non-fertilizer) N supply contributed an average of 164 kg/ha per year (49%) taken up by the fertilized sward, highlighting the potential importance of soil N mineralisation to grassland productivity. Note that these results are for one year at two sites and that conditions may vary between years and at other sites and also that the experiment did not reproduce the cumulative effect of repeated fertilizer application over the grazing year.Funder
Irish National Development Plan; Irish Dairy Levy Research TrustRelated items
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Farm-gate nitrogen balances on intensive dairy farms in the south west of IrelandTreacy, Mark; Humphreys, James; McNamara, Kevin; Browne, R.; Watson, C. J.; Teagasc Walsh Fellowship Programme; European Union; Dairy Levy Research Trust (Teagasc, Oak Park, Carlow, Ireland, 2008)Nitrogen management and farm-gate N balances were evaluated on 21 intensive dairy farms in the south west of Ireland for each of four years (2003 to 2006). The mean annual stocking density was equivalent to 202 kg/ha (s.d. 29.6) of N excreted by livestock on the farm. The mean annual farm-gate N surplus (imports – exports) declined between 2003 and 2006 (277 to 232 kg/ha, s.e. 6.8; P < 0.001) due to a decline in annual N imports (fertilizer, feed and imported manures; 335 to 288 kg/ha, s.e. 6.9; P < 0.001). Overall annual fertilizer N use on the farms decreased during the study period (266 to 223 kg/ha, s.e. 6.5; P < 0.001) mainly due to lower inputs for the first application in spring and for the production of first-cut silage. These decreases were partly offset by applying more slurry in spring for early grazing and for first-cut silage. The introduction of white clover resulted in lower N imports on four farms. Export of N from farms was unaffected by reductions in N imports. The mean efficiency of N use tended to increase over time (0.18 in 2003 to 0.20 in 2006). The large variation in quantities of fertilizer N applied on farms with similar stocking densities suggests potential for further improvements in the efficiency of N use. In terms of fertilizer N use, complying with S.I. No. 378 of 2006 did not require major changes in the N management practiceson 19 of the farms.
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Future global pig production systems according to the Shared Socioeconomic PathwaysLassaletta, Luis; Estellés, Fernando; Beusen, Arthur; Bouwman, Lex; Calvet, Salvador; van Grinsven, Hans J.M.; Doelman, Jonathan; Stehfest, Elke; Uwizeye, Aimable; Westhoek, Henk; et al. (Elsevier, 2019-02-08)Global pork production has increased fourfold over the last 50 years and is expected to continue growing during the next three decades. This may have considerable implications for feed use, land requirements, and nitrogen emissions. To analyze the development of the pig production sector at the scale of world regions, we developed the IMAGE-Pig model to describe changes in feed demand, feed conversion ratios (FCRs), nitrogen use efficiency (NUE) and nitrogen excretion for backyard, intermediate and intensive systems during the past few decades as a basis to explore future scenarios. For each region and production system, total production, productive characteristics and dietary compositions were defined for the 1970–2005 period. The results show that due to the growing pork production total feed demand has increased by a factor of two (from 229 to 471Tg DM). This is despite the improvement of FCRs during the 1970–2005 period, which has reduced the feed use per kg of product. The increase of nitrogen use efficiency was slower than the improvement of FCRs due to increasing protein content in the feed rations. As a result, total N excretion increased by more than a factor of two in the 1970–2005 period (from 4.6 to 11.1 Tg N/year). For the period up to 2050, the Shared Socio-economic Pathways (SSPs) provide information on levels of human consumption, technical development and environmental awareness. The sustainability of pig production systems for the coming decades will be based not only on the expected efficiency improvements at the level of animal breeds, but also on four additional pillars: (i) use of alternative feed sources not competing with human food, (ii) reduction of the crude protein content in rations, (iii) the proper use of slurries as fertilizers through coupling of crop and livestock production and (iv) moderation of the human pork consumption.
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Temperate Grassland Yields and Nitrogen Uptake Are Influenced by Fertilizer Nitrogen SourceHarty, Mary A.; Forrestal, Patrick J.; Carolan, Rachael; Watson, C. J.; Hennessy, Deirdre; Lanigan, Gary; Wall, David; Richards, Karl G.; Department of Agriculture, Food and the Marine, Ireland; Teagasc Walsh Fellowship Programme; et al. (American Society of Agronomy, 25/01/2017)In temperate grasslands, N source influences greenhouse gas emissions. Nitrification and urea hydrolysis inhibitors can reduce these losses. The objective of this study was to evaluate the impact of N source, urease inhibitors, and nitrification inhibitors on temperate grassland yields and N uptake. Experiments were conducted at three locations over 2 years (6 site-years) on the island of Ireland, covering a range of soils and climatic conditions. Results showed that calcium ammonium nitrate (CAN), urea+N-(n-butyl) thiophosphoric triamide (NBPT), urea+NBPT+dicyandiamide (DCD), and urea had equal annual dry matter yield. Urea+DCD had lower dry matter yield than CAN for 3 site-years. Calcium ammonium nitrate and urea+NBPT consistently had the same N uptake, urea+DCD had lower N uptake than CAN in 4 of 6 site-years, urea had lower N uptake than CAN in 2 site-years, and urea+NBPT+DCD had lower N uptake than CAN in 1 site-year. Urea+NBPT is a cost-effective alternative to CAN, which is consistently equal in terms of yield and N uptake in temperate grassland.