1. A case study on the application of dredging material to grassland on peat soil, as a fertiliser supplement. C Bufe

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1 LIST OF POSTERS AT THE INTERNATIONAL FERTILISER SOCIETY CONFERENCE DECEMBER A case study on the application of dredging material to grassland on peat soil, as a fertiliser supplement. C Bufe 2. The impact of liming with different liming material on soil ph. B Čeh 3. Polysulphate - a prolonged release sulphate fertiliser. C J Dawson 4. Sulphur an essential nutrient for legumes. C J Dawson 5. From the drips to the fields : Polyphosphates properties for a better plant nutrition. M Demortier 6. Potential to cultivate soybeans in Sweden importance of soil temperature. F Fogelberg and A Mårtensson 7. Effect of timing of fertiliser N on spring barley yield and protein under Irish conditions. R Hackett 8. Assessing the impact of the urease inhibitor Limus on agronomic and environmental parameters in temperate grassland. D J Krol, P J Forrestal, D Wall, G J Lanigan, J Sanz-Gomez, M Knauer, I Ford, G Kelly and K G Richards 9. AHDB s Nutrient Management Guide (RB29). J Holmes 1. Response of tobacco to new fertiliser blends containing polyhalite in comparison to conventional blends in Tanzania. J Lisuma,, K Pavuluri, D Mlay, K Ahodo, R Meakin and N Kuboja 11. Potato yield and dry matter response to different sources of potassium fertiliser in the UK. T D Lewis and R D J Mitchell 12. POLY4 (polyhalite) as a fertiliser for cotton in Virginia, USA. R D J Mitchell and K Pavuluri 13. Using canopy sensing to improve nitrogen management of brassica vegetables. E Sagoo, A Huckle, J P Newell Price, C White and D Whattoff 14. The effect of cover crops on the availability of nitrogen and phosphorus to the following Maize crop. T Storr, R W Simmons and J A Hannam 15. Phosphorus efficient cereals: is genetic engineering of plant phosphorus the answer? P Withers 16. The Role of phosphorus in the resilience and sustainability of the UK food system. P Withers, M Camargo-Valero, D Cordell, D Doody, B Jacobs, H Jarvie, J Martin-Ortega, M Patton and E Sherry

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4 Introduction. Polysulphate - a prolonged release sulphate fertiliser by: Chris Dawson and Associates, York Polyhalite is an evaporite mineral which exists in relatively few places on earth. It is an unusual combination of potassium, calcium and magnesium in a single complex sulphate crystal, with the formula K 2 Ca 2 Mg(SO 4 ) 4.2H 2 O and is suitable for direct application without processing, unlike most fertiliser products. This mineral is present in quantities probably in excess of 1 billion tonnes at an exceptional 9+% purity below the existing potash seam in the Cleveland Potash Boulby Mine of ICL Fertilizers Ltd. Glasshouse and field trials to establish the full solubility and crop availability of the mineral were commenced in 1999 using product from core samples; the sulphur, potassium, magnesium and calcium were confirmed to be fully available to crops. The polyhalite seam was accessed for mining in September 21. This was the first polyhalite ever to be mined, and Boulby still has the only operational polyhalite mine in the world. The processed polyhalite is now marketed by ICL Fertilizers as Polysulphate, primarily as a sulphate fertiliser having a significant potassium, magnesium and calcium content. The guaranteed minimum analysis of Polysulphate is shown in Table 1. As Polysulphate became commercially more widely used by farmers in the UK, France and other countries it was noticed that the granules sometimes took several weeks to dissolve fully and some questioned its solubility. An experiment was therefore set up to investigate the different rates of dissolution of this and other types of sulphate fertiliser. It was known from earlier experiments and field trials that Polysulphate was fully soluble and that its nutrients Potash Magnesium Calcium K 2 O MgO CaO 14% 6% 17% were able to supply the crop as it required them equally as well as from traditional proven sources (potassium sulphate, magnesium sulphate and di-hydrate calcium sulphate), described as equivalent nutrients in the following example chart for sulphur, taken from a replicated pot trial, without leaching (Figure 1). Sulphur uptake Control Equivalent nutrients Granular Polysulphate CUT 4 CUT 3 CUT 2 CUT 1 Figure 1: Uptake of S by each cut of grass. No significant differences were found between the recovery of nutrients supplied from the equivalent nutrient product and from Polysulphate. Triplicate soil columns (2 g sandy loam; arable Wick series) were installed and flushed twice to clean and equilibrate them. They were then fertilised with granular commercial grade Polysulphate, ammonium sulphate (NH 4 ) 2 SO 4, potassium sulphate K 2 SO 4 or magnesium sulphate MgSO 4. The granules were covered with 1 cm of soil. The soil columns were flushed with 1 pore volume of deionised water each day and the leachate collected for analysis by inductively coupled plasma mass spectrometry for sulphur and the constituent cations. Table 1: Nutrient analysis of Polysulphate. Nutrient Content Sulphate SO 3 48% Method. Knowing that the nutrient recovery from Polysulphate by crops was fully equivalent and complete, an experiment was designed with the University of Nottingham to investigate the rates of dissolution of a number of similarly fully soluble sulphur-containing fertilisers. An apparatus was designed which would permit the daily flushing of columns of soil to which Polysulphate granules and other fertilisers had been added. Figure 2: Apparatus for the determination of the relative rates of dissolution of different sulphur-containing fertilisers. Presented on behalf of ICL Fertilizers Ltd. Polysulphate is a Trademark of ICL Fertilizers.

5 Results. As each of the fertiliser products dissolves the constituent ions are released into the soil solution. The cations tend to become held on the clay and organic matter exchange sites while the sulphate ions move down the profile in the draining water, finally reaching the receiving cup below each column together with some balancing cations. This daily flushing of the columns removes the sulphate which has dissolved from the fertiliser product over the previous 24 hours. Thus the relative rate at which each fertiliser product dissolves, the rate of dissolution, can be determined by the quantity of sulphate which is measured in each cup each day. The results of the first 3 days of daily washing of the columns, measured as the percentages of the total available sulphate which accumulates in the successive cups, is shown in Table 2. There are clear differences between the rates of dissolution between these fertiliser products, with virtually all of the ammonium sulphate products being dissolved within 4-5 days. The rate of dissolution of sulphate of potash was marginally slower, with kieserite being a little slower again. The rate of dissolution of the Polysulphate is considerably slower than all the other products, with only 84% of the total finally released being dissolved by day 3. The results of the experiment are shown in graphical form in Figure 3. Relative sulphate release 1% 9% 8% 7% 6% 5% 4% 3% 2% 1% % Polysulphate Kieserite SOP Amm Sulph Days AS / SOP MgSO4 Polysulphate Days to 9% Figure 3: Relative S release rates, comparing Polysulphate with ammonium sulphate, sulphate of potash and kieserite. Table 2: Accumulating percentages of sulphate flushed from the different products in the first 3 days. Days Ammonium sulphate Sulphate of potash Kieserite Polysulphate The days taken to release 9% of the sulphate from each product is also shown in Figure 3, with ammonium sulphate taking about 2 days, sulphate of potash 4 days, kieserite 11 days and Polysulphate 36 days. Conclusions. The extended release period of the nutrients in Polysulphate, particularly the sulphate, offers considerable potential advantage in practical farm conditions. The uptake timings of nitrogen and sulphur by wheat and other crops are very similar (Figure 4) and, because most sources of nitrogen have high rates of dissolution, multiple dressings of nitrogen are usually applied in order to minimise the potential loss of nitrogen as leached nitrate. The prolonged release pattern of the sulphate from Polysulphate allows the application of a single dressing of sulphate in the spring without major risk of loss of sulphate by leaching. S in wheat crop - kg SO3/ha Apr 19-Apr Sulphur (SO3) 26-Apr 3-May 1-May 17-May 24-May 31-May Nitrogen (N) Figure 4: The extended period of S uptake by wheat, relating to the Polysulphate release curve. 7-Jun 14-Jun 21-Jun 28-Jun 5-Jul 12-Jul 19-Jul 26-Jul N in wheat crop - kg N/ha. Presented on behalf of ICL Fertilizers Ltd. Polysulphate is a Trademark of ICL Fertilizers.

6 Introduction. Sulphur an essential nutrient for legumes by: Chris Dawson and Associates, York It is well understood that a balanced supply of available nitrogen and sulphur (S) is essential for the synthesis of true proteins from the precursor amino acids. A lack of sulphur limits the production of two of the amino acids which are required constituents of all proteins cysteine and methionine. Since before the introduction and use of mineral fertiliser nitrogen the deposition of sulphur to agricultural (and other) land was well in excess of crop and animal requirements and sulphur was not discussed as a crop nutrient. 8, 5 However, by 215 the UK sulphur emissions had declined to little more than 1 kt S/yr and Emissions Fertiliser the need for sulphur fertiliser is recognised and 6, 4 applied by many growers (Figure 1). The majority of the fertiliser sulphur requirement to 3 date has been met using ammonium sulphate. 4, Containing both nitrogen and sulphur this is a 2 useful product for use on crops which require 2, both nutrients, but not for legumes which, 1 because of their Rhizobial associations, do not normally receive any nitrogen fertiliser. However the British Survey of Fertiliser Practice (BSFP) reported in 215 that the dressing cover Figure 1: UK sulphur deposition and use of sulphur fertiliser for sulphur on peas and beans was at most 5% of the area of these crops, compared with 52% for the total arable crop area; over 6% of the wheat area received a dressing of sulphur. There are a number of reasons why these legumes, and others, have not received the sulphur they need, including no doubt the lack of cost-effective reliable sulphate fertilisers which do not contain nitrogen. ' tonnes emission SO In 21 ICL Fertilizers Ltd opened two drift roads into the polyhalite seam below the potash horizon in Cleveland Potash s site at Boulby in the North York Moors National Park, creating the first and only polyhalite mine in the world (Figure 2). The new fertiliser Polysulphate is produced following the crushing and grading of the ore, creating a unique and fully water-soluble potassium magnesium calcium sulphate product. The chemical formula for the polyhalite mineral is K 2 Ca 2 Mg(SO 4 ) 4.2H 2 O and the nutrient analysis of Polysulphate is shown in Table 1. The high sulphur content and the lack of nitrogen but with the additional benefit of three other essential Figure 2: Mining machinery accessing the polyhalite seam. macronutrients - potassium, magnesium and calcium - make this a potentially useful fertiliser for legumes. An initial replicated field trial was set up in conjunction with the International Potash Institute (IPI) to examine its effect on a crop of vining peas (Pisum sativum). Table 1: Nutrient analysis of Polysulphate. Nutrient Content Sulphate SO 3 48% Potash K 2 O 14% Magnesium MgO 6% Calcium CaO 17% Vining Peas ' tonnes fertiliser SO 3 The trial field was a sandy clay loam with adequate nutrient levels of phosphorus, potassium and magnesium; no basal fertiliser dressing was considered necessary by the trial operator and indeed none was possible due to the late integration of the Polysulphate treatments within a larger trial. The pea variety was Jubilee, which was drilled on 6 th April, two weeks after the application of the granular Polysulphate, which had been raked into the seedbed (Figure 3). Three dose rates of Polysulphate were applied at 5, 75 and 1 kg SO 3 /ha equivalent, with the control plots receiving no Polysulphate. No differences in colour or vigour were noted and the crop was harvested on 25 th June. Presented on behalf of ICL Fertilizers Ltd. Polysulphate is a Trademark of ICL Fertilizers

7 There was a considerable difference in yield between the control and the Polysulphate treatments, with the indication that the 75 kg SO 3 /ha rate is likely to be the most appropriate for this crop. The average yield response to the Polysulphate from the treatments was +27.5% (Figure 4). Valuing vining peas at 45/t this additional yield would represent an extra income per hectare of about 58, with the probable cost of the fertiliser being about 22.5/ha. Included in the cost of the Polysulphate is not only the sulphate applied but also some potash, magnesium and calcium. While these nutrients may have marginally influenced the crop yield despite the reasonable soil reserves it is considered that the available sulphate was the primary driver of the yield improvement. 6. Fodder legumes. The trial on vining peas clearly illustrates the potential importance of sulphur as a nutrient for grain legumes, but it is equally necessary for fodder legumes, including clovers (Trifolium spp) and lucerne/alfalfa Crude protein % N : S ratio Figure 3: The vining pea trial without Polysulphate without Polysulphate Yield - t/ha at 15% DM kg SO3/ha 5 kg SO3/ha 75 kg SO3/ha 1 kg SO3/ha Figure 4: Yield response of vining peas to different rates of sulphate from Polysulphate. Target N:S ratio (12:1) with Polysulphate with Polysulphate Figure 5: Beneficial effects of an application of 96 kg SO 3 /ha from Polysulphate on the N:S ratio (upper chart) and crude protein (lower chart) of lucerne. (Medicago sativa). A field trial in Scotland in 217 examined the effect of the application of Polysulphate on the nutritional value of a crop of lucerne. Two zero nitrogen treatments were applied, one control providing 8 kg/ha of phosphate and 12 kg/ha of potash only, and the other, with Polysulphate, providing the same phosphate and potash rates with in addition 96 kg SO 3 /ha plus 34 kg CaO/ha and 12 kg MgO/ha. It was not feasible to measure the yields from the two treatments in this trial, but the crude protein and the nitrogen:sulphur ratios were measured (Figure 5). The N:S ratio in the Polysulphate treatment was improved to the 12:1 target value required for optimal digestibility, while at the same time the crude protein content improved by about 1%. Conclusions. The importance of sulphate fertiliser for grain and fodder legumes is clearly demonstrated by the positive yield and quality improvements seen on peas and lucerne, resulting from the application of Polysulphate to these crops. These results, together with other positive results on soya from South America, confirm the value of Polysulphate as an appropriate fertiliser for leguminous crops. Presented on behalf of ICL Fertilizers Ltd. Polysulphate is a Trademark of ICL Fertilizers

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9 Potential to cultivate soybeans in Sweden - impact of soil temperature Fredrik Fogelberg* and Anna Mårtensson** *Research Institute of Sweden, Uppsala, Sweden ** Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden Question How does soil temperature affect soybean emergence? Background Swedish vegans are willing to pay more for Swedish-grown soybeans. Thus, a grow soybeans in Sweden project has set off. Practical experience shows a very uneven emergence. Our hypothesis is that the uneven emergence can be explained by the soil temperature at seeding. Material and methods 3 seeds of 5 varieties of soybeans (Bohemia, Chiba Green, Lu Duo, Midori, Hui Shu 95-1) were seeded in trays with either seeding compost (highly humified peat ph 7.1) or clay soil (15% clay, ph 7.1). The trays were incubated at either 1 o C, 15 o C, 18 o C or 22 o C for 15 days, 7 replicates, emergence was recorded at intervals. The financial support from Ekhagastiftelsen is acknowledged Results Emergence (%) Emergence (%) A, seeding compost B, clay b b b b 15 a a a 1 5 Days b 22 4 b b 18 ab b 15 2 b a a a a Days The impact of soil temperature on the emergence of soybeans The fastest emergence was at 22 o C. At 15 days, 15 o C, 18 o C and 22 o C emerged equally well. Bohemia, Chiba Green and Midori performed equally well at all temperatures, Luo Duo and Hui Shu 95-1 emerged less well. Conclusions For a successful establishment, seeding at low soil temperatures should be avoided. Classified cold tolerant varieties may not be suitable for cultivation at low soil temperature. a

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11 Assessing the impact of the urease inhibitor Limus on agronomic and environmental parameters in temperate grassland. D.J. Krol a, P.J. Forrestal a, D. Wall a, G.J. Lanigan a, J. Sanz-Gomez b, M. Knauer b, I. Ford c, G. Kelly d, K.G. Richards a a Teagasc, Crops, Environment and Land Use, Johnstown Castle, Co. Wexford, Ireland b BASF SE, Agricultural Solutions, Functional Crop Care, Limburgerhof, Germany c BASF plc, Crop Protection, Business Development, Cheadle, United Kingdom d BASF Ireland Ltd., Crop Protection, Business Development, Cork, Ireland dominika.krol@teagasc.ie Introduction Agriculture is the largest contributor of nitrous oxide (N 2 O) and ammonia (NH 3 ) in Ireland, with nitrogen fertilisation being one of the main sources Novel urea-based fertilisers that incorporate urease inhibitors in their formulations aim to abate these losses while maintaining and enhancing yields Objectives Assess the potential of urea-based fertilisers treated with the urease inhibitor Limus to reduce N 2 O and NH 3 losses while maintaining productivity a Results Methods Field trial in Johnstown Castle Parameters: yield, N 2 O and NH 3 losses (Fig. 1a) Treatments (Fig 1. b): control (C), calcium ammonium nitrate (CAN), urea (U), urea with Limus [NBPT:N-(n-butyl) thiophosphoric triamide + NPPT:N-(n-propyl) thiophosphoric triamide](u+limus ) Fertilisation: 2 kg N/ha/yr in six split applications. NH 3 measures done after one application of 4 kg N b Fig 1 a. Experimental site Fig 1 b. Experimental treatments +8%* +9%* c Fig 2 a, b, c Losses of N 2 O and NH 3 and dry matter yield in temperate grassland following N fertilisation with various fertiliser formulations. Different letter indicate statistical significant differences using Tukey-Kramer grouping for Least Square Means P<?.5 *Percentage values in graph 2.c. indicate relative yield increase (%) compared to untreated urea (U) Discussion and Conclusions N 2 O emissions were highest from CAN, whereas urea treated with Limus mitigated N 2 O to levels not significantly different to that of control. Ammonia losses were largest from urea, however addition of the urease inhibitor Limus (U+Limus ) mitigated losses by 68 % to levels not significantly different to these from CAN (Fig. 2 b) Dry matter yield was not affected by fertiliser formulation (Fig. 2 c) Overall, urea-based fertilisers with added urease inhibitors should be considered as suitable alternative for conventional fertilisers associated with large gaseous N losses Acknowledgements This research was financially supported by the Irish Research Council Enterprise Partnership Scheme Postdoctoral Fellowship (grant number EPSPD/216/54) and BASF as industry partner.

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