The study shows the effect of sulfur (S) fertilization of an alfalfa clover-grass mixture, cultivated on the experimental farm Gladbachhof. Induced by the S fertilization the yield and N and S concentration were positiv influenced

Becker, Konstantin

Fischinger, Stephanie Anastasia

Leithold, Günter

Riffel, Alexandra

Organic Eprints

RAHMANN G & AKSOY U (Eds.) (2014) Proceedings of the 4th ISOFAR Scientific Conference. ‘Building Organic Bridges’, at the Organic World Congress 2014, 13-15 Oct., Istanbul, Turkey (eprint ID 24141)   535 Benefit of sulfate fertilisation in Alfalfa- and  clover grass mixtures in organic  KONSTANTIN BECKER1, ALEXANDRA RIFFEL1, STEPHANIE FISCHINGER1, GÜNTER LEITHOLD1 Key words: sulphur, legumes  Abstract In this study, alfalfa- and clover-grass mixture was fertilized with MgSO4 and CaSO4 (treatments: 1: no treatment, 2: MgSO4 80 S * ha-1, 3: CaSO4 80 kg S * ha-1). The yield, N-content and S-content of the alfalfa- and clover-grass-mixture was clearly positive affected by sulphur fertilization.  Introduction Alfalfa- and clover-grass-mixtures are of high importance for organic farming systems. Their ability to fix atmospheric nitrogen results in high N input into the farming system. It is well known, that nitrogen fixation and plant growth of legumes is affected by sulphur (S) deficiency (Scherer et al. 2007, Varin et al. 2010). Because of the clean air act 91, a decline in S deposits on agricultural crops has been observed throughout Europe during the last decades (Zhao et al. 2002). In consideration of these facts it seems to be obvious, that S-shortage is a common problem in practice of organic farming systems in many regions of Europe. Material and methods  In the years 2010 and 2011, S response trials were at Gladbacherhof, organic trial station of the University Gießen (Villmar Hesse Germany, mean annual temp. 9.3°C, annual precipitation 670 mm, soil texture: clayloam, dairy farm, 1 LU cattle ha-1).  Two sulfate fertilization treatments (80 kg S ha-1 resp. as MgSO4 or CaSO4) were compared with a control (no S) in alfalfa-clover-grass. The experiment was conducted in the second year after establishment (underseed in summer barley) of the alfalfa-clover-grass, and was repeated in two series (2010 and 2011 on different fields). Fertilization was split in 60 kg S ha-1 at the beginning of the growing season (25.03.2010 resp. 10.03.2011) and 20 kg S ha-1 after the first cutting (10.06.2010 resp. 06.06.2011). The experiment was conducted with 4 replications in a randomized block design. Each plot was 3 m x 10 m. Soil samples (0-60 cm depth) were taken at the beginning of the vegetation period (March) and by harvest. Samples from each plot were analyzed for available S (Smin) using the 0,0125 mol L-1 CaCl2 extractable S method and ICP-OES at 181,972 nm. Results In both years (2010 and 2011) S fertilization increased plant available S in the 0-60 cm soil layer (Table 1).  Tab. 1: Smin kg ha-1 0-60 cm depth, different S treatments, Gladbacherhof   after fertilizing first cut second cut third cut fourth cut 2010 Control S 0 2,0 2,8 3,0 0,0 no result MgSO4 S 80 40,5 120,1 59,0 44,7 no result CaSO4 S 80 20,0 39,4 48,0 38,5 no result 2011 Control S 0 7,15 4,1 4,6 9,2 28,8 MgSO4 S 80 87,9 51,7 139,2 85,9 77,3 CaSO4 S 80 49,9 33,3 93,3 60,9 74,2                                                   1 Professorship of Organic Farming, Germany, www.uni-giessen.de/cms/fbz/fb09/institute/pflbz2/olb de, eMail: organ.landbau@agrar.uni-giessen.de BECKER K, et al. Benefit of sulfate fertilisation in Alfalfa- and clover grass mixtures in organic   536 The dry matter yield in the control was with 7,6 t ha-1 and 9,8 t ha-1 in 2010 and 2011 respectively significant lower than in the sulfate fertilized treatments (Table 2).   Tab. 1: Smin kg ha-1 0-60 cm depth, different S treatments, Gladbacherhof  treatment first cut second cut third cut fourth cut Σ 2010 yield DM mixture  (t ha -1) Control 2,72 1,66 2,01 1,24 7,63  a MgSO4 3,13 2,97 3,88 2,08 12,06 b CaSO4 3,44 2,74 3,56 2,06 11,08 b S concentration % DM legumes Control 0,33 a 0,16 a 0,16 a 0,13 a  MgSO4 0,35 a 0,43 b 0,29 b 0,20 b  CaSO4 0,35 a 0,38 b 0,28 b 0,21 b  S concentration % DM grass Control 0,44 a 0,20 a 0,22 a 0,21 a  MgSO4 0,44 a 0,67 b 0,50 b 0,34 b  CaSO4 0,41 a 0,64 b 0,52 b 0,35 b  N concentration % DM legumes Control 3,76 a 2,36 a 2,89 a 2,64 a  MgSO4 4,39 b 3,38 b 3,49 b 2,97 b  CaSO4 4,21 ab 3,42 b 3,54 b 3,01 b  N concentration % DM grass Control 2,19 a 2,05 a 2,55 a 2,00 a  MgSO4 2,49 a 2,58 b 3,30 b 2,82 b  CaSO4 2,36 a 2,51 b 3,46 b 2,78 b  N yield mixture (kg ha-1) Control 89,24 38,15 56,30 29,11 212,80 a MgSO4 120,96 96,08 134,87 59,80 411,71 b CaSO4 124,01 88,85 125,75 64,73 404,34 b 2011 yield DM mixture  (t ha -1) Control 3,82 2,01 2,73 1,23 9,79   a MgSO4 4,86 4,43 2,27 2,35 13,91 b CaSO4 4,50 3,90 2,26 2,56 13,22 b S concentration % DM legumes Control 0,15 a 0,12 a 0,14 a 0,16 a  MgSO4 0,19 b 0,24 b 0,24 b 0,33 b  CaSO4 0,18 ab 0,25 b 0,25 b 0,31 b  S concentration % DM grass Control 0,14 a 0,17 a 0,18 a 0,20 a  MgSO4 0,26 b 0,41 b 0,41 b 0,45 b  CaSO4 0,24 b 0,45 b 0,48 b 0,52 c  N concentration % DM legumes Control 2,59 a 2,61 a 2,79 a 3,19 a  MgSO4 3,17 b 3,09 b 3,12 a 3,66 a  CaSO4 3,07 b 3,13 b 3,12 a 3,79 a  N concentration % DM grass Control 1,81 a 2,09 a 2,27 a 2,54 a  MgSO4 2,16 b 3,26 b 3,78 b 4,28 b  CaSO4 2,14 b 3,03 b 3,58 b 4,29 b  N yield mixture (kg ha-1) Control 85,67 49,19 73,90 37,75 246,52 a MgSO4 140,60 137,13 70,87 86,71 435,31 b CaSO4 125,08 121,07 71,21 97,55 414,91 b  RAHMANN G & AKSOY U (Eds.) (2014) Proceedings of the 4th ISOFAR Scientific Conference. ‘Building Organic Bridges’, at the Organic World Congress 2014, 13-15 Oct., Istanbul, Turkey (eprint ID 24141)   537 Discussion S levels of soil  The S availability in the unfertilized control arranged during the growing periods on a very low level (from 2,0 kg S ha-1 to 9,2 kg S ha-1). Only in September 2011 (not shown) there was an increase of S up to 28,8 kg S ha-1 in the control. This might be a result of enhanced mineralization processes due to higher microbiological activity in the later vegetation period (Scherer 2009). Yield and quality Fertilizing S increased yield 2010 about 50 % and 2011 about 30 %, both MgSO4 and CaSO4. Particular the legumes were positively influenced by S fertilization, whereas the grass was not affected. S fertilization increased S concentration in the shoots (legumes and grass) and in connection with higher yield the harvested S amount, in the sum of the four cuts 18,3 kg S ha-1 in the control plots and about 40 kg S ha-1 in the S-fertilized plots. The S concentration in the shoots clearly increased only after the first cut (< 0,2% (DM) no S; > 0,2% (DM) with S). Sulfate fertilization resulted in considerable increased N yield of the alfalfa clover grass mixture. This was mainly a result of higher N concentration in the leguminous plants in combination with higher growth of this fraction. The control mostly failed below 3 % (DM) while N concentration in fertilized plots reached up to 3,5 % (DM). In both years S fertilizing led to a surplus of 200 kg N ha-1 in the shoot mass compared to no S fertilizing. The results suggest that adequate S supply is of crucial importance for leguminous forage crops. Under S deficiency growth and N accumulation was significantly decreased and resulted in a dramatic reduction of N yield. That means a decline of N input into the whole production system. Providing adequate amounts of plant available S to leguminous forage crops is therefore an important tool to maintain productivity of ecological production system. References  SCHERER H. W., PACYNA S., SPOTH K., SCHULZ, M. 2008: Low levels of ferredoxin, ATP and leghemoglobin contribute to limited N2 fixation of peas (Pisum sativum L.) and alfalfa (Medicago sativa L.) under S deficiency conditions, Biol Fertil Soils, 44: 909-916.  SCHERER, H. W. 2009: Sulfur in soils, review article, Journal of Plant Nutrition and Soil Science 172, pages 326-335  VARIN S., J.-B CLIQUET, S. LEMAUVIEL-LAVENANT 2010: How does sulphur availability modify N acquisitation of white clover (Trifolium repens L.)? Journal of Experimental Botany, Vol. 61, No 1 (2010) pages 225-234 BECKER K, et al. Benefit of sulfate fertilisation in Alfalfa- and clover grass mixtures in organic   538  

Benefit of Sulfate fertilisation in Alfalfa - and clover-grass mixtures in organic farming

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