In order to gain momentum in the consolidation process of no-tillage systems in Europe’s Organic Agriculture, occasional direct seeding (DS) of faba bean (FAB) into a mulch layer of residues from precrop oats should be scrutinized. In contrast to non-legumes, grain legumes do not depend on soil-borne nitrogen due to their ability to fix nitrogen symbiotically. Concerning weed infestation, straw residues left by precrops may at least physically suppress weeds. In order to prove this hypothesis, two field experiments were carried out in 2009 at two sites in the lower Rhineland region, Germany. DS treatments were combined with 0, 4, and 6 t ha-1 of straw residues. Mouldboard ploughing (MP) combined with conventional seedbed preparation was used as control. Compared to the DS treatment without straw residue (0 t ha-1), DS treatments with straw residues (4 and 6 t ha-1, resp.) resulted in significantly lower weed density (70 and 84 % resp.). Neither differences were observed in both shoot dry matter of FAB and weeds for DS with straw residues compared with MP, nor for the grain yields of FAB. We conclude that occasional DS of FAB in OA is successful to reduce annual weeds sufficiently and may not lead to reduced FAB yields

Köpke, Ulrich

P. Massucati, Luiz F.

English

Organic Eprints

European Congress on Conservation Agriculture, Madrid 575-580 (2010)   Weed Control with Straw Residues in Occasional Direct Seeding of Faba Bean (Vicia faba sp.) in Organic Agriculture Massucati L.F.P.1 & U. Köpke Key words: no-tillage system, precrop oats, firm soil mulch husbandry, Organic Farming ABSTRACT In order to gain momentum in the consolidation process of no-tillage systems in Europe’s Organic Agriculture, occasional direct seeding (DS) of faba bean (FAB) into a mulch layer of residues from precrop oats should be scrutinized. In contrast to non-legumes, grain legumes do not depend on soil-borne nitrogen due to their ability to fix nitrogen symbiotically. Concerning weed infestation, straw residues left by precrops may at least physically suppress weeds. In order to prove this hypothesis, two field experiments were carried out in 2009 at two sites in the lower Rhineland region, Germany. DS treatments were combined with 0, 4, and 6 t ha-1 of straw residues. Mouldboard ploughing (MP) combined with conventional seedbed preparation was used as  control. Compared  to the  DS treatment  without  straw  residue  (0 t  ha-1),  DS treatments with straw residues (4 and 6 t ha-1, resp.) resulted in significantly lower weed density (70 and 84 % resp.). Neither differences were observed in both shoot dry matter of FAB and weeds for DS with straw residues compared with MP, nor for the grain yields of FAB. We conclude that occasional DS of FAB in OA is successful to reduce annual weeds sufficiently and may not lead to reduced FAB yields. INTRODUCTION Aims of reducing tillage intensity include to prevent soil compaction and erosion, to improve  top  soil  trafficability  and  to  save  labour  and  energy  costs  (Pekrun  and Claupein  1998).  Moreover,  non-inverting  tillage  procedures  usually  show  higher microbial activity and microbial biomass in the 0-10cm soil layer compared with ploughed soils (Doran 1987, Berner et al. 2008). However, in Organic Agriculture (OA) in the European temperate climate, the use of loose soil husbandry (LSH) – mostly  performed  with  the  mouldboard  plough  (MP)  -  is  still  the  common  soil tillage system (Köpke 2003). Only a few organic farmers in Central Europe use the extreme  option  of  firm  soil  mulch  husbandry  (FSMH),  i.e.  direct  seeding  (DS), mainly due to two reasons: (i.) under temperate climate conditions omitting deep loosening and inversion of the topsoil results in cooler wetter soils in early spring, reducing  mineralization  and  nitrification  of  soil-borne  nitrogen,  as  well  as  its transformation  into  crop  yield  of  non-leguminous  crops.  (ii.)  LSH,  in  particular ploughing, is an effective tool to control annual and perennial weeds (Köpke 2003). In contrast to mainstream farmers, synthetic herbicides are not allowed to be used in OA,  also their natural counterparts  (e.g. natural vinegar, corn gluten, pine wood extracts) that are officially certified in other regions of this globe, are currently not considered as adequate to be used in Europe’s OA (Kühne et al. 2005). In contrast to non-legumes, grain legumes as FAB do not depend on soil-borne nitrogen due to their ability to fix nitrogen symbiotically. For crop establishment their demand for                                                  1 Institute of Organic Agriculture (IOL), University of Bonn, Katzenburgweg 3, D-53115 Bonn, Germany, E-Mail: luiz.massucati@uni-bonn.de, Internet: www.iol.uni-bonn.de European Congress on Conservation Agriculture, Madrid 575-580 (2010)   water is high. Thus, FAB are well-adapted to the wetter no-tilled soil in early spring. During the later stages of crop development FAB possess a high competitiveness against weeds.  Mulch  layers  of  precrops  may  suppress  weeds.  For  efficient  weed  suppression Barberi  (2002)  considers  homogeneous  distribution  of  at  least  4-6  t  ha-1  crop residues  necessary.  Additionally,  allelopathic  action  of  some  oats  genotypes  has been  assumed  (Chou  1986).  For  the  conditions  of  European  temperate  climate, competitiveness of yellow oats (Avena sativa L.) is considered as relatively high when compared with other cereals (Davies & Welsh 2001). Based on this approach we  set  up  field  trials  after  precrop  yellow  oats  in  order  to  test  the  following hypotheses: (i.) Occasional direct seeding of FAB into a mulch layer of precrop oats enables sufficient control of annual weeds; (ii.) Direct seeding of FAB in OA is not possible, unless the weed infestation is sufficiently suppressed. MATERIALS AND METHODS Two one-factorial field trials with four replicates were carried out in 2009 at the organic  research  farm  Wiesengut  (WG)  of  the  University  of  Bonn  in  Hennef (Germany) on a clayey-silty to sandy-silty floodplain sediment (fluvisol, 50°48´ N, 7°17´ E; 62 m a.s.l.; mean annual temperature 10.3°C; mean annual precipitation 840 m). A second trial was conducted in the same year under the conditions of low weed  pressure  at  the    conventional  experimental  farm  Frankenforst  (FF)  of  the University of Bonn in Königswinter (Germany) on a stagnic luvisol derived from loess (50°42' N, 7°12' E; 182 m a.s.l.; mean annual temperature 9.0°C; mean annual precipitation 700 m). DS-treatments were diffferenciated by the amount of straw residues:  0,  4,  6  t  ha-1,  resp.  Mouldboard  ploughing  (MP)  combined  with conventional seedbed preparation, an oil radish winter cover crop, ploughing and seed bed preparation in early spring was used as control. FAB were sown on March 21 and April 7 at site WG (85 grains m-2) and FF (45 grains m-2) respectively, by using a direct seeding machine type SEMEATO SHM 11/13. Weed density of annuals (individuals m2) was determined on February 26 and April 09 at WG as well as on March 10 and May 05 at FF in 0.1 m2 subplots with four replicates per plot. Dry matter of weeds and FAB were determined 88 DAS by harvesting the shoot mass in ½ m2 subplots, with two replicates per plot. Grain yields were determined 130 DAS by harvesting an area of 10 m2 and 20 m2 per plot at WG and FF, respectively. ANOVA was performed by using SPSS (version 18) followed by Shapiro-Wilk’s test. For analysis of variance (ANOVA) means were compared using the Scheffé’s test. RESULTS AND DISCUSSION According to our hypothesis, increased amount of straw residues in DS treatments resulted in significantly lower density of annuals (Fig. 1). Compared with the DS treatment without straw residue (0 t ha-1), DS treatments with straw residues (4 and 6 t ha-1) resulted in a decrease of weed density by about 70 to 84%. Despite the weed controlling effect of MP, the weed density in DS treatment 6 t ha-1 was considerably lower than the density in the control. DS treatments with straw residues (4 and 6 t European Congress on Conservation Agriculture, Madrid 575-580 (2010)   ha-1) showed lower weed dry matter compared with DS without straw. Nevertheless, only  the  DS  6  t  ha-1  treatment  was  significantly  different  from  the  DS  0  t  ha-1 treatment (Fig. 1). Both DS treatments with straw residues were not significantly different  from  the  MP  control.  As  expected,  both  weed  parameters  showed  a considerable weed suppression effect as a function of the amount of straw left in the field.  These  results  confirmed  previous  studies  on  the  effectiveness  of  weed suppression by increasing soil coverage (e.g. Bilalis et al. 2003). In agreement to Barberi  (2002),  efficient  weed  suppression  can  be  achieved  with  straw  residues amounting at least 4 t ha-1. Ind m-20255075100125150350375g m-20255075100125150350375weed densityweed shoot dry matterMPcontrol0 4 6t ha-1 straw residuesabacbcBAABB FIG 1: WEED DENSITY ±SD (IND. M-2) AND WEED SHOOT DRY MATTER ±SD (G M-2) IN FABA  BEAN,  AS  AFFECTED  BY  TILLAGE  TREATMENT:  MOULDBOARD  PLOUGHING (CONTROL), AND DIRECT SEEDING (DS) INTO STRAW RESIDUES OF 0, 4 AND 6 T HA-1, RESPECTIVELY.  DIFFERENT  LETTERS  SHOW  SIGNIFICANT  DIFFERENCE  (SCHEFFÉ TEST, Α<0.05). The lower shoot dry matter and grain yields of FAB in DS plots without straw (0 t ha-1) compared with DS treatments with straw residues (4 and 6 t ha-1), although not significant (Tab. 1) may at least partly be the result of the early competition by the annuals. No significant yield differences  were determined between MP and DS treatments with straw  residues, in contrast to the DS treatment without straw. Reduced weed pressure and vigorous growth of FAB enabled DS treatments with straw residues (4 and 6 t ha-1) to increase the grain yield by0.2 and 0.4 t ha-1, respectively. Concerning previous results (Köpke 2008), costs for labour and fuel inputs were more than five-fold higher in MP compared with DS. Based on these results a0.5 t ha-1 lower grain yield could be accepted for the DS treatments before equalizing the gross margin of the MP treatment. European Congress on Conservation Agriculture, Madrid 575-580 (2010)   TAB 1: SHOOT DRY MATTER ±SD AND GRAIN YIELD ±SD OF FABA BEAN AS AFFECTED BY TILLAGE TREATMENT: MOULD-BOARD PLOUGH (MP, CONTROL), DIRECT SEEDING (DS)  INTO  MULCH  RESIDUES  (0,  4  AND  6  T  HA-1).  DIFFERENT  LETTERS  SHOW SIGNIFICANT DIFFERENCES (SCHEFFÉ TEST, Α<0.05). Shoot dry matter (t ha⁻¹) 10.0 ±1.5 a 8.1 ± 1.5 b 9.1 ± 2.1 ab 9.7 ± 1.9 abGrain yield (t ha⁻¹) 3.1 ±0,8 ab 2.9 ± 0.5 b 3.1 ± 0.7 ab 3.3 ± 0.6 aMP        controloDS in straw residues (t ha⁻¹)0 4 6 CONCLUSIONS Occasional DS of FAB into mulch layers of the precrop oats enables successful weed control of annuals. This DS system can be considered a suitable approach to save labour and fuel, where perennial weeds do not play an important role or can be accepted due to sufficient crop competitiveness.  Failure  of  clear  effects  of  weed  suppression  of  perennials  makes  further investigations necessary. ACKNOWLEDGEMENT We gratefully acknowledge the support of the Federal Agency for Agriculture and Food (BLE), Germany, making this research possible. REFERENCES Barberi, P., 2002. Weed management in organic agriculture: Are we addressing the right issues? Weed Research 42, pp. 177-193. Berner, A., I. Hildermann, A. Fliessbach, L. Pfiffner, U. Niggli and P. Mäder, 2008. Crop yield and soil fertility response to reduced tillage under organic management. Soil and Tillage Research, 101, 89-96. Bilalis, D., N. Sidiras, G. Economou and C. Vakali, 2003. Effects of different levels of wheat straw soil surface coverage on weed flora in Vicia faba crops. Journal of Agronomy and Cropscience, 189, 233-241. Chou, C. H., 1986. The role of allelopathy in subtropical agroecosystems in Taiwan. In Putnam, A. R. and Tang, C. S. (eds): The Science of Allelopathy, New York, pp. 57-73. Davies, D. H. K. and J. P. Welsh, 2001. Weed control in organic cereals and pulses. In Younie, D., Taylor, B. R., Welsh, J. P., Wilkinson, J. M. (eds.):  Organic cereals and pulses: Chalcombe Publications, Lincoln, pp. 77-114. Doran, J.W., 1987. Microbial biomass and mineralizable nitrogen distributions in no-tillage and plowed soils. Biology and Fertility of Soils, 5: 68-75 Köpke, U., 2003. Spezifika der Bodenbearbeitung und Unkrautregulierung im Ökologischen Landbau aus der  Sicht  der  Wissenschaft  und  der  Praxis.  In:  Bodenbearbeitung  und  Unkrautregulierung  im Ökologischen Landbau, KTBL-Schrift 416: 7-22.  Köpke, U., 2008. Anpassungsmöglichkeiten an den Klimawandel durch Bodenbearbeitung und Fruchtfolge. In:  Klimawandel  und  Ökolandbau:  Situation,  Anpassungsstrategien  und  Forschungsbedarf. Kuratorium für Technik und Bauwesen in Landwirtschaft. KTBL-Schrift 472: 141-159. Kühne, S, A. Verschwele, D. v. Hörsten and M. Jahn, 2005. Implementation of bioherbicides and seed treatment  in organic  farming.  In  Köpke,  U., Niggli, U., Neuhoff, D., Cornish, P.,  Lockeretz, W., Willer, H. (eds.): Researching sustainable systems. Proceedings of the First Scientific Conference of the  International  Society  of  Organic  Agriculture  Research  (ISOFAR)  21-23  September  2005, Adelaide, South Australia, pp. 150- 153. Pekrun, C and W. Claupein, 1998. Forschung zur reduzierten Bodenbearbeitung in Mitteleuropa: eine Literaturübersicht. Pflanzenbauwissenschaften, 2 (4): 160-175 

Weed Control with Straw Residues in Occasional Direct Seeding of Faba Bean (Vicia faba sp.) in Organic Agriculture

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