Long-term straw management effects on yields of sequential wheat (Triticum aestivum L.) crops in cla

1、Soil & Tillage Research 71 (2003) 5969Long-term straw management effects on yields of sequential wheat (Triticum aestivum L.) crops in clay and silty clay loam soils in EnglandD.B. Turley a, M.C. Phillips a, P. Johnson b, A.E. Jones b, B.J. Chambers ca ADAS High Mowthorpe, Duggleby, Malton, North Yo

2、rkshire YO17 8BP, UKb ADAS Drayton, Stratford-upon-Avon, Warwickshire CV37 9RQ, UKc ADAS Gleadthorpe, Meden Vale, Mansfield, Nottinghamshire NG20 9PF, UKReceived 16 May 2001 ; received in revised form 20 November 2002 ; accepted 30 November 2002AbstractThe incorporation of chopped wheat (Triticum ae

3、stivum L.) straw into soil by tine cultivation (non-soil inversion) or ploughing was compared with burning straw followed by tine cultivation at six sites in England over a period of 11 years. Three sites had clay soils and three silty clay loam soils. Effects of straw management on weed incidence,

4、take-all (Gaeumannomyces graminis var. tritici) infection and grain yield of following wheat crops and occasional break crops were studied. Soil mineral nitrogen and organic matter contents were measured at the end of the study. Incorporating straw by tines rather than burning reduced mean yield at

5、all but one site. The yield reduction from tine incorporation ranged from 5 to 8% on clay soils and 318% on silty clay loam soils. Ploughing straw into soil only had an occasional adverse effect on yield of following crops. Much of the yield penalty associated with tine incorporation of straw was at

6、tributed to weed competition by Bromus spp. Difficulties in preparing a good seedbed, resulting in variable plant emergence, was the other main cause of lower yields with tine incorporation and in situations where plough incorporation reduced yields compared to burning straw. Method of straw disposa

7、l had no consistent effect on take-all infection. The effects of straw incorporation on soil mineral nitrogen and organic matter contents were small and inconsistent. There was no consistent effect of straw management practice on yield response to additional autumn application of nitrogen fertiliser

8、.These results demonstrate that on those soils where ploughing is preferred, it is a suitable option for disposing of straw. Where non-ploughing methods have traditionally been used after straw burning they can still be employed with success, but occasional ploughing or planting of suitable break cr

9、ops may be required to control grass weeds. 2003 Elsevier Science B.V. All rights reserved.Keywords: Straw incorporation; Weeds; Take-all; Nitrogen; Organic matter; Tillage1. IntroductionDuring the 1970s and 1980s, declining demand for cereal straw in the UK and increased production of Corresponding

10、 author. Present address: 25 Broughton Way, Osbaldwick, Yorkshire Y017 8BP, UK.E-mail address: (D.B. Turley).cereals resulted in a surplus of straw, the majority be-ing burnt in the field. By 1984, 6 million tonnes of straw was being burnt, representing 60% of the wheat growing

11、area (Anon., 1992). This highly visible activ-ity occasionally caused significant damage to hedges, trees and property, and caused public outcry each year. A report by The Royal Commission on Environmental Pollution (1984) recommended a ban on straw burning0167-1987/03/$ see front matter 2003 Elsevi

12、er Science B.V. All rights reserved.doi:10.1016/S0167-1987(03)00018-760D.B. Turley et al. / Soil & Tillage Research 71 (2003) 5969and this was introduced from autumn 1992. By 1992 the amount of straw burnt had reduced to about 2 million tonnes. Previous work had demonstrated the potential for buried

13、 straw to affect the growth and yield of following wheat crops (Oliphant, 1982). With changes in farming practices and a much wider range of soil cultivation equipment available, a new study was designed jointly by ADAS (formerly known as the Agricultural Development and Advisory Service) and the fo

14、rmer Agriculture and Food Research Coun-cil (AFRC). This started in autumn 1983 and tested, on large plots, a range of options appropriate to differ-ent soil types and sites. This paper reports some of the results obtained during a 11-year period at six sites. The experiment investigated method of i

15、ncorporating or burning straw on crop establishment, grain yield, weed and disease incidence, and soil mineral nitrogen and organic matter contents.2. Materials and methods2.1. SitesSix sites across England, ADAS Boxworth in Cam-bridgeshire, ADAS Bridgets in Hampshire, ADAS Drayton in Warwickshire,

16、ADAS High Mowthorpe in North Yorkshire, ADAS Terrington in Norfolk and a farm at Rochford in Essex were selected to represent the main cereal growing areas of England. Descrip-tions of the soil type and particle size distribution for each site are given in Table 1. The sites divide into two broad so

17、il typesclays and silty clay loams. While the textural descriptions of the soils are similar,Table 1Description of soils at experiment sitesathe soils at Bridgets and High Mowthorpe are shallow (3050 cm deep) and overlay chalk, while the soil at Terrington is a deep marine silt clay loam.2.2. Croppi

18、ngThe intention was to grow winter wheat continu-ously throughout the period of the experiment. This had to be modified by including break crops in order to control grass weeds, which could not be adequately controlled by chemical means in wheat. Therefore at several sites oilseed rape (Brassica nap

19、us L.), peas (Pisum sativum L.), linseed (Linum usitatissimum L.) or sugar beet (Beta saccharifera) breaks were intro-duced into the cropping sequence. Table 2 gives de-tails of the crops grown in each harvest year. The crop cultivars grown varied among sites and years, but were typical of commercia

20、l practice. The whole trial area at Rochford had to be ploughed after the 1988 harvest and treatments were re-established. These later data are not reported here.2.3. Treatments and designThe number of cultivation treatments tested varied from 4 to 12 among sites. Three core treatments were included

21、 at each site in each year studied: (1) tine/disc cultivation to 15 cm on chopped straw, (2) plough-ing to 20 cm on chopped straw and (3) straw burn-ing followed by tine/disc cultivation to 10 cm. Only the results of these treatments are reported here. In these treatments, off-set discs and spring-t

22、ine cultiva-tors were used. Ploughing was by reversible mould-board plough, followed by secondary cultivations as necessary.SiteSoil textureUK soil seriesSoil particles (%)SandSiltClay1.BoxworthClayHanslope2431452.DraytonClayEvesham2028523.RochfordClay loamWallasea440564.BridgetsCalcareous silty cla

23、y loamAndover1256325.High MowthorpeStony calcareous silty clay loamWold1463236.TerringtonSilty clay loamAgney116029a Size groupings were clay 2 mm, silt 263 mm and sand 632000 mm. FAO soil descriptions by site(1) and (2) fine textured Calcaric Gleysol, (3) fine textured Eutric Fluvisol, (4) and (5)

24、medium textured Calcaric Regosol, and (6) medium textured Calcaric Fluvisol.D.B. Turley et al. / Soil & Tillage Research 71 (2003) 596961Table 2Crops grown at each site over harvest years 19841994 aSiteHarvest year19841985198619871988198919901991199219931994BoxworthwwwwwwwwosrwwwwosrwwwwlinDraytonww

25、wwwwwwwwwwswwwwwwwwwRochfordwwwwwwwwpeasosrwwwwosrwwBridgetswwwwwwwwwwwwwwswlintritwwHigh MowthorpewwwwwwwwwwwwwwwwwwosrwwTerringtonwwwwwwwwwbosrwwwwbeetsbwwa ww: winter wheat; sw: spring wheat; wb: winter barley; sb: spring barley; trit: triticale (winter); osr: oilseed rape; lin: linseed; beet: su

26、gar beet; peas: spring peas.The treatments were applied to main plots that var-ied in size from 486 to 1728 m2 among sites. The aim was to have large enough plots to operate machinery at speeds used under commercial conditions. Nitrogen (40 kg ha1) was applied in the autumn to sub-plots at all sites

27、 except Bridgets. This nitrogen was deemed to be in excess of that required to optimise yield. Spring nitrogen application rates varied across sites and sea-son, but were designed to optimise yield, taking ac-count of soil type, previous cropping and anticipated yield. There were three replicates of

28、 each treatment on the clay sites and four replicates on the silty clay loam sites.2.4. ManagementStraw was burnt in the swath as soon as possible after harvest and cultivations were carried out as soon as possible. Where straw was incorporated, straw was chopped and spread by combine-mounted straw

29、choppers. The cultivation operations were then car-ried out promptly after harvest to allow the chopped straw maximum time in contact with soil before sow-ing wheat. Soil conditions determined the number and direction of passes required each year. For the non-inversion cultivation treatments this wa

30、s usually two passes of spring-tines followed by one or two passes of disc cultivators. A final seedbed was pre-pared before drilling in October. Sites were treated as a whole for drilling date and all fertiliser and pesti-cide applications. Crops were managed according to best local practice in res

31、pect of inputs to minimise the incidence of weeds, pests and diseases and produce optimum yields.2.5. AssessmentsAssessments and measurements were made of the success of the cultivation treatments at incorpo-rating straw and their effects on subsequent plant growth. Yield of grain was measured by on

32、e to three plot-combine cuts per plot each of between 55 and 69 m2 depending on the width of the com-bine cut at each site. Grain samples were taken for oven determination of moisture content (40 h at 100 C).Soil samples were collected at all sites in July 1990 and November 1994. Soil mineral nitrog

33、en was de-termined by KCl extraction of samples taken from 6 points per plot at four depths (015, 1530, 3060 and 6090 cm). Organic matter was determined by standard potassium dichromate digest method from soil samples bulked from 25 points per plot, to cul-tivation depth (015 cm for tines and 020 cm

34、 for ploughing).Crops were monitored regularly for weeds, pests and diseases, and levels were formally assessed where incidence was deemed likely to influence yield poten-tial and/or differences between treatments were ob-served. Weed numbers were counted in 10 randomly chosen 0.1 m2 quadrats per pl

35、ot and disease assess-ments made on 25 plants lifted at random per plot in spring. Infection of roots by take-all (Gaeumanno-myces graminis var. tritici) was assessed, recording the percentage of plants affected by take-all.Data were subjected to analysis of variance each year. Yields were pooled ov

36、er years for each site to demonstrate the long-term effects of the treatments. Standard errors for treatment means are given together62D.B. Turley et al. / Soil & Tillage Research 71 (2003) 5969with the associated least significant difference (LSD) where analysis of variance indicated differences we

37、re statistically significant.3. Results3.1. Grain yield on clay soils3.1.1. BoxworthMean yield across eight seasons was 5% lower with chop/tine than with burn/tine and chop/plough. Yield varied substantially from year to year, but to a much lesser extent among treatments.Dry soil conditions in autum

38、n 1983 made incorpo-rating straw difficult, particularly by tines, resulting in poorer plant establishment where straw was incorpo-rated and yields were reduced in all cases compared to where straw was burnt.By 1987 meadow brome (Bromus commutatus) was well established on the site. Ploughing straw a

39、nd burning both effectively controlled brome but yields were still low. Oilseed rape was sown in autumn 1987 to allow more effective herbicide control measures. Oilseed rape was sown again in autumn 1990 to con-trol grass weeds. However, herbicide residues and pigeon damage affected both this crop a

40、nd the follow-ing wheat so data for harvests 1991 and 1992 were not presented. The final wheat crop in 1993 again suffered from poor plant establishment on chop/tine, and the recurring presence of meadow brome, and also blackgrass (Alopecurus myosuroides) reduced yield (Table 3).3.1.2. DraytonAcross

41、 11 years chop/tine yielded almost 8% less than burn/tine and chop/plough. Grain yield differed little in the first 5 years, with the relative ranking vary-ing from season to season. By 1989 sterile brome (Bro-mus sterilis) infestation on the chop/tine treatment was serious, though the effect on yie

42、ld was not statistically significant. Both ploughing and burning kept popula-tions of sterile brome under control on this site. Ster-ile brome continued to be abundant on the chop/tine treatment from 1992 until 1994. The effect of the weed infestation on grain yield became progressively worse result

43、ing in a significant yield loss of up to 2.46 t ha 1 in 1994 (Table 3).3.1.3. RochfordThere was no consistent or significant effect of straw disposal method on grain yield during 3 years at Rochford (Table 3).3.2. Grain yield on shallow silty clay loam soils3.2.1. BridgetsIncorporating straw with ti

44、ne cultivation resulted in an average 18% yield reduction compared with burn/tine. Ploughing straw had no adverse effect on mean yield compared with burn/tine. For the first 3 years, poor seedbeds on the chop/tine treatment, due to difficulties in incorporating all the straw into soil, resulted in p

45、oor establishment of the crop. There was also a build up in volunteer wheat and sterile brome plants. This resulted in severe lodging and brome in-festation that significantly reduced grain yield.The site was abandoned in autumn 1990 in an at-tempt to reduce the level of sterile brome and spring bre

46、ak crops were sown until autumn 1993. In 1994, plant population in the chop/tine treatment was only 25% of that in other treatments. The autumn was wet and the loss of plants was possibly due to slug grazing. A high population of sterile brome was also recorded. In this situation, yield was signific

47、antly reduced by tine incorporation of straw (Table 4).3.2.2. High MowthorpeProblems with straw incorporation by tines were encountered where the 8-year mean yield reduction was 13% compared with burning straw. Incorporat-ing straw by ploughing was generally satisfactory, though some negative effect

48、s were recorded in 1986 and 1993. Yield reductions with chop/tine in the first 4 years were attributed to poorer seedbeds, with straw in the surface layer affecting soil consolidation. A cul-tivation pan that formed under the non-plough treat-ments was broken after the 1989 harvest, and this may hav

49、e contributed to the tine treatments out-yielding chop/plough in 1990, though moisture loss may also have been a factor in this dry autumn.In 1992, sterile brome and volunteer infestation led to lodging in the tine incorporation treatment. Oilseed rape was sown in autumn 1992. Cleavers (Galium apari

50、ne) were not well controlled in the oilseed crop and were most abundant on the chop/tine treatment, resulting in significant yield loss ( Table 4).D.B. Turley et al. / Soil & Tillage Research 71 (2003) 596963Table 3Yield of grain (t ha1 at 85% DM for cereals and peas, 91% DM for oilseed rape) for th

51、ree cultivation treatments at the three clay soil sitesaYearTreatmentS.E.PLSD0.05Chop/tineChop/ploughBurn/tineBoxworth19849.8910.1610.810.1490.050.58719856.927.427.320.127ns19867.367.297.690.267ns19875.275.875.620.191ns1988b(osr)3.423.333.270.286ns19898.398.298.040.215ns19907.457.457.960.187ns19936.

52、777.437.430.288nsMean7.437.707.840.0800.010.230Drayton19848.217.758.220.272ns19857.987.697.200.384ns19868.098.378.540.170ns19877.477.637.240.0710.050.27619887.377.507.540.134ns19894.695.686.480.399ns1990b(Sp.W)4.194.094.150.121ns19916.717.437.240.176ns19926.647.066.990.237ns19937.429.518.930.1660.01

53、0.65319946.078.128.530.2710.011.063Mean6.807.357.370.0720.0010.207Rochford19855.615.905.380.105ns19866.426.806.940.283ns19876.325.606.120.178ns1988b(peas)4.824.854.650.050nsMean50.117nsa osr: oilseed rape; Sp.W: spring wheat.b Excluded from mean.3.2.3. TerringtonCompared to straw burning,

54、 a mean yield reduction of 3% was observed with chop/tine, mainly due to ef-fects on crops grown in 1984 and 1994. Incorporation of straw generally presented no difficulties and plant establishment was always good across all treatments. Slug activity resulting in loss of plants was noted in 1986, 1987 and 1988, but this did not affect yields adversely.Oilseed rape was sown in autumn 1988 to com-bat the build up of blackgrass. No di