河南科技大學(xué)機(jī)械外文翻譯

1、Soil & Tillage Research 75 (2004) 7586Effects of agricultural machinery with high axle load on soil properties of normally managed fieldsLothar Schfer-Landefeld a, Robert Brandhuber b, Stefan Fenner c,Heinz-Josef Koch d, Nicol Stockfisch da Prlat-Michael-Hck-Str. 59, D-85354 Freising, Germanyb Bayer

2、ische Landesanstalt fr Landwirtschaft, Postfach 1641, D-85316 Freising, Germanyc Geismar Landstr. 9, D-37083 Gttingen, Germanyd Institut fr Zuckerrbenforschung, Holtenser Landstr. 77, D-37079 Gttingen, GermanyReceived 20 September 2002 ; received in revised form 4 July 2003 ; accepted 10 July 2003Ab

3、stractIn a field study, conducted on 10 conventionally managed field sites in Germany, the effects of high axle loads (1525 Mg) on soil physical properties were investigated. Soil texture classes ranged from loamy sand to silty clay loam. All sites were annually ploughed, and one site was additional

4、ly subsoiled to 40 cm depth. In the context of common field operations wheeling was performed either by a sugar beet harvester (45 Mg total mass, 113 kPa average ground contact pressure) or a slurry spreader (30 Mg total mass, 77 kPa average ground contact pressure). Soil moisture conditions varied

5、from 3.2 to 32 kPa water tension during this pass. Penetration resistance was measured before the pass. Soil cores were collected in a grid scheme at each site before and after the machine passed. Bulk density, aggregate density, air-filled porosity and air permeability at seven distinct soil water

6、tensions ranging from 0.1 to 32 kPa were determined in these cores taken from three layers (topsoil, plough pan and subsoil).At most sites, a pass by the sugar beet harvester or slurry spreader strongly affected topsoil properties. Bulk density and aggregate density increased while air-filled porosi

7、ty and air permeability decreased. The plough pan was already severely compacted before wheeling: therefore changes were small. The subsoil showed no changes or only minor signs of compaction. Only at one site, which was subsoiled the year before, significant signs of compaction (i.e. changes in bul

8、k density, air-filled porosity and air permeability) were detected in subsoil layers.The results show that using present-day heavy agricultural equipment does not necessarily lead to severe subsoil compactionin soils where a compacted plough pan already exists. However, fields which were subsoiled l

9、eading to an unstable soil structureare in serious danger of becoming severely compacted. 2003 Published by Elsevier B.V.Keywords: Compaction; Subsoil; High axle load; Porosity; Air permeability; Bulk density; Subsoiling Corresponding author. Tel.: +49-8161-715811; fax: +49-8161-715816.E-mail addres

10、s: robert.brandhuberlfl.bayern.de (R. Brandhuber).0167-1987/$ see front matter 2003 Published by Elsevier B.V. doi:10.1016/S0167-1987(03)00154-51. IntroductionModern agricultural machines help to reduce labour costs and improve the timeliness of field operations. During the recent decades, the avera

11、ge weight of ma-chines has increased and has resulted in higher axle76L. Schfer-Landefeld et al. / Soil & Tillage Research 75 (2004) 7586and wheel loads. To counteract the negative effects of wheeling on soil structure, wide tires facilitating low inflation pressure have been developed ( Tijink and

12、van der Linden, 2000). This has allowed the mean ground contact pressure to remain approximately constant as machine weight has increased and has alleviated topsoil stress. However, subsoil stress de-pends more on the axle load than on contact pressure as has been shown by calculations (Shne, 1953;

13、Koolen et al., 1992; Hadas, 1994) and measurements (Danfors, 1994; Hadas, 1994). Several studies have confirmed that heavy machinery can lead to com-paction in the subsoil to a depth of at least 50 cm (Etana and Hkansson, 1994; Fenner, 1997; Arvidsson, 1998; Ehlers et al., 2000; Arvidsson, 2001). Th

14、e detri-mental effects of wheeling with high axle loads might last for years (Hkansson et al., 1987; Blackwell et al., 1989; Sharratt et al., 1998; Hkansson and Reeder, 1994; Alakukku and Elonen, 1995). In many studies, however, wheeling conditions differed from actual field traffic in several respe

15、cts. The type of machine, tires, number and speed of passes as well as soil cultivation before or after the treatment did not correspond to those of common field work.The objective of this study was to investigate the effect of specialized agricultural machines with high axle loads used under typica

16、l conditions on the phys-ical properties of a range of soil types. Soil hetero-geneity within the test fields was overcome by using a grid-sampling scheme and a high number of repli-cations.2. Material and methods2.1. Field sites and machine propertiesThe sites of this study were located in southern

17、 (sites AD and F, I and J) and central (sites E, G and H) Germany. Soil properties and conditions dur-ing the machine passes are listed in Tables 1 and 2, respectively. All sites were ploughed annually in au-tumn to a depth of 2030 cm for decades. Additionally, site A had been subsoiled to 40 cm dep

18、th 1 year be-fore wheeling by rigid tines fixed beneath the plough shares. On sites C and F, residues of a catch crop (Sinapis alba L.) formed a mulch layer on the soil surface in spring when the machine passed. The catchcrop had been established in the previous summer af-ter shallow chiselling (sit

19、e C) and ploughing (site F) the soil.Machine passes were integrated into the normal programme of field operations. All machines used had the rear wheels offset from the front wheels so that each tire made its own track (crab steering) with an overlap of about 40% (Brunotte and Sommer, 2000). On the

20、sugar beet sites (A, D, E, GJ), the wheeling was done in the course of the beet harvest conducted by a six-row self-propelled combine harvester (to-tal mass with filled hopper: approximately 45 Mg; front tires: 800/65 R32 M28, inflation pressure 180210 kPa; rear tires: 1050/50 R32, inflation pres-su

21、re 180250 kPa; calculated average ground contact pressure: approximately 129 kPa, ground contact area calculated according to the formula of McKyes (1985) from tire widthtire diameter/2). The sugar beet fields (including the sampling plots) were completely cov-ered by the wheel tracks of the harvest

22、er; some strips, which amount to approximately 40% of the whole area, were covered two times by a wheel because of the overlap of consecutive passages. At sites B, C and F a self-propelled slurry spreader was driven across the plots before seeding maize in spring (total mass with full load: approxim

23、ately 30 Mg; tires: 1050/50 R32, inflation pressure 140180 kPa; calculated aver-age ground contact pressure: approximately 73 kPa). These plots were covered track-on-track without any overlapping. Slurry spreader passes differed from the normal programme of field operation, which would cover only 3.

24、70 m of the 4.50 m working width with tracks. The machines drove with a minimum speed of 1.4 m s1. The soil moisture conditions during the field operations were 90% of water content at pF 1.8 or more. Occasionally, the value was higher than 100% (Table 2).2.2. Sampling and measurementsSoil sampling

25、took place in an area of the field where the machines passed with a filled hopper. Sam-pling was done in a rectangular grid scheme, with 64 (sites BD, F, I, J) or 50 (sites A, E, G, H) inter-sections. The sides of the grid were 2530 m long. On half of the intersection points sampling was per-formed

26、shortly before and on the other half after the machine pass. The time lag between the first and theL. Schfer-Landefeld et al. / Soil & Tillage Research 75 (2004) 758677Table 1Soil particle size distribution, texture class, particle density and organic carbon content of sitesSite/texture classDepth (

27、cm)Particle size (g 100 g1 )Particle densityCorg(Mg m3 )(g kg1 )602000 mm260 mm2 mmA/silty clay loam15205.9463.9530.112.641.3525305.9763.8130.222.641.2238435.7761.8132.422.651.05B/loam152045.0838.2516.672.621.36253041.3537.2221.432.650.85384340.0434.1925.772.660.50C/loam152052.8431.2915.872.621.3125

28、3052.2830.3917.332.650.88384352.7929.6317.592.660.43D/loamy sand152075.8919.314.792.641.12253075.2518.176.582.660.59384373.6417.528.842.670.41E/silty loam15204.1582.8912.962.611.102530Not determined38432.8878.2618.872.640.42F/silt loam152013.0369.4617.512.621.45253012.1469.5918.272.641.0638439.3570.

29、5920.072.670.51G/silty loam15204.2581.6214.132.631.042530Not determined38432.7275.8221.452.660.41H/silty loam15203.3083.5613.142.621.072530Not determined38432.2680.3217.412.650.42I/silty clay loam15209.9165.3424.762.571.89253010.2864.3425.832.581.6738439.2561.9628.792.631.10J/silty loam, silty clay

30、loam15204.9956.9338.092.612.7725304.6956.2539.072.632.4538432.7257.3439.942.661.33second sampling varied between 2 and 30 days (except site E: 60 days), depending on short-term changes of the machine operation schedule and the availability of labour.On all sites except G and H, penetration resistanc

31、e was measured four times within a radius of 30 cm from each intersection point down to a depth of 60 cm immediately before wheeling, using a penetrologger (Eijkelkamp, Giesbeek, The Netherlands) with a cone cross-sectional area of 1 cm2 and an angle of 60. Soil cores of 250 cm3 volume each were tak

32、en verticallyfrom three depths (topsoil, furrow bottom, subsoil; ap-proximately 1520, 2530, and 3843 cm). In order to sample the soil cores manually, a pit was dug at each sampling point. Sites E, G and H were sampled only in topsoil and subsoil. The soil water retention curve, air permeability and

33、bulk density were determined for each core.The water retention curve was measured for ten-sions of 0.1, 0.32, 1.0, 3.2, 6.2 and 10 kPa (pF values of 0, 0.5, 1.0, 1.5, 1.8, and 2.0, respectively) using a ceramic plate apparatus with a hanging water column.78L. Schfer-Landefeld et al. / Soil & Tillage

34、 Research 75 (2004) 7586Table 2Soil water tension and percentage of WFPV at pF 1.8 at the time of passage, machines used and management specialitiesSiteDepthWaterWFPVMachine/date of passManagement specialities(cm)tension (kPa)(%)A152032.093Harvester a /November 1997Subsoiling to 40 cm253032.09338433

35、2.094B15206.2100Spreader b /April 1998253010.097384310.097C15206.2100Spreader/April 1998Shallow chiselling before catch253010.096crop seeding in summer384310.096D15203.2111Harvester/October 199825303.211038433.2115E15206.2100Harvester/October 1998253038436.2100F152010.097Spreader/April 1999Mouldboar

36、d ploughing before25306.2100catch crop seeding in summer38436.2100G152032.092Harvester/October 19992530384332.088H152032.091Harvester/October 19992530384332.089I152032.093Harvester/October 1999253032.092384332.091J152032.095Harvester/November 1999253032.095384332.095a Six-row self-propelled sugar be

37、et harvester.b Slurry spreader.Air capacity was defined as the drained porosity at a water tension of 6.2 kPa. For the water tension of 32 kPa (pF 2.5), a pressure plate apparatus was employed. Vertical pneumatic conductivity (Umwelt Gerte Technik GmbH, Mncheberg, Germany) was measured at each of th

38、e water tensions listed above. These results are presented as air permeability ac-cording to Kmoch (1966).Loose soil was used to determine soil texture as well as aggregate density. The latter was measured with anenvelope density meter by Micromeritics (Micromerit-ics, Norcross, GA).2.3. Statistical

39、 analysisThe MannWhitney U-test was used for sta-tistical comparison of the soil parameters. This non-parametric test is almost as effective as the t-test, but does not require a normal distribution of data or homogeneity of variances. Median values presentedL. Schfer-Landefeld et al. / Soil & Tilla

40、ge Research 75 (2004) 758679in tables and figures characterize the distribution of the data. However, the U-test compares sums of ranks and not median values.For bulk density, porosity and air permeability, each median value represents 2032 single soil cores per site, depending on the number of core

41、s remaining in-tact during the measurement procedure. The aggregate density values are based on 2532 replications for the topsoil and on eight replications for each the plough pan and the subsoil.3. Results3.1. Penetration resistance before wheelingSoil depth (cm)Penetration resistance (MPa)01234010

42、20304050605Fig. 1 shows the penetration resistance values for eight sites before wheeling. Sites C, E and especially D exhibited maximum values at 2732 cm, correspond-ing to the depth of the plough pan. At site D the pan was extraordinarily firm with a penetration resistance of 5 MPa, despite a very

43、 low water tension of only 3.2 kPa. At sites B and F the plough pan was hardly de-veloped and penetration resistance was 2 MPa. Only the subsoiled site A had a penetration resistance of about 1 MPa throughout the top 30 cm, despite the soil being dry during the measurement (32 kPa, Table 2). Sites I

44、 and J had the highest penetration resistance in the upper 15 cm of the topsoil. At these sites, values increased to more than 3 MPa at 30 cm depth, and re-mained at this level throughout the subsoil.site Asite Esite Bsite Fsite Csite Isite Dsite JFig. 1. Penetration resistance with increasing soil

45、depth, measured before the machine pass.3.2. Bulk and aggregate density, porosity and permeability of soils3.2.1. TopsoilTable 3 presents the median values of the most important soil physical parameters before and after passage of the heavy machine, and the statistical significance of the changes. A

46、t sites AF topsoilTable 3Median values of soil physical parameters of the topsoil (1520 cm) and significance of changes due to the passage of heavy machinery aSiteAir capacity (m3 100 m3 )Air permeabilityb (1012 m2 )Bulk density (Mg m3 )Aggregate density (Mg m3 )baslbaslbaslbaslA12.54.383.31.11.411.

47、531.941.95nsB16.79.5105.513.11.411.531.861.89C8.35.216.68.61.531.611.881.91D13.88.28.52.81.561.631.731.77E10.72.811.71.71.401.531.581.66F17.510.5234.025.81.261.371.691.73G6.64.120.43.7ns1.451.51ns1.701.69nsH7.86.3ns9.33.71.461.47ns1.661.64I9.27.6ns59.248.1ns1.411.45ns1.811.82nsJ6.94.6ns42.630.5ns1.2

48、51.23ns1.851.86nsa b: before machine pass; a: after machine pass; sl: significance level.b At 6.2 kPa water tension.80L. Schfer-Landefeld et al. / Soil & Tillage Research 75 (2004) 7586compaction due to wheeling was obvious: bulk and aggregate density increased and air capacity decreased (see also F

49、ig. 2). Most of these changes were signif-icant at the 0.1% level. The greatest reduction in aircapacity took place at site E, where the air-filled pore volume at 6.2 kPa water tension was only 2.8% after passage of the heavy machine. On the other hand, soil compaction led to an increase of water re

50、tentionSoil depth (cm)Soil depth (cm)Soil depth (cm)Soil depth (cm)Soil depth (cm)Pore volume (m3 100 m-3)0203040506015site A2535450203040506015site B2535450203040506015site CTPV25before35afterWFPV (6.2 kPa)before45after0203040506015site D2535450203040506015site E253545Pore volume (m3 100 m-3)020304

51、0506015site F2535450203040506015site G2535450203040506015site H2535450203040506015site I2535450203040506015site J253545Fig. 2. Water-filled pore volume at 6.2 kPa water tension (WFPV) and total pore volume (TPV) before and after the machine pass. Air capacity results from the difference between corresponding values of TPV and WFPV.L. Schfer-Landefeld et al. / Soil & Tillage Research 75 (2004) 758681capacity (i.e. water-filled porosity at 6.2 kPa water tension, F