Effect of soil compaction on sunflower growth

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  • Soil & Tillage Research 68 (2002) 3138

    Effect of soil compaction on sunflower growthYilmaz Bayhan, Birol Kayisoglu, Erkan Gonulol

    Department of Agricultural Machinery, Tekirdag Agricultural Faculty, University of Trakya, 59030 Tekirdag, TurkeyReceived 9 January 2002; received in revised form 27 May 2002; accepted 13 June 2002


    Mechanical resistance caused by soil compaction has significant effect on vegetative and generative plant growth. In thisstudy relation between vegetative and generative growth of sunflower and soil compaction due to wheel traffic was studied.Compaction was applied in the forms of the following treatments: pre-planting in entire plot area (Pre-E), pre-plantingintra-rows (Pre-INTRA), post-planting inter-rows (Post-INTER), post-planting intra-rows (Post-INTRA), post-planting inentire plot area (Post-E), and a control (C).

    During the emergence period, mean emergence dates (MED) and percentage of emerged seedlings (PE) were determinedas the characteristics of vegetative growth. During harvesting period, plant height, stem diameter, head diameter and yieldwere determined as the characteristics of generative growth.

    MED in Post-E was determined as 10.93 days, which was significantly lower than other treatments, while it was found as12.93 days for Post-INTER. The lowest PE was found for Post-E with 78% while the highest PE was found for Post-INTERand C treatments with 96%.

    Compaction caused by Post-E and Pre-E resulted in significantly lower sunflower yields than other treatments. The highestaverage sunflower yields were 3.2657 Mg ha1 for treatment C, and 3.2003 Mg ha1 for treatment Post-INTER, while thelowest average yield was 2.5473 Mg ha1 for Pre-E treatment, and 2.5440 Mg ha1 for Post-E treatment. 2002 Elsevier Science B.V. All rights reserved.

    Keywords: Wheel traffic; Soil compaction; Sunflower; Penetration resistance

    1. Introduction

    Generally, a good soil for crop production containsabout 25% water and 25% air by volume. This 50%is referred to as pore space. The remaining 50% con-sists of soil particles. Anything, for example, tillageand wheel traffic, that reduces pore space results ina dense soil with poor internal drainage and reducedaeration. Intensive uses of machinery in recent years

    Corresponding author. Tel.: +90-282-2931587;fax: +90-282-2931378.E-mail addresses: ybayhan@hotmail.com, ybayhan@tu.tzf.edu.tr(Y. Bayhan).

    are increases in farm tractor power have resulted inheavy implements in the fields. Many problems aroseas a result of heavy implement use one of them beingsoil compaction.

    Compaction may significantly impair the pro-duction capacity of a soil. Many researchers haveinvestigated the effects of wheel traffic on soil com-paction and subsequent crop growth. Honsson andReeder (1994) report a crop yield loss of 14% thefirst year after repeated wheel traffic on agriculturalsoils in seven different countries in Europe and NorthAmerica. This may not immediately become evident.According to Moullart (1998), soil compaction par-ticularly impedes root growth. The aboveground parts

    0167-1987/02/$ see front matter 2002 Elsevier Science B.V. All rights reserved.PII: S0 1 6 7 -1987 (02 )00078 -8

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    of the plants only rarely show a reduced dry matterproduction. Compaction, as evidenced by increasedpenetrometer resistance, reduces the penetrability ofthe soil for roots (Unger and Kaspar, 1994). Khalilianet al. (1991) reported that values of penetration re-sistance over 1000 kPa caused reduction in yield.Ngunjiri and Siemens (1995) studied corn growth af-fected by soil compaction due to wheel traffic beforesecondary tillage. They found that corn yield fromthe treatment with wheel traffic on entire plot areawas significantly lower than the yield from the othertreatments.

    In most studies the traffic has been applied acrossthe entire experimental area. In some of the studies,on the other hand, traffic was applied especially af-ter secondary soil tillage and pre-planting inter-row,intra-row and in entire plot area, and the effects com-paction was observed. However, during especiallypre-planting herbicide application tractor wheel cre-ates additional compaction by pressing on intra-rowor inter-row areas. Effects of this extra compactionhappened after tillage but before planting operationhave not been studied yet.

    In this study, it was aimed to determine the effect ofsoil compaction due to wheel traffic on the vegetativeand generative growth of sunflower, which is widelygrown in Turkey. Pre- and post-planting compactiontreatments were applied inter-rows; intra-rows and inthe entire plot area. A control plot was used for com-parison.

    2. Materials and methods

    The trials were conducted in research area ofTekirdag Agricultural Faculty. After growing seasonof wheat, sunflower was sown in April and harvestedin September 1999. The experimental area comprisedof two adjacent sites used for wheat and sunflowerrotation for several years.

    The loam clay soil is characterized by 35.7% sand,29.8% silt and 35.5% clay. Moisture contents by dryweight of different treatment locations were not sig-nificantly different from one another. Average mois-ture content was 17.5% in the depth range of 010 cm,20.6% in the depth range of 1020 cm, 24.3% in thedepth range of 2030 cm, and finally 24.7% in thedepth range of 3040 cm, respectively.

    Table 1Characteristics of the tractor used in the experiment

    Power (kW) 50Maximum motor rotations (min1) 2500Total weight (Mg) 3.470Front axe weight (Mg) 1.580Rear axe weight (Mg) 1.890Distance between front and rear

    axes (mm)2180

    Track width (mm) 1440Dimension of front wheel 11.224 (6 ply)Dimension of rear wheel 16.914/30 (6 ply)Air pressure of front wheel (MPa) 158.47Air pressure of rear wheel (MPa) 124.02

    Soil was tilled by primary tillage tools such as chiselafter wheat harvest and plough in the autumn beforesoil compaction treatments. In the spring, it was tilledby secondary tillage equipment such as cultivator andseedbed combination implement. For soil compactionoperation and planting, a 50 kW two-wheel drive trac-tor with a weight of 3.470 Mg was used in the experi-ment. Some characteristics of the tractor are given inTable 1.

    The study included six wheel traffic applications:

    1. pre-planting in entire plot area (Pre-E);2. pre-planting intra-rows (Pre-INTRA);3. post-planting inter-rows (Post-INTER);4. post-planting intra-rows (Post-INTRA);5. post-planting in entire plot area (Post-E);6. control (C).

    Traffic treatments were applied by operating thetractor on the wheel tracks as shown in Fig. 1. Arandomized complete block design (RCBD) with sixblocks was used in this experiment. Each block takenas treatment had three plots consisting of three repli-cations. Each plot was in 15 m long including eightrows with 0.7 m inter-row distance. Seeding rate was5.102 seeds m2. Average planting depth was 0.04 m.Planting was performed by pneumatic planting ma-chine widely used in sunflower planting. Planting ma-chinery consists of four shoe coulter, furrow covererand press wheel.

    Penetration resistance was measured in the traf-fic treatments. Compaction treatments performedwere pre-planting in intra-rows (values obtained pre-planting in intra-rows and post-planting in inter-rows

  • Y. Bayhan et al. / Soil & Tillage Research 68 (2002) 3138 33

    Fig. 1. Wheel traffic treatments: (a) C; (b) Pre-INTRA and Post-INTRA; (c) Post-INTER; (d) Pre-E and Post-E.

    and intra-rows), Post-INTER (values obtained in inter-rows and intra-rows), Post-INTRA (values obtainedin inter-rows and intra-rows), Post-E (values obtai-ned in entire plot area), and control (values obtainedpre-planting and post-planting in inter-rows and intra-rows). For the measurements, a mechanical pen-etrometer (Eijelkamp, Stiboka type) was used. Thepenetration values were determined according toASAE standard S313.2 (ASAE, 1994).

    Seedlings were counted several times during theemergence in the rows with 6 m length for eachtreatment. From these counts, mean emergence dates(MED) and percentage of emerged seedlings (PE)were calculated using formulae (1) and (2) (Bilbro andWanjura, 1982):

    MED = N1D1 +N2D2 + +NnDnN1 +N2 + +Nn (1)

    PE =(

    total emerged seedlings/mnumber of seeds planted/m

    ) 100 (2)

    where N is the number of seedlings emerging sinceprevious count and D the number of days post-planting.

    It is usually assumed that yields at the center ofthe plot are more typical of what happens in prac-tice than are yields at the border (Peterson, 1992).Therefore, plant height, stem diameter, head diameterand yield values were measured only on the center ofplot (about 28 m2). Plant height, stem diameter, andhead diameter values were measured from 40 samplesfor each replication. The mature sunflower crop washarvested and threshed by hand and crop yield wasdetermined.

    3. Results and discussion

    3.1. Penetration resistance

    Tractor wheel traffic was found to increase pene-tration resistance (Fig. 2). Penetration resistance inPost-E and Pre-E was found higher than that of theother treatments. Average of penetration resistance inthe depth between 0 and 20 cm was 1.601.85 MPawhich was the peak value of Post-E and Pre-E. The re-lation of penetration values obtained from intra-rowsand yield values were given in Fig. 3. As penetrationresistance values increased, yield reduced significantly(Fig. 3).

    3.2. Mean emergence dates and percentage ofemerged seedlings

    The treatment of compaction significantly affectedthe MED (F = 17.81). For all treatments, the valuesof MED and PE were given in Table 2. The lowestMED was found for Post-E with 10.93 days and thehighest MED was found for Post-INTER with 12.93days (Fig. 4).

    Wheel traffic in treatments was significantly effec-tive on PE (F = 6.33). The lowest PE was foundTable 2Values of MED and PE

    Treatments MED (days) PE (%)Post-INTER 12.93 96.0Post-INTRA 11.21 87.0Post-E 10.93 78.0Pre-E 11.46 82.0Pre-INTRA 11.19 82.0C 11.63 96.4

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    Fig. 2. Penetration resistance as affected by compaction treatment.

    for Post-E with 78% and the highest PE was foundfor Post-INTER and C with 96%. Compaction in theseeded area affected the PE and MED values nega-tively (Fig. 5).

    As penetrometer resistance increased, MED wasdelayed and PE decreased. Similar results were alsoreported by some researchers (Bilbro and Wanjura,1982; Taylor, 1971; Unger and Kaspar, 1994).

  • Y. Bayhan et al. / Soil & Tillage Research 68 (2002) 3138 35

    Fig. 3. The relation of penetration values on intra-rows and yield values.

    3.3. Plant height

    The treatment of compaction significantly affectedthe plant height (F = 3.32). Compaction caused byPre-E treatment resulted in the lowest plant height of1603.3 mm and the highest plant height was found forPre-INTRA with 1648.3 mm (Tables 3 and 4).

    Fig. 4. Values of MED as affected compaction treatment.

    Soil compaction prevented root development in thetreatment of Pre-E in which compaction was appliedin entire area before planting after secondary tillage.Therefore, the shortest plant height was determinedfor the plants obtained from this treatment. Also forthe plants obtained from the treatment of Post-INTRA,plant height was lower than the other treatments. The

  • 36 Y. Bayhan et al. / Soil & Tillage Research 68 (2002) 3138

    Fig. 5. Values of percentage emergence seedlings as affected compaction treatment.

    Table 3Values of MED, PE, plant height, stem diameter, head diameter and yielda


    Post-INTER Post-INTRA Post-E Pre-E Pre-INTRA C

    MED (days) 12.93 a 11.21 bc 10.93 c 11.46 bc 11.19 bc 11.63 bPE 0.96 a 0.87 ab 0.78 b 0.82 b 0.82 b 0.96 aPlant height (mm) 1614.0 bc 1603.7 c 1643.7 ab 1603.3 c 1648.3 a 1614.8 bcStem diameter (mm) 21.4 20.7 21.0 21.9 20.7 20.9Head diameter (mm) 172.7 188.7 197.7 195.0 200.3 180.7Yield (Mg ha1) 3.2003 a 2.6613 b 2.5440 c 2.5473 c 2.5927 bc 3.2657 a

    a The means were taken at P = 0.05. Means having the same letters are not significantly different at the probability of 5%.

    Table 4Statistics of values of MED, PE, plant height, stem diameter, head diameter and yield


    Error means squares Fcal LSD CV

    MED (days) 0.143 17.81 0.6805065 0.0327PE (%) 0.005 6.33 0.1272475 0.0793Plant height 356.03 3.32 34.327 0.0116Stem diameter 0.923 0.69 nsa 0.0455Head diameter 193.5 1.79 ns 0.0735Yield 0.002 175.86 0.1157255 0.0157

    a Non-significant. Significant. Highly significant.

  • Y. Bayhan et al. / Soil & Tillage Research 68 (2002) 3138 37

    Fig. 6. Values of yield as affected compaction treatment.

    reason for this is that resistance of the soil cover on theseed area is too high resulting in a delay in emergence.As a result of this delay, plants could have completedtheir development in an appropriate time. Kok et al.(1996) reported that soil compaction negatively af-fected root development of the plants. Moreover, plantheight is negatively affected by soil compaction too.

    3.4. Stem diameter

    Wheel traffic showed a non-significant effect on thestem diameter (F = 0.69). The lowest stem diameter(20.7 mm) was found for Post-INTRA treatment andthe highest (21.9 mm) was found for Pre-E treatment(Tables 3 and 4).

    3.5. Head diameter

    No statistically significant difference came outbetween treatments according to head diameter(F = 1.79). The lowest head diameter was found forPost-INTER treatment with 172.7 mm and the highestfor Pre-INTRA with 200.3 mm (Tables 3 and 4). As aresult of compaction treatments, it was found that notall of the seeds germinated successfully. Thus, totalplants had low density. Since the plants had a large

    growing space, values of plant height, stem diameterand head diameter were unexpectedly high.

    3.6. Yield

    Wheel traffic in treatments was significantly effec-tive on yield values (F = 175.86). Compaction cau-sed by Pre-E and Post-E resulted in significantly lowersunflower yields compared to other treatments. Thehighest sunflower yield averaged 3.2657 Mg ha1 forC, and 3.2003 Mg ha1 for Post-INTER treatment.The average lowest yield for Pre-E and Post-E treat-ments were 2.5473 and 2.544 Mg ha1, respectively(Fig. 6). Wheel traffic in inter-rows was not found tohave a significant effect on yield. On the other hand,pre- and post-planting wheel traffic was highly ef-fective on intra-rows treatment and consequently onyield (Tables 3 and 4).

    The reason for why the yield for control treatmentwas high was that compaction in this treatment waslow compared to other treatments. In the Post-INTERtreatment in which post-planting compaction was ap-plied inter-rows, there was no negative effect of com-paction on plant development. Therefore, there was nostatistically significant difference between the yieldsobtained from Post-INTER and C treatments.

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    4. Conclusion

    In this study, wheel traffic applied on rows and entirearea before and after planting caused a decrease inyield by negatively affecting vegetative developmentof the plant. Wheel...


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