The effects of tillage systems on soil bulk density and penetrometer resistance of a sandy clay loam soil

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<ul><li><p>This article was downloaded by: [Csumb Calif State Univ]On: 09 October 2014, At: 18:08Publisher: Taylor &amp; FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK</p><p>South African Journal of Plant and SoilPublication details, including instructions for authors and subscription information:</p><p>The effects of tillage systems on soil bulk density andpenetrometer resistance of a sandy clay loam soilJ. T. Steyn a , J. P.C. Tolmay a , J. J. Human b &amp; W. H. Kilian ca Grain Crops Institute, Small Grain Centre , Private Bag X29, Bethlehem , 9700 , Republicof South Africab Department of Agronomy , University of the Orange Free State , P.O. Box 339,Bloemfontein , 9300 , Republic of South Africac Grain Crops Institute, Small Grain Centre , Private Bag X29, Bethlehem , 9700 , Republicof South AfricaPublished online: 15 Jan 2013.</p><p>To cite this article: J. T. Steyn , J. P.C. Tolmay , J. J. Human &amp; W. H. Kilian (1995) The effects of tillage systems on soil bulkdensity and penetrometer resistance of a sandy clay loam soil, South African Journal of Plant and Soil, 12:2, 86-90, DOI:10.1080/02571862.1995.10634342</p><p>To link to this article:</p><p>PLEASE SCROLL DOWN FOR ARTICLE</p><p>Taylor &amp; Francis makes every effort to ensure the accuracy of all the information (the Content) containedin the publications on our platform. However, Taylor &amp; Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose ofthe Content. Any opinions and views expressed in this publication are the opinions and views of the authors,and are not the views of or endorsed by Taylor &amp; Francis. The accuracy of the Content should not be reliedupon and should be independently verified with primary sources of information. Taylor and Francis shall not beliable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilitieswhatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out ofthe use of the Content.</p><p>This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden. Terms &amp; Conditions of access and use can be found at</p><p></p></li><li><p>86 S. Afr. Tydskr. Plant Grond 1995, 12(2 </p><p>The effects of tillage systems on soil bulk density and penetrometer resistance of a sandy clay loam soil </p><p>J.T. Steyn* and J.P.C. Tolmay Grain Crops Institute, Small Grain Centre, Private Bag X29, Bethlehem 9700, Republic of South Africa </p><p>J.J. Human Department of Agronomy,University of the Orange Free State, P.O. Box 339, Bloemfontein 9300, Republic of South Africa </p><p>W.H. Kilian Grain Crops Institute, Small Grain Centre, Private Bag X29 Bethlehem 9700, Republic of South Africa </p><p>Accepted 6 January 1995 </p><p>Concern has been expressed that reduced tillage systems may lead to excessive soil compaction, with a negative impact on crop growth. The objectives of this study were to determine the effects of different tillage systems, namely, minimum tillage (disc and sweep), chisel plough and conventional tillage (plough) on soil bulk density, penetrometer resistance and yield. These effects were determined over a three-year period (1991/1992 and 199211993 seasons) on an Avalon sandy clay loam soil in the central Orange Free State. Results indicated that soil water content at planting was similar for the different tillage systems, except for slight differences in the upper soil depths. Penetration resistance and bulk density increased from a depth of 130 mm down to 290 mm of the soil using disc and sweeps compared with conventional tillage and chisel plough treatments. However, in the deeper soil zones, the tillage system did not consistently influence either bulk density or penetration resis-tance. At a depth of 400 mm, conventional tillage and chisel ploughing resulted in a lower bulk density than minimum tillage. The tillage operations for minimum tillage probably led to compaction in the deeper soil zone. Penetration resistance in the deeper soil zone in all tillage systems restricted rooting, but differences due to the tillage treatment were not sufficient to markedly influence the yield. </p><p>Vrese bestaan dat minimum bewerking mag lei tot die verdigting van grondlae wat die groei van gewasse nega-tief kan be"invloed. Die doel van hierdie stu die was om die uitwerking van minimum bewerking (wisselgang-skotteleg en vlerkskaar), beitelploeg- en konvensionele bewerking (ploeg), op die groei van koring ten opsigte van brutodigtheid, penetrometerweerstand en opbrengs te evalueer. Hierdie bewerkingsbehandelings is oor 'n drie jaar periode op 'n Avalon sandkleileem grond in die Sentraal Vrystaat uitgevoer. Grondwater was tydens plant dieselfde vir elke bewerking, behalwe vir die geringe verskille in die boonste grondlae. Die penetrometer-weerstand en brutodigtheid is verhoog deur wisselgangskotteleg en vlerkskaar vanaf 'n diepte van 130 mm tot 'n diepte van 290 mm in vergelyking met konvensionele bewerking en beitelploeg. Penetrometerweerstand en brutodigtheid onder die bewerkingsdiepte is nie deur die bewerkingsbehandelings beinvloed nie. Op 'n diepte van 400 mm het konvensionele- en beitelploegbewerkings 'n laer brutodigtheid getoon as minimumbewerking. Die penetrometerweerstand in die dieper grondlae was hoog genoeg om wortelgroei te beperk, maar die ver-skille as gevolg van bewerkingsbehandelings was nie genoeg om die opbrengs te be"invloed nie. </p><p>Keywords: Bulk density, penetrometer resistance, tillage systems, Triticum aestivum L. </p><p>* To whom correspondence should be addressed </p><p>Introduction 300 mm of silt loam soil were higher with zero tillage than with minimum tillage or conventional tillage treatments. Hoffman (1990) also observed that bulk densities of zero till-age and minimum tillage increased from the surface of the soil to a depth of 150 mm. Conventional tillage bulk densities increased between the depths of 250 mm and 300 mm. Pene-tration resistance was also higher in the top 250 mm in the minimum tilIage treatments than in the coventional tillage treatments (Hammel, 1989). Tillage does not consistently affect penetration resistance and bulk density, since soil tex-ture, aggregation, organic matter content and moisture condi-tions can influence the sensitivity of the soil to compaction and the persistence thereof (Marshall &amp; Holmes 1979; Voor-hees, 1987). </p><p>Traditional soil management in the central Free State involves late summer and autumn cultivation for residue management, weed control, seedbed preparation and to ameliorate surface compaction due to implement traffic and natural soil settling. Tillage practices may also lead to the breakdown of organic matter, loss of soil moisture and increased susceptibility to wind and water erosion. Conservation tillage, such as mini-mum tillage, can be valuable in combating soil degradation. However, excess compaction may restrict soil aeration and crop root development, thus restricting water uptake, nutrient availability and overall crop growth. Compaction can be eval-uated by penetration resistance and bulk density measure-ments (Grant &amp; Lafond, 1993). </p><p>Hammel (1989) observed that bulk densities in the top Carefoot, Nyborg &amp; Lindwall (1990) observed that bulk </p><p>density did not differ in loam and clay soils which had </p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Csu</p><p>mb </p><p>Cal</p><p>if S</p><p>tate</p><p> Uni</p><p>v] a</p><p>t 18:</p><p>08 0</p><p>9 O</p><p>ctob</p><p>er 2</p><p>014 </p></li><li><p>S.Afr.J.PlantSoiI1995,12(2) </p><p>received three to eight years of zero tillage when compared with conventional tillage. Chang &amp; Lindwall (1989) reported no differences in bulk density between minimum tillage and conventional tillage after 20 years under spring cereal - sum-mer fallow rotation on a clay soil. Bennie &amp; Botha (1986) observed that deep ripping at field water capacity lowered penetrometer resistance and decreased bulk density from 1.76 Mg m-3 to 1.66 Mg m-3 Chang &amp; Lindwall (1992) found only minor differences in bulk density between conventional tillage, minimum tillage and zero tillage after eight years under continuous winter wheat cultivation. </p><p>A well-planned crop rotation system can improve resist-ance to soil erosion and degradation, improve soil fertility, enhance aggregate stability and increase availability of stored water, in addition to being of agronomic and economic bene-fit to the producer (Taylor &amp; Brar, 1991). </p><p>Little information has been collected in the central Orange Free State regarding the effects of different tillage systems on wheat production and soil quality. A study was therefore initi-ated in 1990 to examine the relative performance of minimum tillage, chisel plough and conventional tillage, with regard to wheat production in terms of soil water conservation, soil physical and chemical properties, root development, yield and </p><p>. economy. This paper summarizes the effects of tillage sys-tems on soil bulk density, penetration resistance, yield and soil water content with planting. </p><p>Materials and Methods </p><p>The study was conducted from 1990 to 1993 at Thaba Nchu in the then Bophuthatswana in the central Orange Free State region. The Avalon soil (Family 3100 Kameelbos) had an effective depth of 450 mm. The total rainfall data of the trial period and the average rainfall for Thaba Nchu are shown in Table 1. Three winter wheat (Triticum aestivum L.) cultivars (Carina, Molen and Scheepers 69) were planted using four tillage treatments, namely, two minimum tillage systems (disc and sweeps), chisel plough and conventional tillage. </p><p>The tillage systems were as follows: System J, Conventional tillage: Disc - mouldboard plough (depth 250 mm); disc - sweep (tiller). System 2, Minimum tillage: Disc - disc (depth 100 mm); disc - sweep (tiller). System 3, Minimum tillage: Sweep (tiller) - sweep (tiller) (depth 130 mm); sweep (tiller) - sweep (tiller) System 4, Chisel plough: Sweep (tiller) - chisel plough (depth 250 mm); sweep (tiller) - sweep (tiller) </p><p>87 </p><p>The experimental design was a split plot, with tillage sys-tems being the main treatments and wheat cultivars being sub-treatments. The plot size was 3.73 m x 50 m and each treatment was replicated four times for a total of\ 48 plots. Statistical analysis was conducted using analyses of variance at the 5% significance level of the Tukey test. </p><p>The planting dates were 22 May 1992 and 12 May 1993, using a seed density of 21 kg ha- I and a row spacing of 450 mm. All the plots were fertilized with 30 and 20 kg ha- I </p><p>of nitrogen and phosphate, respectively, with a commercial fertilizer mixture of 3:2:0 (25) + Zn. </p><p>Volumetric soil water content in the root zone was meas-ured every two weeks at 100-mm deep intervals to a total depth of 500 mm, from planting to growth stage 10 (Joubert &amp; Smit, 1977). The penetration resistance was measured at 15-mm intervals down to 400 mm at growth stage 5 (Joubert &amp; Smit, 1977). A battery-driven soil cone penetrometer was used. The maximum pressure applied was 3000 kPa, the cone radius was 20.27 mm and the cone angle was 30. Field water capacity was used as the reference for soil water content for penetrometer measurements. This was achieved by ponding water in dams of 1 m2 and leaving them to drain for 96 h. Plastic sheeting was used to cover the site to minimize evapo-ration. Three penetrations and four replications of each plot were done per dam. </p><p>The bulk density was measured in 1990 before treatments were applied to obtain a reference bulk density of the field as a whole. The influence of tillage systems on bulk density was measured in 1993 when the cultivars were in growth stage 15 (Joubert &amp; Smit, 1977). A trench was dug across 12 plots to determine the bulk density for each tillage system. Three rep-lications per plot at 100-mm intervals down to 400 mm were removed and transported in sawdust. The method used to determine the bulk density was the clod method of Blake (1965). </p><p>Results and Discussion </p><p>The soil water content was not significantly influenced by the treatments and it is reasonable to assume that differences in penetrometer resistance and bulk density are not the result of differences in soil water content (Table 2). No significant dif-ferences in soil water content were obtained and therefore only the soil water content at planting is given. </p><p>Penetration resistance increased with depth under all tillage systems (Figures 1 &amp; 2). This agrees with the findings of Hill &amp; Cruse (1985) and McFarland, Hons &amp; Lemon (1990). There was an indication that a hard pan formed at a depth of </p><p>. 200 - 240 mm with all four tillage systems, although it was not very distinct. Significant differences in penetration resist-ance between tillage systems were obtained during 1992 in </p><p>Table 1 Monthly total rainfall and the average rainfall (";m) of Thaba Nchu for the trial period </p><p>Year Jan. Feb. Mar. Apr. May Jun. JuI. Aug. Sept. Oct. Nov. Dec. Total </p><p>Ave. 60.2 90.7 72.5 58.7 18.6 19.3 9.2 26.7 28.1 80.8 79.5 61.7 605.9 </p><p>91 110.7 0 0 4.8 0 8.2 1.1 0 58.0 123.1 45.3 83.5 444.7 </p><p>92 57.2 12.1 16.0 15.8 0 0 0 21.4 0 50.9 81.9 5.8 261.1 </p><p>93 50.7 62.9 71.6 40.9 16.0 9.8 0 20.5 4.3 145.1 49.7 25.0 496.5 </p><p>Ave. - Average rainfall of Thaba Nchu over a period of 14 years </p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Csu</p><p>mb </p><p>Cal</p><p>if S</p><p>tate</p><p> Uni</p><p>v] a</p><p>t 18:</p><p>08 0</p><p>9 O</p><p>ctob</p><p>er 2</p><p>014 </p></li><li><p>88 </p><p>Table 2 The effects of tillage systems on soil water content (mm) at planting (SOO-mm depth) </p><p>1992 1993 </p><p>Tillage systems mmH20 </p><p>Conventional tillage 81.94 103.38 </p><p>Discing 85.03 95.70 </p><p>Sweeps 79.81 98.29 </p><p>Chisel plough 79.96 98.86 </p><p>the soil zone between 135 mm and 225 mm (Figure 1). No differences in penetration resistance occurred shallower than 120 mm or deeper than 255 mm because of the tillage depths of the implements used. The disc and sweep tillage depths were between 100 mm and 130 mm, while the tillage depths for chisel. plough and conventional tillage were between 200 mm and 255 mm. </p><p>Disc cultivation resulted in a significantly higher pene-tration resistance than conventional tillage at a soil depth of 135 mm. In the soil zone 150 - 195 mm, discing resulted in a significantly higher resistance than conventional tillage and chisel plough. At 180 mm the disc and sweep treatments resulted in significantly higher penetration resistances than conventional tillage, while at the deeper soil layers of 210 -225 mm only discing resulted in a significantly higher resist-ance than conventional tillage (Figure 1). T...</p></li></ul>


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