手推式免耕播種機(jī)三維設(shè)計(jì)【小型電動(dòng)助力播種機(jī)】

手推式免耕播種機(jī)三維設(shè)計(jì)【小型電動(dòng)助力播種機(jī)】,小型電動(dòng)助力播種機(jī),手推式免耕播種機(jī)三維設(shè)計(jì)【小型電動(dòng)助力播種機(jī)】,手推式,播種機(jī),三維設(shè)計(jì),小型,電動(dòng),助力 and climate conditions, thus potentially affecting crop emergence and early growth. of arable crops, progressively achieved in recent years, has been considerable, but new improvements now available need to be individually tested. In a field trial at Udine (NE Italy), the effects four reduction bulk was A soil/seed # K Soil No-tillage; Opener type; Root growth; Seed zone physical properties Abbreviations: CI, covering index; DAS, days after sowing; DDO, double-disk opener; FRSD, furrow roughness standard deviation; PR, resistance; RI, residue incorporation; RLD, volumetric root length density; SOC, soil organic carbon; WSO, wide-sweep opener * Corresponding author. Tel.: +39 049 8272723; fax: +39 049 8272774. E-mail address: matteo.bertocco.1unipd.it (M. Bertocco). see front matter # 2005 Elsevier B.V. All rights reserved. ill.2005.07.011 ofanewkindofwide-sweepopener(i.e.,sidecoulterscurved of upwardsintheirfinalpartandslightlyangledtowardsthedirection The technological evolution of seeders for direct drilling zone properties and root establishment in maize (Zea mays, L.): A comparison with double-disk opener T. Vamerali a , M. Bertocco b, * , L. Sartori b a Dipartimento di Agronomia Ambientale e Produzioni Vegetali, University of Padova, Agripolis, Viale dellUniversita 16, 35020 Legnaro, Padova, Italy b Dipartimento Territorio e Sistemi Agro-forestali, University of Padova, Agripolis, Viale dellUniversita 16, 35020 Legnaro, Padova, Italy Received 17 February 2005; received in revised form 13 July 2005; accepted 29 July 2005 Abstract According to the kind of opener applied, no-tillage seeders can variously modify soil physical properties in relation to soil Effects of a new wide-sweep opener for no-till planter on seed Resear 1. Introduction In the last few years, the economic and environ- mental implications of conventional tillage, such as erosion, compaction andinvertingsoillayers, haveled to re-examination of no-tillage even in Italy (Sartori and Peruzzi, 1994). Especially, in the heavy soils of this country, deep ploughing aims at increasing soil porosity, at least temporarily, in order to create suitable conditions for both seed germination and root growth. Simplification of weed management and higher grain yields of summer crops like maize are generally achieved with respect to no-tillage, as evidencedbythefewdataavailableintheliteraturefor Italy (e.g., Bona et al., 1995). The performance of no-tillage seeders depends on several factors related to field conditions, including type and amount of residues at soil surface, opener design (Morrison, 2002) and the crop to be sown. The implementsoftheseseedersmusthavehighflexibility, so that various crops can be sown in differing field conditions with correct seed deposition (e.g., density, distance, depth). In no-tillage practices, the character- istics of the seed-furrow play an important role in germination. Many authors have pointed out that the most significant factors regulating germination, such as soil matric potential, temperature (Lindstrom et al., 1976; Schneider and Gupta, 1985) and sowing depth (Alessi and Power, 1971; Mahdi et al., 1998) are affected by the soil/opener interaction (Tessier et al., 1991a,b). In particular, in order to maintain constant sowing depth, various types of linkages between opener and seeder toolbar have been proposed during the last few decades. For instance, connection with a spring system, the oldest but simplest solution, is not always adequate to guarantee uniformity of sowing depth, especially in heavy soils. Great improvements have been obtained with parallel linkage, since this allows the opener to follow soil surface profiles accurately. Many of the characteristics of the seed zone in no- tillage depends on the type of opener attached to the seeder (Wilkins et al., 1983) and the two main types used tine and disk may lead to great differences. The tine opener typically creates an appreciable bursting effect in the soil and generally moves a considerable quantity of fine damper aggregates T. Vamerali et al./Soil Tsegaye and Mullins, 1994; Bueno et al., 2002). The type of opener was found to affect emergence and plant establishment markedly (McLeod et al., 1992), especially in crust- forming soils, for which better results are generally obtained with the double-disk opener (Hemmat and Khashoei, 2003). The technological evolution of no-tillage seeders for arable crops, progressively achieved in this sector, has been great, but the large number of improvements now available must be individually tested and care- fully evaluated. In addition, much of the literature on this subject refers almost exclusively to opener/soil interactions,withoutanalysingeffectsoncropgrowth. The effects of furrow shape and its properties on the draft force required by different opener types have been widely studied in relation to soil conditions ch 89 (2006) 196209 197 and operating parameters, such as depth or speed compared with that of a double-disk opener (DDO) the soil profile can be followed by the openers as regularly as possible. For this reason, it has three independent jointed sections, each 1.5 m wide and linked to the rigid frame with four elastic joints. Each section has five openers, for a total of 15 sowing rows, which are laid on three seeding lines and equipped with a single parallel linkage for improved stability. In addition, each section is supported by a front wheel and a rear packer tandem (Fig. 2). The latter is an essential component for the working the seeding unit inthisseeder; it is made of10 wheels per section, with 3.508 tyres and 0.9 bar pressure. The seeder equipped with the DDO is an eight-unit mounted no-till planter with pneumatic seed metering and 0.75 m row spacing, resulting in a 6 m working width. The DDO used here is composed of a single, fluted, round-bladed coulter and a double-disk, associated with two side rollers and two rear V- mounted wheels (Fig. 2). Performance valuation of opener types requires differences among seeders to be kept to a minimum, Resear till air seeder: (a) front chisel; (b) side coulter; (c) end of coulter (curved upwards); (d) multiple seed dispenser; (e) part of parallel linkage. adopted by the no-till planter Max Emerge 2 (John Deere Italia, Milan, Italy). The WSO has a straight axis, ending with a front chisel and two rear side 18-cm wide coulters, which are slightly angled towards the direction of work and curved upwards (908) in their final part (25 mm high) (Fig. 1). The front chisel cuts soil 2530 mm deeper than the coulters. Seed delivery to each unit is through a single pneumatic tube from the centralised volu- metric metering system, which allows the seeder to assume a certain degree of polyvalence. Although various types of deposition (i.e., row spacing) can be set, in our field trial as the first test of this prototype opener maize was sown in rows 0.45 m apart, a distance commonly used in the experimental site. The structure of the seeder equipped with the WSO includes one rigid and one folding frame. The first is supported by a front head-shaft to couple the seeder to the tractor and two rear low-pressure wheels for (Gebresenbet and Jonsson, 1992; Collins and Fowler, 1996; Sanchez-Giron et al., 2005). Instead, only a few studies have examined some crop parameters and they generally deal with drills for autumn sowing of cereals. For instance, Chaudhry and Baker (1988) found that various types of opener led to different types of growth of barley seedlings, i.e., greater shoot androotweights whenbothwinged(T-shaped groove) or hoe (U-shaped groove) types are used instead of the triple-disk one. In this framework, the present study evaluates the performance of an innovative wide-sweep opener, linked to the frame by a double linkage unit. Its effects on some soil physical properties in the seed zone, crop emergence and early root growth of maize were evaluated in various soils over a 2-year period in NE Italy and compared with those of a double-disk opener, which is the most widespread in Italy. 2. Materials and methods 2.1. Description of equipment The performances of a new wide-sweep opener (WSO) with which the no-till air seeder Cerere (Tecnoagricola, Udine, Italy) has been equipped, was T. Vamerali et al./Soil uniformity of sowing depth was calculated as the coefficient of variation of that depth, i.e., the ratio between standard indicate the maximum Y value (c), the x value at half c (m) and the slope at flex (b). 2.5. Seedbed roughness Soil disturbance at the surface caused by the openers was measured across sowing rows (five replicates in both years) in terms of seedbed rough- ness. The contour of the soil profile was marked with black spray on an A4 sheet of white paper (21 cm C2 T. Vamerali et al./Soil Cavalli and Sartori, 1988). 2.7. Soil moisture and bulk density Immediately after sowing (about 4 h later) 5-cm deep undisturbed soil cores 8 cm in diameter were collected, using a hand auger above the centre of the sowing row (five replicates). Gravimetric water content and bulk density were determined after oven- drying at 105 8C to constant weight. In 2003 were samples also taken at six and eight DAS to determine soil moisture only. 2.9. Root growth Soilsampleswerecollectedbymeansofahandauger (8-cmdiameter,5-cmheight)atthethree-leafstageat25 and 30 DAS, on May 21, 2002 and May 15, 2003, respectively.Atthisearlygrowthstage,thediameterof the auger was suitable to collect almost the whole root system of seedlings (preliminary tests) and root deve- lopmentwasnotyetaffectedbytheadoptedplantinter- distances. Samples were taken at two interval depths, 05and510 cm,centringtheaugerabovesingleplants, with six and three replicates in 2002 and 2003, respectively, for a total number of 48 samples in 2002 and24in2003.SoilsampleswerestoredatC018 8Cuntil washingfor2 hinan2%(w/v)oxalicacidsolution.Soil particles were then separated in a hydraulic sieving- T. Vamerali et al./Soil the exception was the drier soil of field C (see data below), for which a significantly shallower deposition was observed with the WSO (17.4 mm versus 26.7 mm). The standard deviation of seeding depths was also not verydifferent between openers, it being 0.73 and 0.63 mm in WSO andDDO,respectively,thusresultinginsimilar values of depth uniformity, although a relatively lower uniformity for tine or hoe openers could be expected, T. Vamerali et al./Soil Chaudhuri, 2001). Nevertheless, in our case, the integrated seed deposition adjustment system asso- ciated with WSO allowed improved accuracy in seeding depth. As regards plant emergence, a general delay was observed for WSO with respect to DDO, especially in 2002, in which almost 1 days delay field A: 0.84 days; field B: 0.75 days was revealed in order to detect 50% of emergence, as evidenced by the m coefficient of the Gompertz regressions (Table 2, Fig. 4). Delayed emergence was almost negligible in ressions) in four fields. Markers represent data. 2003, probably because of the very short germination time(seehighvaluesofcoefficientbinTable2)dueto the high temperature at sowing and the very similar bulk density for the two openers in the first top 5 cm layer. The dynamics of plant emergence were similar in WSO and DDO, particularly in field C, charac- terised by lower soil moisture at sowing a fact that did not allow variations of bulk density to be detected, regardless of opener type. When delay was observed, it may partly have been due to the lower bulk density and associated lower penetration resistance (see below), observed above time is variously affected by some limiting factors, such as water restriction or surface crusting. 3.2. Effects on soil morphology Soil disturbance at the surface was significantly differentbetweenopenersandfieldswithdifferingsoil physical properties (Table 3). On an average (four fields), soil roughness was greater for WSO than for DDO, as evidenced by the higher FRSD, 0.91 and 0.41,respectively.Thisresult,clearly observableinall fields, was due to the different working system of the T. Vamerali et al./Soil Chen etal.,2004),withnotonlydelayedemergence butalso reduced plant population and yield in normal and dry soils when press wheels were not used. Modelling is a good tool to generalise the effects of soil conditions on emergence and it is known that temperature and water potential more than oxygen concentration are the main affecting factors, as expressed by the concept of hydro-thermal time (Gummerson, 1986). Although a sigmoid model is generally used to represent the rate of emergence (see review by Guerif et al., 2001), we found a generally goodfitwiththeGompertzcurve,amodelwidelyused to represent growth dynamics in plants. Because the Gompertz curve does not incorporate symmetry restriction as in the sigmoid model (e.g., logistic) and has a shorter period of fast growth, verification shouldbe made as regards whetherornot this function would be more suitable when part of the emergence Table 3 Effects of opener type on soil disturbance in various fields Field Wide-sweep CI (%) RI (%) FRSD Before After A 69 a 37 b 32 a 1.04 B 79 a 54 b 25 b 0.81 C 67 a 44 b 23 b 0.70 D 67 a 41 b 26 b 1.07 Mean 71 a 44 b 27 A 0.91 Lower-case letters indicate significant differences among observation two other parameters (residue incorporation (RI) and furrow roughness openers are expressed by capital letters (LSD test, P C20 0.05). two openers, the front chisel and side coulters of the WSO exerting both greater and more extended (across row) disturbance and soil mixing than the DDO. The examples of furrow surface traces of the two openers (field A: clay, 31.3% soil moisture) (Fig. 5) show constantly greater profile heights in WSO and the greater FRSD through the 20-cm long observed distance (across row) is appreciable even graphically. The soil profile for DDO was typically V-shaped and the resulting soil roughness was similar among fields, except for field C, which had low FRSD values, probably because of the limited impact of the disks in conditions of low soil moisture (21.2%) (Table 3). Although the surface trace of WSO was not exactly symmetric, a generally lower furrow height with side humps was observed (Fig. 5). This shape should be considered as a result of the particular kind of work done by the side coulters of WSO, which cut and replace soil almost in its original position (see Fig. 3). Nevertheless, we did measure a certain variation in soil roughness in different conditions, with lower FRSD in cases of reduced soil moisture (field C) (both Double-disk CI (%) RI (%) FRSD Before After 75 a 68 a 7 a 0.43 a 83 a 78 a 5 a 0.48 a 81 a 77 a 4 a 0.29 b 88 a 79 a 9 a 0.43 a 82 a 76 a 6 B 0.41 B (beforevs. after sowing) for covering index (CI) or among fields for d deviation (FRSD). For same parameter, differences between Resear soil, openers) and high contents of organic carbon (field B) (only WSO) (Table 3), mainly because of the smaller size of top-soil aggregates. The different working systems of the two openers had also some effects on the covering index (Table 3). DDO did not modify at all the amount of residues at thesoilsurface,northereforethoseincorporatedinthe soil, the CI before and after sowing being 82% and 76% respectively. Instead, in WSO, the front chisel caused appreciable incorporation of residues in all fields (RI = 27%, on average), the CI falling from 71 to 44%, with a tendency towards higher values of residue incorporation with higher FRSD. The resulting different covering index in the two openers may variously affect soil protection (e.g., erosion, water losses) and the fate of residues, which we did not evaluate in the flat plain of our experimental site. If we aim at limiting soil erosion, higher CI values are preferable, although a value (37%) almost double that reported by Dickey et al. (1985) (20%) for reducing erosion by 50% was T. Vamerali et al./Soil year 2003: R 2 = 0.71). Conversely, unexpectedly lower RLD values were found in the top 5-cm layer with respect to DDO in field A (Fig. 9), probably because of the Fig. 9. Distribution of soilroot length density (RLD, data from core represent standard error. zone to different extents than the double-disk type (2), 125137. Chen,Y.,Tessier,S.,Irvine,B.,2004.Drillandcropperformancesas Res. 34 (2), 127139. Dickey, E.C., Shelton, D.P., Jasa, P.J., Petterson, T.R., 1985. Soil Resear (DDO). The WSO, connected to a parallel linkage system, achieved appreciable tillage of soil with higher incorporation of crop residues and uniform sowing depth. Only penetration resistance and bulk density were affected by opener type. Although WSO reduced these parameters more than DDO, the smoothing effect observed at the sowing depth slightly reduced root growth or orientation but not diameter at the three-leaf stage of maize, as happened in the top 5 cm layer of a clay soil with little organic carbon (field A). Independent of furrow zone properties, the two openers behaved stably in the various soils, but in some cases, because of particular initial conditions (e.g., lower moisture: field C), variations were observed,especiallyforWSO,as regardsbulkdensity, soil roughness and sowing depth. These findings, which are a rare example of an integrated approach applying mechanics, soil physics above-notedsmoothingeffect,whichledsomerootsto grow plagiotropically (visual evaluation) at least in this early stage, partially out of the auger soil volume. No differences between openers were observed in terms of root growth at depths below 5 cm, nor at any of the two depths in the other fields, a decrease with depth being normal. The very high values of RLD in fieldB were due to the extremely low PR and thegreat amount of organic carbon. As regards root diameter too, no differences could befoundbetweentheopenersinanyofthetestedfields or depths, although it is known that this root trait is mainly affected by the physical properties of the soil, e.g., penetration resistance, which was variously modified by both openers (Materechera et al., 1992; Tsegaye and Mullins,1994).Nevertheless, it should be recalledthatthePRvaluesinthisstudywereneververy high, not exceeding 400 kPa (field C, 5 cm depth). 4. Conclusions The increasing focus on soil tillage systems with low environmental impact and costs has led to the design of new mechanical solutions, even in Italy. In this study, a new wide-sweep opener (WSO) for no- tillage was found to affect soil properties in the seed T. Vamerali et al./Soil & Tillage208 and root morphology, indicate that closer integration erosionfromtillagesystemusedinsoybeanandcornresidues.T. ASAE 28 (4), 11241140. Gebresenbet, G., Jonsson, H., 1992. Performance of seed drill coulters in relation to speed, depth and rake angles. J. Agric. affected by different drill configurations for no-till seeding. Soil Till. Res. 77 (2), 147155. Collins, B.A., Fowler, D.B., 1996. Effect of soil characteristics, seeding depth, operating speed and opener design on draft force during direct seeding. Soil Till. Res. 39 (34), 199211. Darmora, D.P., Pandey, K.P., 1995. Evaluation of performance of furrow openers of combined seed and fertiliser drills. Soil Till. of several research topics should be taken into consideration, for more insights into the functioning of agricultural machinery. Acknowledgements We are grateful to Claudio Nerva for help in technical drawing and to Gabriel Walton for revision of the English text. References Alessi, J., Power, J.F., 1971. Corn emergence in relation to soil temperature and seeding depth. Agron. J. 63, 717719. Bona,S.,Vamerali,T.,Mosca,G.,1995.Responseoftherootsystem of maize (Zea mays L.) to reduction of inputs. Rivista di Agronomia 29 (3), 339347. Bueno,J.,Hernandez,J.L.,Alvarez,M.,Amiama,C.,2002.Seeding opener and fertiliser placement in no-tillage silage corn produc- tion. In: Proceedings of the International Conference on Agri- cultural Engineering, vol.