Conservation tillage implements and systems for smallholder farmersin semi-arid Ethiopia

M. Temesgen a,*, W.B. Hoogmoed b, J. Rockstrom c, H.H.G. Savenije a,d

a Civil Engineering Department, Addis Ababa University, Ethiopiab Farm Technology Group, Wageningen University, The Netherlandsc Stockholm Environment Institute, Swedend Delft University of Technology, P.O. Box 5048, 2600 GA Delft, The Netherlands

Soil & Tillage Research 104 (2009) 185–191

A R T I C L E I N F O

Article history:

Accepted 11 October 2008

Keywords:

Conservation tillage

Maresha

Ethiopia

Soil moisture

Semi-arid regions

Smallholder farmers

Tie ridger

Subsoiler

Sweep

Broad bed maker

A B S T R A C T

Smallholder farmers in Ethiopia practice traditional tillage systems using an ard plow called Maresha.

Traditional tillage systems that involve repeated cultivations with the Maresha plow have caused land

degradation (a.o. formation of a plow pan) and poor utilization of rainwater that led to low crop

productivity. Experience in other countries has shown that conservation tillage systems could improve

utilization of rain water through increased infiltration. However, the implements used for conservation

tillage in other countries were found to be too heavy and too expensive for smallholder farmers in

Ethiopia. On the other hand, lighter and low cost implements have been developed in Ethiopia as

modifications to the Maresha plow. These implements are the Subsoiler, the Tie-ridger, and the Sweep.

Field tests were carried out to evaluate the modified implements and a rip plant type of conservation

tillage systems using the modified implements. The results showed that the Subsoiler reached a depth of

approx. 24 and 27 cm after 1 resp. 2 passes through the furrow made by the Maresha, and thus was

capable of disrupting the plow pan. Compared to the Maresha plow and the inverted broad bed maker

(BBM), the Tie-ridger required less draft power (79 kg vs. 96 for the Maresha and 103 for the BBM) and

lower lifting force (�43%) while forming furrows with larger (+36 resp. +15%) cross-sectional areas. The

Sweep enabled deeper root growth of tef (Eragrostis tef (Zucc.)) apart from accomplishing sowing

operations faster (+50%). It is concluded that the newly developed implements are suitable to undertake

conservation tillage under smallholder farming systems in the semi-arid regions of Ethiopia. The rip-

plant type of conservation tillage systems, however, was not found to be viable for maize (Zea mays)

production under the study conditions in which loss of soil moisture through evaporation is high. Both

grain and biomass yields were highest in the conventional systems, although differences were

statistically not significant. On the other hand, a reduced tillage system tested on tef resulted in higher

grain yields as compared to conventional tillage.

� 2008 Elsevier B.V. All rights reserved.

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1. Introduction

Ethiopia is located in the Horn of Africa between 38 and 188Nand 338 and 488E. Its population is currently estimated at 60million. Agriculture is the mainstay of the country’s economy with60% of GDP coming from this sector. It is a means of livelihood forabout 85% of the total population. The main power sources inagriculture are humans and animals. Over 90% of the totalagricultural production comes from 5.5 million farmers employing

* Corresponding author at: Addis Ababa University, Faculty of Technology,

Department of Civil Engineering, P.O. Box 385, Addis Ababa, Ethiopia.

E-mail address: melesse_tem@yahoo.com (M. Temesgen).

0167-1987/$ – see front matter � 2008 Elsevier B.V. All rights reserved.

doi:10.1016/j.still.2008.10.026

5 million oxen and cultivating 95% of the arable land (Pathak,1987).

The semi-arid regions in Ethiopia (Fig. 1) cover a total area of301,500 km2. This area represents the crop production zonesuffering from a serious moisture stress (Engida, 2000). It is inthese areas that food insecurity and famine has often beenreported (IGAD and FAO, 1995). Although drought is the majorreason causing famine in Ethiopia, low level of agriculturalproductivity due to poor management of the available resources,particularly water, due to poor rainfall partitioning (high run off,high evaporation and low infiltration), is a very important factorthat has rendered the country even more vulnerable to drought.

The traditional tillage implement in Ethiopia, the Maresha plow,and the related tillage system that requires repeated cultivation,have caused land degradation (poor soil structure, low fertility and

Fig. 1. The dryland areas of Ethiopia.

M. Temesgen et al. / Soil & Tillage Research 104 (2009) 185–191186

loss of soil through erosion) (Bezuayehu et al., 2002), delayedplanting and hard work to both draft animals and human beings(Rockstrom et al., 2001). Poor soil structure has resulted in poorrainwater retention and infiltration (Rockstrom and Valentin,1997; Hoogmoed, 1999) while delayed planting has shortened thelength of the growing period available for the crop (Rowland,1993). The high draught power required for tillage has forcedfarmers to keep a large number of cattle for breeding purposes.Such an overstocking of cattle has in turn led to land degradation(Biamah and Rockstrom, 2000; Jonsson et al., 2000).

1.1. The Maresha plow—opportunities and drawbacks

Farmers in Ethiopia have used the Maresha plow (Fig. 2) forthousands of years (Goe, 1987; Gebregziabher et al., 2006). It isvery simple, light in weight, cheap, and locally made. However, as aconventional tillage implement, the Maresha plow has got severaldrawbacks which arise mainly from the fact that the plow forms aV-shaped furrow and results in incomplete turnover (Sime, 1986).These drawbacks are:

1. Because of the incomplete turnover of the furrows, farmers haveto do repeated tillage in order to produce a fine seedbedespecially for tef. As a result, the soil is excessively pulverizedresulting in a poor structure leading to crust formation.

2. Because of the V-shaped furrow formed by the Maresha plow itis necessary that every two consecutive tillage operations areoriented perpendicular to each other. Thus, in inclined fields oneof the two plowing operations fall along or nearly along theslope. The furrows encourage runoff when they are laid alongthe slope (Edwards et al., 1993; Basic et al., 2001). This is a veryserious problem in Ethiopia because the country is very hillyresulting in large amounts of soil and water loss due to erosion.

Fig. 2. The traditional tillage imp

3. Because of repeated tillage at shallow depth plow pans areformed which hinder water infiltration (Whiteman, 1979) androot growth (Rowland, 1993; Willcocks, 1984).

4. The V-shaped furrow exposes a larger surface area of the soil tothe atmosphere. Rough surfaces appearing during tillageoperations enhance gas exchanges CO2 (Reicosky, 2001)resulting in losses of organic carbon. Moreover, evaporationlosses are higher due to larger surface area exposure.

1.2. Equipment development

Research to improve the Maresha plow began as early as 1939when the Italians introduced the animal drawn mould board plow(Goe, 1987). FAO (Food and Agriculture Organization) conducted aseries of on-farm trials on implements in the 1950s while theAlemaya and the Jimma Agricultural Colleges made efforts toimprove the traditional tillage implement in the early 1960s. In1968, the Chilalo Agricultural Development Unit started researchon several types of tillage implements while the Institute ofAgricultural Research began activities on improving the traditionalimplements in 1974. However, none of these efforts weresuccessful in developing prototypes acceptable by Ethiopianfarmers (Goe, 1987). The major reasons behind the reluctance offarmers to adopt the newly introduced implements were the factthat they were too heavy and expensive.

Recently, the following implements have been developed asattachments to or modifications of the Maresha plow aimed atundertaking field operations related to conservation tillage(Temesgen, 2000).

1. The Subsoiler. Conventional tillage systems often cause theformation of plow pans or hard pans that restrict infiltration androot growth. One of the objectives of conservation tillagepractices is to break the hard pan. The Subsoiler was made byreplacing the tip of the Maresha plow by a narrow metallic partand the wooden boards by a pair of iron rods.

2. The Sweep. The Sweep was made by replacing the woodenboards of the Maresha plow by a pair of rods and a 55 cm widesteel blade that moves horizontally through the soil. The mainpurpose of the Sweep is to improve timeliness of operations, andsecondly, the Sweep is designed to mix fertilizer with the soilbefore tef sowing. It operates shallowly thereby reducing draftpower requirements and increasing speed of operation. As it hasgot a larger width of operation, more area is covered per unit oftime. Traditionally, farmers broadcast fertilizer on the surfaceand do not mix it with the soil. The reason is that if they mix itusing the Maresha plow the fertilizer will be buried too deep forthe shallow-rooted tef crop. Leaving fertilizer on the surfacecauses losses due to volatilizations and sheet erosion. Moreover,the roots of the tef crop are forced to concentrate at the surfacewhere the fertilizer is placed. The former is particularlyimportant when there is a dry spell during which the upper

lement in Ethiopia, Maresha.

M. Temesgen et al. / Soil & Tillage Research 104 (2009) 185–191 187

layer dries out with the moist layer progressively moving downthe soil profile. It is hypothesized that if the Sweep is used to mixthe fertilizer with the soil the roots will grow deeper in search ofthe nutrients thereby enabling the plant to use more water fromthe soil profile.

3. The Tie-ridger. In semi-arid regions of Ethiopia, rainfall is erratic,with high intensity rainfall followed by long dry spells. Water islost through run off and the soil dries out quickly during the dryspells. Tied ridges are a series of basins formed in the field bytying furrows at certain intervals (Temesgen, 2000). The Tie-ridger was made by attaching a blade vertically just behind theplow point that can be lifted by the operator (thus tipping theplow). The blade is designed to make wider furrows withreduced draft power requirement and lower lifting forces.

4. The inverted BBM (broad bed maker). The broad bed maker thatwas initially developed to make broad bed and furrow fordraining excess water in highland vertisols was later modifiedsuch that it can be used as a Tie-ridger (Wondimu et al., 1998).The inverted BBM was made by attaching the wings of the BBMon both sides of the Maresha plow such that it forms amoldboard-type ridger.

1.3. Rip-plant type of conservation tillage systems

The rip-plant type of conservation tillage uses appropriateanimal-drawn equipment such as Subsoilers or rippers. Thesesystems have been extensively tested for smallholder farmers inAfrica (Ahenkorah et al., 1995; Chen and Li, 1998; Steiner, 1998;Biamah and Rockstrom, 2000; Freitas, 2000; Wanders and Stevens,2000). The system involves making furrows at 75 cm spacing usinga ripper and leaving the rest undisturbed. Subsoiling is also madein these lines. Finally, planting is carried out in the same furrows.The system has been found effective and is being popularizedamong smallholder farmers in much of the Southern and EasternAfrican countries. The implements were developed as attachmentsto the moldboard plow frames that are too heavy and unaffordableby smallholder farmers in Ethiopia (Temesgen, 2000; Goe, 1987).

An alternative conservation tillage system was designed usingthe Maresha modified implements. This would be appropriate forrow planted crops such as maize. However, for broadcasted cropssuch as tef there is a need to introduce a reduced tillage system inwhich the field will be plowed once.

This paper presents the results of an evaluation of the Mareshamodified implements and conservation tillage systems on maizeand tef in order to:

1. Evaluate the field performance of the newly developedimplements with particular emphasis on their ability inreducing the time and energy required for the particularoperation and in making more water available to the cropunder rain fed agriculture in sem-arid regions.

2. Evaluate the agronomic performances of the rip-plant typeconservation tillage system and a reduced tillage system for rowplanted and broadcasted crops, respectively.

2. Materials and methods

2.1. Soil and terrain

The study has been undertaken at Melkawoba and Wulinchity.Melkawoba is located 088230N and 398220E with an altitude of1450 m above sea level. The mean rainfall is 600 mm yr�1. The soilsare sandy loam (60% sand, 26% silt and 14% clay) and verysusceptible to compaction similar to the so called sealing crustingand hard-setting (SCH) soils that are common in sub-Saharan

Africa (Hoogmoed, 1999). The test fields have slopes of 12%.Wulinchity is located 088400N and 398260E with an altitude of1447 m. The soils are clay loam with 35% sand, 34% loam and 31%clay. The mean rainfall is 750 mm yr�1. However, poor temporalrainfall distributions cause moisture stress to crops grown in thearea (Mulatu and Regassa, 1986). The slope of the test field atWulinchity was 13.8%.

2.2. Implements

The implements tested were the Maresha plow and the invertedbroad bed maker (BBM) as checks, the Sweep, the Tie-ridger, andthe Subsoiler. The sizes of plots for all implement performancetests were 40 m � 10 m each.

2.3. Draft power requirement

All implements were pulled by a pair of oxen. Measurement ofdraft power requirement was carried out using a 20 kN dynam-ometer with digital display for all the implements. The load cellwas attached between the center of the yoke and the end of theplow beam.

2.4. Subsoiler

The Subsoiler was tested taking into consideration the way itwill be used for conservation tillage. The type of conservationtillage designed for smallholder farmers in the semi-arid regions ofEthiopia involves ripping the field at a spacing of 75 cm, using theMaresha plow, followed by breaking of the plow pan along theripped lines. Hence, the Subsoiler was tested on furrows that wereripped by the Maresha plow. Comparisons were made with the useof the Maresha plow repeatedly along the same furrow to see iffarmers can do without the Subsoiler. Thus, there were five sets ofoperations:

1. Single pass with the Maresha plow (M1).2. Two subsequent passes over the same furrow by the Maresha

plow (M2).3. Three subsequent passes over the same furrow by the Maresha

plow (M3).4. A single pass by the Subsoiler over a furrow made by the

Maresha plow (MS).5. Two subsequent passes by the Subsoiler over a furrow made by

the Maresha plow (MS2).

To measure the depth of penetration loose soil was carefullyremoved from the bottom and edges of the furrow at 10 randomlyselected points along the furrow. Depth of operation was measuredafter each operation. In treatments with repeated passes over thesame furrow, the depth of penetration of a given treatmentrepresents the cumulative depth. The cumulative depth is neededto determine if the plow pan had been disrupted after repeatedpasses. Draft force was also recorded for each test. However, unlikedepth, draft force was not added up because it is more informativeto see the draft forces of each operations separately. The tests werereplicated five times. Duncan’s multiple range test was used fordata analysis. The average soil moisture content was 13.2%. Thefields were free from weeds and crop residues.

2.5. The rip-plant system

Field tests were carried out to evaluate the system for maizeproduction under smallholder farmer’s fields at Melkawoba andWulinchity. The designs were randomized complete block.

M. Temesgen et al. / Soil & Tillage Research 104 (2009) 185–191188

2.6. Treatments

(a) Maize

1. Conventional tillage (3–4 times plowing with the Maresha plow(CONV).

2. Ripping with the Maresha plow at 75 cm spacing followed bysubsoiling using the Subsoiler in the ripped furrows (RIPSUB).

3. Ripping with the Maresha plow at 75 cm spacing followed bysubsoiling using the Subsoiler in the ripped furrows (RIPSU-B + INT). When the maize crop was about 50 cm high haricotbean (Phaseolus vulgaris) was intercropped between maize rows.

4. Ripping with the Maresha plow at 75 cm spacing two times inthe same row (RIP2).

(b) Tef

1. Conventional tillage (4–5 times plowing with the Maresha plow(CONV)).

2. Reduced tillage, ripping with Maresha at 75 cm spacingfollowed by subsoiling in the same furrow (RIPSUBPLOW).Three weeks before planting, the Maresha modified moldboardplow was used to plow the field once.

3. Minimum tillage, ripping with Maresha at 75 cm spacingfollowed by subsoiling in the same lines (RIPSUB).

4. Ripping with the Maresha plow at 37.5 cm spacing and plantingof cow pea (Vigna unguiculata L. walp.) in the row. Three weeksbefore planting, the Maresha modified moldboard plow wasused once (RIPPLOW).

Seedling emergence problems were encountered in the ripplant system tested on maize and hence refilling of gaps was made21 days after planting.

Data collected were seedling emergence of maize, plantpopulation, plant height, biomass and grain yield of both tef andmaize.

Plot sizes were 10 m � 10 m for each plot. Number ofreplications was 8 at each site. In the conventional tillagetreatment, the direction of the first tillage was across the slopewhile that of the second tillage was along the slope. The thirdtillage was carried out across the slope. In the conservation tillagetreatments all the tillage operations were carried out across theslope. At planting, the operations were across the slope, in all cases.All other conditions including soil type, fertilizer applications andweeding were the same for all the treatments.

2.7. Tie-ridger

The Tie-ridger was compared with the Maresha plow and theinverted BBM. It was compared with the Maresha plow because we

Table 1Field performance of the Subsoiler.

Treatmenta Cumulative depth of cutb (mm) STD (�) Nc

M1 154 (a)f 12.5 50

M2 185 (b) 17.2 50

M3 207 (b) 38.2 50

MS 239 (c) 16.9 50

MS2 268 (d) 44.9 50

a M1, M2 and M3 are furrows made by the Maresha plow after passing once, twice and

Subsoiler after passing once and twice, respectively, over a furrow made by the Maresha

with M1 while there was no marked difference in speed in the other treatments.b Cumulative depth is the total depth achieved after the current and previous passec N is the number of readings.d The change in depth refers to differences between two consecutive operations.e The draft force was recorded for the last single operation (see details in Section 2)f Numbers followed by the same letter are not statistically different.

wanted to see whether farmers can undertake tie-ridging with thetraditional implement. Moreover, the inverted BBM was testedbecause Wondimu et al. (1998) reported that it can be used for tie-ridging. The cross-sectional area of the furrows produced wascalculated after determining the maximum depth and width of thefurrows. The cross-sectional area of the furrow is related to thevolume of water that can be retained in the basins created by thetie ridging operation. Ten readings were taken at randomlyselected points at each furrow and the test was repeated five times.

The lifting force required when tying the furrows was measuredusing a simple pre-calibrated pocket balance of 50 kg capacity witha facility to record the maximum force. Ten readings were taken atrandomly selected points at each furrow.

2.8. Sweep

Field performance evaluation of the Sweep in comparison withthe Maresha plow was made

(a) By determining the speed and width of tillage. The test wasrepeated five times and ten readings were taken during eachtest.

(b) By assessing the mixing of fertilizer during tef planting.Fertilizer was mixed with the soil before the seeds werebroadcasted while in the conventional system both the seedsand fertilizer were broadcasted on the surface. Plot sizes were10 m � 10 m. In order to see the effect of mixing of fertilizer bythe Sweep on root growth, the length of roots were measured atmaturity. Fifteen readings were made on each of 8 farmers’fields.

2.9. Statistics

Descriptive statistics and SPSS (SPSS, 2001) were used toanalyze the results.

3. Results and discussion

3.1. Field performance of the Subsoiler

The results of the tests made on the Subsoiler are presented inTable 1. Statistical analysis showed that there were highlysignificant differences in the maximum penetration depthbetween the Subsoiler and the Maresha plow. However, differ-ences between the respective third and second passes were notstatistically significant. The draft forces presented in Table 1 are forthe last single operation. It can be seen that the first furrowrequired by far the highest draft power whereas subsequent passesmade over previously opened furrow required almost half of the

Change in depthd (mm) Draft forcee (N) STD (�) N

0 1068 (a) 124.3 96

31 538 (b) 79.6 84

22 493 (b) 38.7 90

85 522 (b) 43.7 79

29 514 (b) 49.9 81

trice, respectively, over the same line (furrow). MS and MS2 are furrows made by the

plow. Speed of oxen was not measured but it was observed that oxen walked slowly

s were made over the same furrow.

.

Table 2Effect of tillage system on seedling emergence and plant height of maize in 2004.

Treatment Wulinchity Melkawoba

Emergence (%) N Emergence (%) N Plant height (cm) N

CONV 54.4 20 46.5 28 32 100

RIPSUB 45.3 40 37.8 56 24 200

RIP2 46.3 20 39.0 28 25 100

LSD = 7.2 LSD = 17.6 LSD = 5.1

Significant at P < 0.05 NS Significant at P < 0.01

N is the number of readings.

M. Temesgen et al. / Soil & Tillage Research 104 (2009) 185–191 189

draft force of the first pass. In terms of draft power, there is nosignificant difference among the second and third passes with theall the treatments.

When the Subsoiler was used twice over a furrow created by theMaresha plow, it penetrated to a depth of 268 mm. The maximumpenetration resistance of undisturbed soils under the Maresha plowcultivation system as measured using a penetrometer was found tobe located at 180–200 mm but the dense layer extended over thedepth range of 170–250 mm (Temesgen et al., unpublished data).The depth represented the hard pan which should be disrupted inorder to allow infiltration and root growth. The Maresha plow wasnot able to disrupt the hard pan even after it was used three times inthe same furrow. During the third pass, the Maresha plow scratchedover the hard pan. On the other hand, the Subsoiler completelydisrupted the hard pan after two passes over a furrow ripped by theMaresha plow. This is a better combination suited to conservationtillage systems for smallholder farmers in semi-arid regions.

As can be seen in Table 2, the rip-plant type of conservationtillage system resulted in less seedling emergence and establish-ment of maize compared to the conventional tillage. The furrowsthat were made at 75 cm spacing in the rip-plant system were leftopen until planting time while each furrow in the conventionaltillage system was closed by the soil moved during the next pass.Before planting time, there was some dry spell during which theupper layer of the soil dried as the moisture evaporated. Atplanting, the Maresha plow was used to open furrows at 75 cmspacing in all the plots before seeds and fertilizer were placed

Table 3Agronomic performance of different tillage systems on maize, 2004.

Tillage system Wulinchitya

Biomass (kg ha�1) Grain yield (kg h

CONV 4500 1610

RIPSUB 3850 1480

RIPSUB + INTc

RIP2 4010 1600

Values in each column are not significantly different.a Plant population range 41,100–43,600 plants ha�1, plant height 159–170 cm.b Plant population range 29,800–33,600 plants ha�1, plant height 150–167 cm.c Beans intercropped after the maize crop reached knee height failed due to moistur

Table 4Agronomic performances of different tillage systems on tef, 2004.

Tillage systems Wulinchity

Biomass* (kg ha�1) Grain yield (kg h

CONV 2900 1010

RIPSUBPLOW 2940 1030

RIPSUB 2470 820

RIPPLOW 2800 960

* Values in this column are not significantly different.a Plant height range 77.5–85.0 cm, panicle length 31.8–33.9 cm.

manually. In the rip-plant type of tillage system, the same furrowsthat were made at the beginning of tillage were renewed to placeseeds and fertilizer. Renewing the furrows might have made only ashallow scratch of the furrow bottoms which were still relativelydry as the moisture in the upper few centimeters had evaporated.The seeds might have fallen on dry soil thus taking longer togerminate and to emerge.

On the other hand, the planting furrows made in theconventionally tilled plots were produced from a relatively levelsurface and hence fresh furrows were made. The new furrowsproduced in this way were about 10 cm deeper than the originalsoil surface and hence their bottoms were relatively wet. The seedsplaced in these furrows probably got in contact with moist soilresulting in better seedling emergence and establishment.

Moreover, the subsoiled furrows could have had deeper loosesoil beneath the seeds than the ripped ones that probably lost theretained water at greater depths there by providing less moistureto the seeds. The seedling emergence and establishment in thesubsoiled treatment were slightly less than the ones that were onlyripped with the Maresha plow (Table 2).

3.2. Agronomic evaluation of tillage systems

A continuous follow up on the agronomic performance of eachtreatment was made during the season. The conservation tillagetreatments performed better at a later stage in terms of the rate atwhich the crop was growing. However, the effect of poor

Melkawobab

a�1) Biomass (kg ha�1) Grain yield (kg ha�1)

3690 1070

2700 960

2900 890

2900 1010

e stress.

Melkawobaa

a�1) Biomass* (kg ha�1) Grain yield* (kg ha�1)

2360 960

2560 980

1730 830

2390 890

Table 5aDraft force requirement and cross-sectional area of furrows with different implements.

Type of implement Draft force (kg) N STD (�) Cross-sectional area of furrows (cm2) N STD (�)

Maresha plow 103 118 7.09 305 50 30.8

Tie-ridger 79 78 6.01 416 50 38.5

Inverted BBM 96 85 6.88 363 50 46.9

N is the number of readings.

Table 5bLifting forcea required by different implements while tying furrows.

Type of implement Lifting force (kg) N STD (�)

Maresha plow 42.3 50 6.6

Tie-ridger 24.6 50 3.5

Inverted BBM 43.9 50 4.8

N is the number of readings.a Lifting force is the force required by the operator to lift the handle to tie the

ridges.

M. Temesgen et al. / Soil & Tillage Research 104 (2009) 185–191190

establishment at the beginning could be seen in the final results.For maize, although differences are statistically not significant,slightly better results from the conventional tillage were observed(Table 3). The subsoiled plots (RIPSUB) performed less than theripped ones again (RIP2) because of poor seedling emergence at thebeginning. Seeds were placed along the subsoiled plots and hencethe open furrows that lost much of the retained water when theywere exposed to dry and hot weather probably had less moisturefor the seeds resulting in delayed germination and emergence. Therefilled plants lagged behind in establishment and growth.

Results on tef (Table 4) show that the reduced tillage treatmentwhere subsoiling was included gave the highest grain yieldalthough the differences are statistically significant only atWulinchity at P < 0.06. Regular monitoring of the crop perfor-mance has been carried out through out the growing period thatshowed best performance of the crop under the reduced tillagetreatment with subsoiling. The minimum tillage treatment(RIPSUB) performed the least throughout the season. Moreover,the reduced tillage system where subsoiling was not carried out(RIPPLOW) did not perform so well as the reduced tillage wheresubsoiling was included (RIPSUBPLOW).

As in the case of maize, furrows made in the conservation tillagetreatments of the tef fields were left open. This could have resultedin evaporation losses of the moisture. The effect is not expected tobe so severe as the one seen on maize because maize was plantedin June when the soil was dry. Tef was planted in August and hencethe furrows could have had the chance of being rewetted. Besides,one time plowing that was added to the reduced tillage treatments(whether subsoiled or not), 3 weeks before planting, has probablychanged the problem of furrow drying.

Cow pea planted as a cover crop before tef planting failed toestablish due to moisture stress.

3.3. Field performance of the Tie-ridger

The test results of the Tie-ridger are shown in Tables 5a and 5b.The larger cross-sectional area of the Tie-ridger compared to theMaresha plow and the inverted BBM (P < 0.001) would enableretention of more water. Hence, rainfall partitioning can bepositively altered to make more water available for cropproduction in semi-arid regions where, in particular, rainfall iserratic thereby generating higher proportions of runoff.

The draft power requirement (Table 5a) of the Tie-ridger wasalso lower than the other two implements (P < 0.001) whichwould enable the rather weak oxen in semi-arid regions to performthe job of tie-ridging with less energy. Moreover, the lower liftingforce required by the Tie-ridger (P < 0.001), when tying thefurrows (Table 5b), will considerably reduce the drudgery of theoperation. The lifting force was so low with the Tie-ridger becausethe high inclination angle of the blade of the Tie-ridger reduced thevertical soil pressure that resisted lifting.

3.4. Field performance of the Sweep

The efficiency of the Sweep in terms of accomplishing lightworks such as weed control and fertilizer incorporation during tef

planting is higher. The Sweep worked faster because of wideroperation (56.2 cm at a speed of 0.71 m s�1 as compared to 41.2 cmat a speed of 0.63 m s�1 for the Maresha) and lower draft powerrequirement that enabled the oxen to walk faster. Mulatu andRegassa (1986) reported timeliness problem during tef planting.Therefore, such a higher work rate (field capacity of 0.083 ha h�1 ascompared to 0.056 ha h�1 of the Maresha) will enable farmers tofinish planting earlier than with the traditional plow.

Data collected on root length of the tef crop at maturity showedthat the use of the Sweep resulted in an average root length of203 mm compared to 179 mm under the conventional plantingsystem. The roots of the crop planted using the Sweep grew deeperthan those planted conventionally, in all of the 8 farmers’ fields andstatistical analysis revealed highly significant differences betweenmeans (P < 0.001). The mixing of fertilizer with soil duringplanting might have stimulated the roots to grow deeper insearch of nutrients. Deeper roots enable the crop to utilize soilmoisture from lower layers. This is particularly important at thelater growth stages when the upper soil layer dries because of dryspells or early cessation of rainfall.

4. Conclusions

The Subsoiler, when operated in furrows made by the Mareshaplow, penetrated up to a depth that would enable disruption of thehard pan created under the conventional cultivation system of theMaresha plow.

The Tie-ridger made furrows with larger cross-sectional areasthan those made by the Maresha plow and the inverted BBM whilerequiring lower draft forces. The lifting force required by the Tie-ridger when tying furrows was lower than that required by theMaresha plow and the inverted BBM.

The Sweep reduced the time required during planting of tefwhile mixing fertilizer with the Sweep resulted in deeper rootgrowth of tef compared to the conventional planting techniques.

The best of reduced tillage systems tested on tef (RIBSUBPLOW)resulted in higher grain and biomass yield than the conventionaltillage. In semi-arid areas where dry spells are expected betweensubsoiling and planting, conservation tillage systems in which theplanting furrows are closed should be tested for maize productionin order to prevent evaporation losses.

Acknowledgements

The study was financed by the Netherlands Foundation for theAdvancement of Tropical Research (WOTRO) and the Regional

M. Temesgen et al. / Soil & Tillage Research 104 (2009) 185–191 191

Land Management Unit (RELMA) of the Swedish InternationalDevelopment Agency (SIDA).

References

Ahenkorah, Y.E., Owusu-Bennoah, G.N., Dowuona, N. (Eds.), 1995. Sustaining SoilProductivity in Intensive African Agriculture. CTA Publishers, Wageningen, TheNetherlands, p. 29.

Basic, F., Kisic, I., Butorac, A., Nestroy, O., Mesic, M., 2001. Runoff and soil loss underdifferent tillage methods on Stagnic Luvisols in Central Croatia. Soil Till. Res. 62,145–151.

Bezuayehu, T., Gezahegn, A., Yigezu, A., Jabbar, M.A., Paulos, D., 2002. Nature andcauses of land degradation in the Oromiya Region: a review. Socio-economicsand Policy Research Working Paper 36. ILRI (International Livestock ResearchInstitute), Nairobi, Kenya, 34 pp.

Biamah, E.K., Rockstrom, J., 2000. Development of sustainable conservation tillagesystems. In: Biamah, E.K., Rockstrom, J., Okwach, G.E. (Eds.), ConservationTillage for Dryland Farming. Technological Options and Experiences in Easternand Southern Africa. Nairobi: Regional Land Management Unit, Swedish Inter-national Development Agency (Sida). RELMA Workshop Report Series 3, pp. 36–41.

Chen, J., Li, H.W., 1998. Technology and machinery system of mechanized con-servation tillage for dryland maize. J. China Agric. Univ. 3 (4), 33–38.

Edwards, W.M., Triplett, G.B., Van Doren, D.M., Owens, L.B., Redmond, C.E., Dick,W.A., 1993. Tillage studies with a corn-soybean rotation: hydrology and sedi-ment loss. Soil Sci. Soc. Am. J. 57, 1051–1055.

Engida, M., 2000. A desertification convention based on moisture zones of Ethiopia.Ethiop. J. Nat. Resour. 1, 1–9.

Freitas, V.H., 2000. Soil management and conservation for small farms. Strategiesand methods of introduction, technologies and equipment. FAO Soils Bulletin77, 31 pp.

Gebregziabher, S., Mouazena, A.M., van Brussel, H., Ramon, H., Nyssen, J., Ver-plancke, H., Behailu, M., Deckers, J., de Baerdemaeker, J., 2006. Animal drawntillage, the Ethiopian ard plough, maresha: a review. Soil Till. Res. 89, 129–143.

Goe, M.R., 1987. Animal traction on smallholder farms in the Ethiopian highlands.PhD Thesis. Cornell University, pp. 127, 160.

Hoogmoed, W.B., 1999. Tillage for soil and water conservation in the semi-aridtropics. Doctoral Thesis. Wageningen University, The Netherlands, pp. 21–25.

IGAD and FAO, 1995. Crop Production System Zones of the IGAD sub-region. Agrometeorology Working Paper Series No. 10. FAO, Rome, Italy.

Jonsson, L.O., Singisha, M.A., Mbise, S.M.E., 2000. Dry land farming in Tanzania:experiences from the Land Management Program. In: Biamah, E.K., Rockstrom,J., Okwach, G.E. (Eds.), Conservation tillage for dryland farming. Technologicaloptions and experiences in Eastern and Southern Africa. Nairobi: Regional Land

Management Unit, Swedish International Development Agency (Sida), 2000.RELMA Workshop Report Series 3, pp. 96–113.

Mulatu, T., Regassa, T., 1986. Nazret Mixed Farming Systems zone survey report.Research Report No. 2/87. Department of Agricultural Economics and FarmingSystems Research, Institute of Agricultural Research, Addis Ababa.

Pathak, B.S., 1987. Survey of agricultural implements and crop production techni-ques. FAO Field Document 2, Eth/82/004. EARO, P.O. Box 2003, Addis Ababa,Ethiopia, 36 pp.

Reicosky, D.C., 2001. Tillage-induced CO2 emissions and carbon sequestration:effect of secondary tillage and compaction. In: 1 World Congress on Conserva-tion Agriculture, Madrid, 1–5 October 2001, pp. 265–274.

Rockstrom, J., Valentin, C., 1997. Hillslope dynamics of on-farm water flows: thecase of rain-fed cultivation of pearl millet on sandy soil in the Sahel. Agric.Water Manage. 33, 183–210.

Rockstrom, J., Kaumbutho, P., Mwalley, P., Temesgen, M., 2001. Conservation tillagefarming among smallholder farmers in E. Africa: adapting and adopting inno-vative land management options. In: World Congress on Conservation Agri-culture, Madrid, 1–5 October 2001, pp. 363–374.

Rowland, J.R.J. (Ed.), 1993. Dryland Farming in Africa. Macmillan Education Ltd. incooperation with the CTA, Wageningen, The Netherlands, pp. 37, 72.

Sime, M., 1986. Field Performance of the Maresha plow and Nazret plow. AIRIC TestReport No. 14, Agricultural Implements Research and Improvement Centre, Eth/82/004. Institute of Agricultural Research, Addis Ababa, 12 pp.

SPSS, 2001. Statistical Package for the Social Science, Version 10.0. SPSS, Inc., USA.Steiner, K.G. (Ed.), 1998. Conserving natural resources and enhancing food security

by adopting no-tillage. An assessment of the potential for soil-conservingproduction systems in various agro-ecological zones of Africa. GTZ EschbornGermany, 47 pp.

Temesgen, M., 2000. Animal drawn implements for improved cultivation in Ethio-pia: participatory development and testing. In: Kaumbutho, P.G., Pearson, R.A.,Simalenga, T.E. (Eds.), Empowering farmers with animal traction. Proceedingsof the Workshop of the Animal Traction Network for Eastern and SouthernAfrica (ATNESA), 20–24 September 1999, Mpumalanga, South Africa, pp. 70–75.

Wanders, A.A., Stevens, P.A., 2000. Technology transfer and on-farm evaluation ofanimal powered equipment: approach and experience of IMAG-DLO. In: Kaum-butho, P.G., Pearson, R.A., Simalenga, T.E. (Eds.), Empowering farmers withanimal traction. Proceedings of the workshop of the Animal Traction Networkfor Eastern and Southern Africa (ATNESA), 20–24 September 1999, Mpuma-langa, South Africa, pp. 52–60.

Whiteman, P.T.S., 1979. Mekele Research Station, Northern Region: Progress ReportApril 1975–December 1976. Institute of Agricultural Research, Addis Ababa, pp.8–12.

Willcocks, T.J., 1984. Tillage requirements in relation to soil type in semi-aridrainfed agriculture. J. Agric. Eng. Res. 30, 327–336.

Wondimu, B., Getachew, A., Geta, K/Mariam, Dilnesa, E., 1998. BBM Wings beyondwhat they were meant for. AgriTopia 13 (2), April–June 1998.