r79 AL AWAMLA - N" 83 - Décernbre 1993

FURROW OPENERS AND PRESSWHEELSEVALUATION FOR NO.TILL WHEAT SOWING

BAHRI 4.,* VON BARGEN. K**, and BANSAL. R.K.'r

KEY WORDS : Furrow opener, No-till. Conscrvation Tillage .

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ABSTRACTDoublc disc. single disc. and hoe openers combined with doublc-rib and

natrow rounded presswheels mountcd on a Type grain drill were evaluated forsowinq wheat in no-till conditions In a relatively soft soil, the double discopenei was found to be suitablc tbr no-till sowing of wheat . However, in hard{iy soils, hoe opcners performed bettcr tltat other types-of o.pclers because it

fienctrated tlre sbit more easily . Thc greater iunount of soil disturbance andiowcr sectl row soil bulk tlcnsiiy createtl by the hoe opetrer improved soil-seedcontact giving a better plant stand . The presswlrcel type had no significant effecton mosf of ihe parameters studicd . It was observed that good coulters areessential to effbctively cut resiclue to avoid blocking the hoe openers, even if theresidue is only I (o 1.6 t ha-l .

* Centre Régional de la Recherche Agronomique, BP 5E9' Settat' Morocco'** University of Nebraska, Lincoln NB' U.S.A.

180 AL AWAMTA - N" 83 - Décembre 1993

INTRODUCTION

In the semi-arid region of Morocco, water is the most limiting factor for cropproduction . Mean -annual raintàll ranges between 250-450 mm and it is highlyvariable in terms of total amount and distribution (Watts and El Mourid. 1988) .Thus, conservation of soil moisture for crop production is extremely important .Rescarch has been conducted at the Centre Resional de la RechercheAgronomique (CRRA). Settat, Morocco tbr a rrumler of years to evaluatealternate soil management practices. including no-till and minimum tillage, toimprove crop production. mainly wheat and some food legumes . Results haveshown that no-till and minimum tillage practices have potential benefits forstabilizing and increasing wheat yields . Four years research on a vertisol in thesemi-arid region of Morocco showed that no-tillage produced significantly betterwheat yields than minimum tillage, which in tum was much better than theconventional tillage practices currently followed by farmers ( Bouzza, 1990 ).Kacemi (1992) studied tillage effect on wheat yields in rotation with foodlegumes and concluded that minimum tillage is superior to conventional tillagefbr stabilizing wheat yields . The yield advantages from no-till and minimumtillage were attributed to belter soil moisture and soil physical status at thebeginning of the cropping season that allowed early sowing . However. bothresearchers fbuud that wheat crop establishment in relatively hard and dry soilswith residue from the previous crop left on the surface, was a major problem .

The majority of Moroccan farmers sow small grain cereals (wheat andbarley) by broadcasting seeds by hand followed by one pass of an off-set discharrow for seed covering. Some of the progressive farmers have started usinggrain drills However, the conventional grain drills do not have the desireddesign fèatures for no-till sowing . Grain drill specially suited for no-(ill sowingare not yet available in Morocco . On the other hand. there is a wide variety ofno-till grain drills in Europe and North America . But their designs may not suitMoroccan conditions because of difference in soils and environment. Thus, theresearch reported in this paper was conducted with an overall objective todetermine furrow opener and presswheel selection criteria for no-till wheatsowing in Morocco.

MATERIAL AND METHODS

Field experiments were conducted at Lincoln NE, U.S.A . and two locationsin the semi-arid region of Morocco, Sidi El Aydi (SEA) and Jemaat Riah (JR), toevaluate the pertbrmance of double disc, single disc, and hoe openers incombination with double-rib and narrow rounded presswheels, for sowing wheatin no-till conditions .The soil texture and the mean annual rainfall for the threesites are given in Table I which shows that Lincoln soils have high proportion ofsilt. whereas SEA soils have clay and JR soils sand as dominent constituents.The experiment at Lincoln was sown on 23 October 1990 in a field withsoybean residue . At each site in Morocco. two fields, one with light wheatresidue and the other with light lentil residue. were used for the experiment. Theexperiment was sown on 14-15 November l99l at both sites in Morocco Thetreatments consisted of three types of furrow opeuers and two types of

t 8 1 AL AWAMIA - N'83 - Décembre 1993

presswheels. tested iu a randomized complete block design with fourieplications. A no-till grain drill manufactured by Tyc company, I-ockney TX,U.S.A, was fitted with three each of double disc. single disc. and hoe openers .This machine has a fixed 20-cm row spacin-e ard it is equipped with 43-cmdiameter rippled coulters ahead of the openers The presswheel treatmentscousisted of 5.1 x 33 cm ltarrow rounded and 10.2 x 30.5 cm double-ribpresswheels . Each plot was 25 m long and 2 m wide to allow one pass of theTye grain drill which represented all the three furrow openers followed by eithernarrow rounded or double-rib prcsswheels . Observatiorls were recorded only onthe middle row for each opener. to avoid hrrder effect . Procedures adopted tbrrecording field observatiotrs are briefly described below .

Furrow Profile

The furrow profile observation was recorded to quantify the amount of soildisturbance and change in the soil surface configuration . The furrow profilewas traced using a protilometer positioned at right angle to seed rows . Theprofilometer has a series of pins at 15 mm spacings sliding in a vertical plane .When resting on the ground. lhe top edges of the pins. marked on the paper,showed the surface profile across the seed rows . The furrow profile was laterdigitized using Sigma-Scan sofiware and digitizer (Sigma-Scan, 1987) . Thestandard deviation of the furrow profile observatiot)s was taken as the funowroughness coefficient (RF) (Tessicr and Saxton, 1989) This coefficientprovided a quantitativc description of soil disturbance caused by each openerand presswheel combination .

Soil Sampling for bulk density and moisture contentdetermination

Soil samples were talien bcfore sowing and from within-the-row after sowingto determine the ch;mge in soil bulli density and moisture contetrt . Thesemeasurements were talien (hree times for each heatment in each plot . AtLincoln. NE, soil samples were talien from the top 76 mm soil layer using a handheld soil probe of 23 mm internal diameter . At the both sites in Morocco. a handheld soil probe of 31 mm internal diameter was used and samples were takenfiom 0-5 cm and 5-10 cm soil layers .

Seed plncement

Funow opencrs were adjusted in a trial area outside of the experiment beforesowing to obtain the desired seed placement depth . This was achieved byclunging spring pressure aud presswheel-.height at each_opener uxtil all theopeners were operating at the desirecl seeding depth. At JR where the soil wasrelatively hard, maximum spring pressure was applied to force the openers intothe ground . Seeding depth observations were talien at the same time when thefinal plant emergence was counted . Thirty planfs were randomly pulled fromeach plot and the length from the seed to the beginning of the green tissue on thestem was measured . This length was taken as the effective seeding depth . Thetreatments were evaluatcd on the basis of mean seeding depth of 30 plants andthe the associated standard deviation values .

182 AL AWAMTA - No 83 - Décembre 1993

Table I : Soil texture and annual rainfall ât the three experiment sites.

Description

Soil type

Location

Lincoln SEA JR

Silty-clay loam Verlisol Clay loam

Clay (Vo)Silt (7o)Sand (7o)

3060l0

6025t-5

28l 359

Mean annullrain fall(rnm)

760 380 380

Table II : Summary of observations on initial soil physical conditions andresidue levels at Sidi El Aydi and .Iemaat Riah sites.

Sites

Soil moisture

(Vo)

0 - 5 c m 5 - l 0 c m

Soil bulk

(Mg m-3)

0 - 5 c m

density Residue

(Kg ha t

5 - l 0 c m

Sidi El Aydi

Ccreal stubble

Lentil stubble

Jemaat Riah

Cereal slubble

Lentil stubble

t3.7r 3.3

20.515.5

1.09

l . l 9

L 1 6

1.27

I 190

1470

8.0

7.2

r 3.310.6

1 .30

r .2 lr . 4 l

1 .34

I 150

1540

183 AL AWAMLA - No 83 - Décembre 1993

Plant Emergence

At Lincoln NE, plant counts were takcn when the seedlings were about lOcmfrlgft . Most plarts'were at two leaf s_tage . In the experiments conducted inMôrocco, plant counts were talien at l0 days interval starting 20 days after thesowing daG to study the rate o[ emergcnce .

RE,SULTS AND DISCUSSION

Initial conditionsInitial soil physical condilion and residue levels at both sites in Morocco are

given in (Tablè ti) wtrictr shows that soils at SEA had more moisture comparedio Jemaai Riah . Ânother significant difference was between wheat artd lentilstubble fields . Wheat stubbldfields at both locations had higher soil moisture in

5- 10 cm layer compared to lentil stubble fieltls . Bulk density observatious taketrin 0--5 atrd -5-10 cni layers showed that soils at JR were more compacted than alSEA . Cone Inclex dâta talien by a hand-held cone penetrometer presentcd inFiguLc I i l lustmtcs lhe same poirrt .

Fig. I Cone index observations in wheat and lenti lresidue lîelds at SllA and.IR sites.

3,500

3,000

2,500

2,000

1,5(X)

1,000

500

0

A

ntÀJ

xot,socoo

' t

a

SEA nLenlilSEA.{hed

JEq!"dJR lenil

æ

Depth (cm)

184 AL AWAMIA - N'83 - Décembre 1993

Furthermore, wheat residue field at JR was much more compacted than thelentil residue field . But at SEA, there was not much differeirce in the soilcompaction up to 15 cm depth in the wheat and lentil residue fields . Theexperimental fields had light residue, in the range of l.l to 1.6 t ha-l, from theprevious crops even though none of those fields were grazed prior to seeding.

During the sowing operaton, soil and residue flow was very good betweenthe single, and the double disc openers . However. the hoe openers occasionallyplugged with residue especially where the coulter did not cut it elfectively . Ithappened -in wheat residue fields where the slraw was moist and not evenlydistributed on the soil surface .

Furrow profrle

Results from all of the five experiments showed that the eftèct of furrowopener type on the furrow profile was significarlt (P<0.05) at each location whilethat of the presswheel was not (Table III) . In general, in a relatively soft soit atLincoln site. Soil roughness coefficient for single disc opener was higher thanthat tbr the other openers (Table III) . In lentil residue fields ar both sites inMorocco, the soil disturbarce from single disc opener was comparable to the hoeopener . The major diff'erence was that the single disc opener usually opened awider furrow . The hoe opener penetmted deeper and made a rectangula-r furrowprofile causing considerably more soil disturbance . Occasionally, the RF valueswere low because soil fell back in the tunow behind the hoe opener.

In both wheat residue fields, the roushness coefficient was hishest for hoeopener and least lbr the double disc openàr. There appeared to be so'me influenceof the type of residue on the soil movement by the three types of openers .

Furrow compaction

At Lincoln NE. no significiurt differences (b0.05) were found in seed rowsoil bulli densities of 0-5 cm layer because all openers peneffated to the samedepth . However. at both sites in Morocco seed row soil bulk density in 0-5 cmlayer was significantly different (P<0,05) fbr the three furow openers (Table IV). the presswheel type had no significant effect . In general, 0-5 cm layer soil bulkdensity for the hoe opener was significantly (P<0,05) less than the conespondingvalues for the other types of openers (Table IV) . This was probably due to thegreater amount of soil movement by the hoe openers . Hoe opener seem to havea desired tillage-like action in the seed row on relatively hard soils . The greateramount of soil disturbance and low soil bullç density probably improvedseed-soil contact. Soil bulk density observations in 5-10 cm layers did not showany significant elïect of the funow opener and presswheel treatments.

Seed row soil moisture

In the experiment at Lincoln NE. there appeared to be an interaction betweenthe opener type and the presswheel type on seed row soil moisture (P<0,05)(Fig.2) . The hoe opener conserved more soil moisture in the seed row whenfollowed by the double-rib presswheel In contrast, the single disc openerconserved more soil moisture when followed by the narrow rounded presswheel.

185 AL AWAMIA - N'83 - Décembre 1993

Fig. 2Interaction between Opener and Presswheelin conserving seed row moisture.

I

q)

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5o'6

20.0

19.0

18.0

l.lanowrounded

Doublerib

Presswh€el

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Dresenled in Table V . The soil rnoisture corltcnt was recorded somewhat highcratler sowing the experimcnt compared to initial soil moisture given in Table II,especially in the top 5 cm layers . This was because 3mm rain at SEA and 4 mmrain at JR was reCeived during the intervening period . Perhaps, this rainfallerased the treatmetrt effect to some extetlt . At SEA, the effect of treatments wasnot significant on seed row soil moisture in 0-5 cm and 5-10 cm depths, exceptin the case of the top 0-5 cm layer in lentil residue tleld (Table V) ' At JR, eventhough furrow opeuers had a significant efÏect on seed row soil moisture in thewheal residue field, the differences were very small . In general, double-ribpresswheels seem to have been more et'fective ilt furrow closing arld soilôompaction. Concerning the opener type. seed rows sown with the hoe openershad slightly more soil moisture, but this trend was not consistent .

Seeding depth

Before sowing the experiments. each funow opener was carefully adjusted toget an optimum- seeding depth. However. the openers resulted in differentseeding depths, especially in the wheat stubble fields where the residue wastougher and unevenly distributed .

At Lincoln NE, seeding depth from the three types of openers did not differsignificantly (b0,05) regardless of the type of presswheel used (Table VI) . Tltiswas because the soil was quite soft at seeding time . Standard deviations ofseeding depths (Table VII) show that the double disc opener maintainedrelatively better seeding depth uniformity compared to the other two openers .

SD( ; )

- . r ê

H . SO: Single Oræ Opener

OO: Ooubl€ Oisc Opener

H: Hæ Oo€n€r

186 AL AWAMIA - N" 83 - Décembre 1993

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t 9 l AL AWAMIA - N'83 - Décembre 1993

At SEA. 5-6 cm seediltg depth obtairtcd by all the three opener types wasquite satisfactory (Table Vtf . Hôwever. seeding depth of 3,5-4.,5 cm otrtained atJR was somewliat shallow . Tltis was mainly due to higher soil compaction andless soil moisture at JR (Table II) . In lentil fields there was no significantdifference (b0.0-5) among the tlpe of openers . However in the wheat stubblctïelds. the hoe opener appealed t0 have penetrated deeçrer than.-the othcr twoopeners . AIso. tire averà-ùc scetling deptlt was more in the lentil residue fieldtliur in the wheat residue ticld at thc same site. In gcneral, thc presswhcel typchad no effect on seeding depth .

Plant stand

Plant stancl is the ultimate test of a furrow opcner as it reflccts ur overalletfèct of all othcr factors discussed above . Plartt stand observalions at Lincohtshowed lhat lhe double disc opener pcrtbrmed significantly (b0.05) better thanboth single clisc and hoe openers (Tahlc VIII) . It may be due to more unitbrmseeding depth obtained by the double disc opener . Ou an avcrage.46-plants-inlm roù lerigth were counted for the double disc opener cornpared to 33 for thehoe opencr ànd 3l for thc singlc disc opener . Some interaction was observed inthe opener type and the presswheel type . Hoe opcner followed by double-ribpresswheel had a higher plant cmcrgcnce compared to thc hoe opetrer andnarrow rounded presswhcel combination ltt contrast, sirtgle disc openerpcrtbrmed better with narrow rounded prcsswheel .

Tablc VIII : Comparison of furrow openers and presswhe-e\ based.onemerged plant population means at Lincoln, NE experiment'

Funowopener

Presswheel

Double rib Narrow rounded Mean

Hoe

Double disc

Single disc

Mean

45.4

26.4

36.3c

- Plant stand in I m row-

29.1 33.4b*

46.0 45.7a

-Jt .6

31.13c

3 1 . 1 b

LSD (-57o)CY = 29c/o

9.30 I r .39

* Means fbllowecl by thc samc letter arc not signilicanlly dilfcrent (p> 0. 05)

192 AL AWAMTA - No 83 - Décembre 1993

F'ig. 3 Plant stand on different dates in wheat residuefield at Sid El Avdi.

6 2 5

En.s

E

F 1 5oco 1 00.

l-lo€--e-

Double disc- - - D - -

Sirqle dbc. - . . . . L . . . .

wilh nanow round€d

Hoe-.-#

Double disc- - - E f - -

Slnole dlsc. . - À - .withdoublerib

Dec.11 Dec,19 w.24 Jan.3

Dates

The plant stand data from wheat and lentil residue fields at SEA artd JR inMorocco is presented in Figures 3-6, respectively . These graphs show that thenumhr of plants increased steadily for all treatments up to December 24, and insome cases up to January 3 . Observations tiaken on January 3 and january 20showed that in all fteatments plant stand had either stabilized or tended todecline from a prolonged drought . It can also be seen that the maximum plantstand achieved at SEA was between 30 and 35 plants in I m row, depending upon the treatment and the residue situation . In comparison. maximum plant standin I m row at JR was less than 25 in wheat residue fields and around 15 in lentilresidue fields . These differences in plant stand rellect the differences betweenthe two sites in terms of initial soil physical condition and soil moisture(Table lI) .

193 AL AWAMIA - N" 83 - Décelnbre 1993

t ' is. 4 Plant stand on dilterent dates in lenti l-

residue f ' ield at Sidi l) l AYdi'

2 ç

3s ? ô

È

; z scf(

v,

E z oo-

'I 5

7 '

Hoe----rts-

Double disc- - - ] - -

Single disca .

with nanow rounded

Hoe----&-

Double disc- - - E F - -

Sinqle disc

with doubl+rib

D€c. 11 D€c. 19 D€c.24 Jan.3 Jan.20

Dates

Figures 3 antl 5 show that in the whcal residue fields . the plant stand wasalway,s best fiorn thc hoe opener lbllowctl by double disc and sin-gle discopcnèrs. in that older . In the lentil residue ficltls (Fig. 4 arrd 6). tlre differencesamong the openers were not so clear, perhaps because thc type of openers ltad nosignificant el'fbcl on sccding depth . The hoe opgner and thc doublc disc openergave similar plant stands in both lentil rcsidue plots . The factors that secm tohave improved the pcrfonnance of the hcle opener were the grcater amount ofsoil disturbance in the furrow. and somewhat decper sced placemcnt, particularlyin the wheat resicluc fields . Perhaps soil movement in the course of seedingoperation improved seecl-soil contact leading to better germinatim Thepresswheel did not seem to have made a significant dif f-erence on plant stand inany of the experiments at SEA or JR .

t94 AL AWAMLA - N'83 - Décembre 1993

3oÊ: l s.gEÊ

1fr 10c-go.

Fig. 5 Plant stand on different dates in wheat residuefield at Jemaat Riah.

Hoe---c-

Double dbc- - - ] - -Slngle dbc

. . . . 1 . . . .

wilh nrnowroundd with doubbrib

t)€c. 11 Dec. 19 Oæ.24 Jan.3

Dates

SUMMARY AND CONCLUSIONDouble disc, single disc, and hoe openers combined with double-rib and

narrow rounded presswheels mounted on a Tye no-till grain drill were evaluatedfor sowing wheat in no-till conditions at three sites : one at Lincoln. NE , U.S.A.and two in the semi-arid region in Morocco . The soils, residue cover in terms ofits source and quantity, and soil physical condition at the time of sowing wheatwere quite different at those thee sites .

Results showed that for relatively soft and moist soils, such as thoseencountered at Lincoln, the double disc opener is the most suitable for no-tillsowing of wheat .

195 AL AWAMIA - N'83 - Décembre 1993

Fig. 6 Plant stand on different dates in lentilresidue fleld at Jemaat Riah.

20

, 1 5o -

E

E r o(!(t)

od s

offiD€c.11 t)sc.'19 D€c.24

DatesJan. 3 Jan. â)

However, if the soils at the time of sowing are quite dry and hard. asencountered at bth sites in Morocco, a hoe opener design is better suitedbecause it can penetrate the soil more easily . The hoe opener also had atillage-like effect in the funow, compared to other types of openers, whichimproved seed-soil contrct and gave a higher plant stand . The presswheel typehad no significant effect on most of the parameters studied, particularly at bothsites in Morocco . However, the double-rib presswheel appeared to have donebetter seed covering and soil compaction than the n:urow rounded presswheel . Itis also important to have good coulters ahead of the hoe openers to effectivelycut residue and avoid blocking of furrow openers, even if the residue is light,1 to 1,6 t ha-t.

. A

Â.. ^a. . ' ' a

Hoe-+-+--

Double disc- - - E F - -

Sinole disc. - è .with doubledb

ltt ,/ ^ Hoe/..i,,/ --{--',',/ Double disc- - - ] - -

Single disc. . . l } - .

with nanow rounded

,i('itil

197 AL AWAI\'IIA N" 83 - Décembre 19911

ACKNOWLEDGEMENT

The research reportcd here was carricd out with support fiom MIAC urdcrUSAID Proiect No. 608-0136 .

198 AL AWAMIA - N' 83 - Décembre 1993

REFERENCES BIBLIOGRAPHIQUES

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