181

SUMARY OF PHD THESIS

The research for the PhD thesis „Research on the influence of soil tillage system

on Agropyron repens (sin. Elymus repens) and Cirsium arvense crop weed growth” was

organized during the 2009-2011 period, in Cluj Napoca, within the Fruit Growing

Research and Development Station.

The research focuses on finding the influence of four methods of soil tillage on

weed growth in general, with special reference on Agropyron repens and Cirsium

arvense.

Establishing the interaction between the method of soil tillage and the weed

growth was approached starting with the fact that the presence of a species, either

Agropyron repens or Cirsium arvense, interacts with the other weed species, thus the

knowledge of total weed growth and its flower composition seems more illustrating.

The presence of the two species that the thesis referred to is directly related to the

cultivation technology in a crop rotation, specific corn-soybean-wheat crop rotation.

The results included in the thesis focuses on finding the percent in which the two

weed species are found in general weed growth.

The objectives of research are as follows:

1. Establishing the influence of soil tillage method on weed growth in corn crop;

2. Establishing the influence of soil tillage method on weed growth in soybean crop;

3. Establishing the influence of soil tillage method on weed growth in wheat crop;

4. Determining the evolution of weed growth under the influence of a soil tillage

system during the three years corn-soybean-wheat crop rotation;

5. Establishing the influence of weed growth of couch grass on corn, soybean and

wheat crop production;

6. Establishing the influence of weed growth of couch grass on corn, soybean and

wheat crop production;

182

7. Establishing the influence of weed growth of creeping thistle on corn, soybean and

wheat crop production;

The four methods of soil tillage, expressed in experimental factors and the

herbicides used during research were:

Factor A – Method of soil tillage

a1. The conventional system, worked with plough;

a2. The unconventional chisel tillage system;

a3. The unconventional paraplow tillage system;

a4. The direct sowing system

Factor B – The herbicides used

The herbicides used were differentiated depending on the cultivated plant.

The influence of the method of soil tillage on weed growth of Agropyron repens

and Cirsium arvense was tested during a three years crop rotation: corn (2009), soybean

(2010), autumn wheat (2011).

The cultivation technology for every crop culture was zone specific, only the

method of soil tillage and the use of herbicides making the difference.

The hybrid variety used in corn crop was Turda 200 variety, in soybean crop was

Triumf and in autumn wheat crop was Arieşan variety.

The influence of soil tillage system on weed growth with Agropyron repens and

Cirsium arvense was concluded through observations on total weed growth, and special

reference on the percent of these two species in general weed growth, depending on the

method for soil tillage.

Agropyron repens and Cirsium arvense weed growth was tracked down through

the number of plants per square meter and the regeneration capacity of the two species on

the field worked differently with conventional or unconventional systems.

183

Because the percent of the two species in general weed growth was low, a separate

influence of those on crop production could not be expressed, being necessary an

estimation of total weed growth.

In wheat crop the effect of soil tillage on weed growth was observed without

herbicide differentiation. The reason for this choice in wheat crop was the uniformity of

weed species identified in every soil tillage variant, no significant changes being noticed

regarding the number of species and the dicotyledonated / monocotyledonated weed ratio

that would impose herbicidal differentiation.

The field setup of corn, soybean and wheat crops is reproduced in the next

experimental field schemes. For wheat crop only two herbicides were used.

Experimental field scheme for corn crop, 2009

b1 b2 b3 b4 b5 b6 b1 b2 b3 b4 b5 b6 b1 b2 b3 b4 b5 b6

a1

a2

a3

a4

R1 R2 R3

Experimental field scheme for soybean crop, 2010

b1 b2 b3 b4 b5 b6 b1 b2 b3 b4 b5 b6 b1 b2 b3 b4 b5 b6

a1

a2

a3

a4

R1 R2 R3

184

Experimental field scheme for wheat crop, 2011

b1 b2 b1 b2 b1 b2

a1

a2

a3

a4

R1 R2 R3

Experimental conditions and experimental field features are characterized by:

from pedological point of view, the experimental field is an aluvisol-calcaric type on

gravels with a loamy clay texture in the first 40 cm and clay loam texture over 60cm.

Morphologically, the soil identified in the experimental field has the following

succession of horizons: Ap – A/C – Cka, which ensures an useful edafic volume of more

than 50 cm. Within this volume, the roots are present in the first 40 cm, being only

sporadically identified in 40-52 cm horizons and none at depths bigger than 52 cm. Its

worth mentioned that in the first 50 cm no other restricting elements were identified, like

gravel or gleic horizons or salted horizons that would limit the root system development

and implicitly, the development of plants forming the crop rotation structure.

Biological activity within the experimental field soil is in normal limits,

cervotocines and coprolites being identified in the fertile horizon of 0-40 cm depth. The

internal drainage system of soil is good even if at 60-70 cm an excess of clay is

registered; we assume that this excess do not give gleization processes because of the

20% sand presence, which favors the drainage of water excess.

Compaction degree of soil is in normal range, with values of apparent density

between 1,20 and 1,30 g/cm3.

185

The total porosity of soil is 54,0%, which ensures the minimal limit of aeration.

The compaction degree of soil in 0-10 cm depth emphasizes a very good soil

looseness, which favors in the first stage the weed seeds to reach the minimal

germination depth of 3-4 cm, but during vegetation period, in 5-6 cm depth some lack of

water problems rise, following the water evaporation and drainage towards higher depths.

This aspect was observed also at corn crop emergence, when appeared some non-

uniformities related to sowing depth.

As a conclusion, in what concerns the physical features of soil, these are in favor

of growth and development of plants used in the experiments (corn, soybean, autumn

wheat) and are not restrictive for soil tillage systems use, even if the clay content of soil ,

around 41%, is limited.

The above ascertainments are necessary for fundament the effects of soil tillage

both on weed growth and on crop production that may be registered in the experimental

field, then in extensions plots and normal culture.

The chemical features of soil in experimental field are related to soil texture,

respectively to treatments applied in pre-emergent crop, before starting the experiments.

The soil reaction (water pH) is weak alkaline on entire soil profile, with a

moderate content of calcium carbonate, having 8,5 – 9,7% in the first 40 cm, then an

increase to 14% in the 65-75 cm horizon, and then a decrease to a moderate value of

9,4%.

The humus content is medium at surface and low in depth, but traces were

identified until 100 cm, owed to a biological activity in sol, related either to a physical

displacement or a soil micro fauna’s activity.

The nitrogen content is moderate in the first 40 cm, as well as the phosphorous

content, aspect taken into consideration in the crop fertilization within the crop rotation.

186

The potassium content is high, over passing 360 ppm in the first 20 cm, 360 ppm

in 20-40 cm depth and 200 ppm at depths higher than 60 cm.

As a conclusion, the chemical features of soil do not limit the growth and

development of plants in experimental crop rotation.

The soil quality, synthetically expressed in the bonitation chart, correlated to

bonitation of relief conditions and to climatic resources, ensures framing the

experimental filed soil in class 2 of quality, with 73 bonitation points, good favorability

for corn crop, followed by wheat and soybean crop.

The soil influences both production and weed growth degree, Agropyron repens (

sin. Elymus repens) and Cirsium arvense species included.

The influence factors of soil, presented by bonitation chart, are humus reserve,

medium to high, higher useful edafic volume and ground water depth, which in case of

Cirsium arvense species have significant influence.

The bonitation conditions confirm that no atypical factors, like excess of humidity,

flood ability, pseudo-gleization, are involved in influencing the weed growth in crop

cultures, in different ways depending on climatic conditions of the experimental years.

187

ANALYTICAL DATA OF SOIL PROFILE

Horizons Ap Ao Cka Cgo Depth (cm) 5-12 25-36 67-75 103-110 Coarse sand % 3,88 4,37 0,39 0,39 Fine sand % 23,25 22,7 13,92 19,38 Dust I % 12,25 14,99 12,78 11,58 Dust II % 18,61 16,82 24,63 19,41 Clay 0,002mm % 41,98 41,12 48,28 49,24 Texture interpretation Lut

argiloasa Lut

argiloasa Argilo lutoasa

Argilo lutoasa

Scheleton % - - - - Hygroscopicity % - - - - Apparent density g/cm3 1,20-1,30 1,30-1,35 - - Total porosity % 54,0 53,8 - - Interpretation Mare Mare - - pH 8,34 8,22 8,38 8,32 Interpretation Slab

alcalin Slab

alcalin Slab alcalin Slab alcalin

Carbonates CaCO3 % 8,5 9,7 14,0 9,4 Interpretation Moderat

carbonatat Moderat

carbonatat Puternic

carbonatat Moderat

carbonatat Humus % 2,15 2,00 1,27 1,24 Interpretation Mijlociu Slab slab Slab N total % 0,169 0,164 0,116 0,113 Interpretation Moderat moderat slab Slab P205 mobile ppm 34 26 6 6 Interpretation Mijlocie mijlocie Foarte

slaba Foarte slaba

K20 mobile ppm 384 364 206 206 Interpretation Foarte bun Foarte bun Foarte bun Foarte bun SB me - - - - AH me - - - - T me - - - - V % - - - - Interpretation - - - - Other observations - - - -

188

FIŞA DE BONITARE

PENTRU STABILIREA CLASEI DE CALITATE A TERENULUI SITUAT ÎN

CÂMPUL EXPERIMENTAL Nr. ind.

Denumire indicator Cod ind.

Limite de încadrare

Coeficienţi de bonitare ARABIL

GR PB SO 3C T.m.a.(val.corectate)

08,5 8,1-9,0 1 0,9 0,9

4C P.m.a.(val.corectate)

0,650 601-700 0,9 1 0,9

14 Gleizare

00 Negleizat 1 1 1

15 Pseudogleizare

00 Nepseudogleizat 1 1 1

16/17 Salinizare/Alcalizare

00 Nesalinizat 1 1 1

23a Textura (0-20cm)

50 33-45 1 1 1

33 Panta

01 Sub 2% 1 1 1

38 Alunecãri

00 Absente 1 1 1

39 Adâncimea apei freatice

03,5 3,01-5,00 0,9 1 0,9

40 Inundabilitate

0 Neinundabil 1 1 1

44 Porozitatea totalã

+15 39-43 0,9 0,9 0,9

61 Conţinutul de CaCO3

10 8-12 1 1 1

63 Reacţia solului

8,1 7,9-8,4 1 1 1

133 Volumul edafic util

0,88 76-100 1 1 1

144 Rezerva de humus

180 161-200 1 1 1

181 Exces de umiditate

00 Fara exces de umiditate

1 1 1

Produsul coeficienţilor de bonitare

0,73 0,81 0,66

Nota de bonitare

73 81 66

Nota medie de bonitare

73

Clasa de calitate a- II-a

* GR - grâu, PB - porumb, SO - soia

189

Form climatic point of view, the experimental years 2009, 2010, 2011 are

characterized by average temperatures of 11,2 (2009), 12,6 (2010) and 11,7 (2011- July)

and precipitations with values ranging from 756,6 (2009), 710,9 (2010) and 314,4

(2011- July).

Thermal regime during experimental period 2009-2010-2011(July) in Cluj-Napoca

Temperatures (ºC)

Month Annual

average I II III IV V VI VII VIII IX X XI XII

Average 2009 1,9 2,4 4,1 13,7 18,9 19,1 21,1 18,3 14,6 12,8 5,9 2,1 11,2

Average 2010 -0,9 7,0 7,8 12,2 17,5 22,7 23,7 24,1 17,3 10,0 9,8 1,1 12,6

Average 2011 -1,5 -5,2 9,1 14,3 19,1 22,8 23,8 - - - - - 11,7

Normal over 105 years

-4,5 -2,3 3,2 9,1 14,3 17,5 19,3 18,3 14,3 9,1 3,3 -1,6 8,3

± 2009 deviation 2,6 0,1 0,9 4,6 4,6 1,6 1,8 0,0 0,3 3,7 2,6 0,5 2,9

± 2010 deviation 3,6 4,7 4,6 3,1 3,2 5,2 4,4 5,8 3 0,9 6,5 0,5 4,3

± 2011 deviation 3 2,9 5,9 5,2 4,8 5,3 4,5 - - - - - 3,4

Source: USAMV Meteorological Station, Cluj-Napoca

Rain regime during experimental period 2009 -2010 -2011(July) in Cluj-Napoca

Precipitations (mm)

Month Annual Sum

I II III IV V VI VII VIII IX X XI XII

Average 2009 19,8 27,3 26,4 29,8 105,7 64,2 116,3 113,2 119,4 75,4 39,7 19,4 756,6

Average 2010 4,0 14,4 15,6 47,2 105,3 183 121 57 63,2 28 27,8 44,4 710,9

Average 2011 23,4 1,8 7,8 39,0 67,2 80,4 94,8 - - - - - 314,4

Normal over 105 years

26,2 24,5 29,4 47,0 76,3 90,4 82,2 69,3 43,6 41,5 30,9 29,5 590,8

± 2009 deviation

-6,4 2,8 3,0 -17,2 29,4 26,2 34,1 43,9 75,8 33,9 8,8 -10,1

165,8

± 2010 deviation

- 22,2

10,1 13,8 0,2 29 92,6 38,8 12,3 19,6 - 13,5

- 3,1 14,9 120,1

± 2011 deviation

-2,8 22,7 21,6 8 9,1 10 -12,6 - - - - - -276,4

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Results obtained

The results obtained during research period and included in the thesis attempt to

answer to research objectives.

Following is synthetically presented the influence of soil tillage systems and

chemical treatment system for every crop in rotation, with reference to general weed

growth and Agropyron repens and Cirsium arvense species percent.

The special reference for the two species is made because of their specific

breeding particularities, behavior towards the method for soil tillage and the weather

course.

CORN

The results concerning the corn crop weed growth and corn production validates

the direct influence of soil tillage and of herbicides, depending on the variant used.

The analysis of weed growth degree confirms the occurrence of a diversified weed

growing, made of 20 weed species pertaining to 4 groups, annual and perennial

monocotyledonated, annual and perennial dicotyledonated.

The first analysis of registered data on weed number per m2 emphasizes the fact

that the plough working system is able to reduce the degree of weed growth more than

the other experimental systems applied.

Chisel and paraplow working systems induce an increase in weed growth,

compared to the ploughed witness, with 31% for chisel and 22% for paraplow.

The direct sowing in stubble contributes to an increase in weed growth by 48%

compared to ploughed witness and by 17% compared to chisel and paraplow working

variants.

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Considering the higher number of weeds per m2 observed even in the young

vegetation phase of corn, we assume that none of the 4 working systems of soil is able to

solve the problem of weed control in corn crop on soils with features similar to those in

the experiment and normal climatic conditions. If in the first step we estimated the

number of weeds/m2, in the next steps we observed the appearance of other weeds, the

first ones being very well developed, practically compromising the crop from

economically point of view.

A second significant element concerning the weed growth, after the number of

weeds/m2, is the flower composition of weed species. The results showed a higher

percent of dicotyledonated weeds compared to monocotyledonated ones, in all systems

for soil tillage, with slightly differences between them. Thus, in ploughed variant, the

dicotyledonated species (59) represents 184,37% compared to monocotyledonated

species (32); for chisel variant, the dicotyledonated species represents 164,44% compared

to monocotyledonated ones and for paraplow variant the percent is 177,59 compared to

monocotyledonated. For the direct sowing variant the dicotyledonated species represents

159,61% compared to monocotyledonated.

The third significant element is the high percent of annual weeds compared to

perennial ones, in all working variants for soil tillage, thus annual weeds being 3-4 times

more per surface unit compared to perennial ones.

Because the thesis focuses on the relationship between two perennial weed

species, Agropyron repens and Cirsium arvense, with the method for soil tillage, we can

observe that by comparison to the witness variant (ploughed), the other 3 working

systems showed a higher number of Agropyron repens (with 3 to 5 plants), and Cirsium

arvense (with 3 plants).

As for the percent of these 2 weed species, couch grass and creeping thistle, no

significant differences appear between the unconventional systems and direct sowing,

with one observation: paraplow system has a better control of couch grass than chisel

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system, for Cirsium arvense no differences being noticed. The reason for this observation

is the fact that the paraplow, as well as the plough, cuts part of the root system of couch

grass, diminishing the vigor of the plants and their early start in vegetation.

15 days after the corn crop sprouting in the variant were no work has done for crop

maintenance and no herbicide was used, the total number of weeds / m2 was 91 for

ploughed variant, 104 for chisel variant, 111 for paraplow variant ad 135 for direct

sowing variant.

The influence of soil tillage system on weed growth in corn crop depending (2009)

Soil working

system

Total number of weeds (no/sqm)

Total

from

which:

Monocotyledonated Dicotyledonated

Total

from

which:

perennial

annual

Total

from

which:

perennial

annual

a1:plough 91 32 7 25 59 10 49

a2:chisel 104 45 11 34 74 15 59

a3:paraplow 111 40 9 31 71 12 59

a4:direct

sowing

135 52 12 40 83 14 69

Weed growth is significantly influenced by the interaction between the soil

working system and the herbicides used.

The analysis of data referring to chemical control variants confirms a maximum

value for weed growth in variant 6, no herbicide used, were the weed control was covered

only by soil tillage.

The minimal weed growth was identified in variant 2, were the number of weeds

was 23 plants/ m2, followed by variant 4, and were the number of weeds per m2 was 26.

for variants b1 and b4, intermediary values of 37 plants/m2 were registered.

193

Considering the variant 6, no herbicide used, as a witness, by pre-emergent

herbicide treatment with Guardian (2l/ha) or post-emergent treatment on stubble with

Roundup (4l/ha), the weed growth is reduced by 65,75%, having the same flower

composition with the one identified in experimental field.

By completing the total herbicide treatment with a post-emergent one with

Ceredin Super 40, 1l/ha dosage (b2), the weed growth is reduced by 78,71%, the effect of

post-emergent treatment being 12,96%.

The same beneficial effect of reducing the weed growth is observed for post-

emergent chemical treatment with Ceradin, and for pre-emergent treatment with

Guardian, but in this case, the Ceradin effect is only 10,18%.

As for the total chemical treatment with Roundup, compared with pre-emergent

chemical treatment with Guardian, the control effect is the same, at least in what concern

the total number of weeds /m2 determined 15 days after treatment.

By comparing the weed growth reduction in all variants were herbicides were used

with the soil tillage effect, it can be stated that the plowing, as basic tillage, is not able to

ensure weed control, the alternatives being pre-emergent herbicide treatments (that

controls the monocotyledonated perennial and even annual weeds) completed with post-

emergent treatments for dicotyledonated weeds control.

In what concern the two species, Agropyron repens and Cirsium arvense, the

solution is total chemical control with Roundup and even pre-emergent with Guardian.

Cirsium arvense specie is harder to control, being identified in higher numbers in all

treatment variants, pre-emergent, pre-emergent and post-emergent or only post-emergent.

The herbicide treatment system influenced both the number of species and the

ratio between different weed groups.

The highest number of species, 11, was registered in no herbicide variant and the

minimal number in variant 4, with both pre-emergent and post-emergent treatment.

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In what concerns the ratio monocotyledonated / dicotyledonated weeds, it is in

favor of dicotyledonated ones in variants b1, b3, b6, were only pre-emergent or no-

treatment was applied.

For the variants were only post-emergent treatments were applied (b5), the

dicotyledonated weeds were significantly reduced, also in the variant when Ceradin

Super (1l/ha) was applied on an agro fond with total Roundup chemical control in spring.

The structure of weed growth degree with respect to monocotyledonated and

dicotyledonated weeds is in favor of dicotyledonated and especially of annual

dicotyledonated.

The degree and structure of weed growth are elements forming the base of weed

control system and of choice patterns between pre-emergent and post-emergent treatment

or the combination of the two. The answer to this technical problem is given by the

economical efficiency, established at the end for every control system used.

Taking into consideration variant 6 (no herbicidal treatment applied) as witness

variant, in all other 5 control systems the weed growth degree is reduced; this means that

for paraplow variant is a confirmation that any soil tillage has an influence on weed

growth especially when accompanied by chemical control ways.

The number of weed plants identified in the field in chemical treatment variants is

highest for variant 5, when only post-emergent treatment with Ceredin 1 l/ha was applied.

The big number of weed plants is motivated by the lack of control over

monocotyledonated species, which in this variant is virtually equal to dicotyledonated

species, and by the fact that Ceredin doesn’t fully control all species, for instance

Santhium strumarium, Poligonum persicaria and Atriplex patula being identified in

relatively high number per m2.

The lowest number of weed plants was identified in variant 4, when pre-emergent

Guardian 2 l/ha and post-emergent Ceredin 1 l/ha were used.

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For variants 2 and 3 were identified virtually an equal number of weed plants per

m2.

When related to Agropyron repens and Cirsium arvense species, the differentiated

treatments confirm the effect on reducing the number of plants / m2 from 11 to 2, in the

case of Agropyron repens, and from 10 to 3-4 plants /m2 in the case of Cirsium arvense.

In the case of paraplow tillage also, total herbicidal treatment with Roundup do not

totally reduce the 2 species.

The fact that the 2 species are still present in the field, even if in a smaller number,

it is explained also by the deeper placing of root system in soil and by the fact that no

furrow turning up occurs and the root system is not subjected to more stress factors, like

frost in the winter and excessive heat during summer.

The weed growth in direct sowing variant is maintained at highest level from all

experimental plots, with a significant percent of annual monocotyledonated and

dicotyledonated weeds. Chemical treatments influence also in these plots the weed

growth degree.

The highest weed growth appears in variant b6, being identified 128 weed plants /

m2, compared to the lowest value of 57 weed plants/m2.

The weed control degree range between 46,1 – 55,47% in variants where a total

herbicidal treatment with Roundup took place and post-emergent with Ceredin 1 l/ha.

The effect of Ceredin is around 9,37%, when annual dicotyledonated weeds are

dominant.

For pre-emergent chemical treatment with Guardian and post-emergent with

Ceredin, weed control degree ranges between 42,19 – 54,69%, smaller in comparison to

Roundup variant. The effect of Ceredin in this variant is 12,50%. The analysis of these

data shows that when using a pre-emergent chemical treatment, Roundup is preferred

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over Guardian, the control degree being 46,1% for the first herbicide and 42,19% for the

second.

Ceredin herbicide is more effective in variant that uses Guardian, probably due to

remaining dicotyledonated weeds, for which ensures a better control.

When used alone, like in variant b5, Ceredin herbicide achieve a 45,54% weed

control, lower than the total herbicide control with Roundup.

The decrease of weed growth degree because of soil tillage and herbicides is

exemplified also by the crop productions in corn culture.

The analysis of production yields emphasizes crop productions ranging between

4355 – 6356 kg/ ha corn grain, regardless the soil tillage system.

By comparing the crop yields, we observe the highest value of 6356 kg/ ha for

plough tillage system at 28030 cm depth. The explanation is assigned to the positive

effects that the plowing has on water conservation in soil, weed control and enhancing

the microorganisms activity through a better heating of soil during first stage of

vegetation; this favors the better starting in vegetation in the ploughed variant compared

to the other variants. The better start of corn plants in this variant is maintained during the

vegetation period, the plants forming earliest breeding organs (panicle and silk), and at

maturity the water content was lowest.

The soil tillage systems with chisel (a2) and paraplow (a3) registered production at

80-84% of the witness variant (ploughed) value. The 20% difference in minus for chisel

variant and 16% for paraplow variant is related firstly to the higher weed growth degree

registered in this two soil tillage systems. To this is added the less favorable interaction

with fertilizers and the reduction of soil compaction degree, compared to the field where

soil was mobilized by plowing.

197

In variant 4 (a4) only 68% of the witness variant (ploughed) crop yield is

achieved, which raise the question over the economical efficiency of this system for the

corn crop in Cluj Napoca conditions.

Synthetically, considering the ploughed tillage system as witness variant, all the

other 3 systems (a2, a3 and a4) gave crop yields between 4355 and 5082 kg /ha, with

very significant negative differences, with limits between 984 and 1274 for paraplow and

chisel, respectively 2001 kg /ha for direct sowing.

Interaction herbicide – soil tillage – crop yield can be synthetically expressed as

follows:

- for ploughed variant (a1) the best option is pre-emergent herbicide treatment with

Guardian, which gives crop yields benefits of 19%, followed by option with

Guardian and Ceredin, with crop yield benefits of 15%.

- The variant with only post-emergent treatment is not viable, even for ploughed

soil because the presence of annual and perennial monocotyledonated weeds

diminishes the crop yield to 89% of the crop yield of witness variant treated with

Roundup 4 l/ha.

- For chisel and paraplow variants, any of the herbicide treatments applied in b2, b3

and b4 variants is an alternative in comparison to witness treated with Roundup 4

l/ha, the crop benefits for b2 variant ranging between 8 and 11% over a2 and a3

agro fond, and for b3 variant ranging between 2 and 8% over an a2 and a3 agro

fond. Guardian 2 l/ha and Ceredin 1l/ha treatments gave the highest crop benefits,

ranging between 17 and 19% compared to witness variant treated with Roundup 4

l/ha.

- In the plots worked with chisel and paraplow, the only post-emergent Ceredin 1

l/ha treatment is not a solution because the crop production is only 92-95% of the

witness variant treated with Roundup 4 l/ha.

198

SOYBEAN

The soil tillage systems with plough (a1), chisel (a2), paraplow (a3) and direct

sowing (a4) influence the weed growth degree, namely the number of species, the

monocotyledonated/dicotyledonated ratio, and the annual or perennial character of

weeds.

The influence is greater on the weed growth degree and less on number of species.

In general, the species are the same both for annual and perennial monocotyledonated,

the differences being noticed in regard with annual dicotyledonated species. In what

concerns the monocotyledonated/dicotyledonated ratio, the dicotyledonated species have

a higher percent in all soil tillage variants.

A particular element is the presence of Agropyron repens and Cirsium arvense

species, their frequency being higher in chisel, paraplow and direct sowing variants

compared to ploughed variant. This is a significant aspect coming from our observations;

it seems that working the field with the three variants leads to a weed growth of the two

species, for instance in case of couch grass was registered a significant increase from 4 to

20 weed plants in a short period of time, approximately 2 weeks after sowing the soybean

culture.

Synthetically, the weed growth in soybean crop depending on soil tillage system is

confirmed by a variation of weeds number / m2 from 94 (in variant worked with plough)

to 157 (in direct sowing variant). Based on the registered data, we can estimate an

increase by 30,85% of weed growth in paraplow variant, respectively by 138,29% in

chisel variant, compared to variant 1, plough worked soil. The 31-38% increase in the

unconventional variants paraplow and chisel is significant and imposes a change of weed

control strategy, due to the pronounced early start of weed growth which will have an

influence on soybean crop production.

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The degree of weed growth reaches 167,02% in case of direct sowing variant,

which is in accordance to the specialty literature data, which mentioned a higher weed

growth in direct sowing variants.

Synthetically, in what concerns the degree of weed growth in soybean crop related

to soil tillage system, it can be concluded that the plowing ensures the best weed growth

prevention, with only 94 weed plants/m2 compared to the paraplow variants, where weed

growth increase by 30%, in chisel by 38% and in direct sowing variants by 67%.

The soil tillage system influences the total weed growth but also the

monocotyledonated/dicotyledonated ratio, in all variants the dicotyledonated weeds being

dominant, with a 60% compared to monocotyledonated weeds. Consequently, the weed

control strategies have to comprise, in a mandatory manner, dicotyledonated weed

control herbicides because regardless the soil tillage system, this weed group is dominant.

In relation to annual or perennial character of species, the annual ones have a higher share

compared to perennial species.

The Agropyron repens and Cirsium arvense species grow significantly in chisel

and paraplow working variants, 15-17 plants/ m2 compared to 4 plants in ploughed

variants. In the case of direct sowing variant, Agropyron repens specie grow to be 5 times

more present compared to ploughed variant, and this after a short period of time after

starting the culture.

The Cirsium arvense specie is increasing its number of plants in unconventional

variants, reaching to 19 plants / m2 compared to 12 in ploughed variant.

It can be stated that the soil tillage system influences both the total degree of weed

growth in soybean crop and the frequency of dicotyledonated species in spite of the

monocotyledonated ones, respectively increase of weed growth of Agropyron repens and

Cirsium arvense perennial species in all ploughed variants.

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The total degree of weed growth related to chemical treatment variants and soil

tillage systems is presented in the Figure below, confirming that the weed growth is

lowest on the ploughed field regardless the chemical treatment variant, and is highest for

direct sowing variant.

The chisel and paraplow tillage systems behave similarly in all chemical treatment

variants, with differences from a treatment to another, but always the weed growth is

higher on the plough field and lower on direct sowing field.

- a1 - a2 - a3 - a4

Gradul de îmburuienare în funcţie de lucrarea solului şi erbicidele folosite

Lucrarea solului Varianta de erbicidare

b1 b2 b3 b4 b5 b6

Arat a1 37 18 32 38 32 109

Cizel a2 65 55 64 57 57 132

Paraplow a3 68 56 66 62 60 134

Semănat direct a4 73 64 72 78 79 157

0

20

40

60

80

100

120

140

160

b1 b2 b3 b4 b5 b6

The soil tillage systems and the herbicides used have influenced the weed growth

of the culture and consequently, the crop yields obtained in the culture year.

The soil tillage systems in variants a1-a4, ploughed, worked with chisel, paraplow

and direct sowing, ensure soybean crop productions ranging between 2025 kg/ ha for

direct sowing variant and 2499 kg/ ha for ploughed variant; the other variants ensure crop

productions between 2167 – 2278 kg/ ha.

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Compared to witness variant a1, the other working variants of soil allowed

soybean productions of only 81-89%, the differences being very significant negative,

meaning that can be achieved over 2000 kg/ha productions if soil is worked with

paraplow, chisel or direct sowing, but with a minus in crop production of 10,9 to 13,3 %

when using chisel or paraplow, respectively 18,9% when direct sowing is applied in

stubble.

WHEAT

The influence of soil tillage system on weed growth emphasize a different degree

in weed growth depending on tillage system; thus, compared to witness variant with

plough, where 85 plants/mp were identified, in chisel and paraplow working systems the

number of weed plants range between 104-105, meaning an increase with 22-24%. In the

case of direct sowing, the weed growth degree is the highest, reaching 141 plants/mp,

meaning an increase with 65,88%.

The weed growth emphasizes also the percent in which Agropyron repens and

Cirsium arvense appear depending on the soil tillage system; thus, for Agropyron repens,

from plough system to chisel and paraplow, the weed growth degree increase with 37%,

and with 50% in the case of direct sowing.

In the case of Cirsium arvense specie, passing from the classical system to

unconventional system means an increase in appearance with 36% for chisel and

paraplow, and over 100% in case of direct sowing in stubble.

Following a chemical treatment with Icedin Super 1 l/ha, the weed percent reduces

significantly for dicotyledonated species, but annual and perennial monocotyledonated

remain unchanged. In case of perennial dicotyledonated species, a decrease was observed

right after chemical treatment and an increase before harvesting, due to weed breeding

regeneration system. At harvest time, the degree of weed growth is different depending

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on the tillage system, with 27% higher for unconventional variants (paraplow and chisel)

and with 82,7% for direct sowing.

Synthetically, the degree of weed growth depending on tillage system, identified

before harvest time is maintained also at the harvest time.

The wheat production in 2011 confirms the efficiency of unconventional systems

in soil tillage as cultivation technology.

The level of productions ranged between 4067 kg/ha for direct sowing variant and

4632 kg/ha in case of ploughed variant.

The variance analysis emphasizes that in culture year 2011, the unconventional

systems variants registered decreases in crop production with 8-10% for paraplow and

chisel variants, compared to ploughed variant.

The direct sowing variant permitted a minus of 12,2%, meaning approximately

565 kg/ha of wheat.