Effect of Cultural Practices and Fertilizers on Sunflower Yields in Long Term Experiments

Abstract

HELIA, 29, Nr. 44, p.p. 135-144, (2006) UDC 633.854.78:631.41.6:631.81
EFFECT OF CULTURAL PRACTICES AND
FERTILIZERS ON SUNFLOWER YIELDS IN LONG
TERM EXPERIMENTS
Petcu, Gh.*
and Petcu, E.
Agricultural Research and Development Institute (ARDI),
Fundulea, 915200, Romania
Received: September 10, 2005
Accepted: March 25, 2006
SUMMARY
Field experiments were conducted during 1980-2004 at Agricultural
Research and Development Institute from Fundulea (Romania) on a leached
chernozem soil, well drained, formed on loess, with 33% clay content and 2.8%
organic matter in the arable layer. The paper presents aspects regarding the
influence of different soil tillage methods (moldboard plow, chisel, paraplow,
disking), fertilizers and track by track successive passings of tractor (from 1 to
3) prior to seedbed preparation on sunflower yield under dryland conditions.
The developed modern crop production technologies should be improved in
response to concerns about environmental impacts of agriculture towards
cropping intensification reduction. In this context, choice of a good soil tillage
method management is an important decision to improve grain yield and quality. Continuous implementation of optimal rates of fertilizers (from different
chemical types or manure) helps us to obtained more efficient sunflower cropping systems. The wheel pressure induces a soil compaction down to 40 cm
depth, emphasized by an increase of bulk density and a decrease of total and
air porosities below the minimum level needed for normal crop development.
The plant height and leaf area were reduced by compaction, as a result of deteriorated soil conditions for root growth. The root biomass was lower by 16-
33% in compacted soil as compared with non-compacted one.
Key words: crop rotation, soil compaction, fertilizer, root development, biomass accumulation, oil content

Full text

HELIA, 29, Nr. 44, p.p. 135-144, (2006) UDC 633.854.78:631.41.6:631.81
EFFECT OF CULTURAL PRACTICES AND
FERTILIZERS ON SUNFLOWER YIELDS IN LONG
TERM EXPERIMENTS
Petcu, Gh.* and Petcu, E.
Agricultural Research and Development Institute (ARDI),
Fundulea, 915200, Romania
Received: September 10, 2005
Accepted: March 25, 2006
SUMMARY
Field experiments were conducted during 1980-2004 at Agricultural
Research and Development Institute from Fundulea (Romania) on a leached
chernozem soil, well drained, formed on loess, with 33% clay content and 2.8%
organic matter in the arable layer. The paper presents aspects regarding the
influence of different soil tillage methods (moldboard plow, chisel, paraplow,
disking), fertilizers and track by track successive passings of tractor (from 1 to
3) prior to seedbed preparation on sunflower yield under dryland conditions.
The developed modern crop production technologies should be improved in
response to concerns about environmental impacts of agriculture towards
cropping intensification reduction. In this context, choice of a good soil tillage
method management is an important decision to improve grain yield and qual-
ity. Continuous implementation of optimal rates of fertilizers (from different
chemical types or manure) helps us to obtained more efficient sunflower crop-
ping systems. The wheel pressure induces a soil compaction down to 40 cm
depth, emphasized by an increase of bulk density and a decrease of total and
air porosities below the minimum level needed for normal crop development.
The plant height and leaf area were reduced by compaction, as a result of dete-
riorated soil conditions for root growth. The root biomass was lower by 16-
33% in compacted soil as compared with non-compacted one.
Key words: crop rotation, soil compaction, fertilizer, root development, bio-
mass accumulation, oil content
INTRODUCTION
Plant-available water is the most limiting factor to yield potentials of dryland
agriculture in semiarid regions. Therefore, in the semiarid South Great Plains of
Romania, water is often the primary factor influencing management decisions con-
cerning appropriateness of cropping systems and crop selection within cropping
* Corresponding author, Fax: 0040 242 642044; e-mail: petcug@ricic.ro

136 HELIA, 29, Nr. 44, p.p. 135-144, (2006)
systems. Besides the latest movement in land property registered in Romania and
the lack of founds which determined farmers of many agricultural zones to increase
the area planted to sunflowers give presently more problems in crop rotation. Our
objective was to compare the trends of sunflower yields from different treatments in
long-term experiments conducted in the last two decades. A large scale for climatic
parameters in South of Romania, registered year by year, in trial experimentation
period requires new strategies in sunflower cropping in strong dependence with
local conditions.
Crop selection and management strategies for tillage, weeds, organic matter,
fertilizers and residue that will give the most effective use of water are needed
(Stone et al., 2000).
On the other side, an intensive traffic with tractors and other farm vehicles over
arable land leads to soil compaction. Wheel pressure causes a decrease in soil
porosity which affects crop development. The degree of compaction depends
directly on the magnitude of the pressure forces, soil type and its moisture.
The effect of soil compaction on soil fertility and crop yield was studied by sev-
eral authors (Barnes et al., 1971; Eriksson et al., 1974; Soane et al., 1982; Boone,
1986; Hakansson et al., 1988; Sin et al., 1989, 1991). According to their data, soil
compaction determines the rate of deterioration of soil properties regarding water
and air movement and nutrient regime, hinders root growth and brings yield losses.
Although the compacted soil is loosened by plowing, the soil conditions can
became unfavorable for plant growth because a pan may develop in the unworked
subsoil, with impaired structure specific for the compacted soil.
The paper presents some aspects concerning the response of sunflower to dif-
ferent cropping systems and soil compaction intensity.
MATERIALS AND METHODS
The site
A trial was conducted between 1989-2004 at Agricultural Research and Devel-
opment Institute, Fundulea (44°27’N 26°31’W, 67 m above sea level). The soil in the
location was mapped as a moderately leached chernozem soil, well-drained, formed
on loess, with 33% clay content and 2.8% organic matter in arable layer.
The climate is classified as “DFAX type” (de Martonne classification), with high
inequalities for monthly rainfall repartition during year. The annual rainfall during
the trial was characterized by large variability between years and among months in
the same year. Data from Figure 1 have indicated the highest value for rainfall dur-
ing sunflower vegetation in 1991 (572 mm) vs. 305 mm for the trial period average
1987-2004, up to 8 mm higher than long-term average, noticed at Fundulea (1960-
2004).

HELIA, 29, Nr. 44, p.p. 135-144, (2006) 137
Generally, the average monthly air temperatures were higher in the latest dec-
ade than the long-term average (+1.2°C).
Treatments and experimental design
The experimental schedule consists of main cultural practices: crop rotation,
soil tillage method, fertilizers and soil compaction.
The compaction treatments were tested in a fall-plowed field, by successive
passings of a tractor U-650 (of 3800 kg weight) in the spring, prior to seedbed prep-
aration.
The various degrees of compaction were obtained by four wheel traffic treat-
ments:
a. - unwheeled (C0);
b. - one pass of tractor, track by track (C1);
c. - two passes of tractor (C2);
d. - three passes of tractor (C3).
After soil compaction, seedbed preparation was performed by disking. The
crop technology was normal, regarding sowing time (during 15-20 April), plant den-
sity (4.6 plants/m2), fertilization (N100P75) and weed control (chemical and mechan-
ical methods).
Determinations
Soil samples were collected for determination of bulk density immediately after
soil compaction and at harvest. Taking into account the values of bulk density, the
total and air porosities were indirectly determined.
Observations and measurements concerning plant emergence, plant growth,
root development, yield components and main indicators of yield were also made.
F
igure 1: Mean annual rainfalls and air temperatures during vegetation seasons for the
experimental period

138 HELIA, 29, Nr. 44, p.p. 135-144, (2006)
At flowering, the root growth was assessed by the endoscopic method, in the area
round the plant in 0-60 cm layer.
The experiment was stationary, organized in a 6-year rotation (maize after win-
ter wheat) and designed in randomized blocks in 4 replications. The size of experi-
mental plot was of 120 m2.
Statistical analysis
The data obtained during the trial were subjected to the analysis of variance,
using ANOVA test statistical procedures. Differences among the treatments were
evaluated with the least significance difference test (LSD), each mean being com-
pared with the experiment mean or a control value. Pearson correlation coefficients
were used to compare yield performance against some qualitative and growth
parameters. All discussed differences were significant at the P=0.05 probability
level.
RESULTS AND DISCUSSION
Effect of soil compaction on main physical soil indices, plant growth, yield pro-
duction and quality for sunflower cropping.
Table 1 presents the evolution of the main physical indicators of the soil during
1987-2004. In the non-compacted variant, the total air porosity is diminished into
soil, from 0 to 40 cm, while the bulk density increased from 1.22 g/cm3 in the
Table 1: Effect of soil compaction on the main physical indicators of the soil (before sowing),
Fundulea, 1987-2004
Variant Depth Soil moisture Bulk density Soil porosity Air soil porosity
cm % g/cm3%%
C00-10 22.0 1.22 52.3 21.6
10-20 23.7 1.31 50.0 14.8
20-30 23.9 1.38 47.5 10.7
30-40 24.0 1.41 46.2 7.3
C10-10 22.5 1.41 44.4 6.9
10-20 23.9 1.46 44.5 5.3
20-30 23.5 1.47 44.2 4.8
30-40 23.8 1.45 44.9 5.0
C20-10 22.3 1.43 43.1 5.9
10-20 23.6 1.47 43.6 4.3
20-30 23.5 1.46 43.7 3.8
30-40 23.4 1.45 44.1 3.6
C30-10 22.2 1.51 42.9 4.5
10-20 23.7 1.48 43.1 3.0
20-30 23.4 1.47 43.3 3.7
30-40 23.3 1.46 43.9 3.3

HELIA, 29, Nr. 44, p.p. 135-144, (2006) 139
superficial layer to 1.41 g/cm3 into its depth (30-40 cm). In variant C1, with com-
pacted soil and with its bulk density of 1.43 g/cm3, the air porosity was strongly
diminished and in C3 variant these features were very much under the values regis-
tered in non-compacted variant. The increase of the volumetrical weight and the
reduction of the total air porosity in the compacted variants influenced the growth
and development of the root system (Table 1).
The root area and biomass accumulation have showed an important decrease
in the case of variant C3 in the top layer of the soil (from 0 to 10 cm).
One can notice the increasing tendency of the root matter in the 20 – 30 cm
layer, where the compaction has not affected the structure of the soil.
Taking into account the entire weight of the root for each plant, on the whole
depth of the tested soil, an important reduction in root weight in the third variant of
soil compaction.
The total surface of the root registered an important increase in the variant of
slight compaction (C1) and a distinct reduction in the case of C3 (1.50 g/cm3),
(Table 2).
In the variant of severe compaction (C3), the root makes greater efforts, which
calls for a high energy consumption and which has negatively affects root growth
(Russell, 1977).
Coming back to the effect of the diminution of the root matter reduction
determined by the narrowing of the spaces between soil aggregates and of the air
porosity both on growth plant and green matter, we can notice that this effect
appears still from first stage of vegetation. Thus, plant height, leaf area, biomass
accumulation and yield are negatively influenced by soil compaction during the
flowering stage (Table 3).
Table 2: Effect of soil compaction on root growth of sunflower (before 10-leaf stage)
Depth, cm The root area, cm2/plant Biomass accumulation in root, dry matter/plant (g)
C0C1C3C0C1C3
0-10 1286 1341 796 11.5 9.4 7.1
10-20 374 353 210 2.7 1.5 1.6
20-30 348 397 92 2.3 2.2 2.1
30-40 208 217 198 2.1 1.8 1.2
40-50 172 194 114 1.5 1.7 1.1
50-60 112 143 131 0.8 0.5 0.3
Total 2500 2645* 1541000 20.9 17.1013.400
LSD P < 0.05 % 140 (cm2/plant) 3.1 (DM g/plant)
Table 3: Indices of sunflower growth, at flowering stage, depending on the soil compaction
(variation limits during the experimental period)
Treatment Number of plants/ha
x 1000
Plant height,
cm
Leaf area,
cm2/plant
C044.6 168 - 185 3210 - 3460
C140.7 151 - 163 2920 - 3100
C339.5 147 - 159 2780 - 3020

140 HELIA, 29, Nr. 44, p.p. 135-144, (2006)
It is obvious that in both cases of soil compaction, slight (C1) and severe (C3),
dry matter accumulation is decreased not only in the root but also in the shoot and
leaves, this proving that the physiological activity of the plant is affected, a great
part of its assimilates being necessary to obtain the energy for root penetration.
Concerning grain yield, it was evidently reduced in all variants of compaction
and was influenced also by weather conditions (Table 4).
These results have been confirmed by other researchers, who emphasized that
the first element, which acts as a stressing element for root, is the oxygen content
from the soil (Hoffmann, 1982, Gay, 1999).
The changes that occurred in sunflower plants under conditions of soil compac-
tion positively affected the oil content in seeds (Figure 2).
Table 4: Effect of soil compaction on sunflower yield (in kg/ha), Fundulea, 1995-2004
Year of experiment Treatment Average
per year
C0C1C2C3
1995 2130 2260 2260 2050 2175
1996 1590 1250 1200 1010 1263
1997 1690 1600 1360 1230 1470
1998 2540 2430 2270 2360 2400
1999 1960 2190 2330 2210 2173
2000 1340 1610 1580 1360 1473
2001 1470 1260 1300 1150 1295
2002 940 1070 1140 1340 1123
2003 1170 1670 1450 1090 1345
2004 2500 2590 2420 2240 2438
Average period 1733 1793 1731 16040
LSD P < 0.05% 110 (kg/ha)
Figure 3: Relationship between yield and
achene oil content of sunflower
F
igure 2: Effect of soil compaction on achene
oil content (nine-year average)

HELIA, 29, Nr. 44, p.p. 135-144, (2006) 141
Our results confirmed that yield and oil content were negatively and signifi-
cantly correlated (Figure 3).
Effect of alternation soil tillage methods and fertilizers on yield production
in dryland experiments
Only one disking of the soil as well as more ones, surely generate similar situa-
tions to the above mentioned cases.
Analyzing the root system distribution in different depths in the case when the
soil was only disked before sowing, a reduction in root area was observed in com-
parison with the plowed variants (Table 5).
In the case of the different fertilizers applied to the plowed variant, it is obvious
the effect of weather conditions (Figure 1) and fertilization type (Figute 4). In a wet
Table 5: Effect of soil tillage on some features of sunflower plants
Variant
Root area (cm2/pl)
in top soil layer
(0-20 cm)
Yield,
Q/ha
% from
control
Oil content,
%
Oil yield,
l/ha
Disk 860 23.2 89.8 45.8 1065
Plow (20 cm)-(Control) 1750 25.9 100.0 45.1 1169
Plow (30 cm) 1820 26.0 100.3 44.3 1150
Spring plowing 1420 24.3 93.9 45.2 1101
Plow 20 cm/Disk 1250 25.1 97.0 45.5 1144
Plow 30 cm /Disk 1350 25.7 99.4 44.7 1152
Plow 20 cm/Disk (2) 1102 25.5 98.6 44.8 1143
Plow 30 cm /Disk (2) 1230 25.3 97.5 44.0 1112
Plow 20 cm/Disk (3) 853 24.6 95.1 45.7 1125
Plow 30 cm/Disk (3) 925 24.6 95.1 45.4 1116
LSD P< 0.05% 2.3
F
igure 4: The tendency of fertilization on sunflower yield under autumn plowed variant

142 HELIA, 29, Nr. 44, p.p. 135-144, (2006)
year such as 1991, the grain yield from the plowed and manured variant was
reduced due to the nutrient leaching from manure.
The reductions in seed yield observed in 2000, 2001 and 2002 can be attrib-
uted to the negative effects of the low rainfall received by sunflower plants during
growing season, which affected plant growth and, consequently, their performance
(Figure 4).
CONCLUSIONS
1. The root system of the sunflower is a dynamic system with different possi-
bilities of adaptation to unfavorable soil and weather conditions.
2. Soil compaction determines controls/causes reduction of both, biomass
accumulation in the root and grains yield per plant.
3. In the case of disking applied to the soil, similar conditions are registered
for the growth and activity of the root system as in the case of soil compact-
ing with similar effects on the yield.
4. Type of fertilization determines the yield increasing in connection with
weather conditions.
REFERENCES
Ardell D. Halvorson, Alfred L. Black, Joseph M. Krupinsky, Steven D. Merrill, and Donald L.
Tanaka, 1999. Sunflower Response to Tillage and Nitrogen Fertilization under Intensive
Cropping in a Wheat Rotation. Agronomy Journal 91: 637-642
Ardell D. Halvorson, Alfred L. Black, Joseph M. Krupinsky, Steven D. Merrill, Brian J.
Wienhold, and Donald L. Tanaka, 2000. Spring Wheat Response to Tillage and Nitrogen
Fertilization in Rotation with Sunflower and Winter Wheat. Agronomy Journal 92: 136-
144
Barnes, K.K., Carleton, W.A., Taylor, H.M., Throckmorton, R.I., 1971. Compaction of agricul-
tural soils. ASAE Monograph. U.S.A.
Boone, F.R., 1986. Towards soil compaction limits for crop growth Neth. J. Agric. Sci. 34: 349-
360.
Eriksson, J., Hakansson, I., Danfors, B., 1974. The effect of soil compaction on soil structure
and crop yields. Sweed. Inst. Agric. Eng., Uppsala Rep. pp. 354.
Hakansson, I., Woorhees, W., Hugh, R., 1988. Vehicle and wheel factors influencing soil
compaction and crop response in different traffic regimes. Soil Res. 11: 239-282.
Loyd R. Stone, Dwayne E. Goodrum, Mahmad Nor Jaafar, and Akhter H. Khan, 2000. Rooting
Front and Water Depletion Depths in Grain Sorghum and Sunflower. Agronomy Journal
93: 1105-1110
Michael P. Bange, Graeme L. Hammer, Stephen P. Milroy, and Kenneth G. Rickert, 2000.
Improving Estimates of Individual Leaf Area of Sunflower. Agronomy Journal 92: 761-
765
Russell Scott, 1977. Plant root system: Their function and interaction with the soil, Publish.
Mc Grow-Hill Book Comp. Limited, pp. 144-152.
Sin, Gh., Ionita, St., Terbea Maria, Boruga, I., 1989. Einfluss der Bodenverdichtung auf
Wachstum und Ertrag von Feldkulturen und auf einge Parameter beim Pflügen. Wiss.
Tagung des FZB - Müncherberg, DDR, pp. 181-188.
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Proceedings of the International Conference of Sunflower, Pisa, Italy, pp. 422-427.

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Soane, B.D., Dickson, J.W., Campbell, D.J., 1982. Compaction by agricultural vehicles: a review
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36.
INFLUENCIA DE LAS MEDIDAS AEROTÉCNICAS Y
FERTILIZACIÓN EN EL RENDIMIENTO DE GIRASOL EN
LOS EXPERIMENTOS A LARGO PLAZO
RESUMEN
Los experimentos en campo fueron llevados a cabo en el período de 1980
a 2004 en el Instituto de Investigaciones y Desarrollo Agrícolas en Fundulea
(Rumunía) en el chernoziom empobrecido, filtrante, formado en loess, con el
contenido de arcilla de 33% y 2.8% de materia orgánica en el estrato cultivable.
En el trabajo se considera la influencia de diferentes métodos de labranza de
tierra (arado de vertedera, escoplo, subsolador, disqueo), fertilización y los
pasos consecutivos con el tractor (1 a 3 veces antes de la preparación de
presembrado en el rendimiento de girasol, cultivado en la labranza seca). Las
nuevas, modernas tecnologías de producción de plantaciones deben ser ade-
lantadas, como respuesta a reflexión sobre la influencia de la agricultura en el
entorno, en la dirección de disminución de intensidad de la producción. En
ese contexto, la elección del favorable método de labranza de tierra, es una
decisión importante, con la cual pueden mejorarse el rendimiento y la calidad
del grano. La aplicación continua de las dosis de fertilizantes óptimas (mine-
rales y orgánicos) nos ayudó a desarrollar los sistemas de cultivo de girasol
más eficaces. Las ruedas de las máquinas agricultoras causan la compresión
del suelo hasta una profundidad de 40 cm, incrementada por el aumento de
volumen y disminución de la porosidad total y la porosidad aérea debajo del
mínimo aceptable para el desarrollo normal de las plantas. La altura de la
planta y la superficie de hoja, son disminuidas por la compresión del suelo,
como resultado de las empeoradas condiciones del suelo para el desarrollo de
la raíz. La biomasa de la raíz ha sido disminuida por 16-33% en el suelo
comprimido, en comparación con el no comprimido.
EFFET DES MESURES AGRICOLES ET DES FERTILISANTS
SUR LES RENDEMENTS DE TOURNESOL DANS LES
EXPÉRIENCES À LONG TERME.
RÉSUMÉ
Des expériences sur un chernozem appauvri, bien drainé, formé sur le
loess avec un contenu d’argile de 33 % et 2,8 % de matière organique sur une
couche arable ont été effectuées dans les champs de 1980 à 2004 à l’Institut de
recherche et de développement agricole de Fundulea (Roumanie). Cet article
présente l’effet de différentes méthodes de labourage (charrue à soc, chisel,
paraplow, disking), fertilisants et passages successifs du tracteur rangée par
rangée (de 1 à 3) avant la préparation du sol sur le rendement du tournesol
cultivé dans des conditions de terre sèche. Il faut améliorer les nouvelles tech-
nologies de production pour répondre aux inquiétudes concernant les effets de
l’agriculture sur l’environnement en réduisant l’intensification de la culture.
Dans ce contexte, le choix d’une bonne méthode de labourage est important et

144 HELIA, 29, Nr. 44, p.p. 135-144, (2006)
il peut améliorer la production et la qualité des récoltes. Une application con-
stante des doses optimales de fertilisants (minéraux et organiques) contribue
au développement d’un système de culture du tournesol plus efficace. La pres-
sion exercée par les roues cause une compression du sol jusqu’à 40 cm de pro-
fondeur, ce qui est renforci par une augmentation de la densité de la masse et
une diminution de la porosité totale et de la porosité de l’air jusque sous le
minimum acceptable pour le développement des plantes. La hauteur de la
plante et la surface de la feuille ont diminué à cause de la compression qui
forme un sol moins propice au développement des racines. Dans le sol
comprimé la biomasse des racines était inférieure de 16-33% à celle des rac-
ines dans un sol non comprimé.