Effects of Organic and Chemical Fertilizers on Forage Yield and Quality of Globe Artichoke (Cynara scolymus L.)
E. Sharifi Ashorabadi,
To study the effect of organic and chemical fertilizers on forage
yield and quality in globe artichoke (Cynara scolymus L.) an experiment
was conducted using a randomized completed block design (RCBD) with four
replications at the Research Farm of College of Agriculture, University
of Tehran, Karaj, Iran in 2006. The treatments included five levels of
chemical fertilizers, four levels of manure, five levels of mixture of
different ratios of chemical fertilizers and manure (integrated system)
and a control treatment without any fertilizers. Fertilization treatments
significantly affected forage quantity and quality of artichoke. For chemical
fertilizers, total DM yield was increased to 4.13 and 3.7 t ha-1
by the treatments (kg ha-1) N200/P200/K240
and N160/P160/K192, respectively. For
organic systems, the highest yields of 2.86 and 2.77 t ha-1
were obtained by treatments of 30 and 40 tones of cattle manure/ha, respectively.
In the integrated system, the highest DM values of 4.86 and 4.06 t ha-1
were obtained in treatments N80/P80/K96/manure20,000
respectively. The effects of three soil fertilization systems on forage
quality traits were inconsistent. Chemical and integrated systems increased
crude protein (CP), K and P contents in globe artichoke. For dry matter
digestibility (DMD) there were no significant differences among fertilizing
systems, although all of them produced higher DMD compared to control.
For water-soluble carbohydrates (WSC), the positive effect of organic
fertilization was higher than in the other two systems. It was concluded
that artichoke, as a new forage crop, has a good yield and quality potential
for livestock feeding in terms of soil fertilization systems But further
studies would be needed for considering of Artichoke as a new source of
The globe artichoke (Cynara scolymus L.) is a perennial rosette plant
grown throughout the world for its large, fleshy heads. Most of its cultivation
area is in the Mediterranean countries. Other possible uses of Cynara spp.
are the production of lignocellulosic biomass for energy or paper-pulp and grains
for oil and protein production (Jones and Earle, 1966;
Foti et al., 2000). Fresh globe artichoke is used
as good quality forage for livestock (Coon and Ernst, 2003)
and its leaves are used as medication against various diseases (Gebhardt,
Elia and Santamaria (1994) determined the optimum levels
of N, P and K fertilizers for globe artichoke. They declared that nutrient solution
should contain at least 130 mg N L-1 and respective rates of 100
and 250 mg L-1 of P and K for optimum plant growth. These rates increased
plant height, leaf area and number, shoot fresh and dry weight as well as root
dry weight along with the improvement of the root: shoot ratio. In an another
study, Elia et al. (1996) investigated 4 different
ratios 100:0, 70:30, 30:70 and 0:100 of ammonium:nitrate (NH4:NO3)
for artichoke growth. Their results showed that NO3 was the preferred
N form, with 70-100% NO3 resulting in the best vegetative growth,
largest leaf area and root volume and greatest dry weight. Increasing NO3-N
to 100% increased water use efficiency by 2.5-fold compared with 100% NH4.
Gerakis and Honma (1969) reported that the fresh plant
weight of globe artichoke which grows in an organic soil in Michigan (USA) was
markedly influenced by N fertilizer up to 200 kg N ha-1, while P
and K levels had no significant effect. El-Abagy (1993)
investigated three levels of low (71 kg N, 57 kg P2O5
and 119 kg K2O ha-1), medium (142 kg N, 114 kg P2O5
and 238 kg K2O ha-1) and high levels (213 kg N, 171 kg
P2O5 and 357 kg K2O ha-1) of NPK
on globe artichoke production in a clay soil in Egypt. They recommended that
the medium level of fertilizers led to increased plant height, leaf number and
leaf fresh and dry weight. Pedreno et al. (1996)
reported that the reduction of nitrogen application from 500 to 300 kg N ha-1
resulted in reduction of total biomass of artichoke. Salamah
(1997) investigated the response of artichoke (cv. Herious) to N-fertilization
levels ranging from 95 to 380 kg ha-1 in Egypt. Their results indicated
that all the plant growth characteristics such as leaf number and leaf fresh
and dry weight were markedly increased by using 95 to 285 kg N ha-1.
Slightly differences were observed in eco-physiological responses of artichoke
to different levels of nitrogen fertilizer. Foti et al.
(2000) noticed that the response of leaf transpiration and stomatal
conductance to nitrogen rates was not linear. The physiological traits were
higher by using 200 kg N ha-1 compared to control. However, there
was no significant difference between 200 and 400 kg N ha-1. Elia
et al. (1991) evaluated artichoke productivity with N application
rates of 150 and 300 kg N ha-1 compared to the control. They noticed
that the application of 150 kg N ha-1 was sufficient to increase
the yield by 3 t ha-1 through both a higher number and weight of
buds per plant without further increase occurring above 300 kg N ha-1.
Medium NPK fertilizer levels (142 kg N, 114 kg P2O5 and
238 kg K2O ha-1) ranked the first among the three investigated
combinations of NPK levels concerning production of both early and total yield
(El-Abagy, 1993). Moreover, medium level of NPK proved to
be sufficient under clay soil conditions in Egypt for increasing of weight of
bud and its edible part. Pedreno et al. (1996)
announced that bud yield was not affected by increasing N application in calcareous
soil from 300 to 500 kg N ha-1. Salamah (1997)
reported that application of 285 kg N ha-1 promoted earliness and
significantly increased the early yield. However, increasing N fertilization
to 380 kg N ha-1 significantly delayed bud appearance and decreased
the early yield. Bud traits such as length and weight as well as receptacle
diameter were improved by using N fertilization rate higher than 95 kg N ha-1.
Increasing N levels had no effect on the bud diameter and thickness of receptacle.
Foti et al. (2000) demonstrated that 200 kg N
ha-1 as NH4NO3 is sufficient for economic yield
of artichoke in southern Italy. The yield response to nitrogen rates was not
linear. Bud yield with 0 kg N ha-1 was the lowest and followed an
increasing trend in treatments fertilized with either 200 or 400 kg N ha-1.
At the same type, a wide range of soil types can be use for any commercial artichoke
production. However, optimum productivity level was taken on deep, fertile,
well-drained soils of sandy loam to clay loam textures.
The goal of the study was to evaluate the effects of different soil fertilizing
systems on potential forage yield and quality of globe Artichoke (Cynara
scolymus L.) for livestock feeding .
MATERIALS AND METHODS
Field experiment was conducted at the Research Farm of College of
Agriculture, University of Tehran, Karaj, Iran (35°26′ N, 71°28′ E, 1321 m above sea level) during growing seasons of 2005-2006. The location characterized by semi-arid conditions of cold winter
and dry hot summer. The long term average annual participation was 250-400
mm for period 1997-2007. The experiment site has a clay loam, soil with
having pH (7.4), organic matter (6.1 g kg-1), total nitrogen
(0.08%), P2O5 (22.8 mg kg-1) and K2O
(140 mg kg-1). Globe Artichoke (Cynara scolymus L.)
seeds sample of the local ecotypes were provided from Pakan Bazr Inc,
||Used dosages of the soil fertilization treatments and fertilizer
The treatments were arranged as five levels of chemical fertilizer including
N, P and K (Chemical fertilizing system), four levels of animal manure
(Organic fertilizing system) and five levels of combined use of manure
and chemical fertilizers (Integrated fertilizing system) (Table
1). The first half of the nitrogen fertilizer and total phosphorus
and potassium fertilizers were applied before sowing (30 April, 2006)
and the rest at 9-10 leaf stage on 16 July, 2006. The sources of N, P,
K and animal manure were urea, superphosphate, potassium sulfate and dairy
cow manure, respectively. A randomized complete block design was used
with four replications in this study. Plot size was adjusted as to be
9x3.75 m. Spaced plants were established in 5 rows in 75 cm apart with
65 cm spacing within rows in 6 May 2006.
Three or four seeds were sown per hill and thinning was done as to be
one plant per hill after full establishment. Each plot consisted of 60
plants in rate of 3 kg ha-1. Planting date and sowing depth
(4 cm) were as recommended by agricultural specialist for similar farming
conditions. Normal cultural practices were applied uniformly on all units
during the study. The plots were hand-weeded at early vegetative stage
of artichoke. Irrigation was applied regular. Pests were not observed;
therefore, pesticide were not applied. Plants were hand-harvested in areas
of 5 m2 from each plot. Data were recorded at 14-15 leaf, vegetative
rosette stage for aboveground biomass (kg ha-1) and forage
quality in 8 October, 2006. To determined dry matter yield a samples for
each plots was weighed, dried at 70°C for 24 h and reweighed. This
sample subsequently were ground with a Retsch Impeller-type mill (1 mm
screen) for measurements of quality traits.
Quality traits including crude protein (CP %), acid detergent fiber (ADF),
water-soluble carbohydrate (WSC), total ash and dry matter digestibility (DMD)
were estimate by near infrared spectroscopy (NIR). Details of the methodology
and calibrations of NIR are given by Jafari et al.
(2003). In the same procedure, DMD were estimate similar to that described
by De Boever et al. (1994). WSC was determined
using a modification of the method described by Fales et
al (1982). Crude protein % was calculated as Nitrogen %x6.25. Nitrogen was
estimated using a LECO 228 (LECO Corporation St. Joseph. MI, USA) nitrogen determinator.
Total ash were estimated by Ignite a 5 g of sample at 550°C, for at least
2 h and allowed to cool in desiccator and weighted. ADF were determined by Fibertec
(Van Soest, 1994). NIR scanning and spectra analyses were
performed using a Inframatic 8620. The calibration equation were developed using
Multiple linear regression (MLR) with the lowest standard error of prediction
(SEP), high R2 (coefficient of determination (Jafari
et al., 2003). This was the calibration used for all subsequent analyses.
The collected data were analyzed using analysis of variance (ANOVA) SAS-9 software
(SAS, 1989) and mean values were grouped by Duncan (p≤0.05).
RESULTS AND DISCUSSION
Forage Dry Matter
Forage dry matter production is one of the most important quantitative parameters
in a forage crop. Soil fertilizing systems had a significant (p<0.01) effect
on artichoke dry matter production (Table 2). The results of
mean comparisons (Table 3) showed that the highest DM yield
was obtained by application of integrated treatment 8 (N = 80, P = 80, K = 96
kg ha-1 + OM = 20 t ha-1) by 4860 kg dry matter production
per ha. Treatment 6 (N = 200, P = 200, K = 240 kg ha-1) had the highest
productivity of 4130 kg ha-1 among chemical treatments. For organic
fertilization system, treatments 14 (OM = 30 t ha-1) and 15 (OM =
40 t ha-1) had the highest values. Application of any fertilizer
significantly increased biomass of artichoke compared to control. The rates
of increasing are 56, 61 and 6% for chemical fertilizer, integrated system and
organic systems, respectively. Eghbal et al. (2001)
and Adediran et al. (2004) support these results.
It seems that organic fertilizing systems had less effect on biomass compared
to the other fertilizing treatments. This is probably due to the slower nutrient
releasing from manures in the first year of application (transient period).
In some of the integrated fertilizing systems that received higher amounts of
manures than others did, the same results can be expect. However, in some of
the integrated fertilizing systems, biomass increases only because they had
no transient period (Acharya et al., 1998). It
seems that manure or other organic fertilizing will show an increasing effect
on DM yield in the second or third year of application. Similarly, Gerakis
and Honma (1969) reported that application of a mixture of chemical and
manure fertilizers had a significant effect on DM yield. In a similar experiment
Ghosh et al. (2004) obtained the highest values
of DM yield in the integrated fertilizing system compared to organic and chemical
fertilizers in soybean (Glycine max) and sorghum (Sorghum bicolor).
Pomares et al. (1993) studied the effect of three
rates of NPK fertilizer on artichoke (cv. Blanca de Espana) productivity in
Valencia, Spain. There was no significant response on the yield with N rates
higher than 200 kg ha-1, whereas only slight differences were obtained
with 400 or 600 kg N ha-1. Moreover, P and K fertilizers did not
increase bud yield. Their results showed that the available levels of P from
27-33 mg kg-1 and K from 250-282 mg kg-1 in the soil were
adequate for the optimal growth of artichoke. Eghbal and
Power (1999) and Adeddiran et al. (2004) reported
that application of manure fertilizer based on percent of absorbable nitrogen,
could produce the same yield as chemical systems. In contrast, Loecke
et al. (2004) showed that only well-decayed manure could produce
the same yield as the chemical fertilizers. Vanlauw et
al. (2001) showed that application of organic fertilizers alone could
not fulfill the nitrogen requirements of plants. Kramer et
al. (2002) reported that although total nitrogen absorption by plants
in the organic system is lower than in the chemical system, the continuous release
of nitrogen from organic matter lead to a continuous and sustainable nitrogen
absorption that results in a better synchronization between absorption rate
and availability of nitrogen leading to a higher yield. Reviews of previous
studies on the nutritive value of leaves and bracts of artichoke (Cynara
scolymus) suggested that despite relatively low amino acids contents, artichoke
bracts might be use as a constituent of diets for dairy and beef cattle. Its
potassium, iron, manganese and copper are relatively high and its energy value
estimated at 0.76 feed unit kg-1 DM. It was concluded that in cattle
diets, artichoke bracts have a nutritive value similar to that of maize silage
(Galvano and Scerra, 1983). On the other hand, leaves,
stems and industry residues can be used for cattle feeding (Pecaut,
||Mean squares of soil fertilizing system effects on forage
yield and quality traits of globe artichoke (Cynara scolymus)
|Ns: Means no significant at level (p≤0.05), *Means
significant at level (p≤0.05) and **Means significant at level
|| Mean comparison of forage traits as affected by soil fertilization
|*Means in the same column followed by different letter(s)
are significantly different using Duncan test (p≤0.05)
Forage quality was shown close linkage with fiber content, which is needed
in coarse form to maximize rumen function. The lignified part of fiber is indigestible,
yet it is required because unlignified material will not elicit adequate rumination
activities (Van Soest, 1994).
Crude Protein (CP)
There is little published research about forage quality of artichoke. Soil fertilization
treatments significantly (p≤0.05) affected CP% (Table 2).
CP varied from 11.5% in treatment 1 (control) to 15.0% in treatment 11 (N =
200, P = 200, K = 240 kg ha-1 + OM = 5 t ha-1). In chemical
treatments, the Treatment numbers 6, 3, 4 and 5 were at the same statistical
groups by 13.27, 13.5, 14.08 and 14.26 CP%, respectively. For the integrated
system, the highest CP% values were obtained at treatment 9 (14.98%) and 11
(13.95%). For organic system, treatments 9 and 11 with 13.29 and 13.13% had
the highest CP%, respectively (Table 3). Significant differences
were obtained for three fertilizing systems (chemical, integrated and manure
systems) compared to control with the mean values of 18, 16 and 9%, respectively.
The lower CP% for organic treatments were probably due to the slow release of
nitrogen in these fertilizers. These results are strongly supported by other
research. Eghbal et al. (2001) stated that only
about 20 and 35% of nitrogen in manures becomes available to plants in years
1 and 2, respectively.
Dry Matter Digestibility (DMD)
Soil fertilization systems significantly affected DMD (p<0.01) (Table
2). DMD values varied from 65.3% in control to 73.2% in treatment
5 (Table 3). Chemical and integrated fertilization treatments
were grouped in the same statistical category. For integrated fertilization
system, the highest DMD was obtained in treatments 7 (70.83%) and 8 (70.42%).
Treatments 12 and 13 had the highest values at organic system with 70.97%
and 70.37% respectively. Three soil fertilizing systems were increased
the DMD% compared to control treatment. The mean values were 7.5, 6.3
and 5%, respectively. It is likely that the increasing DMD values in chemical
compared to other systems were due to the rapid release of nitrogen from
Water-Soluble Carbohydrates (WSC) The water-soluble carbohydrates in
forage represent the rapidly digestible portion of the non-structural or stored
carbohydrate in the plant. They are important for microbial activities in rumen.
If the WSC are increased before ensiling, the silage pH will increase and silage
quality will decrease (Van Soest, 1994). Soil fertilization
significantly affected the WSC% (p = 0.05). The WSC values varied from 10.6%
in treatment 4 to 13.1% in treatment 6. In the chemical system, except for treatment
4, there was no significant difference among them. Additionally, no significant
difference was observed among five levels of integrated fertilization. The wsc
in organic systems decreased by 1% compared to control.
Acid Detergent Fiber (ADF)
ADF was significantly affected by soil fertilization (p<0.01). The highest and
lowest ADF values were obtained in treatments 14 (OM = 30 t ha-1)
and 6 (N = 200, P = 200, K = 240 kg ha-1) with 73 and 20%, respectively.
Compared to control treatment there was an increasing trend in ADF values from
chemical (-7%) to integrated (-3%) and organic system (+2%). The lower ADF values
in chemical and integrated systems could be explained by rapid release of N
and its consumption by plants (Eghbal et al., 2001).
As mentioned before, only a small portion of N (30%) was likely to have been
released from organic fertilizers in the first year, while almost all the N
in chemical fertilizer was readily available in the same period. This explanation
is supported by the corresponding trend in crude protein content, whereby higher
CP was observed in chemical treatments compared to integrated and organic fertilization
systems (Buxton et al., 1999).
Soil fertilization systems had no significant effect on ash percentage in plants.
Ash varied from 8.3% (treatment 3) to 9.6% (treatment 11). For this trait, organic
and integrated fertilization resulted in higher values than chemical fertilization.
The ash content in plants in organic and integrated systems was higher than
in the chemical one. These results verified by studies that stated soil fertilization
with manures led to increased availability of micronutrients (Rashid
and Ryan, 2004; Elia et al., 1996). Ash percentage
had a positive and significant relation with crude protein content. These results
are agreed with Buxton et al. (1999).
Statistical Correlation Among Traits
Correlation between DM and fresh weight yield was found strongly positive (0.80**).
The correlation between DM and fresh weight yield vs. quality traits were inconsistent,
suggesting that quality traits are largely independent of DM yield; hence, it
should be possible to improve both yield and forage quality. DMD had positive
correlation with CP and strongly negative one with ADF (Table 4).
Because ADF is completely indigestible fiber, a negative correlation between
these two parameters is expected and is in agreement with other work (Abdalla
et al., 2007; Van Soset, 1994; Jafari
and Naseri, 2007).
|| Correlation coefficients between forage yield, quality traits
of globe artichoke (Cynara scolymus) as affected by soil fertilization
|Ns: Means no significant (p<0.01), *Means significant
at level (p<0.05) and **Means significant at level (p<0.01)
Total ash content was found positive but statistically significant with
CP. This result is expected since total ash is produced from minerals. In contrast,
WSC was negatively correlated with both total ash content. For WSC vs. CP, correlations
were negative and non-significant. In agreement, Humphreys
(1989) suggested that in perennial ryegrass, as growth increases with rapid
uptake of nitrogen fertilizer, an increase in CP and a decrease in WSC content
are environmentally induced effects. There was no significant correlation between
forage yield and quality traits, but there was positive correlation between fresh
weight and dry weight (r = 0.8**) (Table 4).
This research has shown that this crop has a high potential and
produce quality forage for the livestock. It is of special interest that
this potential has been achieved (except in the first year) in a low input
management system. It was possible to obtain around 5 t ha-1
dry biomass and up to 30 t ha-1 fresh weight per year. Soil
fertilization had a significant effect on forage yield and quality of
artichoke. Crude protein percent increased in chemical, integrated and
organic systems by 18, 16 and 9% compared to control treatment but nitrogen
had played the most important role on it. This assumption that high solubility
and availability of the nitrogen mineral in chemical and integrated systems
caused a significant increase in it. The effects of soil fertilization
treatments on dry matter digestibility was similar for all treatments
(except Treatment 5). All the fertilization treatments significantly increased
forage quality parameters compared to control.
All obtained findings indicate that the soil on the experimental site
was poor and increasing soil nutrients can enhance the forage quality.
During the study, statistically insignificant responses were obtained
for effects of soil fertilization on fiber (ADF) values, suggesting no
effects on lignifications of the artichoke. Regarding water soluble carbohydrates,
there was no significant differences between chemical and integrated systems
compared to control; however, these treatments had more WSC than organic
system. The correlation between soil mineral nutrients (including nitrogen)
and water-soluble carbohydrates was strongly affected by environmental
factors. The losing rate of the nitrogen was higher for the organic systems
compared to other treatments. The treatments 11 (N = 200, P = 200, K =
240 kg ha-1 + OM = 5 t ha-1) and 9 (N = 120, P =
120, K = 144 kg ha-1 + OM = 10 t ha-1) had the highest
nitrogen loss rate among the integrated treatments. For chemical fertilization,
treatments 5 (N = 160, P = 160, K = 196 kg ha-1) and 6 (N =
200, P = 200, K = 240 kg ha-1) had higher nitrogen loss rate
A lack of quality forage and limited arable lands allocated to forage
crops production in Iran call for a higher attention to be paid to work
on high quality forage crops with high potential for biomass production.
In respect to potential ability of artichoke to produce, 40 and 5 tons
of fresh and dry yield, respectively, per hectare at 20,500 plants/ha
density, it seems to be a good forage crop. But it is suggested that further
complementary studies need to be conducted on this new forage crop in
Iran and further studies on silage properties and quality of artichoke,
the effect of micronutrients on yield and quality of artichoke should
be done. In addition, it is necessary to be done more experiment like
this more than one year to evaluate the effects of fertilizations properly.
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