沙漠研究 19-1, 161 - 164 (2009 )Journal of Arid Land Studies“Desert Technology IX ”
Refereed Paper

Characterization of a Leguminous Plant (Green pea: Pisum sativum L.) and It’s Impact
in the Improvement of Soil’s Fertility in an Arid Area in the Centre of Tunisia
Khouloud BACHAR*1, Mansour HADDAD1, Ali FERCHICHI1
Abstract: In the region of Haddej Bouhedma, leguminous plants are cultivated in “jessers”
where the rainwater is recovered and exploited during the rainy years. The emphasis of thispaper is to characterize the Green pea which is lately introduced to this region and todemonstrate it’s impact in the improvement of the soil’s fertility of the region. For that an insitu investigation and observations on open field have been achieved. Results indicate that thiscrop allows the production and offers an interesting fresh biomass rich on dry matter andnitrogen. Also roots are lined with nodules which are advantageous for soil fertility.
Key words: Fertility, Green pea, Haddej Bouhedma, Soil

1. Introduction
In the south and the centre of Tunisia, agriculture is closely related to the availability of water. It is
localized in oases (around 40 000 ha), some irrigated perimeters, and in the traditional hydraulicconstructions called locally "Tabias and Jessers". The region of Haddej-Bouhedma is located in the centralof Tunisia where Acacia raddiana is very common (Fig. 1). In this area, agriculture is among the maineconomic activities. Thanks to traditional water management rainwater is collected and used for different
plantations like legumes.
The leguminous plants have a high nutritional value due to their richness on protein, minerals,
essential vitamins, carbohydrates and fibre. Legume seeds contain 17% to 40% of proteins, while cereals
do contain 7 to 13%, which equates to the content of the meat on protein 18 to 25% (Genovese and Lajolo,2001). In addition, species belonging to this family improve the soil structure because they fix atmosphericnitrogen which reduces the use of chemical fertilizers and avoids the groundwater’s pollution by nitrate.

Fig. 1. Localisation of the region of Haddej Bouhedma.
1

Institute of Arid Regions, Arid and oasis cultivation Laboratory Km 22, 4119 ElFjé Mednine Tunisia* E-mail: Khouloud_bachar@yahoo.fr, Fax number: 75 228 088

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For the last two decades the pea is the most practiced crop in this region. In addition to it’s high yield, it isalso used for livestock due to it’s high concentration on proteins (Oelke et al., 1991). Auld et al. (1982)
and Oelke et al. (1991) indicate that this crop can be used as green manure to restore the soil organic matter
which provides more than 28 kg / ha of nitrogen to the soil. The purpose of this study is to determine themain steps of the technical itinerary of the pea’s cultivation in this region and it’s impact on the soil
fertility expressed by the nitrogen content.
2. Materials and Methods
To carry out this work, 28 “jessers”, chosen arbitrarily in two representative plains in this area (14“jessers” at El Boua and 14 “jessers” at Hawel El Wad), were visited. In each “jesser” 10 plants wererandomly collected. The biomass formed above and under the ground, nodule’s number, leaf area (cm2)and the pod’s number were observed. The envelopes and seeds, previously counted, were weighed. The
taste of pea was determined both by a tasting panel formed by several people (to judge if the taste is very
sweet, sweet, mildly sweet or unsweetened) and by determining the sugar content with a refractometer.
Dry matter of the envelopes and seeds, were recorded and after drying in the oven, phosphorus, potassium
and sodium content were determined by the conventional methods of analysis based on photometry andspectrophotometry. The nitrogen was analyzed by Kjeldahl method. The nitrogen’s analysis in the soil (ina depth of 20 cm) was conducted in two different plains: El Boua and Hawel El Wed with three repetitions
before and after cropping. Results were interpreted by the use of Student Newman and Keels method.
3. Results and Discussion
3.1. Characterization of the pea grown at Haddej Bouhedma
3.1.1. Growth’s assessment
The average values of the fresh aboveground and underground part’s weight and the leaf surface ofpea are grouped in Table 1. This table shows that the pea was developed in good conditions since theaverage size of a leaf was about 17 cm2. This result explains the formation of an interesting above andunder the ground biomasses having reached respectively 59 and 17 g / plant at El Boua.
The values of the aboveground and underground biomasses and leaf area recorded at Hawel El Wed’s
plain are statistically comparable to those recorded in El Boua although being slightly lower.
Table 1. Mean values per plant (10 repetitions) of the growth’s assessment of the Green pea of the region ofHaddej Bouhedma. Values assigned by the same index are not statistically different at the threshold of 5% by theStudent Newman and Keuls test.
Aboveground part’s fresh weight (AP) : g/plant
Underground part’s fresh weight (UP): g/plant
Leafy’s surface cm²
Average number of nodules

El Bouaa
58.71 a16.71 a17.40 a21.52 aHawel El Wed
49.80 a14.60 a16.70 a17.80 a3.1.2. Dry matter of aboveground (AP) and underground parts (UP)The average values of the dry matter formed in above and under the ground parts are reflected inTable 2. In the two regions, the AP/UP was slightly higher than 1 (1.04 at el Bouaa and 1.19 at Hawel ElWed). This indicates that the plants were well watered due to the exceptional good distribution of rainfall
during this season.
Furthermore, the average content of dry matter in the aboveground part (12.41% and 14.05%)
recorded in the two plains showed that the fodder was rich on this matter. These percentages were quite
near to those found in alfalfa fodder’s (between 17 and 20%) grown in oasis of the South of Tunisia(Maalawi et al., 2006).
3.1.3. Characterization of cloves
The average values of the characterization of pea’s pods are grouped in Table 3. It shows that thesepods had an average weight of 5.36 g, a length of 8.02 cm and contain 7.28 seeds. Our results wereconvenient with those mentioned by Oelke et al. (1991) who reported that the pea pods can reach a lengthof 7.6 cm and contain 4 to 9 seeds. The envelopes represent an average of 55% of the total weight of pods.

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Table 2. Dry matter per plant (10 repetitions) of the aboveground (DMAP) and the underground (DMUP) parts
and the value AP/UP of pea of Haddej Bouhedma. Results are expressed as a percentage by grams of the freshweight of the plant. Values assigned by the same index are not statistically different at the threshold of 5% by theStudent Newman and Keuls test.
Emplacement
El Bouaa
Hawel El Wed%
12.41
14.05

DMAPg/plant
7.29 a3.57 a%
21.36
20.54

DMUPg/plant
7.00 a3.00 a

AP/UP
1.04
1.19

Table 3. Characterization of pea (170 pods).
Average
5.36
8.02
7.28
2.44
2.93
14.00

Average weight of cloves (g)Average length of cloves (cm)Seeds’s number
Seeds’s average weight (g)Envelopes’s average weight (g)Refractive index (%)

Standard deviation
1.79
1.06
1.48
0.881.67
0.03

Table 4. Taste of Green pea (Average of 23 samples).
Judgment
Percentage

Very sweet
13.04

Sweet
39.13

Average swetness
34.78

Non sweet
13.04

Table 5. Average content on minerals in seeds and envelopes of pea (% of Dry Matter).
PlainsElements% Na+% K+%P%N

aboveground
part
0.05
1.00
0.24
3.92

El Bouaa
Underground
part
0.34
2.60
0.75
1.94

Seeds

Envelopes

0.02
3.00
0.44
3.30

0.01
3.00
0.16
2.64

aboveground
part
0.35
1.30
0.10
2.52

Hawel El Wed
Underground
Seeds
part
0.38
0.01
1.50
3.00
0.480.43
1.92
3.41

Envelopes
0.04
3.00
0.10
2.14

The juice of freshly ground seeds had a refractive index of 14% indicating that the pea is rich on
carbohydrates. The tasting test’s results are presented in Table 4. It shows that the pea grown in the regionof Haddej Bouhedma is sweet to mildly sweet which indicate it’s valuable quality.
3.1.4. Analysis of major minerals
The average levels of phosphorus (P), potassium (K+), and sodium (Na+), and reduced nitrogen (N) on
pea’s seeds and envelopes from the two plains are reflected in Table 5. This table shows that the variousorgans of pea were filled with reduced nitrogen (especially in the seeds: 3.3 and 3.41% respectively for El
Boua and Hawel El Wed). Black et al. (1998) and Wang and Daun (2004) found that the total protein’scontent of pea varies from 24.3% to 32.6%.
The levels of sodium, potassium and phosphorus are respectively between 0.01 and 0.38, 1 and 3 and0.24 and 0.75%.
3.2. Nitrogen’s Analysis in the soil before and after the pea’s cultivation
The results of soil’s analysis before and after cropping are illustrated in Figure 2. It shows thepositive effect of this specie on the enrichment of soil on nitrogen both in the two plains. Indeed, thepercentage of nitrogen in the soil increased from 0.02 mg/kg to 1.7 mg/kg in the plain of Hawel El Wed
and from 0.2 mg/kg to 1.0 mg/kg in the El Boua’s plain.
The differences between the test results obtained before sowing and those obtained after the harvest
were respectively 1.68 mg/kg and 0.8 mg/kg. The nitrogen could be very useful for cereals which will besowed in the coming season due to it’s capacity to ameliorate the soil fertility and structure. This nitrogen
fixed by the leguminous plant avoids the utilisation of fertilizers which will pollute the soil. In fact,Kaminski (1991) said that half of the biological nitrogen fixation, which is about 200 million tones per year,
is coming from the symbiotic relation between leguminous plants and rhizobia. According to Elmerich(1993), this production represents two times the world production of nitrogen fertilizers.

16418Before sowing%Nitrogen(x10^-5)16After sowing14121086420HEWELBFig. 2. Soil’s analysis before and after the pea’s cultivation in two plains in the region of Haddej
Bouhedma (Caption: -HEW = Plain Hawel El Wed- -ELB = Plain of El Boua).

4. Conclusions
Cultivated legumes are increasingly occupying the sowed lands on Haddej Bouhedma’s region. This
work was focused on identifying the importance of Green pea and demonstrating its interests in theenrichment of soil on nitrogen.
The results showed that legumes are cultivated in the plains and behind the waterworks during rainyyears. In addition to cereals, the most sowed legume is the Green pea. The crops are not watered; theirfate in store depends on rainfall. The analysis of samples collected in this region have shown that the pea
provide a fodder rich on nitrogen-material and develops a great production of dry matter in theaboveground and underground parts and a very high number of nodules. Moreover, it is advantageous interms of soil’s enrichment on nitrogen.
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