1. Introduction

Cucumber (Cucumis sativum L.) is one of the major vegetable crops produced in Palestine. Estimated area cultivated with cucumber was 23,100 dunum (dunum is 0.1 ha) which constitutes 18.2% of the total area planted with vegetable crops in the West Bank [1].

Cucumber (Cucumis sativus L.) is an important vegetable and one of the most popular members of the Cucurbitaceae family [2]. It is thought to be one of the oldest vegetables cultivated by man with historical records dating back 5,000 years [3]. The crop is the fourth most important vegetable after tomato, cabbage and onion in Asia [4]. The need for renewable forms of energy and reduced cost of fertilizing crops, have revived the use of organic manures worldwide [5]. Improvement in environmental conditions and public health are important reasons for advocating increased use of organic materials [6, 7]. Organic manures can sustain cropping systems through better nutrient recycling and improvement of soil physical attributes [8]. The use of inorganic fertilizer has not been helpful under intensive agriculture because of its high cost and it is often associated with reduced crop yields, soil degradation, nutrient imbalance and acidity [9, 10].

The complementary use of organic and inorganic fertilizers has been recommended for sustenance of long term cropping in the tropics [11]. Nutrients from mineral fertilizers enhance the establishment of crops while those from mineralization of organic manures promoted yield when both fertilizers were combined [12].

The objectives of this study to assess the effect of using organic and chemical fertilizers on cucumber (Cucumis sativum L.) plants, productivity and soil fertility to promote the application of organic fertilizer and decreasing chemical fertilizer used to face the soil deterioration and preserve the natural resources.

2. Material and Method

Cucumber Experiment was conducted to comparison between organic and chemical fertilizers on cucumber (Cucumis sativus L) yield and some soil properties was studied in a field experiment at Thenaba farm, Tulkarm, located in the west bank, Palestine, during the summer seasons of 2012. The experiment was a completely randomized experimental design included two greenhouse one donum (1000m²) for each, contains 25 rows and 1400 cucumber plants. The soil had a clay texture (67% clay), EC (1.9 dS m^-1), bulk density (1.4 g cm^-3) and organic matter 8.2 g kg^-1, PO₄ 19.5% and NO₃ 11.4 N kg^-1 on a dry weight basis.

The first treatment was greenhouse (G1) under the greenhouse conditions were chemical fertilizers used during the agricultural season. The second treatment was Greenhouse (G2) were the soil mixed with compost based on available N in the compost (recommendation of N fertilizer for cucumber). Cucumber seedlings with four leaves were transplanted by hand in rows with 1 m row spacing and 0.5 m seedling spacing. Drip irrigation systems were adopted in the experiment, based on the conventional schedule. The plants were grown with a 26/18°C day/night temperature regimes. Other aspects of crop management followed conventional practices. Cucumber was starting harvested weekly on April during 2012.

Soil Measurements was dried at 70°C to become constant weight and this weight was recorded. The dried soil samples were ground and sieved through 2.0 mm mesh. The total N was determined in compost by the kjeldahl method [13]. Nitrate was determined in the soil according to Singh [14]. Bulk density of compost was estimated as a ratio between oven dry weights to their volumes as g cm^-3 as reported by Okalebo et al. [15]. Soil pH was measured in 1:2.5 (soil: water) suspension [16] and in a 1:5 ratio (compost: water) suspension for compost. Electrical conductivity (EC) was measured in the compost with a 1:10 (compost: water) ratio. Organic matter (OM) percent was calculated as: OM% = TOC (%) X 1.724. Total phosphorus was measured calorimetrically using a spectrophotometer after wet digesting the soil samples in concentrated H₂SO₄ + HClO₄ [17].

The fertilizer regime was different between (G1) and (G2). The organic fertilizers (G2) were used contains compost as solid materials 600 kg/dunum added to the soil as line before agriculture and extract liquid organic fertilizers added during the agricultural period with irrigation water. On the other hand, (G1) were used different chemical fertilizers before and during the agricultural period as show in (Table1).

Table 1. Organic (compost) and chemical fertilizers used in agricultural period Fertilizer Components Amount Unit Chemical fertilizers (G1) Ammonium sulphate (NH4)2SO4 36 kg Phosphoric acid H3PO4 25 litter Iron chelates Fe-EDDHA 1900 g Shefer fertilizer 7,3,7 (NPK) 65 litter composed fertilizer 11,8,22 (NPK) 28 kg Organic Fertilizers (G2) Compost Organic bulk 600 kg Echostar Organic carbon & nitrogen (mixed of carbon and nitrogen) 45 litter Compost extraction Organic materials 360 litter

3. Result and Discussion

3.1. The Effect of Fertilizers Regime on Soil

The effects of Organic protected agricultural area on living systems, particularly the effect on growth of plants have been the objective of numerous researchers. The soil experiment used originally clay soil texture, the results of soil analysis before and after planting shown in table (2). The results show that most soil characteristics were improvements after used compost were soil sample analysed. Based on compost properties, the compost appears to be the best suited as soil amendment. The characteristics of organic (composted) fertilizers was used in the experiment illustrated in table (3). In our results, compost addition was found to not only increase crop yield, but also to improve soil properties and fertility in terms of organic material content, permeability, available water capacity, air-filled porosity and the nitrogen increased in the soil with the increase of organic nitrogen applied as well as soil organic C [18]. Mathur, et, al. found that compost enhances the environmental sustainability of agriculture by decreasing chemical inputs and increasing soil organic matter. Adding different organic compost to the soil caused remarkable improvement of different growth characters and yield [19]. Also, Adrien [20], said the application of organic manures significantly increased levels of organic C and N and the formation of water-stable aggregates, as compared with application of chemical fertilizers.

Table 2. Some chemical composition of the soil samples before and after agricultural practices Soil pH EC dS m-1 NO3 % K % Na % Before 7.4 1.9 11.4 1.4 3.6 After 7.0 1.8 44.2 5.2 3.0 PO4 % C/N ratio OM g/kg Bulk Density g cm-3 N g/kg Before 19.5 7.4 8.2 1.4 2.1 After 30.7 25.8 45.7 1.00 4.6

Table 3. The characteristics of organic fertilizers which used in the experiment Compost analysis pH 6 to 7 C/N ratio 22 Particle size (inch) < 1/2 Electrical conductivity (mmho/cm) 2.5 Moisture content % 50 Organic Matter 47% Total phosphor 2 % Organic carbon 38% Total potassium 0.32% N-NO3 300PPm N-NH4 200PPM nematode nil Bacteria coli nil

In general, chemical fertilizer application rates in intensive agricultural systems have increased dramatically during recent years in Palestine, especially in greenhouse vegetable production systems. Because of higher yields and income, the highest chemical fertilizer inputs can lead to marked deterioration in soil and groundwater quality and the systems are clearly unsustainable. However, the use of inorganic fertilizers alone may cause problems for human health and the environment that means the excess use of chemical fertilizers in agriculture can lead to nitrate accumulation into plant parts especially on edible parts. Abd El-Hamied [21], found that the nitrate accumulation in editable plants is a problem when eaten. Part of the ingested nitrate may be converted to nitrite causing methaemoglobinaemia or even to carcinogenic nitrosamines the determination of nitrate and nitrite in food stuffs become increasingly important because of the concern over excessive human dietary intake of these species, causing a health hazard.

3.2. The Effect of Fertilizers on Water Requirement and Plants Productivity

Organic fertilizers can be substituted for commercial fertilizers; however, information is sparse on the interaction of irrigation quantity and nutrient source on cucumber (Cucumis sativus L.) production. In our study evaluated nutrient source and quantity of irrigation (water requirement) and yield of cucumber grown under protected agriculture. Our results show that clearly different water requirements between soil and plant treated with chemical fertilizers (G1) and soil and plant treated with organic fertilizers (G2) during the agricultural period as show in Figure 1. Were the water requirements was higher (213 m³/ season) were chemical fertilizers (G1) used more than organic fertilizers (180 m³/ season) (G2) during the three months of agriculture period, it means that the type fertilizers used (chemical or organic fertilizers) gives directly effects on water requirements.

These results indicated that use of compost fertilizers could save water with an average of 8, 12, 13 m³/month respectively, and 33m³ for the agricultural season of the applied water to cucumber crop.

Figure 1. Water requirements for cucumber plants treated with chemical and organic fertilizers during agricultural period

Mady, A. indicated that levels of compost fertilizers could save water with on average of 14, 12.79, 29.07 and 444.19% of the applied water to cucumber crop under water stress treatments of 40, 60, 80 and 100 % from field capacity, respectively and might be due to increase of field capacity, Permanent wilting point percentage and available water by adding compost fertilizer while, bulk density was opposite [22].

Also, Mamo, et, al. found that the extract Compost addition was found to not only increase crop yield, but also to improve soil fertility in terms of organic C and N content, permeability, plant available water capacity and air-filled porosity [23].

Vegetative Growth and yield of the Cucumber Plants affected by the fertilizers regimes were different results shown in figure 2. The results show that using chemical fertilizers regime gives early harvested during the first month were gives 197 kg/ donum comparing with 90 kg / donum were used organic fertilizers regime.

Figure 2. Crop productivity for cucumber plants treated with chemical and organic fertilizers during agricultural period

El-Sheikh, et, al. showed that adding organic manure at the rate 45 kg/540 m² at each irrigation significantly resulted in higher yield than chemical fertilizer treatments [24].

Aly, studied the effect of applying organic and chemical fertilizers on cucumber yield and fruit characteristics. He found that organic treatment (10 m³ compost/540 m²) gave significantly greater early, exportable and total yield than inorganic (chemical) treatment [25].

But with increasing time organic fertilization had increasing effect on the productivity, were the second and third months gave highest productivity, were in the third month treated with compost compared to chemical fertilizers used were 4455 and 3840 kg respectively, with sum of productivity for the agricultural season found that the productivity were higher in treatment with compost (7005 kg/dunum) comparing with (6017 kg/ dunum) treatment with chemical fertilizers as shown in figure 3, that means the organic fertilizers need enough time to analyses in soil and give good and natural effect.

Aly, [26] added that average fruit weight, length, diameter, length / width ratio, fruit firmness, T.S.S., total sugars, chlorophyll and ascorbic acid content were significantly increased by using compost of organic materials over the inorganic treatment. Tara et al., adding, different organic compost to the soil caused remarkable improvement of different growth characters and yield [27].

Figure 3. Average cucumber yield treated with chemical and organic fertilizers at the end agricultural period

Mady, concluded that in order to produce higher yield and high quality of cucumber by irrigation at 80% from field capacity with 2.05 or 1.30 kg/m² of compost [28].

Wang Ying et al. said, Amino acid fertilizers can promote crop growth, strengthen resistance, improve soil conditions and increase crop yields [29]. WANG Xue-jun et al., studied the effects of conventional fertilizer with soluble fertilizer containing amino acids on yield and economic benefit of cucumber .The results showed that the additional application of soluble fertilizer with amino acids could increase the cucumber yield [30].

4. Conclusions

Cucumber grown in optimal weather and soil conditions requires both water and nutrient availability. Irrigation systems are essential to apply water in arid regions; however, optimal use of water and organic nutrients to meet crop requirements is essential to achieve maximum yield productivity. Toward to use compost fertilizers could save water with agricultural season of the applied water to cucumber crop.

Compost application is the best management system in sustainable agriculture for increasing soil fertility, cucumber yield and decrease the cost of N mineral fertilizers. On the other hand, the excess use of nitrogen fertilizers in agriculture can lead to soil deterioration, nitrate accumulation in the plants and groundwater pollution.

ACKNOWLEDGEMENTS

Thanks are due to the Prof. Dr. Marwan Awartani, President, Palestine Technical University Kadoorie for generous support.