RESPONSE OF FODDER BEET TO PARTIAL SUBSTITUTION OF NITROGEN FERTILIZER BY BIO-FERTILIZERS AND ITS ECONOMIC RETURN

RESPONSE OF FODDER BEET TO PARTIAL SUBSTITUTION OF NITROGEN FERTILIZER BY BIO-FERTILIZERS AND ITS ECONOMIC RETURN

Azza Kh. M. Salem¹; M.Y. Abou-Zeid ² and S.M. H.Eissa³

1-    Forage Crops Research Dept., Field Crop Research Inst., ARC, Giza, Egypt

2-    Microbiology Dept. Soils, Water and Environment, Res. Inst., AR C, Giza, Egypt

3 - Economic and Environment Evaluation Res. Dep., Central Laboratory

For Design and Statistical Analysis Research, A.R.C., Giza, Egypt

Key Words: fodder beet, productivity, quality, nitrogen fertilizer, Azospirillum, Azotobacter, nitrogenase, dehydrogenase.

ABSTRACT

This investigation was conducted for two 2016-2017 and 2017-2018 seasons at  Agric. Res. Station (30° 02' N latitude and 31° 13' E longitude, altitude 22.50 m above sea level), Giza, Egypt, to study the response of fodder beet (Beta vulgaris) c.v. Voroshenger to partial substitution of mineral N fertilizer by bio-fertilizer (full recommended dose of mineral N fertilizer, 75% RD of mineral N fertilizer +bio-fetilizer , 75% RD of mineral N fertilizer, 50% RD of mineral N fertilizer + bio-fertilizer, 50% RD of mineral N fertilizer and bio-fertilizer).The experiments were laid out in a complete randomized block design with three replicates and could be results summarized as follows:-

Applying bio-fertilizer with 75% RD of mineral N fertilizer increased root diameter, root and shoot length, plant height, fresh and dry of shoot and root yields fed^-1, crude protein content and digestible crude protein and CF yields. N, P, K% and their uptake were increased as a result of fertilizer application (75 % RD of mineral N fertilizer + bio-fertilizer) in both seasons. In respect to the enzymatic activities, nitrogenase enzyme activity of two seasons significantly increased as a result of inoculation + 50% of the full recommended rate of mineral N fertilizer. While, dehydrogenase activity and population density of tested bacteria in the rhizosphere were significantly increased by applying biofertilizer + 75% RD of mineral nitrogen fertilizer n. Moreover, inoculation with the used biofertilizer led to significant increases the population density of tested bacteria in the rhizosphere of this plant. The highest gross margin (GM) was achieved from the treatment T₂ (75% RND mineral fertilizer with bio- fertilizer) compared with other treated treatments in both seasons. In addition, the use of bio-fertilizer reduces the environmental pollution.

 INTRODUCTION

        In Egypt, great attention in the last few years have been paid for increasing the fodder beet (Beta vulgaris L.) cultivated area due to the insufficient green forage production for the demand of animal consumption in the early of summer date, which is usually. It is characterized by high production in forage yield, high energy value and can be used for dairy cattle feeding (Badawi et al., 2002). Fodder beet contains a high dry matter yield and is known for its high nutritional value as it is a good source of energy for animals (Ibrahim, 2005). Its carbohydrates content is about 71.69% of dry matter (Abdallah and Yassen, 2008).

            Fodder beet requires large amounts of nitrogen. Various authors have reported that an increased rate of N fertilization significantly promoted vegetative growth, increased. Abdel-Gawad, et al. (2008) reported chemical compositions (crude protein, ash and digestible crude protein percentages) of fodder beet were significantly increased by increasing nitrogen fertilizer level, while crude fibers % take the opposite trend. Sebahattin and Osman (2010) found that nitrogen fertilizer applications increased root yield, dry matter yield, crude protein content, crude protein yield, root diameter and root length. Khogali et al. (2011) found that Leaves exceeded tubers in crude protein, raw fiber and ash highly significantly while tubers were superior to the leaves in dry matter.                                                                                                       

      Integrated use of bio-fertilizers and mineral fertilizers is the best option not only to reduce the intensive consumption of chemical fertilizers but also to preserve the soil with minimal undesirable effects and to maximize fertilizer use efficiency in soil (Palm et al., 2001)

      The bio-fertilizers (microbial inoculants) in many plants have been established, which effectively supplement the need for nitrogen and reduce the cost of production and environmental pollution by reducing the rates of used mineral-N fertilizers (Ouda, 2002). Biological fertilizers include organic fertilizers (manure, etc.), which are presented in an available form due to the interaction of microorganisms or because of their association with plants (Sujanya and Chandra, 2011). When bio-fertilizers are used as seed or soil inoculants, they multiply and participate in nutrient cycling and benefit crop productivity (Singh et al., 2011). Bio-fertilizers are helpful alternative to inorganic fertilizers that improve soil quality and it are a natural product which carries living microorganisms derived from the root or cultivated soil (Attarde et al., 2012 and Ramakrishnan and Selvakumar, 2012) and it maintains the soil environment rich in all kinds of micronutrients and macronutrients by nitrogen fixation, phosphate and potassium solubilisation or mineralization, release of plant growth regulating substances, production of antibiotics and biodegradation of organic matter in the soil (Sivakumar et al., 2013).

      Abdelaal and Tawfik (2015) found significant increase in root length, root diameter and root fresh weight as well as root yield/ fed as a result of treated sugar beet plants with combination of bio-fertilizers and 105kg mineral nitrogen. Hussein et al. (2015) found that applying bio-fertilizer to dill plant significantly increased plant height, number of branches, root length, fresh and dry weights. Sayed-Ahmed et al. (2016) indicated that using only bio-fertilizer gave the lowest values of root length, root diameter, root fresh weight and top fresh weight/g as well as root yield. While using bio-fertilizer with mixed Microbeen and Rhizobacterin gave increase in values of mentioned rails in the other direction. El- Safy (2018) indicated that increasing nitrogen fertilizer levels from 60 up to 100 kg N fed^-1 combined with bio-fertilizer (Rhizobacterin) significantly increased fresh top yield of sugar beet through the two seasons.

     Recently, under Egyptian conditions greet attention is being devoted to lowering the high rates of mineral fertilizers, the cost of production and environmental pollution by reducing doses of nitrogen fertilizers using bio-fertilized farming systems. So, Bio-fertilization technology has taken apart to decrease production costs and at the same time avoid environmental hazards. Therefore, the objective of this study to investigate the effect of partial substitution of mineral nitrogenous mineral fertilizers via bio-fertilizer on growth, yield, chemical constituents and some enzymatic activities in the rhizosphere of fodder beet plant as well as reduce the cost of production and environmental pollution.

MATERIALS AND METHODS

 A field experiment was conducted for two seasons of 2016-2017 and 2017-2018 at Agric. Res. Center Station (30° 02' N latitude and 31° 13' E longitude, altitude 22.50 m above sea level) at Giza Governorate, Egypt, to study the response of growth, yield and quality of fodder beet (Beta vulgaris L.) c.v. Voroshenger to partial substitution of mineral N fertilizer by bio-fertilizerand its economic return. Seeds of fodder beet were obtained from Forage Crops Res., Dep., ARC, Giza, Egypt. The experimental location is shown in Table (1). The particle size distribution of the soil sample was determined as described by Blackmore (1972).Soil organic matter, EC and pH were determined according to Black et al. (1982).   

Table (1): Some physical and chemical soil characteristics of the experimental  Site (mean over 2017 and 2018 seasons).

The experiment was established in a complete randomized blocks design with three replicates , each experimental basic unit included five rows at 60 cm apart and 30 cm between hills, resulted in an area of 6 m² (1/700 fed). The preceding summer crop was maize in both seasons. Fodder beet seeds were sown at a rate of 3kg fed^-1 on 1^st Nov. and 3^rd Nov. in the first and second season, respectively. Three seeds were planted in each hole; the plants were thinned twice; the 1^st at 30 days after planting (DAP) to leave two plants per hill and the 2^nd at 45 days after planting to leave one plant per hill. The common agricultural practices for growing fodder beet according to the recommendations of Ministry of Agriculture were followed. The treatments of N were 100%, 75% and 50% from recommended doses of N (100 kg urea) as urea (46%N), 100 kg P₂O₅ as calcium superphosphate (15.5 % P₂O₅) and 100 kg K2O per fed)  as potassium sulphate (48 % K₂O). The whole amount of calcium superphosphate was added before sowing during soil preparation, but the amount of urea and potassium sulfate divided into two equal quantities, the first application was done after thinning and the second one was carried out after two months from the first one.

Treatments can describe as follows:

1. 100% RD of mineral N fertilizer (control).

2. 75% RD of mineral N fertilizer + bio-fertilizer (Azotobacter chrococcum and Azospirillum brasilense)

3. 75% RD of mineral N fertilizer without bio-fertilizer.

4. 50 % RD of mineral N fertilizer + bio-fertilizer.

5. 50 % RD of mineral N fertilizer without bio-fertilizer.

6. Bio-fertilizer.          

Bacteria used as a bio-fertilizer were Azotobacter chrococcum and Azospirillum brasilense, which were produced by Bio-fertilizer Unit, Microbiological Department, Soils, Water and Environment Res. Inst.ARC Giza, Egypt.

Preparation of bacteria inocula:

Bacteria used were grown on nutrient broth (Difico Manual, 1984), peptone (5 g/L) and beef extract (3g/L) put in a flask containing 1L of distilled water, all sterilized in autoclave at 121ºC for 20 minutes. The flask was left at room temperature for 2 hours till cool. After that, bacteria were inoculated in sterile room conditions. The flask which inoculated was incubated at 30 ºC for 24 hours to obtain population of about 10⁹cfu / mL culture.

Finally, seeds were inoculated before sowing. Equal amounts of liquid culture of Azotobacter chrococcum and Azospirillum brasilense (which contains approximately 10⁹cfu ml^-1) were mixed together and applied before inoculation. The Arabic gum was added, as an adhesive agent, to the bacterial suspension (5%W/V). Each inoculated grain received approximately 10⁶ bacterial cells.  In addition, the bio-fertilizer culture (2.5 L of Azotobacter and Azospirillum culture + 20.5 L tap water) was added two times after one month  and three months from sowing to the plots which treated with bio-fertilizer at the rate of 2.5 L /plot.

A-Fodder beet morphological characters:-

At maturity, the three middle rows of each plot were harvested to determine the following characters:

            Five plants were taken randomly from each plot to determine the following growth traits and forage yield (Albayrak and Cama, 2006).

1-Root length (cm).

2- Shoot length (cm)

3- Plant height (cm)

4- Root diameter (cm) =Circumference of a circle when the maximum width of root divided on 2.14.

5- Fresh and dry weights of roots, shoots and their total: all plants of each plot were taking and weight in kg/plot, then transferred to t/fed.

B- Chemical composition:

The chemical analysis was determined for nitrogen, phosphorus, and potassium according to the method described by Cottenie et al. (1982).

b-Crude protein (Cp) % was estimated by multiplying total N content in root and shoot %    by 6.25 (Hymowitz et al., 1972).

b-Crude fiber percentage (CF%):  was determined in root and shoot by the method of A.O.A.C., 2005.

C- Digestible crude protein (DCP %) =(CP%X0.9115)-3.62 according to Church (1979) content in root and shoot.

d- Yields of crude protein, digestible crude protein and crude fiber /fed.

C-Microbiological Analysis:

        Densities of Azotobacter and Azospirilla were determined in the rhizosphere of fodder beet plants on modified Ashby's medium (Abdel-Malck, and Ishak, 1968) and Semi-solid malate medium (Döbereiner, 1976), respectively using the most probable number technique (Cochran, 1950).

     Nitrogenase (N₂-ase) and dehydrogenase enzyme activities in the rhizosphere of fodder beet plants were estimated after 120 days from sowing according to Hardy et al. (1973) and the method described by Thalmann (1967), respectively.

Economic evaluation and statistical analysis:

According to Heady and Dillon (1961) economic evaluation calculated for yield (ton fed^-1), total variable cost, Gross Income (GI), Gross Margin (GM) and Benefit/Cost ratio (B/C) where:

Gross Income (GI) = price of unit L.E X Yield (t fed^-1)

Gross Margin (GM) = Gross Income – Total cost

Benefit/Cost ratio (B/C) =Gross Margin (GM) /Total cost

Statistical analysis by using analysis of variance method according to Snedecor and Cochran (1982) and MSTAT-C program Ver.4 (1986). Differences among means were tested by L.S.D. at 0.05 level of significance.

RESULTS AND DISCUSSION

Effect of N and Bio- fertilizers inoculation on:

A-1-Growth characters of fodder beet:-

                  Data presented in Table (2) indicated that plant height, shoot length, root length and root diameter as growth characters of fodder beet was significantly affected by N mineral and N-bio-fertilizer treatments in both seasons. Data revealed that fodder beet plants fertilized by 75% RD of mineral N fertilizer + bio-fertilizer gave the highest values followed by those fertilized by control (Full RD of mineral N fertilizer) followed by 50% RD of mineral N fertilizer + bio fertilizer followed by 75% RD of mineral N fertilizer without bio followed by 50% RD of mineral N fertilizer without bio, and the lowest value was showed with those fertilized by bio-fertilizer only for these characters in both seasons. The increasing of these traits as a result of application N fertilizers may be due to the synthesize auxins, cytokinins and gibberellins like compounds via asymbiotic N₂-fixing bacteria. These compounds increase the rate of seed germination and stimulate the development of root tissues leading to an increase in the capacity of the root system to provide nutrients and water to above ground organs of plants (Arkhipova et al., 2007) as well as stimulating vegetative growth, hence increasing root length and diameter. With this respect, Rodriguez et al.(2006) stated that the acidification of the rhizosphere environments through metabolic production of hydrogen ions alters the pH sufficiently to mobilize soil minerals .Our results were supported by similar results obtained by Abdel-Gawad, et al. (2008) for plant height and shoot length and Hussein et al. (2015) for root diameter.

Table 2: Effect of bio-mineral fertilization on growth of fodder beet (2016-2017  and 2017-2018 seasons)