Dinamic of Bacteria Desnitrificants and Nitrificants in the Rizospheric of Wheat with Slow Release of Fertilizer, Irrigated with Waste or Well Water

doi:10.4236/aim.2013.34048

Paper Menu >>

Journal Menu >>

Advances in Microbiology, 2013, 3, 343-349

http://dx.doi.org/10.4236/aim.2013.34048 Published Online August 2013 (http://www.scirp.org/journal/aim)

Dinamic of Bacteria Desnitrificants and Nitrificants

in the Rizospheric of Wheat with Slow Release of

Fertilizer, Irrigated with Waste or Well Water

Sandra Grisell Mora-Ravelo1*, Francisco Gavi Reyes2, Jesús Pérez Moreno3,

Juan José Peña Cabriales2, Leonardo Tijerina Chávez4, Ma. de Lourdes de la Isla de Bauer2

1Posgrado en Biología, Instituto Tecnológico de Ciudad Victoria, Ciudad Victoria, México

2Programa de Hidrociencias, Colegio de Posgraduados, Montecillo, México

3Programa de Edafología, Colegio de Posgraduados, Montecillo, México

4Departamento de Biotecnología, CINVESTAV, Irapuato, México

Email: *[email protected]

Received May 30, 2013; revised June 30, 2013; accepted July 10, 2013

tion License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly

cited.

ABSTRACT

The study of the paper about the rhizosphere in the transformation of nitrogen compounds can generate knowledge of

the microbial and biochemical atmosphere of the rhizosphere of wheat, for the understanding of the dynamics of the N

in agricultural zones, with the purpose of optimizing the fertilizer use and increasing the productivity of the cultures.

Therefore, the objective of the present work was to know the effect the rhizosphere in the dynamics of the bacterial

populations that take part in the cycle of the N in wheat nourished with slow release fertilizer and one commercial, irri-

gated with waste water or well. Analyses in the soil took place vertisol used in the experiment with the rhizospheric and

non rhizospheric fraction. The slow release fertilizer used has a matrix enriched with N and P and is in the process of

being patented (it explains in materials and methods). Each fertilizer was evaluated and the combination of the slow

release fertilizer with organic fertilizer. The technique of the number most probable was used (MNP) to carry out the

quantification of the nitrificants and denitrificants bacteria to the 55, 67 and 97 days after sowing (Dds). The results

obtained for the MNP of denitrificants bacteria and Nitrosomonas indicate that the effect average of the types of water,

soil and fertilizers, as well as their interaction to each other was not significant (p > 0.05). The effect of the fertilizing

type and soil (rhizospheric and non rhizospheric) in the MNP of Nitrobacter was significant (p < 0.05). The tendencies

show that the non rhizospheric soil is more favorable for the development of denitrificants bacteria and Nitrobacter,

whereas the MNP of Nitrosomonas was greater in rhizospheric soil.

Keywords: Nitrificants; Vermicompost; Nitrites; Nitrates; Ammonium

1. Introduction

The rhizosphere constitutes the surface and the immedi-

ate region the root surrounds, that provides with an eco-

logical niche to the microorganisms of the soil since in

her the nutriments are more available. The atmosphere

rhizospheric is a scene integrated by the interaction soil,

plants and organisms. Between these the bacteria and

fungi are in greater density in the rhizosphere than that in

the soil without roots [1]. The interactions between the

microorganisms and the roots determine the rhizosphere

effect, on same populations and the activity of the mi-

croorganisms on the availability of the nutriments for the

plants [2,3].

In nitrificants bacteria, rhizospheric are developed (Ni-

trobacter and Nitrosomonas); and denitrificants bacteria

(Brasilense Azospirillum, Bacillus azotoformas, thioba-

cillus desnitrificans, Pseudomonas, etc.), those alto-

gether play an important role inside of the cycle of the N.

The nitrificants bacteria they are of quimiotrofic me-

tabolism and the oxidation of the 4 to 2

NH NO



, it

serves like power plant as these microorganisms whereas

the Corg they obtain it from the fixation of the CO2, of the

air or the atmosphere of the soil. The growth of these

bacteria is smaller than the growth of the majority of the

*Corresponding author.

S. G. MORA-RAVELO ET AL.

344

bacteria of the soil that are of quimiotrofic metabolism

[4,5].

Within the microorganisms, the bacteria constitute the

only group that has the physiological characteristic to

cause the denitrification. All the bacteria denitrificants

are anaerobic, with the exception of the species of the

sort Propionibacterium that fermenters anaerobic they

are forced that is able to carry out the denitrification.

Most of the denitrificants bacteria they are of quimio-

trofic metabolism since they use carbohydrates, organic

acids and diverse organic compounds like C and power

plant during their anaerobic cycle in the presence of di-

verse oxides of N [6].

The activity, diversity and structure of these microor-

ganisms are sensible to the changes in the edafic atmos-

phere caused by the carbon sources and energy, pressure,

ventilation and interaction between the microorganisms,

pH, humidity, temperature, content of oxygen and nutria-

ments available [7]. The most important factor is the

availability of nutriments because it promotes the activity

of the microorganisms in the rhizosphere, measurement

like rhizosphere phantom, which is of 2, 5 ground times

greater fertilized than in grounds non fertilized; also mic-

robiota measured with 14C is tripled when fertilizers are

applied.

2. Materials and Methods

This study was conducted in two phases. The first corre-

sponded to establishing a greenhouse test for generating

environments where microorganisms would study popu-

lations and the second consisted of determining the inci-

dence microbial laboratory. A haplic vertisol from Gua-

najuato, Mexico was used [8]. The physical and chemi-

cal properties of the studied soil and water are shown in

Tables 1 and 2. We used wheat (Triticum aestivum L.)

variety “Tlaxcala F2000” classified as having an inter-

mediate cycle and developed for natural rainfall condi-

tions by the INIFAP (Instituto Nacional de Investiga-

ciones Forestales, Agropecuarias y Pecuarias). This

wheat has an average cycle of 118 days, with a harvest-

ing interval from 107 to 135 days [9]. The applied fertili-

zers were: monoammonic phosphate plus urea termed a

“commercial fertilizer” (CF), a vermicompost termed

“organic fertilizer” (OF), and a slow release fertilizer

(SRF) called “GAPU” (constituted by a clay matrix en-

riched with 8.1 and 6.3% of N and P in weight, respec-

tively, in process to be patented). The treatments were

designed to evaluate the simple effect of each one of

these fertilizers and the combination of SRF plus OF.

Vermicompost (containing 1.37% and 0.75% of N and P,

respectively) was produced with residues of plants used

for gardening. Used waste and well waters came from

urban zones from Montecillo, Texcoco, Mexico. The

dose of fertilization of N and P used for the greenhouse

Table 1. Physical and chemical characteristics of the experi-

mental soil.

Variable Method Value Units

N MicroKjeldahl 0.07 %

Extractable P Olsen 34 mg kg−1

Organic matter Walkley and Black 1.4 %

CCI Extraction with

ammonium acetate 39 cmolc kg−1

pH (relation 2:1)Potentiometer 7.76

E.C. Conductimeter 0.69 dS m−1

Sand Bouyoucos 10 %

Lime 17 %

Clay 73 %

Textural class Clayish

E.C. = Electrical conductivity, CCI = Capacity of cationic interchange.

Table 2. Physical and chemical characteristics of the ex-

perimental water.

Variable Value Units

Waste water Well water

Total N 72 32.00 mg L−1

N-NO3 6 22.27 meq L−1

N-NH4 55 8.64 meq L−1

Soluble P-PO4 11 0.86 mg L−1

Total P 39 0.60 mg L−1

pH 7.05 7.45

E.C. 0.59 0.59 dS m−1

E.C. = Electrical conductivity.

experiment was greater than that recommended in the

studied area in eastern Mexico “Bajío Guanajuatense”

where the studied soil was collected. Following the re-

commendation of Terman, et al. (1962) [10] for green-

house experiments, the dose was equivalent to 360 and

257 kg of N and P per ha, respectively. All N and P were

applied at the time of sowing. The experimental units

(EU) consisted of cylindrical pots which contained 2 kg

of soil: without plants (designed to collect non rhizo-

spheric soil) and with three plants (from which the rhi-

zospheric soil was collected). The number of cylindrical

pots was calculated so that in every date of sampling

(55.67 and 97 days after sowing) three experimental units

by treatment were collected (Table 3).

In order to obtain the rhizospheric soil, the soil portion

used was that strongly adhered to the root. Ten grams

were weighed separately of rhizospheric and non rhizo-

S. G. MORA-RAVELO ET AL. 345

Table 3. Treatments in the experiment.

Number

treatment

Type

soil

Type of

fertilizer

Type of

water

Number

replicates

1 RS CF Waste water 3

2 RS CF Well water 3

3 NR CF Waste water 3

4 NR CF Well water 3

5 RS SRF Waste water 3

6 RS SRF Well water 3

7 NR SRF Waste water 3

8 NR SRF Well water 3

9 RS OF Waste water 3

10 RS OF Well water 3

11 NR OF Waste water 3

12 NR OF Well water 3

13 RS SRF + OF Waste water 3

14 RS SRF + OF Well water 3

15 NR SRF + OF Waste water 3

16 NR SRF + OF Well water 3

17 RS C Waste water 3

18 RS C Well water 3

19 NR C Waste water 3

20 NR C Well water 3

Total

units

number

of experimental 240 Unit

SR = Rhizospheric soil, NR = Non rhizospheric soil; CF = Commercial

fertilizer, SRF = Slow release fertilizer, OF = Organic fertilizer (vermicom-

post), C = Control.

spheric soil. Each of these samples was added to 90 mL

of Ringer solution. In the determination of the microbial

incidence, the technique of the most probable number

(MPN) was used for the quantification of nitrificant and

denitrificant bacteria [11]. Selective growth media for the

fractions of the rhizospheric and non rhizosphereic soil

were used. A series of ten dilutions was used to inoculate

five tubes with each level of dilution (10−8 to 10−5). The

cultures were incubated to 28˚C during 7 and 21 days for

the denitrificant and nitrificant bacteria, respectively and

their presence was identified by using specific diagnostic

tests. (CaCO3) NH4 was used for Nitrosomonas, (CaCO3)

NO2 for Nitrobacter and of Griess-Ilosvay reagent for

both groups [12].

3. Results

The experimental design did not allow statistical eva-

luation of sampling interaction with the other factors

evaluated: type of water, fertilizers and soil type (vs. rhi-

zosphere. Rhizospheric not) for any of the populations of

bacteria quantified. Figure 1 shows the temporal changes

of the populations of denitrificant bacteria of non

rhizospheric soil in relation to plant age with waste water

and well water. In general terms, there was an increase in

denitrificant bacteria populations, when the plan age in-

creased, indepently of type of water. The average effect

of the types of water, soil and fertilizers (as well as their

interactions between them) was not significant (p > 0.05)

on the development of the denitrificant bacteria popula-

tions, evaluated MPN. In general terms, The populations

denitrificant were higher in non rhizospheric in relation

to those found in rhizospheric soil, independently of the

type de water. In average, denitrificant from non rhizo-

spheric soil populations were higher in well water than in

waste water. Mean while, the opposite trend was obser-

ved in rhizospheric soil (Table 4).

(a)

(b)

Figure 1. MPN of denitrificant bacteri a in non-rhizospheric

soil irrigated with (a) waste water or (b) well water. CF =

Commercial fertilizer, SRF = Slow release fertilizer, OF =

Organic fertilizer (vermicompost), C = Control. Vertical

lines show 95% confidence intervals.

S. G. MORA-RAVELO ET AL.

346

In relation to fertilizers, the highest populations of de-

nitrificant bacteria were observed in Fertilizer slow re-

lease and the lowest ones were recorded in Commercial

Fertilizer (Table 5).

Pointed out that plant organic compounds can be used

as a source of nutrients energy to desnitrificants bacteria.

Also it is inferred, that the waste water can contain in its

M. O factors of growth for same the bacteria; neverthe-

less the toxic elements can predominate in their negative

effect that limits the increase of the bacterial population

[13]. It was observed (Table 5) that when SRF was ap-

plied there is minor proliferation of denitrificants bacteria,

compared with the witness and the application of other

fertilizers (OF and CF) and his combinations. This can

indicate that the N of the SRF is less susceptible to lose

itself by denitrification.

Figure 2 shows the temporal changes of the populations

of Nitrobacter bacteria of non rhizospheric soil in rela-

tion to plant age with waste water and well water. In

general terms, there was an increase in denitrificant bac-

teria populations, when the plan age increased, inde-

pently of type of water.

The average effect of the types of water, soil and fer-

tilizers (as well as their interactions between them) was

not significant (p > 0.05) on the development of the Ni-

trobacter bacteria populations, evaluated MPN. In gen-

eral terms, the populations Nitrobacter were higher in

non rhizospheric in relation to those found in rhizo-

Table 4. Average of MPN of denitrificant bacteria in two

types of water and soil during three samplings.

Type of water Rhizospheric

soil

Non rhizospheric

soil Average

Waste water 0.65 × 105 0.82 × 105 0.73 × 105

Well water 0.26 × 105 7.3 × 105 3.7 × 105

Average 0.45 × 105 4.1 × 105

Table 5. Average of the MPN of denitrificant bacteria in

rhizospheric soil and non rhizospheric soil with addition of

three types of fertilizer.

Fertilizer Rhizospheric soil Non rhizospheric

soil Average

CF 6.5 × 105 8.3 × 105 7.4 × 105

C 5.4 × 105 6.4 × 105 5.9 × 105

OF 0.31 × 105 0.83 × 105 0.57 × 105

SRF + OF 0.27 × 105 0.37 × 105 0.32 × 105

SRF 0.11 × 105 0.11 × 105 0.11 × 105

Average 2.52 × 105 3.2 × 105

CF = Commercial fertilizer, SRF = Slow release fertilizer, OF = Organic

fertilizer (vermicompost), C = Control.

(a)

(b)

Figure 2. MPN of Nitrobacter in non-rhizospheric soil irri-

gated with (a) waste water or (b) well water. CF = Com-

mercial fertilizer, SRF = Slow release fertilizer, OF = Or-

ganic fertilizer (vermicompost), C = Control. Vertical lines

show 95% confidence intervals.

spheric soil, independently of the type de water. In aver-

age, Nitrobacter from non rhizospheric soil populations

were higher in well water than in waste water. Mean

while, the opposite trend was observed in rhizospheric

soil (Table 6).

In relation to fertilizers, the highest populations of Ni-

trobacter bacteria were observed in Fertilizer slow re-

lease and the lowest ones were recorded in Commercial

Fertilizer (Table 7). Figure 3 shows the temporal

changes of the Nitrosomonas populations of bacteria of

non rhizospheric soil in relation to plant age with waste

water and well water. In general terms, there was an in-

crease in Nitrosomonas bacteria populations, when the

plan age increased, indepently of type of water (Table 8).

In Table 9, it was observed that the fertilizers that

promote the MNP of Nitrobacter are the SRF and the CF.

The most probable number of the denitrificants bacteria

is greater than in Nitrobacter and Nitrosomonas as it in-

dicates [14] that indicates for example the root of wheat

has a strong effect on the microbial populations within

S. G. MORA-RAVELO ET AL. 347

Table 6. Average of MPN of Nitrobacter in two types of wa-

ter and soil during three samplings.

Type of water Rhizospheric

soil

Non rhizospheric

soil Average

Waste water 7.2 × 105 10 × 105 8.6 × 105

Well water 3.5 × 105 2.6 × 105 3.1 × 105

Average 5.3 × 105 6.3 × 105

Table 7. Average of the MPN of Nitrobacter in rhizospheric

soil and non rhizospheric soil with addition of three types of

fertilizer.

Fertilizer Rhizospheric

soil

Non rhizospheric

soil Average

CF 12 × 105 1.3 × 105 6.7 × 105

C 9.2 × 105 6.3 × 105 7.7 × 105

SRF 1.9 × 105 0.9 × 105 1.4 × 105

SRF + OF 1.9 × 105 5.2 × 105 3.5 × 105

OF 1.1 × 105 6.4 × 105 3.7 × 105

Average 5.2 × 105 4.0 × 105

CF = Commercial fertilizer, SRF = Slow release fertilizer, OF = Organic

fertilizer (vermicompost), C = Control.

(a)

(b)

Figure 3. MPN of Nitrosomonas in non- rhizospheric soil

irrigated wi th (a) waste w ater or (b) well water. CF = Com-

mercial fertilizer, SRF = Slow release fertilizer, OF = Or-

ganic fertilizer (vermicompost), C = Control. Vertical lines

show 95% confidence intervals.

which denitrificant emphasizes the high number of bac-

teria.

4. Discussion

In this experiment, we possibly suppose that there was no

an independently marked rhizospheric effect of the type

of fertilizer and used water, had to that the sampled

rhizospheric zone was not the adapted one, due to the

space so reduced in that were the wheat plants. However,

the MNP of the bacteria studied in this work was not

affected by the zone by the roots nor by the fertilization

with N as it concludes [1,2,15]; which they investigated

that the composition of the community of bacteria in the

rhizosphere is affected by the complex interaction be-

tween the type of soil, species of plants location of the

zone by the roots and the nitrogen fertilization. Appar-

ently, there was no a marked rhizospheric effect on Ni-

trosomonas (Table 9), because the existing potential in

this zone to carry out the liberation of the 4



, consti-

tutes necessary the power provision for the development

of this sort of nitrificants bacteria [16]. Contrary to the

referred thing by [17] on the inhibiting effect caused by

the organic compound presence on the development of

the nitrificantes populations, it was verified in the present

investigation that in the rhizosphere, in which a great

abundance of organic compounds exists, these popula-

tions were stimulated (Tables 6 and 7), which agrees

with the results obtained by [18], for the rhizosphere of

Table 8. Average of MPN of Nitrosomonas in two types of

water and soil during three samplings.

Type of waterRhizospheric

soil

Non rhizospheric

soil Average

Well water 6.1 × 105 3.1 × 105 4.6 × 105

Waste water 2.2 × 105 2.3 × 105 2.3 × 105

Average 4.1 × 105 2.7 × 105

Table 9. Average of the MPN of Nitrosomonas in rhizosphe-

ric soil and non rhizospheric soil with addition of three ty-

pes of fertilizer.

Fertilizar Rhizospheric

soil

Non rhizospheric

soil Average

CF 9.3 × 105 3.0 × 105 6.2 × 105

C 4.8 × 105 4.1 × 105 4.5 × 105

OF 3.1 × 105 2.2 × 105 2.7 × 105

SRF + OF2.1 × 105 2.8 × 105 2.5 × 105

SRF 1.6 × 105 1.7 × 105 1.7 × 105

Average 4.2 × 105 2.8 × 105

CF = Commercial fertilizer, SRF = Slow release fertilizer, OF = Organic

fertilizer (vermicompost), C = Control.

S. G. MORA-RAVELO ET AL.

348

some plants. However, the magnitude of the development

shown by the nitrificants bacteria in the rhizosphere of

wheat, and with its development in the fraction of the

rhizospheric soil (Figure 2), it suggests in her takes place

an effective process of nitrification [19]. Woldendorp

and Laanbroek (1989) [20] reported that the rate of nitri-

fication is a predominant process in the rhizosphere,

which can lead to a considerable production of 3



this zone. However, it was difficult to make a real esti-

mation of the rate from production of 2

in the rhizo-

sphere, which can lead to a considerable production of

3 in that zone, since in her great part of the N avail-

able is directed towards immobilization and the absorp-

tion by the roots. The denitrificants bacteria also were

stimulated in greater number of cells as much in the

rhizosphere of the ground as in the non rhizospheric soil

the population increase can be in favor certain not only

of the great present availability of composed of carbon;

but also by the exudate production in the rhizosphere,

which can lead to a considerable production of 3

NO 



the part of the nitrificants bacteria, since he himself ion is

used by the denitrificants bacteria like electron acceptor

before the reduced present oxygen concentration in the

rhizosphere [21]. The number of cells or MNP was ob-

tained in Nitrobacter and Nitrosomonas was greater to

which this is reported generally can be viable since al-

though the conditions in which work was of anaerobiosis

the sort of the Nitrobacter can grow occasionally under

anaerobic atmosphere breathing where the M. O. is min-

eralized [4,22,23]. Kowalchuk and Stephen, (2001) [4],

emphasized that when the technique of the MNP is used

the value of the Nitrosomonas underestimates low values

of the real number of cells caused by factors as pH and

the provision of N. Also, Watson [24] reported that the

count of Nitrobacter is influenced by pH. Although in

our case we discarded that pH has been the factor that I

influence in the number of cells that we reported for

these sorts. We agree with reported by Rice and Pan-

choly [25] who emphasize that the MNP can be a ques-

tionable procedure of count, this is important if they are

possible to be seen that they exist alternative in the inter-

pretation of the changes of and 3 in the soil.

The low concentrations of 3 can be the result of the

best efficiency in the conduction of these and the in-

crease of the 4 can be due to the increase of N in

the soil. A low concentration of 3 can as resulting

from happen in an actively nitrificant habitat the denitri-

fication or by the fast conduction towards the plants as it

indicates Allison and Prosser [26]. On the other hand,

also it can be that the efficiency of the method of the

MNP low is compared with other methods possibly this

must to the selectivity of means of used growth and to

the presence of added cells to the dissolutions as they

indicate [27]. However, the MNP of Nitrobacter and

NO 

NO 

NH 

NO 

Nitrosomonas of these sorts suggest both processes





and 2



3) respectively are similar

so that both steps produce different amounts from energy.

From the uncertainty of the method of the MNP diverse

mechanisms exist that can explain this:

NO

1) Nitrosomonas it has a greater mortality than the Ni-

trobacter. This happens particularly in soils where this

sort (Nitrosomonas) is died by the acid production [27,

28].

2) Heterotrofic development of Nitrobacter species

[29].

3) Anaerobic growth of Nitrobacter through



and organic substrat [30].

4) Denitrificants relation / between Nitro-

bacter and bacteria [31]. 2

NO

5. Conclusions

1) The effects of the types of water, fertilizer and ground

the MNP of denitrificants bacteria and those affected in

form differential that take part in the transformation of



to 3



(Nitrobacter and Nitrosomonas). NO

2) The MNP of the denitrificants bacteria was not af-

fected by the types of fertilizer, soil and water of irriga

tion.

3) The MNP of Nitrobacter was promoted positively

by the type of soil and fertilizer in average. Nitrobacter

was developed better in the non rhizospheric soil. This

sort of bacteria was stimulated by the OF and the combi-

nation of SRF + OF. The waste water did not have an

effect in the MNP of this group of bacteria compared

with the well water.

4) The MNP of Nitrosomonas. It was affected only by

the type of soil. This sort of bacteria have better devel-

opment in the rhizospheric soil.

6. Acknowledgments

This study was financed by project CONACYT 38999.

REFERENCES

[1] J. M. Lynch, “Resilience of the Rhizosphere Anthropo-

genic Disturbance,” Biodegradation, Vol. 13, No. 1, 2002,

pp. 21-27. doi:10.1023/A:1016333714505

[2] P. Marschner, C.-H. Yang, R. Lieberei and D. E. Crowley,

“Soil and Plant Effects on Bacterial Community Compo-

sition in the Rizosphere,” Soil Biology and Biochemistry,

Vol. 33, No. 11, 2001, pp. 1437-1445.

doi:10.1016/S0038-0717(01)00052-9

[3] C.-H. Yang and D. E. Crowley, “Rhizosphere Microbial

Community Structure in Relation to Root Location and

Plant Iron Nutritional Status,” Applied and Environ-

mental Microbiology, Vol. 66, No. 1, 2000, pp. 345-351.

doi:10.1128/AEM.66.1.345-351.2000

[4] G. A. Kowalchuk and R. J. Stephen, “Ammonia-Oxiding

S. G. MORA-RAVELO ET AL.

349

Bacteria: A Model for Molecular Microbiology Ecology,”

Annual Review of Microbiology, Vol. 55, 2001, pp.

485-529. doi:10.1146/annurev.micro.55.1.485

[5] P. Kent, and J. Triplett, “Microbial Communities and

Their Interactions in Soil and Rhizosphere Ecosystems,”

Annual Review of Microbiology, Vol. 56, 2002, pp.

222-236. doi:10.1146/annurev.micro.56.012302.161120

[6] W. De Boer and Y. G. A. Kowalchuk, “Nitrification in

Acid Soils: Micro-Organims and Mechanisms,” Soil B iol-

ogy and Biochemistry, Vol. 33, No. 7-8, 2001, pp. 853-

866. doi:10.1016/S0038-0717(00)00247-9

[7] A. G. O’Donell, M. Seasman, A. Macrae, I. Waite and J.

T. Davies, “Plants and Fertilazers as Drivers of Change in

Microbial Community Structure and Function in Soil,”

Plant and Soil, Vol. 232, No. 1-2, 2001, pp. 135-145.

doi:10.1023/A:1010394221729

[8] INEGI (Instituto Nacional de Estadística, Geografía e

Informática), “Síntesis de Información Geográfica de

Guanajuato,” Carta Estatal de Suelos, Anexo Cartográfico,

México, 2001a.

[9] M. Villaseñor, E. Espitia, J. Huerta, A. María, L. Osorio

and A. Aguirre, “Tlaxcala F2000: Nueva Variedad de

Trigo Para Siembras de Temporal en México,” SAGAR,

INIFAP, CIRCE, Campo Experimental Valle de México,

Folleto Técnico N., Chapingo, Estado de México, México,

Vol. 1, 2000, p. 20.

[10] G. L. Terman, D. R. Boulding and J. R. Webb. “Evalu-

ation of Fertilizers by Biological Methods,” Advances in

Agronomy, Vol. 14, 1962, pp. 265-319.

doi:10.1016/S0065-2113(08)60440-X

[11] H. J. Benson, “Microbiological Applications,” Brown

Company Publishers, Dubuque, 1981, p. 450.

[12] C. A. Black, D. O. Evans, I. L. White, L. E Ensminger

and F. E. Clark, “Methods of Soil Analysis. II. Chemical

and Microbiological Properties,” American Society of

Agronomy, Madison, 1965, pp. 1788.

[13] G. Oron, C. Campos, L. Guillerman and M. Salgot,

“Wastewater Treatment, Renovation and Reuse for Agri-

cultural Irrigation in Small Communities,” Agricultural

Water Management, Vol. 38, No. 3, 1999, pp. 223-234.

doi:10.1016/S0378-3774(98)00066-3

[14] C. R. Ferrera, “Efecto de la rizosfera,” In: C. R. Ferrera

and J. M. Pérez, Eds., Agromicrobiología, Colegio de

Postgraduados, Campeche, 1995, pp. 36-53.

[15] P. Marschner, J. Gerendás and B. Sattelmacher, “Effect of

N Concentration and N Source on Root Colonitation by

Pseudomonas Fluorescens 2-79 RLl,” Plant Soil, Vol.

215, No. 2, 1999, pp. 135-141.

doi:10.1023/A:1004373007606

[16] L. W. Belser, “Population Ecology of Nitrifying Bacte-

ria,” Annual Review of Microbiology, Vol. 3, 1979, pp.

309-333.

doi:10.1146/annurev.mi.33.100179.001521

[17] J. H. G. Slangen and P. Kerkhoff, “Nitrification Inhibitors

in Agriculture and Horticulture: A Literature Review,”

Fertilizer Research, Vol. 5, No. 1, 1984, pp. 1-76.

doi:10.1007/BF01049492

[18] H. K. Russell and L. N. Nelson, “Interactions among

Nitrogen-Transforming Bacteria and Nitrogen-Fixing

Pisum sativum L. in Laboratory Sand Columns,” Plant

Soil, Vol. 122, No. 2, 1990, pp. 157-167.

doi:10.1007/BF02851970

[19] P. Berg and T. Rosswall, “Seasonal Variations in Abun-

dance and Activity of Nitrifiers in Four Arable Cropping

Systems,” Microbial Ecology, Vol. 13, No. 1, 1987, pp.

75-87. doi:10.1007/BF02014964

[20] J. W. Woldendorp and H. J. Laandroek, “Activity of Ni-

trifiers in Relation to Nitrogen Nutrition of Plants in

Natural Ecosystem,” Plant Soil, Vol. 115, No. 2, 1989, pp.

217-228. doi:10.1007/BF02202590

[21] R. Y. Stanier, E. A. Adelberg and J. L. Ingraham,

“Microbiología,” Reverte, Barcelona, España. 1984. pp.

836.

[22] G. J. Holt, R. N. Krieg, P. H. Sneath, J. T. Staley and S. T.

Williams, “Bergey Manual of Determinative Bacterial-

ogy,” Williams & Wilkins, Baltimore Maryland, 1994, pp.

448-453.

[23] W. De Boer, P. J. A. Klein Gunnewiek and D. Parkinson,

“Variability of N Mineralization and Nitrification in a

Simple, Simulated Microbial Forest Soil Community,”

Soil Biology & Biochemistry, Vol. 28, No. 2, 1996, pp.

203-211. doi:10.1016/0038-0717(95)00124-7

[24] S. W. Watson, “MNP Tecnique for Population Nitrifier,”

In Syst. Bacterial, Vol. 21, 1971, pp. 254-270.

[25] E. L. Rice and S. K. Pancholy, “Methods for Estimating

Nitrifier Populations Inhibition of Nitrification by Climax

Ecosystems,” American Journal of Botany, Vol. 60, No. 7,

1973, pp. 691-702. doi:10.2307/2441448

[26] S. M. Allison and J. I. Prosser, “Ammonia Oxidation at

Low by Attached Populations of Nitrifying Bacteria,”

Soil Biology & Biochemistry, Vol. 25, No. 7, 1993, pp.

935-941. doi:10.1016/0038-0717(93)90096-T

[27] W. De Boer, P. J. A. Klein Gunnewiek and H. J.

Laanbroek, “Ammonium-Oxidation at Low pH by a Che-

molithotrophic Bacterium Belonging to the Genus Nitro-

spira,” Soil Biology & Biochemistry, Vol. 27, No. 2, 1995,

pp. 127-132. doi:10.1016/0038-0717(94)00157-V

[28] L. Klemedtsson, Q. Q. Jiang, A. K. Klemedtson and L. R.

Bakken, “Autotrophic Ammonium-Oxidising Bacteria in

SWEDISH Mor Humus,” Soil Biology and Biochemistry,

Vol. 31, No. 6, 1999, pp. 839-847.

doi:10.1016/S0038-0717(98)00183-7

[29] W. De Boer, P. J. A. Klein Gunnewiek, M. Veehuis, E.

Bock and H. J. Laanbroek, “Nitrification at Low pH by

Aggregated Chemolithotrophic Bacteria,” Applied and

Environmental Microbiology, Vol. 57, No. 12, 1991, pp.

3600-3604.

[30] A. Teske, E. Elm, J. M. Regan, S. Toze, B. E. Rittmann

and D. A. Stahl, “Evolutionary Relationships among Am-

monia- and Nitrite-Oxidizing Bacteria,” Journal of Bac-

teriology, Vol. 176, No. 21, 1994, pp. 6623-6630.

[31] J. G. Kuenen and L. A. Robertson, “Combined Nitrifica-

tion-Denitrification Processes,” FEMS Microbiology Re-

views, Vol. 15, No. 2-3, 1994, pp. 109-117.

doi:10.1111/j.1574-6976.1994.tb00129.x