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Examination of Some Parameters for Ecological Growth of Maize in Pelic Vertisol

  • I. Stoimenova
  • E. Djonova
  • A. Taleva
  • N. Kaloyanova
Chapter
Part of the Environmental Earth Sciences book series (EESCI)

Abstract

The increases in doses of nitrogen fertilization decreased the depressing effect of the used herbicides and stimulated their biological degradation. The bacteria, microscopic fungi and cellulose decomposing microorganisms took part in the biological herbicide degradation process during the first days of application of herbicides, whereas the actinomicetes and microbes, utilizing nitrogen, took part at the later phases of the process. The observed soil chemical changes and the ratio between the main groups of soil microorganisms had a temporary effect and did not influence negatively the maize development.

Keywords

Fertilization Nitrogen Maize 

1 Dynamics of the Soil Microflora, Depending on the Level of Nitrogen Fertilization and Application of Herbicides

The herbicide substances show different effectiveness in specific soil and climatic conditions, which is reflected both in the number and the content of the weeds, as well as in the dynamics and the diversity of the soil microflora [1, 2, 3, 4]. Therefore their examination during the growth of maize in the particular agro-ecological conditions is required in order to determine the herbicide effect and the danger of contamination of the soil with residual quantities.

The purpose of the experiment is to study the effect of the Lacorn combi herbicide (applied independantly and in combination with Atrazine) and its interaction with other forms of nitrogen fertilization on the dynamics and the diversity of the soil microflora.

The variations in the species and quantitative structure of the microbial population (at depth from 0 to 20 cm), depending on the studied factors, are studied in the dynamics on selective nutrition media by the decimal dilution test.

In maize growth it is found that the soil microorganisms actively participate in the biological decomposition of the herbicide combination Lacorn combi (5,500 ml/ha), and the relative part taken by the different physiological groups depends on the nitrogen fertilization and the climatic conditions (Table 1). On the 35th day after the introduction of the herbicide substance the amonifying bacteria, the microscopic fungi and the cellulose decomposing microorganisms decrease their number up to 30% in the variant with N20 in comparison to higher doses of nitrogen fertilization. In the same period a some stimulation of the development of the actinomicetes from the applied herbicide established, where no effect of the tested doses of nitrogen fertilization is examined.
Table 1

Dynamics of some main groups soil microorganisms after application of Lacorn combi (5,500 ml/ha)

Variants

Amonifying bacteria 1 × 106

Actinomycetes 1 × 106

Microscopic tungi 1 × 104

Cellulose decomposing microorganisms 1 × 104

Days after treatment

35

60

90

35

60

90

35

60

90

35

60

90

N20 + herbicide

3.70

4.85

6.20

1.35

2.42

1.70

13.00

28.45

39.95

11.34

29.35

61.65

N40 + herbicide

4.15

6.30

6.60

1.40

3.55

3.10

28.60

36.35

36.70

76.30

83.40

96.45

N80 + herbicide

4.20

5.60

7.00

1.08

2.65

2.90

20.00

31.65

37.00

106.80

97.33

104.80

N20

4.10

5.65

7.00

0.99

3.20

1.65

23.35

21.75

35.25

56.80

72.20

81.50

N40

4.65

5.95

7.90

0.81

1.90

2.05

41.70

35.30

56.65

72.95

69.40

94.95

N80

3.70

7.80

6.90

0.95

2.90

2.40

38.35

18.30

49.95

68.35

71.33

80.00

On the 60th day the negative effect of the herbicide substance continues on the amonifying bacteria, the microscopic fungi and the cellulose decomposing microorganisms, again most strongly shown at N20. With the actinomicetes no significant changes in the population are observed. Until the 90th day the numbers and the structure of the population is almost completely restored.

The data on Table 1 show that the applied nitrogen in increasing doses decreases the suppressing effect of Lacorn combi and stimulates the biological detoxification of the herbicide substance. The examined herbicide contributes to the increase of the numbers of microorganisms in the soil, related to the nutrition and the development of the maize.

In a field experiment with maize the effect of the herbicide substances Lacorne combi (5,500 ml/ha)+Atrazine (1,600 g/ha) on the same groups of microorganisms in the soil layer 0–20 cm. The experiment has been carried out in dynamic and includes the same periods of soil sampling after herbicide application.

The data presented in Table 2 show that the herbicide substances applied in combination with nitrogen norm N40 leads to increase of the population of the amonifying microorganisms, actinomicetes, and the microscopic fungi through the whole experimental period. With the cellulose decomposing microorganisms such stimulation is observed at N80, distinctly displayed on the 90th day after the treatment. This is probably related to the products, received as a result of the decomposition of the herbicide substance in the soil and the deir different influence on the examined groups of soil microorganisms.
Table 2

Dynamics of some main groups soil microorganisms after application of Lacorn combi (5,500 ml/ha) + atrazine (1,600 g/ha)

Variants

Amonifying bacteria 1 × 104

Actinomycetes 1 × 104

Microscopic tungi 1 × 103

Cellulose decomposing microorganisms 1 × 103

Days after treatment

35

60

90

35

60

90

35

60

90

35

60

90

N20 + herbicide

7.43

5.20

4.13

3.43

3.56

5.56

59.50

36.00

30.00

20.00

56.00

23.00

N40 + herbicide

8.51

8.60

8.00

6.55

5.66

7.46

36.50

63.00

16.00

81.50

66.00

100.00

N80 + herbicide

4.92

5.60

3.23

5.64

4.83

5.13

13.00

10.00

20.00

93.00

71.00

143.00

N20

8.05

5.90

4.20

4.32

5.63

9.96

68.00

33.00

26.00

69.50

53.00

70.00

N40

6.45

8.93

7.60

4.03

10.20

5.60

33.00

60.00

23.00

99.50

83.00

53.00

N80

6.86

7.13

8.33

4.05

6.56

8.30

91.50

53.00

50.00

75.00

93.00

126.00

In the process of biological degradation of the herbicide substance Lacorn combi+Atrazine the amonifying bacteria, the actinomicetes and the microscopic fungi participate in the first days after the treatment, whereas the cellulose decomposing microorganisms participate at the later stages of detoxification of the herbicides.

2 Conclusions

  1. 1.

    The application of higher doses of nitrogen fertilization decreases the depressing effect of the tested herbicide – for Lacorn combi up to N80 and for the combination Lacorn combi+Atrazine up to N40.

     
  2. 2.

    The determined changes in the microbial population during the two experiments have temporary effect and do not have negative effect on the structure of the microbial population.

     

References

  1. 1.
    Assae NA, Turco RF (1995) Accelerated biodegradation of atrazine by microbial consortium is possible in culture and soil. Biodegradation 5:29–35Google Scholar
  2. 2.
    Dovies DH et al (1995) Risk evaluation of reduced dose approaches to weed control in cereals. 9th Symposium, Challenges for weed science in a changing Europe, Budapest, vol 2, pp 459–467Google Scholar
  3. 3.
    Parry KP (1989) Herbicide use and invention. In: Dodge AP (ed) Herbicides and plant metabolism. Cambridge University Press, Cambridge, pp 1–20Google Scholar
  4. 4.
    Rocha F (1995) Reducing inputs of herbicides on dryland areas. 9th Symposium, Challenges for weed science in a changing Europe, Budapest, vol 2, pp 478–482Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2010

Authors and Affiliations

  • I. Stoimenova
    • 1
  • E. Djonova
    • 2
  • A. Taleva
    • 2
  • N. Kaloyanova
    • 2
  1. 1.N. Poushkarov Institute of Soil ScienceSofiaBulgaria
  2. 2.Department of Soil MicrobiologyN. Poushkarov Institute of Soil ScienceSofiaBulgaria

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