International Journal of Horticulture 2015, Vol.5, No.3, 1
-
12
2
different management practices is required. Chemical
weed control is a better supplement to conventional
method and forms an integral part of the modern crop
production. It is quick, more effective, time and labour
saving method than others (Tahir et al., 2009).
Presently a number of herbicides like pendimethalin,
metribuzin and oxyfluorfen
etc.
are commercially
available for weed control in turmeric.
Herbicides are extraneous to soil component pools,
and are expected to affect the catalytic efficiency,
behavior of soil enzymes (Bollag and Liu, 1990;
Sannino and Gianfreda, 2001), which contribute to the
total biological activity of the soil-plant environment
under different states (Dick, 1995; Dick, 1997). The
interaction
between
herbicides
and
soil
microorganisms may be of practical significance
because of possible inhibition in microbial activities
contributing to soil fertility. Various studies have
revealed that the herbicides can cause qualitative and
quantitative change in enzyme activity (Sannino and
Gianfreda, 2001; Min et al., 2001; Saeki and Toyota,
2004; Sebiomo et al., 2011, Xia et al., 2011). Hence,
the effects of herbicides on soil microbial
communities addressing the apprehensions about the
environmental impacts of herbicide use. Several
scientific investigations have suggested the
importance of preserving soil fertility and quality, and
consequently soil microbial population. As the soil
microorganisms are very sensitive to low
concentrations of contaminants and rapidly response
to soil perturbation, they are considered as an
indicator of soil pollution (Shen et al., 2005). The
enzyme activities are considered to be sensitive to
chemical pollutants/agrochemicals and have been
proposed as potential indicators for measuring the
degree of pollution of contaminated soil (Aoyama and
Nagumo, 1995; Insam et al., 1996; Kuperman and
Margret, 1997), and referred to as markers of soil
environmental purity (Aon and Colaneri, 2001). The
evaluation of soil enzyme activities may provide
useful information on microbial activity and be
helpful in establishing the effects of soil specific
environmental conditions (Andreoni et al., 2004). An
alternation in soil microorganisms, their number,
activity and diversity may serve as indicators of soil
fertility (Milosevia et al., 1997) and reflect the soil
quality (Schloter et al., 2003). However, most of the
studies were focused on single application for a short
period, which may provide a realistic evaluation of the
effects of herbicides on soil microorganism (Haney et
al., 2000). However, the knowledge about the effect of
herbicides on soil microbial population in long-term
applications has been limited. Being a long duration
crop, pre-emergence herbicides alone will not provide a
sustainable and effective weed management. Based on
the above constraints, we are taken the objective of study
the efficacy of pre and post emergence herbicides in
IWM on weed control and herbicide residues effect in
soil microbial populations of turmeric.
Materials and Methods
Field experiments were carried out during
kharif
2012
at Agricultural Research Station, Bhavanisagar of
Tamil Nadu Agricultural University, to evaluate the
integrated
weed management with pre and post
emergence herbicides in turmeric. The details of the
experiment, the materials used and the methods
employed during the course of investigation are
presented in this chapter.
Soil characteristics
Composite soil sample was collected at random prior
to the experiment, pooled and analysed for physico-
chemical characteristics. The soil of the experimental
field was red sandy loam in texture belonging to
Typic
Haplustalf
. The nutrient status of the field was low in
available nitrogen, medium in available phosphorus
and high in available potassium. The detailed
physico-chemical properties of the experimental field
are furnished in Table 1.
Table 1 Physico-chemical characteristics of the experimental
fields
Character
Kharif-
2012
A. Mechanical Composition (Piper, 1966)
Clay (%)
17.5
20.38
Silt (%)
9.75
Fine sand (%)
31.32
Coarse sand (%)
38.43
Texture
Red sandy
loam
B. Chemical Properties
pH (1:2 soil: water extract) (Jackson, 1973)
7.35
EC dSm
-1
(1:2 soil: water extract) (Jackson, 1973) 0.19
Organic carbon % (Walkley and Black, 1934)
0.54
Available nitrogen kg ha
-1
(Subbiah andAsija, 1956)
235.0
Available phosphorus kg ha
-1
(Olsen et al., 1954) 17.45
Available potassium kg ha
-1
(Stanford and
English, 1949)
388
Season
The experiments were conducted during
kharif
(May-June) season, 2012.
