Directory UMM :Data Elmu:jurnal:S:Soil & Tillage Research:Vol52.Issue3-4.Oct1999:
Soil & Tillage Research 52 (1999) 203±216
Land con®guration and soil nutrient management options
for sustainable crop production on Al®sols and
Vertisols of southern peninsular India
R. Selvarajua,*, P. Subbiana, A. Balasubramaniana, R. Lalb
a
Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore 641 003, Tamil Nadu, India
b
School of Natural Resources, Ohio State University, Columbus, OH, USA
Received 16 June 1998; received in revised form 12 January 1999; accepted 24 August 1999
Abstract
Land con®guration in combination with nutrient management has the potential to improve the productivity of Al®sols and
Vertisols in the semi-arid tropics. A four year (1989±1990 and 1992±1993) ®eld experiment was conducted at Coimbatore,
India on Al®sols (Chromic Cambisol) to compare the effect of land con®guration and nutrient management practices on yield
of rainfed sorghum (Sorghum bicolor (L.) Moench). The land con®guration treatments were ¯at bed (FB, the traditional
practice), open ridging (OR, ridges, 45 cm apart and 30 cm high) and tied ridging (TR, same as OR plus ridges were tied
randomly). The manure and fertilisers were farm yard manure (FYM, livestock excreta plus litter at 5 Mg haÿ1) and coir dust
(CD, by-product after the extraction of coir from the coconut (Cocos nucifera L.) husk at 12.5 Mg haÿ1) in combination with
nitrogen (N) and phosphorus (P) fertiliser levels. Tied ridges stored 14% more soil water and produced 14% and 11% more
grain and straw yields of sorghum, respectively, than did ¯at bed. However, crop yield in TR was comparable with OR.
Application of CD at 12.5 Mg haÿ1 combined with 40 kg N haÿ1 and 9 kg P haÿ1 was bene®cial for more soil water storage
and increased yield of sorghum by 7% over FYM at 5 Mg haÿ1 40 kg N haÿ1 and 9 kg P haÿ1. In Vertisols (Vertic
Cambisols), experiments were conducted for two years (1991±1992 and 1992±1993) to evaluate land con®guration practices.
The treatments were broad bed furrow (BBF, 120 cm wide bed with 30 cm wide and 15 cm deep furrows on both sides),
compartmental bunding (CB, bunds of 15 cm height formed in all the four sides to form a check basin of 6 m 5 m size),
ridging (RD, ridges were formed for each and every row of the crop manually at four weeks after sowing) and FB under
sorghum pigeonpea (Cajanus cajan (L.) Millsp) and pearl millet (Pennisetum glacum (L.) Stuntz) cowpea (Vigna
unguiculata (L.) Walp) intercropping separately. Compartmental bunding stored 22% more soil moisture and increased the
yield of sorghum pigeonpea intercropping than did FB in a low rainfall year. In a high rainfall year, BBF produced 34% and
33% more grain yield of sorghum and pearl millet base crops, respectively, over FB. However, BBF and CB were comparable.
Pigeonpea intercrop under sorghum followed the same trend as its base crop, whereas, yield of cowpea differed compared to
the pearl millet base crop. Tied ridging and application of manures (CD or FYM) in combination with inorganic N and P
fertiliser can increase the soil water storage and yield of crops compared to traditional ¯at bed cultivation in rainfed Al®sol
and related soils of semi-arid tropics. Similarly BBF and CB land con®guration practices could be adopted on Vertisols for
*
Corresponding author. Tel.: 91-422431222; fax: 91-422430657
E-mail address: agronomy@tnau.kovai.tn.nic.in (R. Selvaraju)
0167-1987/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 7 - 1 9 8 7 ( 9 9 ) 0 0 0 8 3 - 5
204
R. Selvaraju et al. / Soil & Tillage Research 52 (1999) 203±216
better water conservation to increase the soil fertility and productivity of intercropping systems. # 1999 Elsevier Science B.V.
All rights reserved.
Keywords: Land con®guration; Manures; Fertiliser levels; Al®sol; Vertisol
1. Introduction
The predominant soils of semi-arid tropics (SAT) of
peninsular India are Al®sols and Vertisols (Murthy et
al., 1981). Despite their importance in food production
for growing populations of this region, productivity of
these soils has remained low and unstable owing to
climate and soil-related constraints.
Al®sols often have shallow effective rooting depth,
low water holding capacity, and thus, can traditionally
support one crop grown as a monoculture, particularly
under rainfed situations. Accelerated runoff and soil
erosion (Sharma et al., 1988), surface sealing and
crusting (Mullins et al., 1990), low soil organic carbon
content, and low inherent soil fertility (Das et al.,
1991) are among major factors responsible for low
crop yields from these soils. Surface con®guration,
such as tied ridges, have been used to trap runoff when
rainfall exceeds in®ltration (Hulugalle, 1990) in
drought-prone shallow soils of the West African Sahel.
Ridges are advantageous on some nutrient de®cient
soils in Savannah region of Nigeria to concentrate the
fertile top soil and to conserve water (Lal, 1995).
However, on similar soils in India, Ali and Prasad
(1974) reported no bene®cial effects of ridging either
on water conservation or on grain yield of pearl millet.
Moreover, high rates of runoff and erosion, poor
germination and emergence (because of low soil water
contents and high incidence of surface sealing) caused
low yields in Al®sols (Singh and Subba Reddy, 1988).
Field studies have shown that application of farm yard
manure (FYM) increases soil water content, seedling
emergence (Joshi, 1987), soil organic matter content,
and yield of pearl millet, cotton (Gossypium hirsutum
L.) (Gupta et al., 1984) and sorghum (Cogle et al.,
1997).
Coir dust, a by-product from coconut (Cocos nucifera L.) coir industries obtained as a waste after the
extraction of coir from the husk is used for increasing
the yield of crops and for enhancing the water retentivity and water availability of Al®sols (Raniperumal
et al., 1991). Application of coir dust at 12.5 Mg haÿ1
enhanced the grain yield of sorghum by 38% over
control (Ramasamy and Sreeramulu, 1983). Gupta and
Abrol (1993) reported that chiseling of a red sandy
loam along with mixing of coir dust at 10 Mg haÿ1
increased the groundnut (Arachis hypogaea L.) pod
yield. Similarly, use of organic mulches and manures
signi®cantly increased soil water reserves and crop
yields in low fertility Al®sols (Durgude et al., 1996).
Raghuwanshi and Rajivumat (1994) reported advantages of application of FYM with inorganic nitrogen
(N) and phosphorus (P) on sorghum yield. Therefore,
soil management in dryland cropping for Al®sols
should aim to ensure that soil physical properties at
the start of the wet season favour effective water entry
and storage, easy seed bed preparation, and low risk
crop establishment (Smith et al., 1992).
Vertisols are potentially productive soils within the
semi-arid tropics of peninsular India. These soils have
high water holding capacity and traditionally intercropping is practised during the north-east monsoon
(October±December) season (Selvaraju and Ramaswami, 1997) to reduce the risk of crop failure. Major
soil-related constraints in Vertisols include low water
in®ltration, high incidence of inundation, accelerated
runoff and soil erosion during high rainfall year, and
drought stress during the low rainfall year. Consequently, crop yields on Vertisols using traditional
systems of management are low (Lal, 1995). Vertisols
of the semi-arid tropics in India, however, have a fairly
high potential for crop production when improved soil
and water conservation practices are adopted for
alleviating soil-related constraints (Sivakumar et al.,
1992).
Experiments have been conducted in central India
(CRIDA, 1983) on land con®guration practices in an
effort to conserve more rainfall for stabilising crop
yields. These experiments have documented the
advantages of broad bed and furrow systems for soil
water conservation (ICRISAT, 1981) and increasing
crop yields (Bhatawadekar, 1985). Reddy et al. (1992)
observed that sowing of crops on a grade and ridging
later consistently increased soil water content and crop
R. Selvaraju et al. / Soil & Tillage Research 52 (1999) 203±216
yield. Similarly compartmental bunding produced a
higher grain yield of pearl millet (CRIDA, 1983)
compared with that of the ¯at bed method of sowing.
On the other hand, experiments conducted at ICRISAT
(1982) showed no distinct yield advantage caused by
land con®guration adopted during the cropping season. In some Vertisols of south central India, no
difference in grain yield of sorghum was observed
with compartmental bunding and ridging over traditional ¯at bed cultivation (CRIDA, 1990).
A review of literature on management of Vertisols
suggests that land con®guration practices reduce the
risk of crop failure only in certain situations. Yet, crop
production effects of these practices have not been
investigated for most commonly practised intercropping systems of the region. Most of the experiments
conducted have been limited to a few ecoregions, and
have focused primarily on monocultures.
The objectives of this work were to: (1) determine
the effect of land con®guration and nutrient management practices on soil water content and yield of
rainfed sorghum in Al®sols, and (2) evaluate the
effectiveness of land con®guration practices on soil
205
water content, soil fertility, crop establishment,
growth and yield of sorghum pigeonpea and pearl
millet cowpea intercropping systems in Vertisols.
2. Materials and methods
2.1. Climate and crops
Field experiments were conducted at Coimbatore,
India (118N latitude and 778E longitude). The mean
annual rainfall (83 years) at Coimbatore is 648 mm
distributed over about 50 rainy days with a 30% annual
coef®cient of variation. The traditional dryland cropping period is either from the third week of September
or from October to January (Fig. 1). The rainfall is of
the monsoon type, with a south-west monsoon from
June to September and a north-east monsoon from
October to December. The annual mean maximum
and minimum temperatures are 31.58C and 21.28C,
respectively. The region is characterised as semi-arid
tropics (SAT) climate (Sehgal et al., 1992). Long-term
mean rainfall and rainfall during the study period for
Coimbatore are given in Table 1. Two predominant
Fig. 1. Mean monthly rainfall and evaporation during the cropping season at Coimbatore in southern peninsular Indian drylands.
206
R. Selvaraju et al. / Soil & Tillage Research 52 (1999) 203±216
Table 1
Long-term mean monthly temperature and rainfall and rainfall during the study period at Coimbatore, India
Month
September
October
November
December
January
Long-term mean
Rain in study period (mm)
Max. temp. (8C)
Min. temp. (8C)
Rainfall (mm)
1989±1990
1990±1991
30.7
30.4
29.3
28.9
31.1
22.0
22.0
21.1
19.6
21.7
68.0
146.0
118.0
41.4
14.0
57.3
213.1
67.8
18.1
28.7
63.2
136.9
93.7
7.0
27.4
29.6
81.5
26.1
1.0
0
154.7
87.1
306.6
8.1
0
387.4
385.0
328.2
138.2
556.5
Total
soils of the region are Al®sols and Vertisols, which
occur side by side. Sorghum and pearl millet are
usually intercropped with pulses under dryland conditions during the north-east monsoon season in Vertisols, while sorghum monoculture is the predominant
system in Al®sols. Groundnut and cotton are also
grown on Al®sols and Vertisols, respectively.
2.2. Experiment I (Alfisol)
2.2.1. Site and soil characteristics
Experiment I was conducted over four years (1989±
1990 and 1992±1993) at the Millet Breeding Station of
Tamil Nadu Agricultural University. The soil, a red
sandy loam (Al®sol) with 1±2% slope, is classi®ed as
®ne, mixed isohyperthermic Typic Haplustalf in soil
taxonomy (Soil Survey Staff, 1992) and Chromic
Cambisol in FAO (FAO, 1993) soil classi®cation.
The top 15 cm of surface soil had a pH of 7.3, cation
exchange capacity of 18 cmol () kgÿ1 and concentration of organic carbon of 4.0 g kgÿ1. The surface
soil (0±15 cm) consisted of 660 g kgÿ1 sand, 110 g
kgÿ1 silt, 230 g kgÿ1 clay, a bulk density of 1.55 Mg
mÿ3, porosity of 41.5 m3 100 mÿ3 and hydraulic
conductivity of 2.89 10ÿ5 m sÿ1. The site was continuously cropped either with sorghum or pearl millet
every year.
2.2.2. Experimental set-up and management
The experiment was established as a split-plot
design with four treatments and three replications.
Flat bed (FB), open ridging (OR), and random tie
ridging (TR) were the main plot treatments. The
subplot treatments, comprising organic manures and
N and P levels, were: (1) farm yard manure (FYM) at
5 Mg haÿ1 40 kg N and 9 kg P haÿ1 (FYM
1991±1992
1992±1993
N40P9), (2) FYM 5.0 Mg haÿ1 20 kg N and 4.5 kg
P haÿ1 (FYM N20P4.5), (3) coir dust (CD) at
12.5 Mg haÿ1 40 kg N and 9 kg P haÿ1 (CD
N40P9), and (4) coir dust (CD) at 12.5 Mg haÿ1
20 kg N and 4.5 kg P haÿ1 (CD N20P4.5).
Before the crop was sown, the experimental ®eld
was uniformly ploughed once with a mouldboard
plough (25 cm) and then harrowed twice (12 cm) with
a nine tine cultivator. The FB treatment did not receive
any land con®guration practice. Ridges were made
using a bullock drawn ridger, 45 cm apart and about
30 cm high for the OR treatment. In addition, TR
involved building ties manually at random to create a
series of basins for soil water conservation. Required
quantities of CD and FYM as per the treatments were
applied uniformly on the soil surface before sowing
and not incorporated, which acted as both surface
mulch as and organic manures. The farm yard manure
(FYM) contained 37 kg N haÿ1, 17.5 kg P haÿ1 and
78 kg K haÿ1, and the CD contained 34 kg N haÿ1,
12.5 kg P haÿ1 and 94 kg K haÿ1. Sorghum variety
(CO-26), was sown every year during the third week of
September. Seeds were sown by hand in lines at
double the desired plant population. Approximately
20 days after planting, seedlings were thinned to give
the desired plant population of 148 103 plants haÿ1.
The individual plot size was 7.2 m 6 m with 1.5 m
margins on both sides to curtail run-on to adjacent
plots. The plots received variable N and P as per the
treatment schedule, through urea (46% N) and single
superphosphate (7% P) respectively. Fertiliser was
placed in the seed row and covered with soil. The
N fertiliser was applied in two splits, 50% at seeding
and remaining 50% four weeks later, and the entire P
was applied at seeding. All plots were weeded manually once at 4±6 weeks after seeding.
R. Selvaraju et al. / Soil & Tillage Research 52 (1999) 203±216
2.2.3. Data collection and analysis
Soil water content was estimated in two depths
(0±15 and 15±30 cm) gravimetrically using ®ve soil
sub samples taken per treatment on 30 and 90 days
after sowing (DAS) in 1991±1992 and 1992±1993
cropping seasons, respectively. Grain and straw yields
were determined at maturity from the entire plot. The
data on soil water content, sorghum grain and straw
yields were subjected to analysis of variance
(ANOVA) and statistical signi®cance was expressed
as an LSD (least signi®cant difference) test (Gomez
and Gomez, 1984).
2.3. Experiment II (Vertisol)
2.3.1. Site and soil characteristics
The site of Experiment II was the eastern block
of Tamil Nadu Agricultural University Farm, about
a km (1000 m) away from the site for Experiment I.
The soil at the site is a medium deep black soil
(Vertisol) with a sandy clay loam texture (342 g kgÿ1
clay (
Land con®guration and soil nutrient management options
for sustainable crop production on Al®sols and
Vertisols of southern peninsular India
R. Selvarajua,*, P. Subbiana, A. Balasubramaniana, R. Lalb
a
Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore 641 003, Tamil Nadu, India
b
School of Natural Resources, Ohio State University, Columbus, OH, USA
Received 16 June 1998; received in revised form 12 January 1999; accepted 24 August 1999
Abstract
Land con®guration in combination with nutrient management has the potential to improve the productivity of Al®sols and
Vertisols in the semi-arid tropics. A four year (1989±1990 and 1992±1993) ®eld experiment was conducted at Coimbatore,
India on Al®sols (Chromic Cambisol) to compare the effect of land con®guration and nutrient management practices on yield
of rainfed sorghum (Sorghum bicolor (L.) Moench). The land con®guration treatments were ¯at bed (FB, the traditional
practice), open ridging (OR, ridges, 45 cm apart and 30 cm high) and tied ridging (TR, same as OR plus ridges were tied
randomly). The manure and fertilisers were farm yard manure (FYM, livestock excreta plus litter at 5 Mg haÿ1) and coir dust
(CD, by-product after the extraction of coir from the coconut (Cocos nucifera L.) husk at 12.5 Mg haÿ1) in combination with
nitrogen (N) and phosphorus (P) fertiliser levels. Tied ridges stored 14% more soil water and produced 14% and 11% more
grain and straw yields of sorghum, respectively, than did ¯at bed. However, crop yield in TR was comparable with OR.
Application of CD at 12.5 Mg haÿ1 combined with 40 kg N haÿ1 and 9 kg P haÿ1 was bene®cial for more soil water storage
and increased yield of sorghum by 7% over FYM at 5 Mg haÿ1 40 kg N haÿ1 and 9 kg P haÿ1. In Vertisols (Vertic
Cambisols), experiments were conducted for two years (1991±1992 and 1992±1993) to evaluate land con®guration practices.
The treatments were broad bed furrow (BBF, 120 cm wide bed with 30 cm wide and 15 cm deep furrows on both sides),
compartmental bunding (CB, bunds of 15 cm height formed in all the four sides to form a check basin of 6 m 5 m size),
ridging (RD, ridges were formed for each and every row of the crop manually at four weeks after sowing) and FB under
sorghum pigeonpea (Cajanus cajan (L.) Millsp) and pearl millet (Pennisetum glacum (L.) Stuntz) cowpea (Vigna
unguiculata (L.) Walp) intercropping separately. Compartmental bunding stored 22% more soil moisture and increased the
yield of sorghum pigeonpea intercropping than did FB in a low rainfall year. In a high rainfall year, BBF produced 34% and
33% more grain yield of sorghum and pearl millet base crops, respectively, over FB. However, BBF and CB were comparable.
Pigeonpea intercrop under sorghum followed the same trend as its base crop, whereas, yield of cowpea differed compared to
the pearl millet base crop. Tied ridging and application of manures (CD or FYM) in combination with inorganic N and P
fertiliser can increase the soil water storage and yield of crops compared to traditional ¯at bed cultivation in rainfed Al®sol
and related soils of semi-arid tropics. Similarly BBF and CB land con®guration practices could be adopted on Vertisols for
*
Corresponding author. Tel.: 91-422431222; fax: 91-422430657
E-mail address: agronomy@tnau.kovai.tn.nic.in (R. Selvaraju)
0167-1987/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 7 - 1 9 8 7 ( 9 9 ) 0 0 0 8 3 - 5
204
R. Selvaraju et al. / Soil & Tillage Research 52 (1999) 203±216
better water conservation to increase the soil fertility and productivity of intercropping systems. # 1999 Elsevier Science B.V.
All rights reserved.
Keywords: Land con®guration; Manures; Fertiliser levels; Al®sol; Vertisol
1. Introduction
The predominant soils of semi-arid tropics (SAT) of
peninsular India are Al®sols and Vertisols (Murthy et
al., 1981). Despite their importance in food production
for growing populations of this region, productivity of
these soils has remained low and unstable owing to
climate and soil-related constraints.
Al®sols often have shallow effective rooting depth,
low water holding capacity, and thus, can traditionally
support one crop grown as a monoculture, particularly
under rainfed situations. Accelerated runoff and soil
erosion (Sharma et al., 1988), surface sealing and
crusting (Mullins et al., 1990), low soil organic carbon
content, and low inherent soil fertility (Das et al.,
1991) are among major factors responsible for low
crop yields from these soils. Surface con®guration,
such as tied ridges, have been used to trap runoff when
rainfall exceeds in®ltration (Hulugalle, 1990) in
drought-prone shallow soils of the West African Sahel.
Ridges are advantageous on some nutrient de®cient
soils in Savannah region of Nigeria to concentrate the
fertile top soil and to conserve water (Lal, 1995).
However, on similar soils in India, Ali and Prasad
(1974) reported no bene®cial effects of ridging either
on water conservation or on grain yield of pearl millet.
Moreover, high rates of runoff and erosion, poor
germination and emergence (because of low soil water
contents and high incidence of surface sealing) caused
low yields in Al®sols (Singh and Subba Reddy, 1988).
Field studies have shown that application of farm yard
manure (FYM) increases soil water content, seedling
emergence (Joshi, 1987), soil organic matter content,
and yield of pearl millet, cotton (Gossypium hirsutum
L.) (Gupta et al., 1984) and sorghum (Cogle et al.,
1997).
Coir dust, a by-product from coconut (Cocos nucifera L.) coir industries obtained as a waste after the
extraction of coir from the husk is used for increasing
the yield of crops and for enhancing the water retentivity and water availability of Al®sols (Raniperumal
et al., 1991). Application of coir dust at 12.5 Mg haÿ1
enhanced the grain yield of sorghum by 38% over
control (Ramasamy and Sreeramulu, 1983). Gupta and
Abrol (1993) reported that chiseling of a red sandy
loam along with mixing of coir dust at 10 Mg haÿ1
increased the groundnut (Arachis hypogaea L.) pod
yield. Similarly, use of organic mulches and manures
signi®cantly increased soil water reserves and crop
yields in low fertility Al®sols (Durgude et al., 1996).
Raghuwanshi and Rajivumat (1994) reported advantages of application of FYM with inorganic nitrogen
(N) and phosphorus (P) on sorghum yield. Therefore,
soil management in dryland cropping for Al®sols
should aim to ensure that soil physical properties at
the start of the wet season favour effective water entry
and storage, easy seed bed preparation, and low risk
crop establishment (Smith et al., 1992).
Vertisols are potentially productive soils within the
semi-arid tropics of peninsular India. These soils have
high water holding capacity and traditionally intercropping is practised during the north-east monsoon
(October±December) season (Selvaraju and Ramaswami, 1997) to reduce the risk of crop failure. Major
soil-related constraints in Vertisols include low water
in®ltration, high incidence of inundation, accelerated
runoff and soil erosion during high rainfall year, and
drought stress during the low rainfall year. Consequently, crop yields on Vertisols using traditional
systems of management are low (Lal, 1995). Vertisols
of the semi-arid tropics in India, however, have a fairly
high potential for crop production when improved soil
and water conservation practices are adopted for
alleviating soil-related constraints (Sivakumar et al.,
1992).
Experiments have been conducted in central India
(CRIDA, 1983) on land con®guration practices in an
effort to conserve more rainfall for stabilising crop
yields. These experiments have documented the
advantages of broad bed and furrow systems for soil
water conservation (ICRISAT, 1981) and increasing
crop yields (Bhatawadekar, 1985). Reddy et al. (1992)
observed that sowing of crops on a grade and ridging
later consistently increased soil water content and crop
R. Selvaraju et al. / Soil & Tillage Research 52 (1999) 203±216
yield. Similarly compartmental bunding produced a
higher grain yield of pearl millet (CRIDA, 1983)
compared with that of the ¯at bed method of sowing.
On the other hand, experiments conducted at ICRISAT
(1982) showed no distinct yield advantage caused by
land con®guration adopted during the cropping season. In some Vertisols of south central India, no
difference in grain yield of sorghum was observed
with compartmental bunding and ridging over traditional ¯at bed cultivation (CRIDA, 1990).
A review of literature on management of Vertisols
suggests that land con®guration practices reduce the
risk of crop failure only in certain situations. Yet, crop
production effects of these practices have not been
investigated for most commonly practised intercropping systems of the region. Most of the experiments
conducted have been limited to a few ecoregions, and
have focused primarily on monocultures.
The objectives of this work were to: (1) determine
the effect of land con®guration and nutrient management practices on soil water content and yield of
rainfed sorghum in Al®sols, and (2) evaluate the
effectiveness of land con®guration practices on soil
205
water content, soil fertility, crop establishment,
growth and yield of sorghum pigeonpea and pearl
millet cowpea intercropping systems in Vertisols.
2. Materials and methods
2.1. Climate and crops
Field experiments were conducted at Coimbatore,
India (118N latitude and 778E longitude). The mean
annual rainfall (83 years) at Coimbatore is 648 mm
distributed over about 50 rainy days with a 30% annual
coef®cient of variation. The traditional dryland cropping period is either from the third week of September
or from October to January (Fig. 1). The rainfall is of
the monsoon type, with a south-west monsoon from
June to September and a north-east monsoon from
October to December. The annual mean maximum
and minimum temperatures are 31.58C and 21.28C,
respectively. The region is characterised as semi-arid
tropics (SAT) climate (Sehgal et al., 1992). Long-term
mean rainfall and rainfall during the study period for
Coimbatore are given in Table 1. Two predominant
Fig. 1. Mean monthly rainfall and evaporation during the cropping season at Coimbatore in southern peninsular Indian drylands.
206
R. Selvaraju et al. / Soil & Tillage Research 52 (1999) 203±216
Table 1
Long-term mean monthly temperature and rainfall and rainfall during the study period at Coimbatore, India
Month
September
October
November
December
January
Long-term mean
Rain in study period (mm)
Max. temp. (8C)
Min. temp. (8C)
Rainfall (mm)
1989±1990
1990±1991
30.7
30.4
29.3
28.9
31.1
22.0
22.0
21.1
19.6
21.7
68.0
146.0
118.0
41.4
14.0
57.3
213.1
67.8
18.1
28.7
63.2
136.9
93.7
7.0
27.4
29.6
81.5
26.1
1.0
0
154.7
87.1
306.6
8.1
0
387.4
385.0
328.2
138.2
556.5
Total
soils of the region are Al®sols and Vertisols, which
occur side by side. Sorghum and pearl millet are
usually intercropped with pulses under dryland conditions during the north-east monsoon season in Vertisols, while sorghum monoculture is the predominant
system in Al®sols. Groundnut and cotton are also
grown on Al®sols and Vertisols, respectively.
2.2. Experiment I (Alfisol)
2.2.1. Site and soil characteristics
Experiment I was conducted over four years (1989±
1990 and 1992±1993) at the Millet Breeding Station of
Tamil Nadu Agricultural University. The soil, a red
sandy loam (Al®sol) with 1±2% slope, is classi®ed as
®ne, mixed isohyperthermic Typic Haplustalf in soil
taxonomy (Soil Survey Staff, 1992) and Chromic
Cambisol in FAO (FAO, 1993) soil classi®cation.
The top 15 cm of surface soil had a pH of 7.3, cation
exchange capacity of 18 cmol () kgÿ1 and concentration of organic carbon of 4.0 g kgÿ1. The surface
soil (0±15 cm) consisted of 660 g kgÿ1 sand, 110 g
kgÿ1 silt, 230 g kgÿ1 clay, a bulk density of 1.55 Mg
mÿ3, porosity of 41.5 m3 100 mÿ3 and hydraulic
conductivity of 2.89 10ÿ5 m sÿ1. The site was continuously cropped either with sorghum or pearl millet
every year.
2.2.2. Experimental set-up and management
The experiment was established as a split-plot
design with four treatments and three replications.
Flat bed (FB), open ridging (OR), and random tie
ridging (TR) were the main plot treatments. The
subplot treatments, comprising organic manures and
N and P levels, were: (1) farm yard manure (FYM) at
5 Mg haÿ1 40 kg N and 9 kg P haÿ1 (FYM
1991±1992
1992±1993
N40P9), (2) FYM 5.0 Mg haÿ1 20 kg N and 4.5 kg
P haÿ1 (FYM N20P4.5), (3) coir dust (CD) at
12.5 Mg haÿ1 40 kg N and 9 kg P haÿ1 (CD
N40P9), and (4) coir dust (CD) at 12.5 Mg haÿ1
20 kg N and 4.5 kg P haÿ1 (CD N20P4.5).
Before the crop was sown, the experimental ®eld
was uniformly ploughed once with a mouldboard
plough (25 cm) and then harrowed twice (12 cm) with
a nine tine cultivator. The FB treatment did not receive
any land con®guration practice. Ridges were made
using a bullock drawn ridger, 45 cm apart and about
30 cm high for the OR treatment. In addition, TR
involved building ties manually at random to create a
series of basins for soil water conservation. Required
quantities of CD and FYM as per the treatments were
applied uniformly on the soil surface before sowing
and not incorporated, which acted as both surface
mulch as and organic manures. The farm yard manure
(FYM) contained 37 kg N haÿ1, 17.5 kg P haÿ1 and
78 kg K haÿ1, and the CD contained 34 kg N haÿ1,
12.5 kg P haÿ1 and 94 kg K haÿ1. Sorghum variety
(CO-26), was sown every year during the third week of
September. Seeds were sown by hand in lines at
double the desired plant population. Approximately
20 days after planting, seedlings were thinned to give
the desired plant population of 148 103 plants haÿ1.
The individual plot size was 7.2 m 6 m with 1.5 m
margins on both sides to curtail run-on to adjacent
plots. The plots received variable N and P as per the
treatment schedule, through urea (46% N) and single
superphosphate (7% P) respectively. Fertiliser was
placed in the seed row and covered with soil. The
N fertiliser was applied in two splits, 50% at seeding
and remaining 50% four weeks later, and the entire P
was applied at seeding. All plots were weeded manually once at 4±6 weeks after seeding.
R. Selvaraju et al. / Soil & Tillage Research 52 (1999) 203±216
2.2.3. Data collection and analysis
Soil water content was estimated in two depths
(0±15 and 15±30 cm) gravimetrically using ®ve soil
sub samples taken per treatment on 30 and 90 days
after sowing (DAS) in 1991±1992 and 1992±1993
cropping seasons, respectively. Grain and straw yields
were determined at maturity from the entire plot. The
data on soil water content, sorghum grain and straw
yields were subjected to analysis of variance
(ANOVA) and statistical signi®cance was expressed
as an LSD (least signi®cant difference) test (Gomez
and Gomez, 1984).
2.3. Experiment II (Vertisol)
2.3.1. Site and soil characteristics
The site of Experiment II was the eastern block
of Tamil Nadu Agricultural University Farm, about
a km (1000 m) away from the site for Experiment I.
The soil at the site is a medium deep black soil
(Vertisol) with a sandy clay loam texture (342 g kgÿ1
clay (