Soil Physical Constraints and their Management

1. SOIL PHYSICAL CONSTRAINTS AND THEIR MANAGEMENT
Tamil Nadu state with an area of 1,29,951 Sq.Km. lies at 8 0 5' and 130 40' North
latitude and 760 15' and 800 70' East longitude, with a warm climate and located in the east of the
Western ghat and has a gradual slope to the east extending upto the low hills of the Eastern ghats.
Physiographically it is divided into (i) The Coastal plain (ii) the Eastern ghat (iii) The plateau area
and (iv) The Western ghat.
The coastal plain stretches about 992 Km. from Pulicate lake to Cape Comerin with
three sub regions viz., the Northern plain, the Cauvery delta zone and the Southern plain. It is
about 86 to 96 Km. wide with an average elevation of 80 m. The Northern plain comprises of
Chingleput , a major part of South Arcot, the eastern part of North Arcot and Northern part of
Trichi districts. The Cauvery delta zone consists of Tanjore and part of Trichi, where as the
Southern Coastal plain is shared by Ramnad, Thirunelveli and Kanyakumari districts.
The Eastern ghat area between the rivers of Palar and Cauvery and the Coastal plain is
balked by discontinuous lines of hills, the Javed, Sherveroys, Kalrayon, Pachaimalai and Kolli
malai. North of the Palar river, smaller or even more broken hills are linked with the tails of
Guddapah in the Nagari hills. Across the Cauvery, further detached leads on to the long
Varashanad, Audipatty range and then to Cardomam hills. This line of discontinuous hills are
known as The Eastern ghat.
The area between the Eastern and Western ghat lies the Plateau area with elevation
ranging from 170 to 650 metres. Hence the topography is undulating. The Plateau is fringed on
the west by a group of hills known as Western ghats. On either side of the Palghat gap, the
highest mountains of the Peninsula dominates. They are the Nilgiris in the north and the Anamalai,
Palani and Cardomam hills in the south.
Soils of Tamil Nadu
The soil of Tamil Nadu are highly heterogeneous having different parent materials of
metamorphic, sedimentary, acid igneous rocks rich in soda lime feldspars, amphiboles and
pyroxenes of gnessic rocks, chernochites and sand stones. Thus it endowed with the collection of
five major soil order viz., Alfisol, Entisol, Vertisol, Inceptisol and Ultisol. Therefore it opens
avenue to carry out diversified research on physico chemical properties and also biophysical
1

2. properties at greater length and breadth. The total geographical area of Tamil Nadu is about 13
m.ha, out of which 8 m ha of the soils are of red in nature, 2 m.ha alluvial, 2 m.ha black and the
rest lateritic. Because of the diversified nature, characterised by their different origin, location and
soil forming processes, these soils are found to possess various types of soil constraints.
The plant nutrient availability in soil is a measure of soil fertility, while the soil physical
environment is the kingpin which regulate the retention and movement of soil moisture, soil
aeration, soil nutrient movement, soil temperature, seed germination, seedling establishment, root
penetration and proliferation etc. Hence, soil physical environment directly and indirectly controls
all the other factors influencing the plant growth and in turn the production potential of the crop.
Recently, under the fold of Integrated Nutrient Management technique, organic and
Integrated Farming System, an attempt has been made to increase the crop production under
rationalised plant nutrient management, where the management of physical condition plays a
pivotal role. Besides by ameliorating certain physical constraints existing in the marginal and
submarginal lands, it would be easier to enhance the production potential of the crop in an unit
area. Knowingly or unknowingly, the poor soil management, unexpected natural calamities often
affect the soil environment and arrest its productivity. By judicious application of all the required
plant nutrients at times fail to yield good results. It might be due to unforeseen weather conditions
like heavy rain, stagnation of water, long dry spell or continuous cultivation which finally affects
the physical environment like infiltration, moisture retention and transmission, soil compaction and
aggregation leads to soil physical constraints constantly.
The most frequently occurring soil physical constraints in the state of Tamil Nadu are
excessive permeable soils, sub soil hardpan soils, slow permeable soils, fluffy paddy soil, surface
crusting and shallow soils. The nature and extent of the soil physical constraints in the soils of
Tamil Nadu are not delineated by the staff of Soil Survey and Land Use Planning and hence, one
of the major objectives of the AICRP on "Tillage Requirements of Major Indian Soils under
Different Cropping Systems" is to characterise the major soil series of Tamil Nadu for their
physical constraints. In Tamil Nadu, so far six districts viz., Coimbatore, Salem, Dharmapuri,
Trichi, Madurai and North Arcot were surveyed for identifying the areas having soil physical
constraints and suitable technologies were developed and test verified in farmer's holdings
continuously for more than three years. The following are the major soil physical problems
commonly met with in Tamil Nadu.
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3. Table 1 Delineation of physical constraints in the soils of Tamil Nadu state
Soil series Area in Problems
sq.km. Identified Per cent
Coimbatore district
Peelamedu
Dasarapatty
Perianaicken 739 Slow permeable 4.69
palayam soils
Irugur
Palladam 6,519 Excessively
Vannapatty permeable soils 41.82
Tulukkanur 1,320 High sub soil
Pichanur bulk density 8.46
Dharmapuri
Dharmapuri
Nattam Slow permeable
Hosur 526 soils 5.47
Vannapatty 3,774 Excessively 39.24
permeable soils
Trichi
Irugur
Tulukkanur
Palladam 2,800 Excessively 32.00
Vannapatty permeable soils
Peelamedu
Kallakudi
Poovalur 1,243 Slow permeable 14.20
Mudukulam soils
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4. Soil series Area in Problems
sq.km. Identified Per cent
Madurai district
Anaiyur Subsoil
Madukkur 2,450 compaction 30.0
Irugur 1,837 Excessively 22.5
Palladam permeable soils
Salem district
Irugur
Mallasamudram Excessively
Mallur 1,845 permeable soils 21.35
Peelamedu 420 Slow permeable 4.85
soils
Vellalur 209 Shallow soils 2.45
North Arcot district
Udic Haplustalf 1,448 Sub soil 17.61
Typic Rhodustalf hardpan
Typic Ustifluent 524 Excessive 6.37
permeable soils
Typic Ustorthents 384 Shallow soils 4.67
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5. The consolidated survey report of the Tamil Nadu is presented in Table 2.
Table 2 Extent of soil physical constraints in Tamil Nadu
Total Geographical Area = 130 lakh ha.
Districts Area Excessive Slow Subsoil Shallow
permeable permeable hardpan soils
soils soils soils
Coimbatore 15.8 6.5 0.7 1.3 -
Dharmapuri 9.6 3.8 0.5 - -
Trichi 8.8 2.8 1.2 - -
Madurai 8.2 1.8 - 2.5 -
Salem 8.6 1.8 0.4 - 0.2
North Arcot 8.2 0.5 - 1.5 0.4
Total 59.2 17.2 2.8 5.3 0.6
% surveyed 45.5
% to surveyed area 29.3 5.0 8.8 1.0
The common soil physical constraints often encountered in Tamil Nadu are
• Sub soil hard pan
• Excessive permeability
• Surface soil crusting
• Fluffy paddy soils
• Slow permeability
Out of the total area of the state (130 lakh ha.) 45.5 per cent was surveyed out of
which, 29.3 percent of the surveyed area was found to possess excessive permeability, 5.0 per cent
slow permeability, 8.8 per cent sub soil hard pan and 1.0 per cent are shallow soils. The results
also indicated that the most of the soil physical constraints viz., the excessive permeability, sub
soil hardpan and shallow soils, which are associated with red soils, are predominant in the soils of
Tamil Nadu owing to the fact that about 60 per cent of the soils of Tamil Nadu belong to this
category. The characteristics of the soils possessing soil physical constraints, extent and their
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6. management practices are briefly discussed here under:
Excessive permeable soils
Excessive permeable soils are those having high amount of sand exceeding 70 per cent.
Due to this, the soil is inert and unable to retain water and nutrients. These soils being devoid of
finer particles and organic matter, the aggregates are weakly formed, the non-capillary pores
dominating with very poor soil structure. Due to low retention capacity of the soils, the fertilizer
nutrients are also lost in the drainage water.
The excessive permeable soils are spread over 6,519 sq.km in Coimbatore, 3,774
sq.km in Dharmapuri, 2,800 sq.km in Trichi, 1,837 sq.km in Madurai, 1,845 sq.km in Salem and
524 sq.km in North Arcot districts. The excessive permeable soils can be managed by adopting
the techniques given below:
• Compacting the field with 400 kg stone roller (tar drum filled with 400 kg of sand or stone can
also be used) 8 - 10 times at optimum moisture conditions.
• Application of clay soil (Soil Breeding) up to a level 100 t ha-1 based on the severity of the
problem and availability of the clay material.
• Application of organic materials like farm yard manure, compost, press mud, sugar factory
slurry, composted coir pith, sewage sludge etc.
• Providing asphalt sheet, polythene sheet etc., below the soil surface to reduce the infiltration
rate.
• Crop rotation with green manure crops like Sunnhemp, Sesbania, Daincha, Kolinchi etc.
Sub soil hard pan
The sub soil hard pan in red soil is due to the illuviation of clay to the sub soil horizon
coupled with cementing action of oxides of iron, aluminum and calcium carbonate, which
increases the soil bulk density to more than 1.8 Mg m-3. Further, the hard pan can also develop
due to continuous cultivation of crops using heavy implements upto certain depth constantly.
Besides, the higher exchangeable sodium content of clay complex in black soil areas also resulted
in compactness of the sub soil. All put together lowered the infiltration and percolation rates,
nutrients movement and free air transport within the soil profile. It prevents the root proliferation
and limits the volume of soil available for nutrient uptake resulting in depleted, less fertile surface
soil. Due to this, the contribution of sub soil fertility to crop growth is hampered.
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7. The sub soil hard pan areas are found in 1,320 sq.km in Coimbatore, 2,450 sq.km in
Madurai and 1,448 sq.km in North Arcot districts. Depending upon the depth of occurrence of
hard pan, the management practices are to be adopted. Hence for soils having sub soil hard pan at
shallow depth, the following technologies could be adopted.
• Ploughing the soil with chisel plough at 0.5 m interval criss cross at 0.5 m depth once in 2-3
years.
• Application of organics to improve the aggregation and soil structure so as to prevent further
movement of clay to the lower layers.
• Deep ploughing of the field during summer season to open up the sub soil.
• Cultivating deep rooted crops like tapioca and Cotton so as to encourage natural breaking of
the hard pan.
• Raising deep rooted semi perennial crops like mulberry, jasmine match wood tree etc., can also
help in opening up the sub soil hard pan.
Slow permeable soils
Slow permeable soils are those soils having infiltration rates ranging from less than 6 cm
per day due to high clay content of the soil. Due to low infiltration rates, the amount of water
entering the soil profile is reduced thus increasing the run-off. Further, it encourages erosion of
surface soil leading to nutrient removal in the running water. More over, due to heavy clay
content, the capillary porosity is relatively high resulting in impeded drainage and reduced soil
conditions. This leads to increase of some soil elements to the level of toxicity to the plants. It
also induces nutrient fixation in the clay complex thereby making the nutrient becoming unavail-
able to the crop, eventually causing deficiency of nutrients.
The results of the work carried out in the scheme had indicated that the slow permeable
soils extended over an area of 739 sq.km in Coimbatore, 526 sq.km in Dharmapuri , 1243 sq.km in
Trichi and 420 sq.km in Salem districts. The constraints in such soils can be managed by adopting
suitable management practices like,
• Provision of drainage facilities either through open drains or closed sub surface drains.
• Forming contour bunding and compartmental bunding to increase the infiltration rates of the
soils.
• Application of huge quantities of river sand or red soils of coarser texture to dilute the
heaviness of the soil.
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8. • Application of liberal doses of organic manures like farm yard manure, compost, green
manure, composted coir pith, sewage waste, press mud etc.
• Adopting ridges and furrows, raised beds, broad bed and furrow systems of irrigation.
• Application of soils conditioners like H-concentrate, vermiculite, Jalasakti etc., to reduce run-
off and soil erosion.
Shallow soils
The shallow soils are characterised by the presence of the parent rock immediately
below the soil surface at about 15 - 20 cm depth. This restricts the root elongation and spreading.
Hence the crops grown in these soils necessarily be a shallow rooted crops, which can exhaust the
soil within 2 - 3 seasons. There fore frequent renewal of soil fertility is a must in these soils.
Among the six districts surveyed, the shallow soils are prevalent in a notable proportion
of 209 sq.km. and 384 sq.km. in Salem and North Arcot districts respectively. These soils can be
managed by growing crops which can with stand the hard rocky sub soils like Mango, Ber, Fig,
Country goose berry, West Indian cherry, Anona, Cashew, Tamarind etc.
Technologies for soil physical constraints, demonstrated to the farmers through field
experiments
The various technologies like chisel technology for sub soil hard pan soils, compaction
technology for the soils having excessive permeability and fluffyness, and other management
practices to overcome the slow permeable soils, surface crusted soils in addition to the
technologies developed are demonstrated to the farmers through field experiments and on farm
trials. The details of soil characteristics, extent, technologies and the results of experiments
conducted are detailed below.
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9. Chisel technology for sub soil hard pans
In Tamil Nadu, red soils (Alfisols) occupy 8 million hectares which constitutes 62 per
cent of the total geographical area. The occurrence of hard pan at shallow depths is the major
prevalent soil physical constraints in these soils. The agricultural crops are not able to enjoy the
full benefits of the soil fertility and nutrient use due to this major cause. The reasons for the
formation of sub surface hard pan in red soils is due to the illuviation of clay to the sub soil hori-
zons coupled with cementing action of oxides of iron, aluminium and calcium carbonate. The sub
soil hard pan are characterised by high bulk density (>1.8 Mg m-3) which in turn lowers infil-
tration rate, water holding capacity, available water and movement of air and nutrients with
concomitant adverse effect on the yield of crops.
Technology to overcome sub soil hardpan
To eradicate the problems of sub soil impervious layer in red soils, many trials were
conducted in farmer's field / Tamil Nadu Agricultural University farms with chisel plough, which
proved effective than any other implements in successfully break opening of the hard pan, there by
helped to facilitate better root growth, nutrient and water movement with concomitant increased
productivity.
Methodology
• The field is to be ploughed with chisel plough at 50 cm interval in both the directions.
• Chiselling helps to break the hard pan in the sub soil besides it ploughs up to 45 cm depth.
• The farm yard manure or press mud or composted coir pith at 12.5 t ha-1 is to be spread
evenly on the surface.
• The field should be ploughed with country plough twice for incorporating the added manures.
• The broken hard pan and incorporation of manures make the soil to conserve more moisture
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10. Experimental results
Field experiments were conducted using chisel plough under rainfed and irrigated
conditions and the results are furnished hereunder.
The results of the experiment conducted in farmer's holding at Kande Kounden Chavadi
(Pichanur soil series) with sorghum as the test crop indicated that chiselling at 0.5 m interval and 1
m interval being on par recorded higher grain yield (Table 3).
Table 3 Effect of chiselling on the grain yield of sorghum (Mg ha -1) and soil physical
properties
Treatments Bulk density Hydraulic conductivity Grain Yield
(Mg m-3) (cm h-1) Mg ha-1
Chiselling(0.5m apart) 1.42 11.9 4.72
Chiselling(1.0m apart) 1.45 9.7 4.08
Chiselling(1.5m apart) 1.58 9.1 3.71
Unchiselled 1.65 5.2 3.42
The effect of chiselling was much realised in the residual crop than the first crop (Table
4). The effect of chiselling at closer interval was spectacular as could be seen from the yield data
of second crop compared to chiselling at wider intervals. The experiments conducted on both
seasons clearly indicated the need for breaking the dense layer occurring at shallow depth with
closer intervals of chiselling for obtaining higher yield of sorghum crop.
Table 4 Residual effect of chiselling on the grain and straw yield of sorghum
Treatments Yield (Mg ha-1)
Grain Straw
chiselling (0.5 m apart) 4.48 20.37
chiselling (1.0 m apart) 3.91 14.00
chiselling (1.5 m apart) 2.51 11.22
Unchiselled 1.37 9.22
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11. In order to evaluate the efficacy of chisel plough with other tillage implements
commonly used by the farmers in soils having hardpan, a trial was conducted with tapioca as the
test crop and the results proved the superiority of chisel plough than the disc plough (Table 5)
Table 5 Comparative efficacy of chiselling on the tuber yield of tapioca
Treatments Tuber yield Bulk density (Mg m-3)
t ha-1 0-20cm 20-40cm 40-60cm
Chisel plough 53.79 1.527 1.666 1.635
Disc plough 49.46 1.564 1.698 1.692
Country plough 43.97 1.575 1.729 1.759
Similar trend of results were also obtained when groundnut was raised as the test crop.
Trials conducted with cotton as the test crop in farmer's holding at Valukkuparai of
Madukkarai block where the actual problem of subsoil hard pan exists. The results revealed that
chiselling at 0.5 m interval with application of composted coir pith at 12.5 t ha 1- recorded 29 per
cent yield increase over unchiselled plots (Table 6).
Table 6 Effect of chiselling and composted coir pith on bulk density and kapas yield of Cotton
Treatments Cotton kapas Bulk density (Mg m-3)
Yield 0-15 15-30 30-45
(q ha-1) cm cm cm
Unchiselled 7.8 1.552 1.714 1.745
chiselled(0.5 m apart) 9.5 1.513 1.548 1.745
chiselled + CCP 10.1 1.459 1.523 1.594
CCP = Composted coir pith @ 12.5 t ha-1
After the harvest of cotton, maize Co 1 and sorghum Co 26 were raised as first and
second residual crops. In both the crops, chiselling at 0.5 m apart with composted coir pith at
12.5 t ha-1 recorded 21 and 15 per cent yield increase over the control respectively, revealing the
advantageous effect even for one or more residual crops.
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12. The mobility of nitrogen and potassium ions was studied both in chiselled as well as in
unchiselled plots (Table 7). The nitrogen and potassium mobility were observed up to 45 cm
depth due to chiselling, whereas in the unchiselled plot (control) the N and K mobility was
restricted with the surface layer. Thus chiselling besides providing conducive physical
environment, helps in the nutrient mobility particularly N and K.
Table 7 Mobility of nitrogen and potassium ions in chiselled and unchiselled plots
Depth (cm) chiselled Unchiselled
KMnO4-N NH4OAc-K KMnO4-N NH4OAc-K
kg ha-1 kg ha-1 kg ha-1 kg ha-1
0 - 15 217 213 224 342
15 - 30 226 303 210 190
30 - 45 236 118 172 69
45 - 60 150 64 145 56
With a view to demonstrate and to disseminate the chiselling technology large scale
demonstrations were conducted in Pichanur soil series. Demonstration plots in an area of 8 acres
were laid out in Kande Koundan Chavadi in farmer's field with rainfed sorghum Co.24 as the test
crop (Table 8) which proved the beneficial effect of chiselling to the farming community.
Table 8 Effect of chiselling on the yield of rainfed Sorghum
Treatments Grain yield Straw yield
t ha-1 t ha-1
Country plough 0.54 2.19
Chisel plough 0.82 2.69
The grain yield of sorghum was found to be higher in chiselled plot compared to
country ploughing treatment. The residual effect of chiselling was also studied in the same plots
with Ganga 5 maize. The grain yield in chiselled plots was 3.27 t ha -1, while it was 2.69 t ha-1
under the unchiselled plots, proving the superiority of chiselling.
Demonstration trials for chiselling were also conducted with groundnut, blackgram,
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13. maize tomato, samai as the test crops which again proved the beneficial effect of chiselling
technology.
Economics of chiselling
The field experimentation and On Farm Trial (OFT) results showed that chiselling at 0.5
m apart enhanced the yield of crops and improved the soil physical properties. However, any
technology could be successful only if the return by adopting it is economical. Hence the
economics of the chiselling technology was calculated for different crops.
The economics worked out for sorghum Co 23 showed that a net profit of Rs 1125
ha-1 could be obtained by adopting chiselling technology for loosening sub surface compact layers
(Table 9).
Table 9 Economics of chiselling in sorghum
Treatments Yield (t ha-1)
Grain Straw Value (Rs ha-1)
Control 3.42 10.45 5,838
Chiselling 4.72 13.51 7,964
Increase over control 1.30 3.05 2,526
Cost of chiselling - - 1,000
Net profit - - 1,125
The economics of chiselling in tobacco crop is furnished in Table 10.
Table 10 Economics of chiselling in tapioca
Particulars Tuber yield (t ha-1) Value (Rs ha-1)
Control 44.0 15,400
Chiselling 53.8 18,830
Increase over control 9.8 3,430
Cost of chiselling - 1,000
Net profit - 2,430
The results showed that chiselling in the hard pan soils improved the tapioca tuber yield
by 22 per cent and there by resulting in a net profit of Rs. 2,430 ha-1. The economics of chiselling
was worked out for groundnut, blackgram and maize are given in table 11.
Table 11 Economics of chisel technology for groundnut, blackgram and maize
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14. Crops Yield (t ha-1) Value of grain (Rs ha-1)
Unchiselled Chiselled Unchiselled Chiselled Net profit
Groundnut 1.34 2.18 4,704 7,642 2,240
Blackgram 0.39 0.64 1,584 2,591 308
Maize 2.10 3.27 4,620 7,190 1,870
The net profit ranged from Rs. 308 for blackgram to Rs. 2,240 ha -1 for groundnut crop.
The chiselling was more beneficial for groundnut crop by breaking the sub soil hard pan in red soil,
thus facilitates the peg formation.
Conclusion drawn from the chiselling experiments
• Reduces the bulk density by 0.2 to 0.4 Mg m-3.
• The hydraulic conductivity was almost doubled in sub soil i.e. below 15 cm to 45 cm depth.
• Conserves around 30 to 40 per cent more soil moisture.
• Roots proliferation is improved by 40 to 45 per cent.
• Nutrient mobility especially N and K increased by 20 to 30 per cent and 30 to 40 per cent
respectively to sub surface layers.
• Enhances the crop yield
1. Sorghum : 25 - 30 per cent
2. Tapioca : 20 - 25 per cent
3. Groundnut : 15 - 20 per cent
4. Cotton : 25 - 30 per cent
• Residual effect can be realised for three seasons.
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15. Technology developed for excessive permeable soils
Sandy soils containing more than 80 per cent sand fractions occur in coastal areas, river
delta and in the desert belts. Such soils do occur in Coimbatore, Trichi, Kanyakumari, Tanjore,
Tirunelveli districts and in parts of coastal areas in Tamil Nadu. Delineation of areas for soil
physical constraints in Tamil Nadu focused that a total area of 14.93 lakh hectares were affected
by excessively permeable soils.
The nature of excessive permeability of the sandy soil results in very poor water
retention capacity, very high hydraulic conductivity and infiltration rates. So whatever the
nutrients and water added to these soils are not utilized by the crops and subjected to loss. In
addition, it is not providing anchorage to the crops grown.
Compaction Technology
To correct the textural weakness of these sandy soils and to make them suitable for
sound farming, various ameliorative measures have been devised by the scientists of Tamil Nadu
Agricultural University. Introduction of artificial barriers in the sub soil zone using asphalt,
bitumin and cement dust have been found to arrest the higher rate of nutrient and water losses in
sandy soils. But the prohibitive cost of sub surface barriers make practically unavailable to
farmers. So, for such soils compaction technology developed by Tamil Nadu Agricultural
University scientists proved to be very effective.
Methodology
• The soils should be ploughed uniformly.
• Twenty four hours after a good rainfall or irrigation, the soil should be rolled 10 times with
400 kg stone roller of 1 m long or an empty tar drum filled with 400 kg sand.
• Then, shallow ploughing should be given and crops can be raised.
Other management practices
• Use of minimum and frequent irrigations.
• Form minimum plot size.
• Adopt more number of splits for fertilizer application especially for nitrogen and potassium.
Results from the field experiments
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16. A field experiment was conducted initially in the sandy soils of Tindivanam (South
Arcot district, North eastern zone) with groundnut as test crop. The soil was compacted from the
surface at 10 per cent moisture level by making 10, 15 and 20 passes of stone roller weighing 400
kg, after 24 hours and 48 hours of irrigation. The surface soil was then loosened by using a
country plough and groundnut was raised.
The results revealed that there was an increase in pod yield of Groundnut by 11 per cent
due to compaction of sandy soil with 15 passes of roller after 24 and 48 h of irrigation over
control. In addition, it increased the bulk density of the soil by 0.12 to 0.19 Mg m-3 and there by
resulting in reduced infiltration rate and hydraulic conductivity. For groundnut crop, the
compaction with 15 passes of stone roller after 24/48 h of irrigation was helpful in enhancing the
pod yields besides establishing good physical condition in soils.
In an another field experiment in farmer's field at Mankarai in Coimbatore district
(Western zone) with maize as the test crop, the compaction technology proved its benefit over the
existing method of cultivation. The infiltration rate of the soil was significantly reduced by
compaction (Table 12).
Table 12 Effect of compaction on Infiltration rate of the soil
Treatments Infiltration rate (cm h-1)
Control 14.88
10 passes 11.84
15 passes 10.40
20 passes 7.84
Compaction with stone roller in the field of high permeability was significantly effective
in increasing the bulk density (from 1.49 to 1.62 Mg m-3) and in reducing infiltration rate (from
16.6 to 7.84 cm h-1), moisture retention from 7.71 to 10.62 per cent. As the number of passes
increased the bulk density also increased. However 10 passes of roller was significantly superior
in giving the highest grain and straw yields (36 and 39 per cent increase in yield respectively over
control).
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17. In an another field trial conducted in farmer's holding at Veerapandipudur (Coimbatore ,
Western zone) to test the compaction technology with sorghum as test crop. The results showed
that as the number of rollings increased, the bulk density was increased from 1.51 to 1.71 Mg m -3
in the surface layer of 0 - 15 cm depth and from 1.49 to 1.64 Mg m -3 in the sub soil layers. The
infiltration rate decreased from 32.0 for control plots to 11.2 cm h-1 in the plots which received
12 passes of stone roller However, the highest grain yield of Sorghum (20 and 25 per cent over
control) was obtained by passing of stone roller 9 times, after 24 h of irrigation and 6 times after
48 h of irrigation respectively. The treatments with 9 passes of stone roller after 24 h of irrigation
appeared optimum for higher grain yield of Sorghum by increasing the bulk density and lowering
the infiltration rate.
Field experiments were conducted with groundnut (POL 2) crop in farmer's holding at
Veerapandipudur Coimbatore (Western zone) with 0, 5, and 10 passes of 400 kg stone roller after
24 h of irrigation as treatments. Increase in the levels of compaction, increased the bulk density at
all three depths with concomitant moisture retention from 5.85 to 7.39 per cent. Infiltration rate
was predominantly reduced to 59.79 cm h-1 from 70.66 cm h-1. Increased pod yield and haulm
yields were recorded (18 and 13 per cent over control) by compacting the soil with 400 kg stone
roller 10 times.
To test verify the compaction technology under rainfed conditions field experiment was
conducted with the test crop of groundnut followed by residual crop of tomato (Pusa ruby) and
groundnut (TMV 3) in the farmer's holding at Coimbatore. Half of the area was left uncompacted
and the other half was compacted with 400 kg stone roller 10 times, 24 hours after a rain fall
(Table 13)
.
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18. Table 13 Effect of compaction on crop yields (t ha-1)
Treat Main crop First residual Second residual
ment Groundnut Tomato Groundnut
Pod yield Fruit yield pod yield
Compacted 2.42 3.40 2.35
Uncompacted 2.02 2.95 2.11
The results indicated that in the first crop of Groundnut, the compaction technology
helped in enhancing the pod yield by 20 per cent over control (Table 13). The residual effect was
well reflected in the second and third crop of Tomato and Groundnut. Tomato - Pusa ruby, the
first residual crop gave 15 per cent increased yield and the second residual crop recorded 11
percent increased yield over the control. Thus it is very clear that compacting the soil by passing
400 kg stone roller 10 times is more advantageous for improving the crop yields, that apart, the
residual effect can be realised for three years. Similar types of responses to compaction was also
observed in maize followed by groundnut crop in cultivator's field at Veerapandy Pudur.
Conclusions from the compaction technology experiments
• Conserves more moisture (20 to 25 per cent).
• Prevent nutrients from leaching and retains in the surface layer upto 20 to 25 %, 5 to 10 % and
25 to 30 % with respect to N,P and K)
• Enables better seed soil contact
• Enhances the yields of main and residual crops
1) Groundnut : 15 - 20 per cent
2) Maize : 25 - 30 per cent
3) Sorghum : 20 - 25 per cent
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19. Compaction technology for fluffy paddy soils
In Tamil Nadu fluffy rice soils are prevalent in Cauvery delta and in many parts of the
state due to the continuous rice - rice cropping sequence. The traditional method of preparing the
soil for transplanting rice consists of puddling, which results in substantial break down of soil
aggregates into a uniform structureless mass. Under continuous flooding and submergence of the
soil for rice cultivation in a cropping sequence of rice - rice - rice, as in many parts of Tamil Nadu,
the soil particles are always in a state of flux and the mechanical strength is lost leading to the
fluffiness of the soils. This is further aggravated by in situ incorporation of rice stubbles and
weeds during puddling. This causes sinking of draught animals and labourers during puddling.
This has been thus, an invisible drain of finance for the farmers due to high pulling power needed
for the bullocks and slow movement of labourers during the puddling operations. Further the
fluffiness of the soil lead to very low bulk density and thereby leading to very rapid hydraulic
conductivity and in turn the soil does not provide a good anchorage to the roots and the potential
yield of crops is adversely affected.
Technology
In Tamil Nadu due to continuous and intensive cropping of rice. Puddling poses a big
problem of sinking of draught animals and labourers to more than knee deep. Hitherto the only
remedial measure adopted by the farmers was engaging very light animals like the Umbalachari
breeds. Now big and heavy Kangayam breeds are engaged for puddling operations which further
aggravated the problem and hence to prevent the sinking, compaction technology was developed
by the scientists of Tamil Nadu Agricultural University.
Methodology
• The irrigation should be stopped 10 days before the harvest of rice crop
• After the harvest of Rice, when the soil is under semi - dry condition (proctor moisture level),
compact the field by passing 400 kg stone roller or an empty tar drum filled with 400 kg of
sand 8 times.
• The usual preparatory cultivation is carried out after compaction.
Results from the field experiments
19

20. To overcome the fluffiness in rice fields, a field trial was conducted with rice (Paiyur-1)
in wet lands, Tamil Nadu Agricultural University farm, Coimbatore. The treatments imposed were
preparatory cultivation under dry condition after compacting the field with 400 kg stone roller by
passing 8 and 16 times. The results exhibited that 8 passes of roller was optimum for compacting
the soil, besides increasing the yield of rice grain by 35.5 per cent over control, where preparatory
cultivation was done under dry condition, the increase was only 31.4 per cent under puddled
condition.
Another field trial with rice (Ponmani) as test crop in wet land was carried out. The
treatments imposed were compaction by passing 400 kg stone roller 8 times and application of
gypsum at 2 t ha-1. Compaction increased the grain yield of ponmani by 17.8 per cent over the
control. Second crop of rice (IR-50) was sown in the same plot to study the residual effect of
compaction. Yield of rice in the compacted puddled field was enhanced by 10 per cent over the
control.
Soil surface crusting
In Tamil Nadu, soil moisture is a very serious constraint in dry belts, but even the small
amount of rainfall received is capable of developing the surface crusts. This problem is prevalent
mostly in red soil areas (Alfisols) and is of greater magnitude in districts like Trichy, Pudukottai,
Ramnad and Tirunelveli. Surface crusting is due to the presence of colloidal oxides of iron and
aluminum in Alfisols which binds the soil particles under wet regimes. On drying it forms a hard
mass on the surface. The surface crusting results in the prevention of germinating seeds,
retardation of root growth, poor infiltration increased surface run off and poor aeration in the
rhizosphere.
Results of the field Experiments
A field trial with greenroom was conducted by applying different levels of farm yard
manure and lime at National Pulses Research Center, Vamban, Pudukottai District (Table 14).
Table. 14 Effect of FYM and Lime on the physical properties of soil and yield of Green
gram
Treatments Grain yield Bulk density Total porosity
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21. t ha-1 Mg m-3 Per cent
Lime at 2 t ha-1
+ 0.24 1.45 40.3
FYM at 10 t ha-1
Control 0.20 1.48 39.7
Combined application of lime and farm yard manure enhanced the yield by 20 per cent
over control besides improving the physical properties of the soil.
In an another experiment with organics application to mitigate the surface crusting
problem, application of gypsum at 10 t ha-1 recorded the highest grain yield of cowpea (35 per
cent increase over control) closely followed by sheep manure application. The lowest yield was
recorded in the control plots.
Management of slow permeable soils
Delineation work carried out in Tamil Nadu exposed that 14.32 lakh hectares of land
are affected by slow permeable soils. Slow permeable soil is mainly due to very high clay content
and poor drainage conditions which results in poor aeration and water stagnation and ultimately
leads to poor crop growth and in certain cases leads to complete death of crops.
Results from the field experiments
A field experiment was conducted with sorghum Co.24. employing different cultural
methods, the highest grain yield of sorghum was obtained from the raised bed plots, followed by
sowing on the ridges, while the least yield was recorded from the flat beds. The second crop of
Cotton MCU.9. raised in the same plots, the results showed that the flat bed system was superior
by registering the highest yield (1.02 t ha-1)
Addition of organics namely FYM / Composted coir pith / press mud at 12.5t ha -1
found to be optimum for the improvement of the physical properties besides, it facilitates water
movement to the root zone.
For rainfed crops ridges are formed along the slopes for providing adequate aeration to
21

22. the root zone. Interception drainage channels should be provided to carry the excess water to rice
fields located at lower end of the slope.
The bulk density was found to be reduced due to increase in non-capillary pores in
upper 10 cm layer of raised bed besides increase in yield of crops by forming raised and sunken
beds.
To reduce the amount of water retained in black clay soils during first 8 days of rainfall,
broad beds of 3 - 9 m wide should be formed either along the slope or across the slope with
drainage furrows in between broad beds.
22

23. the root zone. Interception drainage channels should be provided to carry the excess water to rice
fields located at lower end of the slope.
The bulk density was found to be reduced due to increase in non-capillary pores in
upper 10 cm layer of raised bed besides increase in yield of crops by forming raised and sunken
beds.
To reduce the amount of water retained in black clay soils during first 8 days of rainfall,
broad beds of 3 - 9 m wide should be formed either along the slope or across the slope with
drainage furrows in between broad beds.
22

24. the root zone. Interception drainage channels should be provided to carry the excess water to rice
fields located at lower end of the slope.
The bulk density was found to be reduced due to increase in non-capillary pores in
upper 10 cm layer of raised bed besides increase in yield of crops by forming raised and sunken
beds.
To reduce the amount of water retained in black clay soils during first 8 days of rainfall,
broad beds of 3 - 9 m wide should be formed either along the slope or across the slope with
drainage furrows in between broad beds.
22