Agric Res (March 2014) 3(1):87–91 DOI 10.1007/s40003-014-0098-6
BRIEF RESEARCH ARTICLE
Pothole Formation and Occurrence in Black Vertisols of Central and Western India J. Somasundaram • R. S. Chaudhary • Brij Lal Lakaria R. Saha • N. K. Sinha • R. K. Singh • Pramod Jha • R. K. Singh • A. Subba Rao
•
Received: 5 October 2013 / Accepted: 20 January 2014 / Published online: 11 February 2014 Ó NAAS (National Academy of Agricultural Sciences) 2014
Abstract Soil cracks are a unique feature of black vertisols. Evaporation loss is inevitable from lateral exposure of surface and sub-surface cracks. On the other hand, these cracks provide increased opportunity for soils to recharge during the rainy season. In this process, water that drains into larger size cracks moves down the soil profile and eventually results in pothole formation due to the existence of a network of sub-surface cracks. An investigation was done to evaluate pothole characteristics under different land use systems in black vertisols of central and western regions of India. In both the regions, the potholes had smaller volume in arable land than in non-arable uncultivated land. The size and volume of potholes in central India were greater compared to that in western India, where the highest volume of potholes was registered under perennial vegetation followed by agriculture–horticulture system, uncultivated fallow fields and arable lands. However, cultivated fields had less a incidence/occurrence of potholes than uncultivated fields. Similarly, the marginal land in western India registered the highest volume of potholes than other land use systems. The study gives insight to some of the researchable issues and strategies to minimize soil slumping in black vertisols, characterization of soil properties within and adjacent to potholes as well as soil and nutrient loss through potholes. Keywords
Pothole formation Vertisols Soil slumping Land use
Introduction Rain-fed regions of India have different soil types besides climatic extremes. Consequently, soil-associated problems and rainwater management strategies also differ [4]. The
J. Somasundaram R. S. Chaudhary R. Saha N. K. Sinha (&) R. K. Singh Division of Soil Physics, Indian Institute of Soil Science (ICAR), Berasia Road, Nabibagh, Bhopal 462038, Madhya Pradesh, India e-mail:
[email protected] B. L. Lakaria P. Jha Division of Soil Chemistry, IISS, Bhopal 462038, Madhya Pradesh, India R. K. Singh CSWCRTI, Research Centre, Kota 324 002, Rajasthan, India A. Subba Rao IISS, Bhopal 462038, MP, India
best epitome of the statement is that central and western India is characterized by sub-humid and semi-arid climate. In the state of Madhya Pradesh, a major soil groups are alluvial, black vertisols, mixed red and black, red and yellow and skeletal soils. About 54.2 % area of the state (about 16.7 M ha is composed of black vertisols [5, 10, 11] and these are distributed in the Narmada valley, Malwa plateau and Satpura ridge along with some patches in the eastern part of the grid and the Bundelkhand region. The south-eastern part of the state of Rajasthan (with 72 % arable land area under rain-fed farming) is very productive, and also where medium-deep black vertisols occupy about 0.97 m ha area [12]. Black vertisols exhibit special challenges for many agronomic activities. When wet and fully saturated, these soils are massive, with very low infiltration, poor traffickability, poor oxygen diffusion and root zone aeration, narrow water content range for soil working, and significant surface runoff and erosion during the rainy season.
123
88
Agric Res (March 2014) 3(1):87–91
This results in considerable loss of nutrients and decline in crop production [1, 2]. Such black vertisols and associated soils occupy an area of 73 m ha, covering 22.5 % of the sub-humid and semi-arid tropics of India. In the arid and semi-arid regions of western India, black vertisols have columnar and prismatic structure in the sub-surface horizons [3]. Further, on account of the dominance of smectite clay minerals, swell shrink, slickensides, periodic cracking and high clay content ([30 %) are major diagnostic characteristics of all vertisols [2, 9, 14, 15, 20]. Soil cracks are one of the most striking feature of these black vertisols and they foster water recharge during rainy spells, while also increasing soil–air interface [7, 8, 18, 19] leading to development of potholes [17]. A network of surface and sub-surface cracks is the prerequisite for pothole formation. The size of the cracks gets larger when two or more such cracks meet. Consequently, the runoff drains into these cracks, where a deep and wide hole is formed during the rainy season. Such holes are locally known as potholes or pipe holes (Fig. 1a). In this process, the top soil at the edge of the cracks get slumped down into the crack, resulting in formation of potholes. Through sub-surface cracks/channelshe eroding soil may join somewhere with the adjoining ravine systems posing a serious problem of gully head extension that results in loss of arable land and crop productivity. There is very scanty information available on the formation of potholes and their occurrence in black vertisols. This paper describes the formation and occurrence of these potholes in black vertisols of central and western India under different land use systems.
Materials and Methods Black Vertisols in Central India The study area is located in Vindhyan plateau of western Madhya Pradesh (latitude: 23°180 1400 to 23°180 4800 N; longitude: 77°240 1700 to 77°240 580 ’E; elevation: 485 above mean sea level). In the capital, Bhopal, the soil is medium deep to very deep, spread over 19.27 m ha area. Soils are ‘clayey’ (50–55 % clay), non-calcareous of near normal to alkaline (6.5–8.0) in reaction and poor to medium in organic carbon (0.25–0.5 %), characterizing to the family of non-calcareous vertisols (isohyperthermic-typic Haplustert). The region is characterized by semi-arid to subhumid monsoon climatic conditions with an average annual rainfall of 1,200 mm. These soils also have a narrow soil water regime for field operations. An annual runoff to the extent of 10–20 % of the rainfall commonly occurs in this region and this may carry away 6–43 t ha-1 of fertile surface soil as silt annually [10, 11].
123
Fig. 1 Crack before rains (a) that lead to pothole formation in black soils (b, c)
Black Vertisols in Western India The study area is located in Kota district of south-eastern Rajasthan (latitude: 25°130 2900 to 25°140 1800 N; longitude: 75°520 1800 to 75°520 4400 E; elevation: 257 above mean sea level), having an average annual rainfall of 740 mm. Soils
Agric Res (March 2014) 3(1):87–91
of the study area are classified under Kota series are deep to very deep and occur on gently sloping land with less than 2 % gradient. A CaCO3 layer generally occurs below 90–110 cm [13]. Soils are predominantly fine textured ([35 % clay) and belong to the hyperthermic family of Typic Chromusterts. The study area comprises two distinct landscapes, the agricultural table lands and the ravenous lands adjoining Chambal river. The physiography is constituted of gently sloping (up to 1 % slope), moderately well-drained table lands in the immediate vicinity of ravines. However, the ravine lands are 6–9 m deep and ‘V’-shaped with more than 18-m wide gully network that is under the influence of back flow from the Chambal river. During summer, large size cracks develop due to high smectite clay minerals and excessively high temperature that results in faster drying up of the soil. As the monsoon strikes, the runoff water of the gently sloping topography drains into the cracks and results in sudden slumping of surface soils that lead to pothole formation. Thus, the investigation was initiated to observe these potholes under different land uses. Systematic observations of pothole characteristics, viz. length, width and depth were taken up during dry spells after the onset of monsoon under various land use systems in central India, namely arable land, uncultivated fallow, agriculture–horticulture system and perennial vegetation (Acacia nilotica) lands. In the western region, observations were recorded for arable land and uncultivated fallow and marginal land. A corresponding number of observations taken were 6, 5, 15 and 20 for central and 17, 5 and 5, respectively, for western India. Subsequently, the total volume of potholes (V) was computed using the following equation assuming a semielliptical shape of the potholes under various fields. Area ¼ P A B V ¼ ð4=3Þ P A B C ðA; B; and C are the semi - axes of an ellipsoidÞ where A is the mean width of the potholes (m), B the mean length of the potholes (m) and C the mean depth of potholes (m) (Fig. 1b, c).
Results and Discussion Pothole Formation The genesis of potholes was observed through visits to the mentioned lands after the rainy season. As usual in heavy black vertisols, cracks initiate after cessation of the monsoon and their development progresses from about late November to early June depending extremes of summer and soil moisture stress (Fig. 1a). In arable land after
89
harvest of summer (Kharif) (south-west monsoon, June– September) crops, the soil surface is exposed and cracks develop which affects winter (Rabi) (north-east monsoon, October–January) crop productivity due to rapid depletion of moisture from the soil. These cracks provide increased opportunity to soils for recharging moisture during the rainy season on one hand and water draining into larger size cracks moves down the soil to eventually get the soil slumped, resulting in potholes formation on the other due to the existence of a network of sub-surface cracks (Fig. 1b, c). Also, in lands adjoining ravine systems, pothole formation poses serious problem of gully head extension that results in loss of arable land and its productivity. Potholes Under Different Land Use Systems We hypothesized that land use systems have great influence on soil cracking and formation of potholes in black vertisol. The observation on pothole characteristics indicated that in both the regions the potholes had smaller volume under arable land than in non-arable uncultivated land. The size and volume of potholes in central India were greater compared to that in western India, where the highest volume of potholes was registered under perennial vegetation followed by the agriculture–horticulture system, uncultivated fallow fields and arable land (Table 1). However, cultivated fields had less incidence/occurrence of potholes than uncultivated fields. This was ascribed to regular ploughing of field that helps in churning accumulated clay in the lower depths. In contrast, marginal land in western India registered the highest volume of potholes than in other land use systems. Under both the regions, uncultivated fields had greater volume of potholes than cultivated fields. This was attributed to the existing potholes that have not been disturbed as well as to the natural gentle slope facilitated by the runoff of water that traverses a longer distance with heavy sediment load to enter these cracks. This in turn leads to formation of potholes as well as enhancement in their size (Table 1). The mean data of pothole characteristics in central India revealed that length, width and depth varied from 0.33 to 0.73, 0.29 to 0.50 and 0.26 to 0.44 m, respectively, across different land use systems. Similarly, in western India, the dimensions of potholes varied from 0.25 to 0.58, 0.21 to 0.55 and 0.31 to 0.57 m, respectively. Amongst the different land use systems, perennial vegetation (Acacia nilotica) fields in central India had greater volume of potholes (1,832 m3 ha-1), followed by agriculture–horticulture fields (1275 m3 ha-1), uncultivated fallow fields (698 m3 ha-1) and arable land (328 m3 ha-1). Similarly, marginal lands in western India (adjacent to ephemeral streams) recorded the highest volume of
123
90
Agric Res (March 2014) 3(1):87–91
Table 1 Pothole characteristics under different land use systems in central and western India S. No.
Land use systems
A
Central India (Bhopal)
Length (m)
Width (m)
Depth (m)
Volume (m3 ha-1)
1
Arable land (n = 6)
0.33 ± 0.02 (13.24)
0.29 ± 0.02 (16.43)
0.26 ± 0.01 (12.09)
328
2
Uncultivated fallow (n = 5)
0.39 ± 0.03 (15.93)
0.40 ± 0.03 (18.81)
0.33 ± 0.01 (8.35)
698
3
Agri-horti system (n = 15)
0.73 ± 0.06 (33.85)
0.34 ± 0.05 (54.51)
0.46 ± 0.03 (22.34)
1,275
4
Perennial vegetation (Acacia nilotica) (n = 20)
0.58 ± 0.05 (38.35)
0.50 ± 0.05 (22.84)
0.44 ± 0.05 (54.84)
1,832
B
Western India (Kota, south-eastern Rajasthan)
1 2
Arable land (n = 17) Uncultivated fallow (n = 5)
0.25 ± 0.02 (29.91) 0.58 ± 0.05 (18.89)
0.21 ± 0.01 (26.48) 0.41 ± 0.06 (32.72)
0.32 ± 0.04 (46.48) 0.31 ± 0.09 (62.59)
234 573
3
Marginal land (n = 5)
0.46 ± 0.05 (25.95)
0.55 ± 0.05 (19.88)
0.57 ± 0.02 (8.23)
1,155
Values in parentheses are coefficient of variation, ± standard error mean
potholes (1155 m3 ha-1) followed by uncultivated fields (573 m3 ha-1) and arable lands (328 m3 ha-1). Somasundaram et al. [17] reported the maximum volume of potholes in the uncultivated fields than in the cultivated fields. Amongst the cultivated fields, control plot (without conservation measures) and uncultivated fields had the maximum volume of potholes, followed by conservation bench terrace, residue-incorporated fields and contour furrow (CF). The lower volume of potholes in contour furrow fields than control (without conservation measures) fields was assigned to better moisture regime in the soil profile due to greater absorption of rainfall across the field. Hullugalle et al. [6] studied the soil properties near the cracks and reported that more stable aggregates also occurred with intensive tillage in soils adjacent to cracks. These differences were fewer or absent when tillage intensity and frequency were either reduced (minimum tillage) or eliminated. With intensive tillage, exchangeable Ca2?, CEC and CaCO3 were lower and organic C and plastic limit higher in soil adjacent to cracks than in soil away from cracks (bulk soils). Furthermore, the similarity between soil adjacent to cracks and bulk soil under either minimum or no tillage was due to the occurrence of stable, undisturbed bio-pores. Significant differences in physical and chemical properties can occur between soil adjacent to cracks and bulk soil. Management of Potholes In general, potholes and cracks are a characteristic feature of the black vertisols. However, application of manures and amendments such as crop residues help minimizes cracks by promoting soil aggregation and also improving organic matter content in the soil. Creation of dust mulch on the surface also reduces cracks which help in successful growth
123
of crops due to regulated vapour diffusion and water uptake from sub-surface layers that still remain wet. Tillage and crop rotation directly influence various facets of soil structure. Thus, selection of proper tillage/cultivation practices is imperative for these black vertisols. Annual deep ploughing or sub-soiling helps mix the soil. The clay accumulates increasingly where cracks intersect (intersecting slickensides). As the clay accumulates in the sub-surface soil (at 60–70 cm), enormous pressure is developed as a result of the swelling (when wet) and shrinking (when dry). Thus, cracks widen during the dry season. Ploughing of land immediately after harvesting of crop during the post-rainy season not only helps pulverize the soil thereby improving moisture absorption and retention, but also prevents weeds from setting in, exposes hibernating insects (such as beetles, weevils and butterflies) and disease-causing organisms to the summer heat, while improving soil fertility. Intercropping of cereals and pulses such as the sorghum and pigeon pea system is effective in controlling crack formation due to their contrasting rooting patterns [16], which aids aggregate formation and breaking of the sub-surface hardpan. Selection of short duration crops, which complete their grainfilling stage before crack development is another option to minimize the problem. In situ moisture conservation practices such as construction of contours or graded bunds, mulching, intercultivation, etc. also help to reduce the problem of crack formation and potholes due to improved moisture regime in the profile. Somasundaram et al. [17] reported that soil conservation measures such as CF and incorporation of residues had minimized the pothole formation in black vertisols of the Chambal region. Some of these researchable issues are suggested based on the study of soil and nutrient loss through potholes, strategies to minimize soil slumping in black vertisols and characterization of soil properties in potholes.
Agric Res (March 2014) 3(1):87–91
91
Conclusions Cultivated fields recorded the lowest volume of potholes than other land use systems such as uncultivated fields, marginal lands, perennial vegetation (Acacia nilotica) and agriculture–horticulture lands due to regular ploughing of fields that help in churning accumulated clay in the lower depths, whereas in uncultivated/perennial vegetation fields, higher amount of runoff water getting into existing cracks might have facilitated more incidence of pothole formation. Conservation tillage and suitable land use with good soil conservation practices such as contour furrows or graded bunds at regular intervals for breaking the slope can lead to reduced pothole formation. Incorporation of organic manure/crop residues leads to improved aggregation and stability of the soil which can help in reducing the formation of wide cracks and, in turn, preventing loss of fertile topsoil through potholes during the rainy season. Acknowledgments The authors thank Dr. V. N. Sharda, former Director, CSWCRTI and Member ASRB, for constant encouragement and Dr. S. N. Prasad, former Head, CSWCRTI, Regional Centre, Kota, Rajasthan, for providing the facility. The authors also sincerely thank Mr. Dhoom Singh, Mr. Vikram Chauhan, Mr. N. K. Meena and Mr. P. R. Raibole for their help. Authors profusely thank Mr. Vivian Morris Dey for his painstaking efforts in language editing of the Manuscript.
7.
8. 9.
10.
11.
12.
13.
14.
15. 16.
References 1. Chan KY, Hodgson AS (1981) Moisture regimes of a cracking clay soil under furrow irrigated cotton. Aus J Exp Agric Anim Husb 21:538–542 2. Coulombe CE, Wilding LP, Dixon JB (1996) Overview of vertisols: characteristics and impacts on society. Adv Agron 57: 289–375 3. Das DK, Agrawal RP (2002) Physical properties of soils. In: Sekhon GS et al (eds) Fundamentals of soil science. Indian Society of Soil Science, New Delhi, pp 71–92 4. Gupta RK (2002) Natural resources conservation technologies for black soils region of peninsular India. J India Soc Soil Sci 50:438–447 5. Gupta RK, Varade SB, Sahrawat KL (1991) Soil related constraints in crop production-Black soils region of Central and Peninsular India. In: Biswas TD, Narayanaswamy G, Goswami NN, Sekhon GS, Sastry TG (eds) Soil related constraints in crop production. Indian Society of Soil Science, New Delhi, pp 38–51 6. Hullugalle NR, Weaver TB, Finlay LA, Entwistle PC (2001) Physical and chemical properties of soil near cracks in irrigated
17.
18.
19.
20.
vertisols sown with cotton-wheat rotations. Arid Land Res Manag 15:13–22 Karanthansis AD, Hajek BF (1985) Shrink-swell potential of montmorillonite soil in udic soil moisture regime. Soil Sci Soc Am J 49:159–166 Lima LA, Grismer ME (1992) Soil crack morphology and soil salinity. Soil Sci 153:149–153 Mcgarity JW, Hoult EH, So HB (1984) The properties and utilization of cracking clay soils. Reviews in Rural Science University of New England, Armidale Ramesh P, Ghosh PK, Reddy KS, Ajay, Ramana S (2005) Assessment of biomass productivity and sustainability of soybean based cropping system at three levels of N in deep vertisols of SAT India. J Sustain Agric 26:43–59 Randhawa NS, Rao RM (1981) Management of deep black soils for improving production levels of cereals, oilseeds and pulses in the semi-arid region, In: Improving the management of India’s Deep black soils, ICRISAT, Patencheru, A.P, pp 67–80 Shyampura RL, Sehgal J (1995) Soils of Rajasthan for optimizing land use, NBSS Publ. Soils of India Series. National Bureau of Soil Survey and land Use Planning, Nagpur, 76?6 Sheet soil map (1:500,000 scale) Singh SK, Baser BL, Shyampura RL, Narain P (2003) Genesis of lime nodules in Vertisols of Rajasthan. J India Soc Soil Sci 51: 273–279 Singh SK, Baser BL, Shyampura RL, Narain P (2004) Variation in morphometric characteristics of Vertisols in Rajasthan. J India Soc Soil Sci 52:214–219 Soil Survey Staff (2010) Keys to Soil Taxonomy, 11th edn. USDA-Natural Resources Conservation Service, Washington DC Somasundaram J, Chauhan V (2008) Impact of Different Land Uses on Cracking Pattern of Black soils in South-eastern Rajasthan. In: Natural Resources Management for Sustainable Development in Western India, Prasad et al (eds.), Indian Association of Soil and Water Conservationists (IASWC), Dehradun and Central Soil & Water Conservation Research & Training Institute, Research Centre, Kota, Rajasthan, Allied Publishers Private Ltd, New Delhi, pp 105–108 Somasundaram J, Singh RK, Prasad SN, Sethy BK, Kumar A, Ramesh K, Lakaria BL (2011) Management of black Vertisols characterized by potholes in the Chambal region, India. Soil Use Manag 27:124–127. doi:10.1111/j.1475-2743.2010.00321 Stirk GB (1954) Some aspects of soil shrinkage and the effect of cracking upon water entry into the soil. Aus J Agric Res 5: 279–290 Swartz GL (1966) Modification of cracking pattern of black earth of Darling Downs, Queens lands. Queens lands J Agric Anim Sci 23:279–285 Virmani SM, Sahrawat KL, Burford JR (1982) Physical and chemical properties of vertisols and their management. In: Vertisols and rice soils of the tropic. Symposia papers II, Transactions of the 12th International Congress of Soil Science, Indian Society of Soil Science, New Delhi, India, pp 80–93
123
