Abstract: The present study was conducted to assess the physico-chemical characteristics of selected areas and to compare the different methods of organic matter determination. Soil samples were collected from different areas of Rawalpindi and Fateh Jang for the estimation of soil texture, soil pH, electrical conductivity, saturation percentage and available sodium and potassium contents and for the comparison of routine method of organic matter determination with the active organic matter determination method. A total of 24 composite soil samples were collected from six locations, Fateh Jang, Adiayla, Taxila, Swan, Kahuta and Gujar Khan. These soil samples were analyzed. All the samples were loam in texture. Soil pH values of all less than 8.0 and electrical conductivity of all soil samples was normal except Taxila which showed very high salt deposition. Available sodium was satisfactory while in available potassium, 42% samples were satisfactory and 58% were adequate. Comparison of both methods of organic matter estimation is not a true presentation of organic matter contents of soil.
INTRODUCTION
Total area of Pakistan is 79.61 m ha, out of which 20.61 m ha are cultivated, 3.16 m ha are under forests and 11.10 m ha are not available for cultivation (GOP, 1993). About 5.13 m ha in Pakistan are salt effected soils, of which 80% salt effected soils are in Punjab. Soils of Pakistan are mostly saline sodic and constitute 56% of salt effected area.
Soil and water as the basic natural resources are essential for crop production and soil is a non-renewable source upon which the mankind depends for his survival. Historically the rise of great civilization has been inexorably linked to quality of soil and the availability of water (Lone, 1995). Equally, the demise of such civilization is attributed to mismanagement of soil and in its broadest sense. Crop productivity and soil fertility were thus synonyms. In today’s overcrowded world, the challenge to feed and cloth the burgering population of developing countries is a chanting task. Yields have to be increased from existing land areas, adding fertility to the soils to satisfy the demands of higher yielding crops is essential. Soils vary greatly in their capacity to grow crops without fertilizers, even the richest soils experience declining yields without man’s intervention. In essence, soil is not always a perfect medium for growing plants (Brady and Weil, 1996).
In most of soils in Pakistan have been exhausted due to continuous crop production and less replenishment, particularly in rainfed areas. Balanced use of fertilizers is a basic need for boosting crop production. The soils of Pakistan are characteristically low in organic matter <1% (Hassan, 1975; Tahir, 1980; Azam, 1988). Out of 6000 samples analyzed for organic matter, 61.8% sites were deficient in Punjab (Malik et al., 1984). Studies on different crops had shown large increase in yields in soils deficient in organic matterunder increasing level of N and P (Khan et al., 1987) and green manuring (Akram et al., 1982). Farm Yard Manure (FYM) is very useful to improve the physical condition of soils and offset nutritional problems of the plants (Ghafoor et al., 1990) and if it is used continuously, it helps in lowering soil pH, increase in organic matter, Cation Exchange Capacity (CEC) and exchangeable cations (Lohia et al., 1980). Bhariguvanshi (1988) observed that long term application of FYM and fertilizers resulted in improving Water Holding Capacity (WHC) by 25% in sandy loam and 35% in clay loam soils and not effecting soil pH while use of fertilizers alone increased salt content (conductivity) of soils.
Tiessen et al. (1994) reported that many tropical soils are poor in inorganic nutrients and rely on the recycling of the nutrients from soil organic to maintain fertility. In undisturbed rainforests such nutrients are recycled through the litter. The role of humus quality and its environmental functions has been discovered only during the last 30 years, whereas the role of organic matter in soil fertility has been well known for hundred of years (Hargitai, 1993). Syres and Springett, 1984 reported that earthworms play an important role to redistribute organic materials within the soil, increase the soil penetrability and under certain conditions, influence ion transport in soils. The availability of N, P, K and organic contents of the soil at 0 to 15, 15 to 30 and 30 to 45 cm depths were estimated in a long term field experiment testing Farm Yard Manure (FYM) and fertilizer N doses in a pearlmillet wheat cropping sequence. Application of (FYM) increased available P, K and organic C content of soil at all depths and doses of fertilizer N (Gupta et al., 1992).
Organic matter is the most widely acknowledged core indicator of soil quality, temporal changes in soil active organic matter may provide an early indication of soils capability to perform under different management practices. Active organic matter determination is a highly simplified method in which neutral dilute solution of Potassium permanganate and other chemicals react with most of Active Organic Matter, changing the deep purple colour of solution to light pink colour or colourless. The lighter the colour or colourless of KMnO4 solution after reacting the soil, the greater the active organic matter content and better will be the soil quality. Compared to total soil organic matter, the active organic matter measured by this method is closely related to crop yield and soil quality parameters.
As the essential elements substitute for one another, so it is critically important to identify where and when these deficiencies occur. That’s why the role of soil and plant analysis comes in. Techniques have been developed to evaluate soil fertility constraints, based on soil chemical extraction and analysis of plants on such soils. Both are complementary and when calibrated with field crop response to fertilizer, provide a rational basis to identify that what type of element is missing and how much fertilizer to apply. Therefore soil and plant analysis laboratories have a vital role in agricultural development.
Therefore, the present study was planned to assess the present fertility status of Rawalpindi and Fateh Jang area and to compare two different methods of organic matter determination.
MATERIALS AND METHODS
The present study was conducted in the areas of Rawalpindi and Fateh Jang during 2003. Twenty four composite soil samples from six areas, Fateh Jang, Adiayla, Taxila, Swan, Kahuta and Gujar khan were collected from 0-30, 30-60, 60-90 and 90-120 cm depths. The samples were analyzed for physico-chemical characteristics such as soil texture (Ryan and Marter, 1992), soil pH, Electrical Conductivity (EC), saturation percentage (U.S. Salinity Lab. Staff, 1954), sodium, potassium (Richards, 1954) organic matter (Moodie et al., 1959). And also methods of active organic matter determination was compared with the routine organic matter determination method.
RESULTS AND DISCUSSION
Soil analysis of Fateh Jang: Textural analysis of Fateh Jang area was sandy loam and pH of this area varied from 7.63 to 7.98 at different depths. Electrical conductivity of soil ranged from 0.388 to 0.708 dS m-1, which increased up to 90 cm from top and at the depth below 90 cm, it decreased. As the total soluble salts increased with the depth, so Na and K contents also increased with depth. The salts in soil of this area are of Na and K. Saturation percentage was 35%. Values of Potassium contents for soil depths were 80, 120, 460 and 600 meq L-1, respectively. So potassium increased with the depth significantly (Table 1). Qureshi et al. (2001) and Muhammad (1978) reported similar results. Similarly Sodium contents also increased with the depth and its values for soil depths were 115, 124, 161 and 218 meq L-1, respectively. Organic matter varied from 0.655 to 0.932%. Active organic matter was excellent i.e., within 0.75-1.00% in all depths. So both the methods of organic matter estimation agreed within this area.
Soil analysis of Rawalpindi (Adiayla): Textural analysis of Adiayla area was sandy loam and pH of this area varied from 7.88 to 7.91 at different depths. Electrical conductivity of soil ranged from 0.397 to 0.219 dS m-1. The maximum value i.e., 0.39 dS m-1 was found in 0-30 cm depth which might be due to salt deposition while the minimum value i.e., 0.219 dS m-1 was found in 90-120 cm depth which might be due to low pH and exchangeable cautions. Shakirullah et al. (1996) reported similar results. Saturation percentage was 36%. Values of Potassium contents for soil depths from top to bottom were 440, 680, 60 and 60 meq L-1, respectively. Maximum value i.e., 680 meq L-1 was found in 60-90 cm depth and 90-120 cm depth of soil. These values of Potassium correspond to the values of electrical conductivity. Values of sodium contents for soil depths from top to bottom were 89, 121, 154 and 115 meq L-1, respectively. Maximum value i.e., 154 meq L-1 was found in 60-90 cm depth of soil. While minimum value i.e., 89 meq L-1 was found in 0-30 cm depth of soil. Values of organic matter for soil depth from top to bottom were 0.518, 0.69, 0.725 and 0.863%, respectively. Active organic matter was excellent i.e., 0.50-0.75% in lower three depths of soil. Here both methods of organic matter estimation did not agree within this area.
Soil analysis of Kahuta: Textural analysis of kahuta area was sandy clay loam in 0-30 cm depth and sandy loam in lower three depths and pH of this area varied from 7.76 to 7.97 at different depths. Electrical conductivity of soil ranged from 0.424 to 0.190 dS m-1, which was found in 90-120 cm and 30-60 cm depth series of soil, respectively.
| Table 1: | Physico-chemical characteristics of soil collected from different areas |
| AOM = Active Organic Matter, OM = Organic Matter, T = Texture, S% = Saturation Percentage | |
Saturation percentage was 35%. Potassium contents of soil ranged from 660 to 80 meq L-1, which decreased up to 90 cm from top and at depth below 90 cm, it increased. Value of Sodium contents for soil depths top to bottom were 197.8, 121.9, 131.9 and 69 meq L-1, respectively (Table 1). Organic matter varied from 0.172 to 0.69%. Active organic matter was excellent i.e., within 0.75-1.00% in upper two depths and good i.e., within 0.5-0.7% in lower two depths of soil. So both the methods of organic matter estimation agreed except 0-30 cm depth of soil.
Soil analysis of Rawalpindi (Swan): Textural analysis of Swan area was sandy loam in 0-30 cm and sandy clay loam in lower three depths of soil and pH varied from 7.79 to 7.95. Tariq et al. (1998) reported similar results. Electrical conductivity of soil ranged from 0.516 to 0.351 dS m-1. Maximum value i.e., 0.516 dS m-1 was found in 90-120 cm depth of soil. Saturation percentage was 38%. Potassium contents varied from 210 to 100 meq L-1, which increased with depth significantly. Values of Sodium contents for soil depths from top to bottom were 71.3, 165.6, 85.1 and 98.9 meq L-1, respectively. Organic matter showed values for soil depths from top to bottom, were 0.587, 0.499, 0.69 and 0.828%, respectively. Active organic matter was excellent. So, both methods of organic method estimation did not agree within this area.
Soil analysis of Taxila: Textural analysis of Taxila area was loam, which remained up to 90 cm from top and at the depth below 90 cm it was clay loam. pH of this area varied from 7.40 to 7.48, which increased with depths of soil. Electrical conductivity of soil ranged from 4.77 to 5.84 dS m-1, which may be due to the use of drainge water for irrigation. Similar results were reported by Chaudhary et al. (2001). Saturation percentage was 39% Potassium contents varied from 120 to 600 meq L-1, which increased with the depths significantly. Values of sodium contents for soil depths from top to bottom were 575, 690, 225.4 and 506 meq L-1, respectively. Organic matter varied from 0.172 to 0.828%. Active organic matter was excellent in 0-30 cm depth and was good up to bottom, so both methods of organic matter did not agree within this area.
Soil analysis of Gujar Khan: Textural analysis of Gujar Khan area was clay loam in 0-30 cm depth and sandy clay loam in lower three depths of soil. pH of soil varied from 7.54 to 7.84. Electrical conductivity of soil depths ranged from 0.512 to 0.778 dS m-1, which was found in 90-120 cm depth and 0-30 cm depth of soil, respectively. It did mean, there was high salt concentration in uppermost depths of soil. Saturation percentage was 40.5%. Potassium contents varied from 540 to 660 meq L-1, which decreased up to 90 cm from top and at the depth below 90 cm, it increased. Khalid et al. (2002) reported similar results. The highest K contents may be due to medium to heavey textured soils in this area. Saleem and Bertistisson (1978) reported that soils with high clay content had higher available K. While sandy soils are deficient in K (Mian and Ashraf, 1980). Sodium contents of soil depths from top to bottom were 506, 25.3, 27.6 and 101.2 meq L-1, respectively. Organic matter of soil depths varies from 0.518 to 0.966%. Active organic matter was excellent. So, both methods of organic matter estimation almost agreed within this area.