Soil Fertility and Salinity Status of Attock District
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Soil fertility status of Attock district 505 SOIL FERTILITY AND SALINITY STATUS OF ATTOCK DISTRICT Obaid-ur-Rehman, Bashir Ahmad* and Sher Afzal** ABSTRACT A total of 20711 soil samples collected from all tehsils of Attock district (6696 samples from tehsil Attock, 2917 from Fateh Jang, 2582 from Pindi Gheb, 5552 from Jand and 2964 samples from Hassan Abdal) were tested in Soil and Water Testing Laboratory, Attock, Pakistan during 2004-05 to 2007-08. Samples were analysed for different parameters like soil reaction (pH1:10), electrical conductivity (EC1:10), soil texture, soil organic matter (SOM) and plant available phosphorus (Olsen-P). The results revealed that pH, ranged between 7.5-8.5 in 94.62 percent samples while 99.60 percent samples were normal with respect to salinity/sodicity (EC < 4 dS/m and SAR < 15). Similarly 21.15 percent samples were light (sandy loam) and 78.70 percent were medium (loam) in texture. Soils were poor in organic matter (91.32% samples had less than 0.86% OM) and available phosphorus (99.49% samples had less than 7 mg P/kg soil). Depending upon the soil analyses, farmers were guided and fertilizer recommendations were served according to crop, soil and water/rainfall conditions for harvesting higher yield of different crops. KEYWORDS: Soils; soil fertility; salinity; soil texture; Pakistan. INTRODUCTION Attock, previously named as Campbellpur, comprises six tehsils with 72 union councils and is located at 33° 46' 20 N Latitude and 72° 22' 6 E Longitude. It is spread at an altitude of 348 meters (1145 feet) from sea level. Total estimated population of the district was 1518000 by the end 2008 of which 80 percent is rural and 20 percent urban (14). Annual average rainfall for the last five years (2004-08) of Attock district is 694 mm (1029 mm in Hassan Abdal, 711 mm in Attock, 825 mm in Fateh Jang, 544 mm in Jand and 360 mm in Pindi Gheb tehsils). On an average, rainfall is scanty, uncertain and unevenly distributed and is mostly received in monsoon season. In winter, minimum temperature falls below 0°C with frost while maximum temperature exceeds 45°C in summer. Crop sector consists of 7-8 crops [wheat, chickpea, lentil and rapeseed in winter (rabi) while groundnut, maize, mung, mash in summer *Agricultural Officers (Lab.), **Agricultural Officer (Field), Soil and Water Testing Laboratory, Attock, Pakistan. J. Agric. Res., 2010, 48(4) 506 O. Rehman et al. (kharif) with some area under vegetables (potato, peas, onions, garlic) and orchards (citrus, peach, grapes, etc.)]. The detail of area, yield and production of major rabi and kharif crops in district Attock are given in Annexure-I (1). According to latest statistics, total geographical area of district Attock is 692000 hectares with cultivated area of 318000 hectares. Total net cropped area is 23000 hectares of which 70 percent is for rabi and 30 percent for kharif crops (9). As regards nutrient use in Attock, 35 kg NPK per hectare per annum is used with N:P ratio of 4.40:1 against recommended ratio of 2:1(Annexure-II). So the present nutrient use rate is far below the recommendation and it is further skewing in favour of nitrogen. Soil fertility status varies with nature of cropping pattern and management practices. In Pakistan, entire available soil is almost nutrient deficient (5). Soils are generally deficient in organic matter content reflecting the severe deficiency of nitrogen (almost 100 %) with phosphorus deficiency in more than 90 percent soils and potassium in 50 percent soils (Annexure-III). Micronutrients; zinc, boron and iron are also emerging as deficient (7). Ahmad and Khan (1) declared that 75-92 percent soils of Pakistan are deficient in organic matter (0-1%), 70-95 percent in phosphates and 20-60 percent soils in potash. Crop yield increases 30-50 percent with balanced fertilization and production with 50 percent balanced fertilizer adoption can be increased by 20 percent of current national production (2). Soil fertility status of Attock (16, 17), Rawalpindi (12) and Gujrat (15) has shown that soils are deficient in organic matter and available phosphorus and fertilizer recommendations/application on the basis of soil tests are pre-requisite for higher crop yields. Furrukh et al. (11) studied farmers’ fertility management pattern with available resources and technology like chemical fertilizers, land type, cropping pattern, fallow system and cultural practices. Farmers in rainfed tract of northern Punjab (Pakistan) i.e. Potohar Plateau, classify their lands into two main types, Lepara (near the homestead with more organic matter) and Mera (far from homestead with less or no organic matter) on the basis of FYM application. The objective of present study is to assess the soil fertility and salinity status of Attock district for formulation of optimum fertilizer recommendations for different crops grown in the area. MATERIALS AND METHODS This study was conducted in Soil and Water Testing Laboratory, Attock, Pakistan during 2004-08. Composite soil samples from all tehsils of district Attock (Attock = 6696, Fateh Jang = 2917, Pendi Ghab = 2582, Jand = 5552 J. Agric. Res., 2010, 48(4) Soil fertility status of Attock district 507 and Hassan Abdal = 2964 samples) were collected from 0-15 and 15-30 cm depths for crops and vegetables while 0-15, 15-30, 30-60, 60-90, 90-120 and 120-150 cm depths for fruit plants and orchards. Samples were air-dried, ground and passed through a 2 mm sieve and analysed for physical and chemical properties. Soil texture was determined by measuring soil saturation percentage (13). Similarly soil reaction (pH) and electrical conductivity (EC) were recorded with pH meter and EC meter, respectively by making soil and water suspension of 1:10 (13). Samples were also analysed for organic matter (10) and extractable phosphorus (18). The criteria used for the classification is given in Table 1 as described by Malik et al. (13). Table 1. Criteria of parameters used for classification. (a) Soil texture Saturation percentage Textural class 0-20 Sand 21-30 Sandy loam 31-45 Loam 46-65 Clay loam 65-100 Clay (b) Soil salinity/sodicity Status pH EC (dS/m) Normal (salts free) < 8.5 < 4 Saline < 8.5 > 4 Saline sodic > 8.5 > 4 Sodic > 8.5 < 4 (c) Nutrient status Status Organic matter (%) Olsen P (mg/kg soil) Poor < 0.86 0-8 Satisfactory 0.86-1.29 8-15 Adequate > 1.29 > 15 Source: Malik et al. (13) RESULTS AND DISCUSSION Soil texture The results (Table 2) showed that 21.15 percent soils in Attock district were sandy loam and 78.70 percent soils were loam in texture. Heavy textured soils (clay loam) were noticed at few sites (0.15 %). In tehsil Attock, 11.92 percent soils were sandy loam and 87.78 percent soils were loam. In tehsils Fateh Jang and Hassan Abdal, 99.93 and 99.40 percent soils were loam, respectively. In Pindi Gheb, 32.50 percent soils were sandy loam and 67.31 percent soils were loam. In tehsil Jand, 49.17 percent soils were sandy loam J. Agric. Res., 2010, 48(4) 508 O. Rehman et al. while 50.83 percent soils were loam. This shows that soils are quite heterogeneous and variable in texture. Regarding ranges (Table 3a & b), minimum saturation percentage (18%) appeared in tehsil Jand while maximum (86 %) was found in tehsil Attock. These results are in conformity with those of Rehman et al. (17) and Pervaiz et al. (15). Dissolved salts (electrical conductivity) Dissolved salts in soils create hindrance in normal nutrient uptake process by imbalance of ions, antagonistic and osmotic effects. Normally for research purpose, electrical conductivity of soil extract (ECe) is used for total dissolved salts but for assessing soil salinity and sodicity for advisory purpose, a soil- water suspension of EC1:10 is normally used as described in the manual of Malik et al. (13). Various workers (12, 15, 17) used the same method for electrical conductivity. However, EC1:10 is converted to ECe by multiplying with the factor Saturation percentage/100 as described by US Salinity Lab. Staff (4). The data (Table 2) showed that 99.60 percent of soil samples analysed in district Attock were free from salinity/sodicity. All tehsils showed similar trend i.e. > 99 percent soils had total dissolved salts in normal range except a few sites (0.38 %) which were sodic in nature. Regarding ranges of EC (Table 3a & b), minimum value (0.02 dS/m) was observed in tehsil Attock while maximum value (9.50 dS/m) was noticed in tehsil Fateh Jang during the year 2004-05. However, higher EC was also observed in tehsil Pindi Gheb (4.20 dS/m) and Jand (4.96 dS/m). Attock and Hassan Abdal tehsils had low dissolved salts i.e. EC < 1.70 and 1.50 dS/m, respectively. The reason for low accumulation of salts in soils is that texture of the most of soils is sandy loam to loam and high and sporadic rainfall in monsoon season leaches / washes the salts, if any, from the root zone. The drainage is also very good due to high slopes. Salt affected area was negligible in Campbellpur (renamed as Attock) as per survey carried out during 1971 (14) but with the passage of time, no considerable increase in salt affected area was observed which might be due to soil texture. These results are in line with those of Rehman et al. (17) and Mahmood et al. (12). Soil reaction (pH) The results (Table 2) further revealed that 5 percent soils at district level had pH < 7.5, which are considered as the best for agricultural use especially for growing high value crops, fruits and vegetables.