CHAPTER III Materials and Methods The soil tests (Rathore et al., 1995) and plant analysis (Takkar et al., 1989) used to be the criteria to delineate the deficient regions and sampling was done by random method. An attention was paid to collect the geo – referenced samples and the whole district was taken as an eight taluk mapping units. The soil survey, sampling and experiments were done in Nagapattinam district of Tamil Nadu between 2008 and 2011 to evolve an ideal soil quality assessment. The details of the study carried out, material used, technologies adopted in collection of soil and plant samples and methods adopted for the analysis of physico – chemical and macronutrients status in this investigation are briefly described in this chapter. 3.1. Study area and Location The location of experiment site was Nagapattinam district, that lies on the shores of the Bay of Bengal between Northern Latitude 10.10' and 11.20' East Longitude 79.15' and 79.50' This is peninsular delta district surrounded by Bay of Bengal on the East, Palk Strait on the South and land on the West and Northern Side. This District is predominantly, a coastal district having a large coast line of 141 kilometres. This District is having an area of 232257 ha in its fold. This district is enveloping 8 taluks and 518 revenue villages are shown in map 3.1. and table 3.8. The Reconnaissance soil survey of Nagapattinam district had indicated 18 soil series along with Sand, Swamp, Reserve forest viz., Alathur(Alt), Adhanur(And), Kohur (Khv), Kalathur(Klt), Kallivayal(Klv), Kondal(Knd), Kivalur(Kvr), Melkadu(Mlk), Nedumbalam(Ndb), Nagapattinam(Ngp), Padugai(pdg), Sikar(Skr), Sethi(Sth), Thiruvengadu(Tvg) and Valathalagudi(Vld). 55 The distribution of these soil series in 8 taluks of Nagapattinam district (Table 3.1) are presented as follows: Fig. 3.1: Location and Study Area 56 Table 3.1: The distribution of the Soil series of Nagapattinam District Sl.No. Soil Series Map Table Percent to Total 1 Sand - 2.03 2 Swamp - 1.28 3 Reserve forest - 2.0 4 Alathur Alt 0.23 5 Adhanur And 15.25 6 Kohur Khr 0.61 7 Kalathur Klt 19.34 8 Kallivayal Klv 3.74 9 Kondal Knd 7.46 10 Kivalur Kvr 11.04 11 Melkadu Mlk 10.35 12 Nedumbalam Ndb 4.07 13 Nagapattinam Ngp 0.65 14 Padugai Pdg 7.37 15 Sikar Skr 2.96 16 Sethi Sth 2.32 17 Thiruvengadu Tvg 2.61 18 Valuthalagudi Vld 6.69 Total 100 3.1.1. Taluk 1: Kutthalam (Table 3.8) Kutthalam Taluk is one of eight taluks of Nagapattinam district, covering 55 revenue villages and extending 17,087 ha. It occupies 7.35% area of the district. It is encountered by Tharangambadi and Mayiladuthurai taluks, Thanjavur and Thiruvavur districts with the part of Karaikal, Union territory of Pondicherry. Kalathur (Klt), Adhanur (Adn) and Podugai (Pdg) are the three important types of soil series. Paddy cultivation is the important occupation for the farmers as it is a main part of their family income. 57 3.1.2. Taluk 2: Mayiladuthurai (Table 3.8) Mayiladuthurai Taluk, covers 67 revenue villages and extending 24,485 ha. It occupies 10.54% area of Nagapattinam district. There were 335 soil samples five from each village analysed for soil quality of Mayiladuthurai taluk. It is compassed by Sirkali, Tharangambadi and Kutthalam taluks, Thanjavur and Cuddalore districts. Kalathur (Klt), Adhanur (Adn) and Podugai (Pdg) are the three important types of soil series. Paddy cultivation is the main occupation and an important source of income for the farmers in these taluks. 3.1.3. Taluk 3: Kilvelur (Table 3.8) Kilvelur Taluk, covers 55 revenue villages and spread over 27,445 ha. It occupies 11.82 % area of Nagapattinam district. There were 275 soil samples five from each village tested for soil quality. It is round about by Thiruvarur district, Nagapattinam, Thirukkuvai, Vedaranyam taluks and Bay of Bangal. Kivalur (Kvr), Sikar (Skr), Sethi (Sth), Nagapattinam (Ngp), Kohur (Khr) and sand are the soil series of this taluk. 3.1.4. Taluk 4: Vedaranyam (Table 3.8) Vedaranyam Taluk is one among eight taluks of Nagapattinam district, covering 57 revenue villages and extending 47,029 ha. It occupies 20.25 total percentage area of the district. It is surrounded by Thirukkuvalai and Kilvelur taluks of the same districts, Thiruvavur district, east and southward by Bay of Bengal. The soil series are Melkadu (Mlk), Nedumbalam (Ndb), Kallivayal (Klv), Alathur (Alt), Swamp, Reserve forest and Sand. Paddy cultivation is done for former’s income. Hence the land was cultivable for paddy, pulses, sugarcane and cotton which are the major crops in these soil series. 3.1.5. Taluk 5: Nagapattinam (Table 3.8) Nagapattinam Taluk, has 85 revenue villages and extending 30,231 ha. It occupies 13.02% area of the district. There were 425 soil samples five from each village analysed for soil quality of Mayiladuthurai taluk. It is surrounded by Karaikal (part of Union territory of Pondicherry), Bay of Bangal ocean, Kilvelur 58 taluk of the same district and Thiruvarur district. Kalathur (Klt), Adhanur (Adn), Kohur (Khr), Kivalur (Kvr), Padugai (Pdg), Sethi (Sth) and Nagapattinam are the important types of soil series. Paddy, banana, groundnut, gingelly, sugarcane, flowers, vegetables and cotton are the important crops cultivated in this taluk. 3.1.6. Taluk 6: Sirkali (Table 3.8) Sirkali Taluk, covers 94 revenue villages and spread over 44, 214 ha. It occupies 19.04 % area of Nagapattinam district. There were 470 soil samples, five from each village tested for soil quality. This is surrrounded by Tharangambadi, Mayiladuthurai taluks, Cuddalore district of Tamilnadu and Bay of Bangal in the east. The soil series are Adhanur (Adn), Kondal (Knd), Thiruvengadu (Tvg), Valuthalagudi (Vld) and reserve forest (RF). Paddy, sugarcane, cotton and vegetables are the important crops for these soil series. 3.1.7. Taluk 7: Tharangambadi (Table 3.8) Tharangambadi Taluk, covers 70 revenue villages and spread over 27, 726 ha. It occupies 11.94 % area of Nagapattinam district. There were 350 soil samples, five from each village tested for soil quality. This taluk is round about by Kutthalam, Mayiladuthurai, Sirkali taluks, Bay of Bengal, Karaikal and Thiruvarur district of Tamilnadu. The soil series are Kalathur (Klt), Padugai (Pdg) and Adhanur(Adn). Paddy, sugarcane, cotton, banana, vegetables and flowers are the important crops for these soil series. 3.1.8. Taluk 8: Thirukkuvalai (Table 3.8) Tharangambadi Taluk, covers 70 revenue villages and spread over 27, 726 ha. It occupies 11.94 % area of Nagapattinam district (Table 3.2). There were 350 soil samples, five from each village tested for soil quality. This taluk is round about by Kutthalam, Mayiladuthurai, Sirkali taluks, Bay of Bengal, Karaikal and Thiruvarur district of Tamilnadu. The soil series are Kalathur (Klt), Padugai (Pdg) and Adhanur(Adn). Paddy, Sugarcane, cotton, banana, vegetables and flowers are the important crops for these soil series. 59 Table 3. 2. The geographical extent of the taluks in Nagapattinam District S.No Name of The Taluks Extent (ha) Total (%) No. of Villages 1 Kutthalam 17,087 7.35 55 2 Mayiladuthurai 24,485 10.54 67 3 Kilvelur 27,445 11.82 55 4 Vedaranyam 47,029 20.25 57 5 Nagapattinam 30,231 13.02 85 6 Sirkali 44,214 19.04 94 7 Tharangambadi 27,726 11.94 70 8 Thirukkuvalai 14,040 6.04 35 Total 2,32,257 100 518 3.2. Methods of Soil Sampling A visual survey of the field was made for sampling. The soil colour, texture, management and cropping pattern was considered for preparing sampling unit. A V-shaped cut was made with a spade to remove 1 to 2 cm slice of soil. The surface soil samples were collected from 0-15 cm depth by spade and put in a clean bucket. The soil samples poured out from the bucket on a piece of clean paper and mixed thoroughly. Then spread the soil evenly and divided it into 4 quarters. Two opposite quarters were rejected and mixed the rest of the soil again. Repeated the process till left with about half kg of the soil, collected it and put in a clean polythene bag which was properly marked to identify the sample. Details of the samples was written in the information sheet, one copy was put in 60 the bag and tied well. The packed soil samples were taken to the laboratory for air dried. Such samples were ground with a wooden pestle and mortar so that the soil aggregate are crushed but the soil particles do not break down. After grinding, the soil was screened through a 2 mm sieve. The practice of passing only a portion of the ground sample through the sieve and discarding the remainder is erroneous. This introduces positive bias in the sample as the rejected part may include soil elements with differential fertility. The entire sample should, therefore, was passed through the sieve except for concretions and pebbles of more than 2 mm. The coarse portion on the sieve should be returned to the mortar for further grinding. Repeated sieving and grinding was done till all aggregate particles were fine enough to pass the sieve and only pebbles, organic residues and concretions remain out. After the sample was passed through the sieve, it was again mixed thoroughly. The soil samples should be stored in cardboard boxes. These boxes should be numbered and arranged in the soil sample room for further soil quality analysis, by which soil physico – chemical parameters and macronutrients were determined. 3.3.