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Soil Chemical Analysis of Kazi and Kazi Organic Tea Garden and Compared to Ordinary Tea Gardens of Bangladesh

Tea is grown in Bangladesh under marginal climatic and soil conditions. Its production is greatly influenced by many physical, chemical, biological and natural factors. The increasing land use intensity without adequate and balanced use of chemical fertilizers and with little or no use of organic manure has caused severe fertility deterioration of our soils resulting in stagnating or even declining of crop productivity. The need of the hour is to achieve substantially higher crop yield than the present yield levels from our limited land resources on a sustainable basis. A feasibility study was carried out of one and only organic tea garden namely Kazi & Kazi Tea Estate at Panchaghar and compared to ordinary tea gardens located at Sylhet namely Zareen Tea Estate, Nurjahan Tea Estate and Malnichara Tea Estate as secondary data to investigate the fertility status of soil. Results of the present study showed that soil solutions were acidic in nature in all seasons. Medium to high soil organic matter, medium to high available iron and phosphorous, and low availability of potash showed that soils were not sufficiently fertile for crop production. Student t-test values of all the parameters with control sample showed statistically significant results for SOM and available P. The critical values have been fixed at 0.1% for N and 1% for OM, 10 μg/g for P, 80 μg/g for K, 25 μg/g for Mg, 90 μg/g for Ca, 2 μg/g for Zn and 20 μg/g for S. The nutrient status is much higher in Kazi & Kazi organic tea estate in compared to other ordinary tea estates in Bangladesh.


Introduction
Tea (Camellia sinensis L.) is grown on different land elevation which is the oldest and best beverage in the world next to water. Tea is to be considered as the most popular and cheapest temperate drink in the world. Tea is an intensively managed perennial monoculture crop cultivated on large-and small-scale plantations situated between 21˚3'N and 26˚15'N latitude and between 89˚0'E and 92˚41'E longitude [1]. Tea cultivation in Bangladesh developed concurrently with the northeast Indian tea during early part of the 19th century. Bangladesh tea grows in the three fairly divergent ecological zones, namely Surma valley in greater Sylhet, Halda valley in Chittagong and Karatoa valley in Panchagarh district [2].
The tea industry of Bangladesh dates back to 1857. Now tea is an agro-based labor-intensive industry of Bangladesh. It plays an important role in the national economy through trade balancing and employment generation. At present, there are 166 tea estates in Bangladesh. On an average, Bangladesh produces 63 million kilograms tea annually. Today Bangladesh tea is occupying about 3% plantation area of world tea, producing as much as 2% of tea production in the world. It occupies the 9 th position, out of 40 countries, in tea horizon as regards the plantation size and production-level, while the 8 th position regarding per unit production [3].
Modern scientific technology encourages the use of chemical pesticides, herbicides, fungicides and chemical fertilizers for the high crops production. It creates the whole agriculture production chemicalization environment and soil become unhealthy all biodiversity and ecosystem have been sick and whole ecology becomes chemicalized. Whereas organic agriculture is a production system that sustains the health of soil ecosystems, biodiversity and cycles adapted to local conditions rather than the use of inputs with adverse effects. Organic tea Farming promotes and enhances biodiversity, biological cycles, soil biological activity through management practices that restore maintain and enhance ecological harmony. The organic tea production system is different from conventional tea production [4]. Organic manure is applied to tea as green manure or as one of many other organic materials, some of which have been allowed to decompose. In favorable circumstances soil fertility and structure are improved. A bed of humus is formed which supports an active micro fauna which speeds decomposition converting nutrients to an available form. Erosion is reduced and the infiltration of water improved [5]. will not develop fully when the soil or the sub-soil is either saturated or even nearly saturated with water for more than a very short period [6]. The chemical requirement of tea soil is very specific, requiring 1) the absence of more than small amounts of calcium and 2) the presence of very definite acidity both in top soil and sub-soil. It seems probable that failure of tea in many areas has been due to high pH, although it has been attributed to climate and others cause.
Tea is grown in a wide variety of soil types and its growth is favored in acidic conditions, with pH values ranging between 5.0 and 5.6. Although it will grow in soil pH as low as 4.0, soil pH only marginally higher than 5.6 is considered unsuitable without pH adjustment. Soils with pH values > 6.5 are not amenable to treatment for commercial tea growing [7]. Therefore, the main objectives of this research were 1) to assess the chemical properties and nutrient status of tea soils, and 2) to encourage the organic farming system for long term fertility of soil.

Sampling Site
The sampling sites were selected for collecting the samples in organic tea gar-
Three pits were dug in each of the tea estates and 4 soil samples were collected from each depth of the profile. All of the soil samples of respective depth were well mixed and composite samples were prepared. They were brought to the laboratory and air-dried ground and sieved at 2 mm sieve. The ground samples were kept in a plastic bottle and preserved in the laboratory till chemical analysis. The following parameters of the soil were determined [9].

Laboratory Analysis
Most of convenient methods were used in this chemical analysis. Soil pH was determined electrochemically with the help of glass electrode pH meter [11]. The ratio of soil water was 1:2.5. The organic carbon was determined volumetrically by wet oxidation method [12]. Organic matter was calculated by multiplying the percentage of organic carbon with conventional Van bemmelen's factor of 1.724 [13]. The total N of the soil was determined by micro Kjeldhal's method following sulfuric acid digestion [11]. The C/N ratio of the soil was calculated by dividing the percentage of total carbon by the percentage of total nitrogen. The available P of soil was determined by Olsen extraction; 0.5 N NaHNO 3 at pH-8.5 (Soil:Extractant = 1:10) using a chemico visible spectrophotometer at 882 nm wavelength as Molybdophosphoric blue color method in a sulfuric acid system [11]. Available Fe was extracted with 1N NH 4 OAC (pH = 3.0). The extract was analyzed by spectrophotometer at 510 nm by Colorimetric method [11]. The

Statistical Analysis
The experimental data were statistically analyzed. Analysis of variance (ANOVA) was computed. It was done to obtain the difference among different among gardens and depths.

Results and Discussions
Tea soils are highly weathered, extremely acidic and low in fertility status. Furthermore, these soils do not receive deposits of fertile silt by flooding; rather they suffer from erosion. The most suitable tea soil is thought to be light, friable and well drained having soil pH from 4.5 to 5.8 [14]. The critical values have been fixed at 0.1% for N and 1% for organic matter. The minimum level of nutrient status of tea soil should be 10 μg/g for P, 80 μg/g for K, 25 μg/g for Mg, 90 μg/g for Ca, 2 μg/g for Zn and 20 μg/g for S [1]. The pH of the surface soil is slightly higher than the subsurface soil in almost all the sampling places. Further the statistical analysis showed that there was no

Available P & Fe Content in Collected Soil Samples
The available P & Fe was determined and results were presented in Table 2. Approximate amount of available P & Fe was found in the soils of all tea estates.
The mineralogy of the soils might be responsible for such phenomena.
The statistical evaluation of the results for available Phosphorus of the investigated soils did not differ significantly from each other in available Phosphorus contents. However, P was uniformly distributed in different depth of soil profile.
Furthermore, there was no significant difference among tea estates but there was a significant difference among the depths of the profiles.

Content of Exchangeable Na, K, Ca and Mg
The contents of the exchangeable Na, K, Ca and Mg were present in Table 3.
The exchangeable Na contents were higher than those of K. The highest concen- The statistical analysis showed that there was no significant difference among tea estates but there was a significant difference among the depths of the profiles.  The results varied widely among themselves in exchangeable Na, K, Ca and Mg contents with the depth of profiles. Their contents were very low in the soils of all 3 tea estates probably because of leaching of these cations under very acidic conditions (pH = 4) prevailed in soils of 3 tea estates. Such low contents of these exchangeable bases might influence the CEC of the soils that affect nutrient retention of the soil profile. However, the nutrient status of Kazi and Kazi Tea Estate was remarkable and relatively high than other tea estates

Content of Soil Organic Carbon, Organic Matter, Total N and C/A Ratio
Organic carbon, Organic matter, and total N contents at different depths of the soil profile of 4 tea estates were presented in Table 4. The organic matter contents of the soils of ordinary tea estates were generally low (<1.5%) but enrich of Kazi & Kazi organic tea estate in the soil profiles influencing the contents of soil nitrogen. Organic matter (OM) content decreased with increasing depth of soil profile. In addition, cation exchange capacity and interrelated parameter to organic matter exhibit a similar trend like organic matter.
The ANOVA tests showed that there was no significant difference in %OC of the tea estates, while a significant difference exists within the soil profiles. Furthermore, the statistical analysis of the results showed that there was a difference in organic matter contents between organic tea estates and ordinary tea estate as well as in the different depth of the soil profiles. From the results further showed Open Journal of Soil Science that OC and N were the highest in the topsoils of the sampling locations and then declined with depth. The soil consisting of less than 0.1% N is considered poor for tea cultivation [15].

Conclusions
The