West Bengal in India

The second largest tea producing state of India is West Bengal. Darjeeling districts itself produces 25% of India’s total tea production. The Tea cultivation is being carried over centuries in Indo-Burma mega-biodiversity hotspot of Assam and Dooars region of West Bengal. The tea twigs (bushes) are pruned on every four to five years to maintain their vegetative growth as well as to adopt crop-husbanding practices. This process will support to adopt the proper soil conservation practices and prevent further degradation of soil resources for sustainable productivity of tea .Tea being a foliage crop, the shoots (two leaves and a bud) are harvested at regular intervals. In this process, nutrients are removed from the plant-soil system and they should be replenished to maintain the nutritional condition of the soil. To restore the soil fertility, manures, other than organic or biomanure are being used in several crop fields. Since India is a second highest in tea export, the use of chemical manure and pesticide decreases its export demand. Since organic manures, including Bioinoculant or biofertilisers are gaining momentum day by day to cope up the growing demand of “organic crops”, the use of biofertilisers in tea field is of great importance.

Soil fertility is the capacity of soils to make nutrients available to plants. The nutritional condition of arable soils can be related to yields in order to develop proposals for fertilization (Tisdale et al., 1985). Nutrient management in tea plantations is an important aspect and nutrients are supplied mainly through manures other than chemical. However, it is widely accepted that a balanced manure application with efficient use of other inputs is the key to achieve higher crop production (Karthikeyini, 2002). Continuous and heavy applications of chemical / mineral manures lead to the deterioration of soil properties besides causing environmental damage. The uses of organic manures and biofertilisers could reduce these problems as they are advantageous over manures other than organic or biomanure to improve soil fertility. Thus, it is felt necessary to integrate three different sources of nutrients viz., organics, chemicals and bioinoculants, for more efficient and economical production system in the long run. Bioinoculants or bioaccelerant are ecofriendly and a cost effective manure instead of manures other than organic or biomanure (Karthikeyini, 2002). The literature reveals related to the use of organics and biomanures in tea crop is very much low or limited. Therefore, there is a necessity to study the influence of integrated application of organic manure and biomanures with possible reduction of inorganic manures on yield and quality of tea.

Organic farming is gradually replacing classical or conventional farming due to increasing demand for organic food and growing environmental concerns (Hansen et al., 2001). The application of inorganic manures to enhance and maintain soil fertility and crop productivity often negatively affects the biogeochemical cycle (Perrott et al, 1992; Steinshann et al., 2004). In the last few decades the application of N, phosphorous and potassium (NPK) manures in crop production is growing rapidly (Adesmoyee and Kloepper, 2009). Classical or conventional farming using chemical manure leads to negative impact such as soil erosion, leaching and runoff of nutrients, loss of organic matter, pollution of natural water, impairment of environment quality, and evaporation of greenhouse gases, especially N, leading to environmental pollution and health hazards (Tilman, 1998; Tilman et al., 2002; Gyaneshwar et al., 2002; Kennedy et al., 2004, Adesmoyee and Kloepper, 2009). Therefore, it is now important to find out alternative ways of manure management in crop cultivation. Organic farming is able to increase the level of total N, nitrate and available phosphorus in soil and preventing nutrient leaching (Hansen et al., 2001). It has given attention to the farmers, scientists and policy makers look at the integrated approach to nutrient management in order to make crop cultivation sustainable and less dependent on manures other than chemical.

Biological N fixation or accumulation of N in soil is an inexpensive source of N for higher yields in nonleguminous crop, e.g., rice and wheat farming systems (Akond, 2007). Azotobacter is the genus consists of the members which are aerobic, free-living, N-fixing bacteria that are found throughout the world (Becking 1981, Tchan and New 1984, Thompson and Skerman 1979 and Subba Rao 1982). The Azotobacter was first isolated and described by Beijerinck in 1901 (Subba Rao 1982). Besides N fixation, Azotobacter has been found to synthesize growth promoting substances and antibiotics (Robson and Postgate 1980). These bacteria have one of the most highly active.

Cytochrome oxidases known (Jurtshuk et al, 1978, Jurtshuk et al, 1981), as well as highly active superoxide dismutase and catalase systems (Jurtshuk et al, 1984). Having these attributes, Azotobacter can play nutritional and stimulatory roles and can benefit the plants with its manifold action. Azotobacter inoculation has been shown to promote the growth and yield of a wide variety of plants like cereals, pulses, vegetable crops, fruit crops and cash crops (Bhandari and Somani 1990). It has been noted that Azotobacter is among the first organisms to develop in a newly formed soil, and the number of this organism in soil runs parallel with its fertility (Bhat 1961).