Management of Tea and its Associated Forest Crops for Sustainable Environmental Development and Tea Production in Bangladesh

ABSTRACT

Since 1995, an elaborate study was conducted on tea plantations of Bangladesh to evaluate the status of tea production. An effort was made to analyze the reasons for low yield and productivity and to find out easy and sustainable practices to improve the yield and production, to meet the growing demand of tea, considering the habit and habitat of tea plants. Importance of tea was studied from the historical past, present consumption trend and prevailing price and its future forecast on its popularity as a safe natural leaf beverage in the health conscious world.

During this study, the importance of shade and associated trees was reviewed to provide tea plants’ natural habitat, protection from adverse climatic conditions and to ensure optimum growth conditions for sustainable cultivation of tea crop. Considering the geographical location, height of the trees and undulation of the terrain, critical distance of the shade trees was ascertained by applying geometrical formulae viz. for flatland estates: Tan ? = Perpendicular/ Base and for undulated hilly lands: Sin A/a = Sin B/b = Sin C/c. Importance of some non-legume shade trees for improvement of soil was also studied. A remarkable result was obtained during this study that, available phosphorus (P), calcium (Ca) and magnesium (Mg) under Phyllanthus emblica (Emblic myrobalan or Indian goose berry, Bengali: Amloki) soil is 23.75, 3.58 and 1.46 times higher than that of Albizzia odoratissima (Black Siris). Similar results was also obtained for Terminalia belerica (Beleric myrobalan, Bengali: Bohera) where P, Ca, and Mg was 1.46, 8.79 and 2.96 times more than the soil under A. odoratissima respectively.

Behavioral study of tea plants was made under close observation. It has been investigated that, tea plants possess distinct territorial dominating habit over the other tea plants. The root system also possesses triple storey behavior, which was first time noticed during this research. The spreading of the roots are in the top soil, a middle storey for monsoon water table and third spreading at down below, for searching water and nutrients during the dry winter period. This habit has adapted the evergreen tea plant to remain active throughout the year, especially, in the adverse conditions. Depth of root zone is a critical factor for the growth and yield of tea. Environmental conditions, especially, drainage system and water holding capacities are identified as the limiting factors, which are influencing greatly the overall health and survival of tea.

During the habitat study, it was found that the area suitable for tea is in critical condition, as, most of the marginal flats are facing drainage problem. Rising of catchments bed by paddy cultivation and blockage of streams and rivers by dams, roads and bridges for agricultural and transportation purposes are causing serious effect on the rhizosphere of the tea plants and squeezing the tea area at an alarming rate. Protection of catchments and habitat restoration by making forest grooves with indigenous species to keep the water table at desired level, erosion control and creation of microclimate with diversified flora and fauna are essential. Indicator plants are identified for making immediate decision for raising plantations with suitable plantation crops. Long term rehabilitation practices are also formulated for improvement of soil for establishment plantations, especially for tea.

During the long study, branch angle is found as an important criterion for calculating surface area of a bush. Measuring the area of plucking surface with central dominance, comfortable manual plucking height and the branch angle, the critical spacing and optimum planting population was formulated. In this case, the geometrical formula was also used. The preconditions for healthy and functional frame formation are carefully scrutinized. The study also reveals that, healthy root system and reserve food help the plants recovering from pruning shock quickly. Regulated shade, mulching, biomass return to the soil and post pruning sanitation etc. are the essential for healthy growth of tea plant.

Reconsolidation of bush population is one of the important criterions for this long life duration plantation crop. Every year huge quantities of plants are in-filled in the vacant spaces but the success is very poor. The reasons for the failure to bringing a productive bush were investigated during this study. It is found that, a multiple factors are responsible for the failure; of which the most important one is the suppressing behavior of the root system of the previously existed neighboring bushes, although, it was earlier thought that the suppression from the side canopies resulted poor growth and weak framed bush.

Pruning is the most critical cultural practice of tea which was carefully investigated. All pre and post pruning conditions for a healthy vegetative growth of tea were studied. The effect of complete defoliation during final frame formation was studied and it was found that the bush frames were severely affected by cheap drugs drying out due to exposure in dry weather condition and lost their ability to give new shoots from the spreading surface but from the lower region, few shoots arose vertically which resulted broom shaped ill frame and it is concluded with negative effect of complete defoliation during immature stage.

For a sustainable and environment friendly culture, collaborative practices are scrutinized from past and present scientific researches and formulated the appropriate practices suitable for this region. For a sustainable culture, both organic farming and integrated pest management systems were emphasized along with the varied environmental factors related to habit and habitat, to improve tea production