The standard methodology to assess the productivity and nutrient dynamics on plantation bamboos has not been suggested so far. With an experience of cultivation practices and research, an attempt was made to standardize the methodology to evaluate the productivity and nutrient dynamics on plantation bamboo.
The methodology includes:
(i) Nursery management techniques,
(ii) Growth studies,
(iii) Biomass estimation,
(iv) Bio-chemical analysis,
(v) Nutrient dynamics etc.
(i) Nursery Management Techniques:
(a) Preparation of Nursery:
A nursery are of 10 x 5m should be prepared in a field and filled with a mixture of soil and sand in the ratio 3:1. The seedlings were obtained from tissue culture methods and kept in polythene bags. It should be pricked out from the bags when about 7cm in height. About 25-30 seedlings planted in 1m2 of raised nursery bed. Watering should be done 2-3 times a day and care should be taken to avoid over- saturation. Nursery beds should be provided with a coconut thatch to protect the seedlings from direct sunlight.
(b) Transplanting:
The seedlings in the nurseries should be uprooted carefully and transplanted to the field. The seedlings planted in pits of size 45 x 45 x 45 cm at a spacing of 6 x 6 m with 250 seedlings /ha-1. One week prior to planting, the pits should be treated with 0.01 per cent Aldrex and 0.05 per cent Bavistin to prevent termite and fungal attack.
Planting must be completed before the monsoon fully sets. To provide better initial environment to the seedlings, the upper half of the pit should be filled with a mixture of 25 gram Vijay complex, 17: 17: 17 per pit and the lower half with original soil.
The transplanted seedlings should be watered for two hours regularly in the morning and evening. Weeding should be done as and when required. Care should be taken to avoid water logging. The plantation should be protected against damage by rodents, grazing and browsing animals.
(c) Production of Culms:
All transplanted seedlings will produce rhizomes, which will produce a number of lateral culms to form clumps. The productivity of bamboo is assessed by recording the number of new culms produced annually. At a given site, the production of new culms will mostly dependent on the clumps of the previous year, the degree of congestion and clump age.
(ii) Growth Studies:
Growth Measurements:
To study the growth measurement, fifteen clumps should be randomly selected and should be identified with paint marking. The number of culms in these selected clumps should be counted. New culms sprouting from the selected clumps will be taken for growth measurements. In each clump, five newly sprouted culms should be marked with paint, totaling 150 observations.
On alternate days the height of each culm will be measured, and after it had reached 1.37 m height, the diameter at breast height (DBH) should be recorded. All observations will include for the basal area girth, DBH and growth in height on all culms.
(iii) Biomass Estimation:
To estimate the total biomass in relation to organic productivity, 15 culms should be randomly selected from each age group. For reasons of economy the rhizome should be excavated only three in from each age group. After felling, the total height of each culm, diameter at breast height (DBH), basal area and number of nodes should be measured and sub-divided into leaves, branches, culm and rhizome. Fresh weight of the components should be estimated in the field and sub-samples from each component should be brought to the laboratory in plastic bags.
The sub-samples were then oven dried at 103°C ± 2°C to a constant weight. From the oven, dry weight of the samples, the total standing biomass of each age group will be calculated by multiplying the total number of the bamboos of different ages with the average dry weight of the sample.
(iv) Biochemical Analysis of Bamboo Leaf:
The entire productivity of bamboo will ultimately depend upon the photosynthetic efficiency of the leaf. Hence, studies on biochemical analysis of bamboo leaf should be undertaken in the plantations. Fifteen culms from each age group should be selected for the biochemical analysis. Fresh leaves should be taken for chlorophyll, carotenoids protein total soluble carbohydrates and starch.
(v) Nutrient Dynamics:
(a) Nutrient Analysis:
The bamboo should be reduced to sawdust by means of an electrical saw. The saw dust should be sieved initially with 65 meshes cm-2and later with 200 meshes cm-2. The material retained during the second sieving will be called “average wood” and used for the analysis. Nitrogen and Phosphorous should be estimated as described by Armstrong et al., (1976) using the Technicon Autoanalyser -II (Gedko International, U.K).
The sample should be digested in a Kjeldatherm digestion system KT 408 (bonn) at 400°C for 3 hours. One gram sample should be digested in digestion tubes with both 2.5 g potassium sulphate and 5 ml H2SO4. After digestion and cooling, the digested sample should be make upto 50 ml with distilled water and used for analysis of N and P.
The nutrients K, Ca and Mg should be analysed using an atomic adsorption spectrophotometer (Perkin – Elmer 5000 USA) after wet digestion of a 1g sample with a triple acid mixture (10 ml conc. HNO3, 4 ml HCIO4 and 1 ml conc. HCI).
The digested samples were filtered through whatmann No. 42 filter paper and should be made upto 100 ml with distilled water and this solution should be stored and used for analysis. All analysis should be performed on the average of three replicates.
(b) Nutrient Retained:
The nutrient retained in the average annual production of bamboo should be obtained by multiplying the biomass components by their respective nutrient concentration.
(c) Nutrient Return:
Estimation of litter production and nutrient return should be carried out in the bamboo plantations to study the dynamics of nutrients. Nine litter plots sized 1 x 5m should be laid down randomly throughout the sample plot. The litter – plots should be marked enclosing the area with nylon thread.
The contents in the litter plots should be sampled completely by the end of every month and separated into leaf-litter and twig-litter. Fresh weight should be estimated in the field and the sub-samples of each component should be taken to the laboratory. The sub-samples were then oven dried at 80°C to a constant weight. From the oven-dry sample weight the total dry weight of the litter can be calculated.