8.2.Effect of different soil preparations on moisture conservation

In the year 1986-87, an experiment was conducted to monitor the effect of different soil preparations viz; pitting, trenching, saucer shape pits and ploughing on the growth of seedlings of different species.

8.3 Soil conservation

The normal practice of trenching all along the contour lines across the slopes is an old method of soil and water conservation in dry areas. However, systematic experiments have not been carried out to assess the different types of soil conservation measures. In the year 1987-88, construction of check dams and gully plugs was undertaken along with planting of various species in Nandi hills as a measure to conserve soil and moisture. It is gratifying to note that the area is slowly getting stabilized. The accumulation of silt near check dams is considerable indicating that soil erosion is getting arrested. Besides, planting of Agave and Bamboo has helped in stabilizing the gullies. There was also an attempt to plant Khus grass to check soil erosion. It has proved successful in some of the eroded areas.

8.4 Agave Plantation

Agave plantations were done on degraded sites over hillocks with steep slopes. The three species of Agave viz; Agave cantala , Agave americana and Agave sisalana were tried with different spacing and planting techniques, at Turalligudda of Channapatna Research center and at B.G.Kere of Challakere Research center. The rate of growth, number of leaves per plant and the rate of silt accumulation etc. are under observation.

9.1 Vermicompost

Vermi-compost refers to the manure prepared by the action of earthworms on any organic matter like cow dung, vegetable matter, leaf litter etc. Earthworms are voracious feeders of any organic matter and assimilate only 10-15 per cent of the feed. The worm cast is very rich in nutrients, containing 0.52 per cent Nitrogen, 0.9 per cent Phosphorous and 0.2 to 0.5 per cent Potassium. Another advantage is that these nutrients are in readily available form because of mineralization. In every forest nursery, production of vermi-compost can be taken up at relatively low cost.

The technique of preparation of vermi-compost is not cumbersome. Cement tanks or wooden trays of convenient sizes can be used for this purpose. Saw dust or husk or coir or gunny and fine sand are used as the bedding material and spread in 3cm thick layers. On this, organic matter is spread. Initially a small quantity of cow dung has to be mixed to make the feed more palatable for worms. This has to be spread uniformly on the surface to a height of not more than 5cm, as worms are surface feeders. Then worms are introduced. They feed on the organic matter. The feed is to be supplemented as and when required. The worm casts should be taken out, air-dried and sieved to remove cocoons and small worms, which can be reintroduced. The cast or the vermi-compost is stored for use as manure. The foundation bed is to be changed once in 3-6 months. Care is to be taken to protect the worms from ants, termites etc. Water logging of the beds should be prevented. Through this technique, continuous production of vermi-compost is possible to meet the requirement of the nurseries.

9.1.1 Vermicompost at Gungargatti (Dharwad )

9.2 mycorrhizae and its application

Some of the endo-mycorrhizal species, which are tried at Dharwad Silviculture laboratory during 1993-94, are the following. Glomus mosseae is mainly specific to Tamarind whereas Gigaspora is specific to Leucaena leucocephala and Casuarina equisetifolia , though there are reports that they perform well on a wide range of forest species. The starter culture was obtained from UAS, Bangalore and taken-up for further multiplication in the laboratory by using soil rite perlite as rooting media and maize as host plant. A plant nutrient solution that contained all major & minor nutrients and trace elements for the balanced growth of the plant was used. After raising the maize and mycorrhizal crop for about 100 days, it was harvested and tested for spore formation at UAS, Dharwad. The culture produced was of high standard, which was taken up for field trial to study its efficacy and also further multiplication.

9.4 VAM culture at Bangalore Research Center

10.1 BIOLOGICAL CONTROL of Teak skeletOnizer

The laboratory for production of Trichogamma, an egg parasite of Teak Skeletoniser, was established in the year 1986. An experiment over an area of 4.00 ha was carried out by releasing 4 lakhs eggs at the rate of 1 lakh egg/ha in the 1982 Teak plantation of Haliyal division. A total of 19 releases at an interval of 10 days were made between June 1987 and December 1987. Samples of 20 leaves each were taken, both from treated and control plots at monthly intervals. A visual assessment of leaf damage was made, average number of larvae present per leaf and percentage of parasitisation of eggs was worked out. It could be seen that there were fewer larvae per leaf and correspondingly less damage in the treated plot.

Another experiment on biological control for Teak skeletoniser Hapalia machaeralis (Lepidoptera: Pyralidae) was initiated in the year 1988- 89 in the Teak plantation of Karka in Haliyal Range . One-hectare plot was selected and demarcated for the release of Trichogamma egg parasite and the remaining area of the plantation was considered as the control plot.

The egg parasites produced at Forest Research Laboratory, Dharwad were released at the rate of four lakh parasites/ha (Twenty cards each containing about 20,000 eggs) at 10 days intervals. A total of 20 releases were made from 8.6.1989 to 26.12.89. The egg parasite cards were randomly distributed in the selected one ha of Teak plantation, 24 hours before adult emergence.

The incidence of pests during the year of study appeared to have been low on account of continuous heavy rains with few sunny days.