Behavioural responses of desert gerbil, Meriones hurrianae after removal of scent marking gland.

The desert gerbil, M. hurrianae scent marks the general substratum in its territory with the sebum exudation of mid abdominal gland and urine. Having assessed number of functions, which scent marking plays in the social life of these rodents, the scent marking behaviour was studied in animals, in which the gland was surgically removed and was compared with that of intact rodents. After recovery from the operation, the scent marking frequency of both male and female M.hurrianae declined significantly and was maintained at a low level. Surprisingly, scent marking with urine also declined considerable with time. After 5 months of the operation, desert gerbils were given a choice to respond to male and female sebum odours. The frequency of their scent marking with either sebum or urine did not show any significant enhancement as compared to their initial marking rate. However, the duration of their stay and scent marking frequency near the source of the sebum odour was more that in the clean side of the cage. The role of such altering behaviors of M. hurrianae and their impact on social organization are discussed.

Effect of supplementary feeding of vitamin K1 on difethialone treated Indian gerbil, Tatera indica Hardwicke in laboratory.

Two dosages (1 and 2 mg/kg) of vitamin K1 supplementation for 5 and 15 days were given to Indian gerbil T. indica fed on difethialone bait (0.0025%) for one day. The results indicated that the lower dosage could not reverse the anticoagulation process, however the period of mortality was considerably increased from 3-9 days (in control) to 5-14 days (5 days supplementation regime). Subsequently when the vitamin K1 dosage was doubled and given for 15 days, there was 100% reversal of anticoagulation process and all the test gerbils became normal within a month of poisoning with difethialone bait.

Evaluating second year cropping on jhum fallows in Mizoram north-eastern India: Energy and economic efficiencies.

Energy and economic efficiencies were evaluated on young (6 year) and old (20 year) jhum fields in Mizoram, north-eastern India during second year of cropping, and were compared with those in the first year. The effect of auxiliary measures such as tilling the soil or application of fertilizers (chemical or farm-yard manure or both in combination) was also examined on energy and economic efficiencies. The results indicated that traditional jhum cultivation is labour intensive and energy efficient, producing almost 15-20 times of energy invested. Energy and economic efficiencies decline with shortening of jhum cycle. These efficiencies decline further from first to second year of cropping. Tilling is not useful to improve either energy or economic efficiency. Fertilizer application, which is though profitable from the point of view of economic efficiency, is highly energy inefficient. Application of fertilizers during second year cropping can be encouraged. Organic manuring may be a better option than others to alleviate energy efficiency. However, a combination of organic and inorgamic manuring could be the best option to enhance economic efficiency.

Evaluating second year cropping on jhum fallows in Mizoram, north-eastern India—Phytomass dynamics and primary productivity.

Cropping on jhum fallows in north-eartern India is predominantly done for one year in a jhum cycle. If second year cropping is done, expanse of the forest land required for slashing and burning could be reduced significantly. We tested this hypothesis in a young (6 yr) and an old (20 yr) jhum fallow. We also evaluated if the productivity during second year cropping could be alleviated by auxiliary measures such as tilling the soil or application of fertilizers (chemical or farm-yard manure or both in combination). The results demonstrate that the ecosystem productivity (total dry matter production) and economic yield (rice grain production) decline with shortening of jhum cycle. Second year cropping causes a further decline in ecosystem productivity in old jhum field, but not in young jhum field. Economic yield from second year cropping in its traditional form (without any fertilizer treatment) is not much lower than that in the first year, and can be improved further by manuring the soil. Tilling of soil improves neither ecosystem productivity nor economic yield. Different fertilization treatments respond differently; while inorganic manuring enhances ecosystem productivity, a combination of inorganic and organic manuring improves economic yield.

Nutrient cycling in an excessively rainfed subtropical grassland at Cherrapunji.

Cycling of six mineral elements (N, P, K, Na, Ca and Mg) was studied in a humid subtropical grassland at Cherrapunji, north-eastern India during 1988-1989. Elemental concentrations in the shoot of four dominant grass species, viz., Arundinella khaseana, Chrysopogon gryllus, Eragrostiella leioptera and Eulalia trispicata were very low, and none of the species appears suitable for fodder use. Among different vegetation compartments, live root was the largest reservoir of all the nutrients (except Ca) followed by live shoot, dead shoot, litter and dead root. For Ca, live shoot was the major storage compartment. The total annual uptake (kg ha-1) was 137·3, 10·4, 51·1, 5·5, 8·7 and 18·2 for N, P, K, Na, Ca and Mg, respectively. In an annual cycle 98% N, 77% P, 49% K, 109% Na, 87% Ca and 65% Mg returned to the soil through litter and belowground detritus. A major portion of Ν, Ρ and Na was recycled through the belowground system, whereas nearly half of K, Ca and Mg was recycled through the shoot system. Precipitation acts as the source of Ν and Ρ input, but at the same time causes loss of cations.