Science Vision

59-67

Authors: L. Hnamte, C. Lalrammawia, B. Gopichand

Intensive jhum cultivation is the biggest ecological threat due to its associated problems such as biodiversity loss, deforestation, soil erosion and the gradual reduction of land productivity in Mizoram. The intrinsic practice of jhum cultivation still dominated the farming system in Mizoram to a large margin. Four levels of nitrogen, phosphorus and potassium soil fertilizer application in local maize variety was conducted in 2 years, 3 years and 5 years jhum cycles. Strong significant (P<0.05) response to fertilizer application occurred in the growth and yield performance of maize. Different period of jhum cycles also had significant (P<0.05) effect in growth and yield with highest productivity in longest jhum cycle. Taking account of the poor soil nutrient content and the acidic soil in Mizoram, application of urea at lower rate under longer jhum cycle may be adopted.

74-81

Authors: J. Blick, S. Kumar, V. K. Bharati, S. Kumar

Arsenic is a naturally occurring element found primarily in rocks, soil, water, and plants in the Indian sub-continent. Natural events, such as infiltration to water, dissolution of minerals from clay, and erosion of rocks, can release arsenic into water. Arsenic is usually found in inorganic forms in water, the most predominant form being arsenate [As (V)], with arsenite [As (III)] under some conditions. In organism, it bonds with carbon and hydrogen, forming organic arsenic. The contamination of groundwater by arsenic in Chawngte, Mizoram, India is likely to happen due to its sharing of a common land border with Bangladesh. Groundwater and rainwater are the most important supplementary sources of drinking water in region. Hence, residents of Chawngte are relying on tuikhurs (spring) and other natural sources. It has been observed that several number of tube wells, tuikhurs and hand pumps, exist in any cluster or community. Generally, not all tube wells and hand pumps in an area are affected by arsenic. Therefore, the immediate challenge is to find out the unaffected ones in the affected areas and commence routine monitoring in order to stop using the currently affected tube wells as soon as arsenic is detected. The physico-chemical parameters like pH, EC, TDS, total hardness, total chlorides, iron and free chlorine are well within the acceptable limits for drinking water. Arsenic and turbidity are slightly higher than the acceptable limits but still within the permissible limit of 0.05 mg/l and 5 NTU respectively.