An exponential increase in the human population has drastically reduced the length of fallow period (<5 years) in widely spread shifting cultivation (
Jhum
). This has increased the invasion of weeds and decreased soil fertility and crop productivity, and consequently raised concern of food security for the local farming communities. The present study was conducted in two
jhum
fallows (FL-10 and FL-15) to understand the response of fallow length and applications of indigenous soil microbes and rock phosphate on the levels of soil fertility and crop productivity. The results showed greater soil physicochemical properties in FL-15 compared to FL-10. Burning significantly increased the levels of soil pH, avail P, avail N in the soil, whereas, the same decreased the levels of soil C, MBC and SM in both the sites. Among treatments, the synergistic effect of rock phosphate and microbial inocula showed greater improvement in soil biochemical properties, and showed a climactic increase over control in crop productivity and rice yield in all sites. Maximum rice grain yield and productivity was recorded in FL-15 followed by FL-10. This study concludes that a mixture of rock phosphate and microbial inocula from the rhizosphere soil of early regenerating plant is effective in increasing soil fertility and crop productivity, and can be used as an important tool to sustain crop productivity and food security in the region.
Forests are the main repository of biodiversity and play an important role in maintaining the ecological balance of nature. The status of species diversity reflects the health of the ecosystem. Therefore, the information on variation in the flora, for example, species composition, diversity and the basal area within any ecosystem like the forest of Mizoram University campus, Tanhril village, Aizawl would be important in understanding the forest wealth of the campus. Keeping in view, the study was analyzed the composition and diversity of Mizoram University campus by laying 16 (10 m ×10 m) quadrats at random locations during 2015-2016. A total of 35 tree species belonging to 30 genera and 22 families were recorded in the forest communities of University Campus. Aporusa octandra was the most dominant tree species with maximum 31.50 importance value index (IVI), 3.29 Shannon diversity index (H0) and 6972 Simpson’s index (D) followed by Castanopsis tribuloides (28 IVI, 0.22 H0 and 5256 D) and least dominant species recorded were: Albizia odoratissima, Anogeissus acuminate, Lithocarpus elegans, Oroxylum indicum. This study suggests that the forest patches are recovering after the establishment of the University because of adequate protection which was degraded in the past by the villager for collecting the trees for firewood, edible wild food and selecting the mature trees for felling. Therefore, further studies on regeneration potential of tree species would be crucial for the conservation of ecologically important species and to assess rates of their recovery following the disturbance.
Soil carbon is one of the most affected variables to land-use change in tropics. The soil carbon flux plays a major role in regulating microbial activities and nutrient distribution in soil. This study aimed to evaluate the soil carbon stock in various land uses at different depths in the hilly terrain of Mizoram, Northeast India. Soil samples at 0-10 cm, 10-20 cm and 20-30 cm soil depths were collected from Rubber plantation (RP), Oil palm plantation (OPP), Teak plantation (TP), Bamboo Forest (BF), 5 years fallow (5YF), 10 years fallow (10YF), Tephrosia candida plantation (TCP), Horticulture garden (HORT), Homegarden (HG) and Natural forest (NF). Soil carbon stock varied significantly (p <0.05) across the land uses and depths. The soil under Tephrosia candida stand had significantly (p <0.05) higher values of C stock (73.66 Mg ha-1) which may be due to high biomass, dense vegetative cover and high C in root exudates. The minimum C stock estimated in Horticulture garden (43.28 Mg ha-1) is probably due to reduced soil organic matter. Soil carbon stock in Homegarden, Teak plantation, Bamboo forest and Rubber plantation ranged from 46.82 Mg ha-1 to 59.34 Mg ha-1 whereas 5 years and 10 years fallow land, Natural forest and Oil palm plantation ranged from 61.35 Mg ha-1 to 73.35 Mg ha-1. The study indicated that the land use change in the mountainous region significantly affected the carbon stock in the soil. A proper land use management strategies to increase the soil organic matter is recommended to enhance the carbon stock in this region.
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