Arun Jyoti Nath

Effects of Tillage Practices and Land Use Management on Soil Aggregates and Soil Organic Carbon in the North Appalachian Region, USA

Abstract Promoting soil carbon sequestration in agricultural land is one of the viable strategies to decelerate the observed climate changes. However, soil physical disturbances have aggravated the soil degradation process by accelerating erosion. Thus, reducing the magnitude and intensity of soil physical disturbance through appropriate farming/agricultural systems is essential to management of soil carbon sink capacity of agricultural lands. Four sites of different land use types/tillage practices, i) no–till (NT) corn (Zea mays L.) (NTC), ii) conventional till (CT) corn (CTC), iii) pastureland (PL), and iv) native forest (NF), were selected at the North Appalachian Experimental Watershed Station, Ohio, USA to assess the impact of NT farming on soil aggregate indices including water–stable aggregation, mean weight diameter (MWD) and geometric mean diameter (GMD), and soil organic carbon and total nitrogen contents. The NTC plots received cow manure additions (about 15 t ha−1) every other year. The CTC plots involved disking and chisel ploughing and liquid fertilizer application (110 L ha−1). The results showed that both water–stable aggregation and MWD were greater in soil for NTC than for CTC. In the 0–10 cm soil layer, the > 4.75–mm size fraction dominated NTC and was 46% more than that for CTC, whereas the PL > NTC > CTC, being 35%–46% more for NTC over CTC. The NT practice enhanced soil organic carbon content over the CT practice and thus was an important strategy of carbon sequestration in cropland soils.

Ecological implications of village bamboo as global climate change mitigation strategy

Purpose – The present study seeks to evaluate the role of village bamboo management in the rural landscape of North East India in global climate change mitigation.Design/methodology/approach – A set of 100 home gardens and 40 bamboo groves were selected from Irongmara and Dargakona village, in Cachar district, Assam, North East India through random sampling. Sampling was done mostly for smallholders. Culm growth, carbon storage, carbon sequestration and carbon in litter floor mass and soil of bamboo growing areas in homegarden was explored from 2003‐2007.Findings – Culm growth extension revealed the brief periodicity of culm growth in a single growth period. Of the total carbon storage soil contributed 84.6 per cent of the total (50.1 Mg ha−1) followed by carbon in above ground vegetation 15 per cent (9 Mg ha−1) and carbon in litter floor mass 0.4 per cent (0.2 Mg ha−1).Practical implications – Bamboo plantation development and its management in home gardens has social, ecological and economical benefits ...

Impact of land use changes on the storage of soil organic carbon in active and recalcitrant pools in a humid tropical region of India

Quantifying soil organic carbon (SOC) dynamics is important in understanding changes in soil properties and carbon (C) fluxes. However, SOC measures all C fractions and it is not adequate to distinguish between the active C (AC) and recalcitrant or passive C (PC) fractions. It has been suggested that PC pools are the main drivers of long term soil C sink management. Therefore, the present study was undertaken with the objective of determining whether or not SOC fractions vary with land use changes under a humid tropical climate in the North East India. A chronosequence study was established consisting of natural forest, Imperata cylindrica grassland and 6, 15, 27 and 34yr old rubber (Hevea brasiliensis) plantations to determine changes in the different fractions of SOC and total SOC stock. SOC stocks significantly varied with soil depth in each land use practice. SOC stocks increased from 106Mgha-1 under 6yr to 130Mgha-1 under 34yr old rubber plantations. The SOC stocks under 34yr old plantations were 20% higher than that under I. cylindrica grassland, but 34% lower than SOC stocks recorded under natural forest soil. The proportion of AC pools decreased with increase in plantation age, AC pools being 59% of SOC stock in 6yr old stands and 33% of SOC stocks in 34yr old plantations. In contrast, the proportion of PC pools increased from 41% of SOC stock in 6yr old plantation to 67% of SOC in 34yr old plantation. In the 50-100cm soil depth, the PC pool under 27-34yr old plantations was comparable with that under natural forest but much higher than in I. cylindrica grassland. Therefore, it is concluded that old rubber plantations can play a significant role in long term soil C sink management.

Population status and regeneration of a tropical clumping bamboo Schizostachyum dullooa under two management regimes

Schizostachyum dullooa (Gamble) Majumder ‘dolu bamboo’ is a thin walled sympodial moderate sized to large tufted bamboo, dominant in the successional fallows of northeast India. The impact of resource management on productivity and sustainability of the species was evaluated by investigating the population status and regeneration in Cachar tropical semi evergreen forest under private property resource management (PPRM) and common property resource management (CPRM) regimes. Population status revealed current-year, one-year, two-year and three-year-old culms contribute 54%, 24%, 16% and 6% of the total culms per clump, respectively, under PPRM. Three-year-old culms were absent in CPRM and population status was thus represented by current year (83%), one-year (16%) and two-year (1%) old culms. Net change, rate of change and % gain in population for different age classes showed the prevalence of management practices under CPRM was unscientific. Efficiency of new culm production per clump used as an index of regeneration was 69.7% in PPRM and 59.88% in CPRM. New culms produced under CPRM were small and thin. We conclude that CPRM is inappropriate for a long term economic and ecological sustainability of the species and alternative management protocols are needed for conservation of the species.

Net ecosystem productivity and carbon dynamics of the traditionally managed Imperata grasslands of North East India

There have been few comprehensive descriptions of how fire management and harvesting affect the carbon dynamics of grasslands. Grasslands dominated by the invasive weed Imperata cylindrica are considered as environmental threats causing low land productivity throughout the moist tropical regions in Asia. Imperata grasslands in North East India are unique in that they are traditionally managed and culturally important in the rural landscapes. Given the importance of fire in the management of Imperata grassland, we aimed to assess (i) the seasonal pattern of biomass production, (ii) the eventual pathways for the produced biomass, partitioned between in situ decomposition, harvesting and combustion, and (iii) the effect of customary fire management on the ecosystem carbon cycle. Comparatively high biomass production was recorded during pre-monsoon (154 g m-2 month-1) and monsoon (214 g m-2 month-1) compared to the post-monsoon (91 g m-2 month-1) season, and this is attributed to nutrient return into the soil immediately after fire in February. Post fire effects might have killed roots and rhizomes leading to high belowground litter production 30-35 g m-2 during March to August. High autotrophic respiration was recorded during March-July, which was related to high belowground biomass production (35-70 g m-2) during that time. Burning removed all the surface litter in March and this appeared to hinder surface decomposition and result in low heterotrophic respiration. Annual total biomass carbon production was estimated at 886 g C m-2. Annual harvest of biomass (estimated at 577 g C m-2) was the major pathway for carbon fluxes from the system. Net ecosystem production (NEP) of Imperata grassland was estimated at 91 g C m-2 yr-1 indicating that these grasslands are a net sink of CO2, although this is greatly influenced by weather and fire management.

Fired Bricks: CO2 Emission and Food Insecurity

Abstract Fired bricks are used for construction purposes over the millennia, going back to the Indus Valley Civilization. The traditional brick‐making process involves removal of agriculturally productive topsoil rich in clay and soil organic matter contents. In addition to the removal of the fertile topsoil and accelerated degradation by other processes, the traditional clay brick making process also emits CO2 and other gases into the atmosphere. Therefore, the present study aims to assess the impact of brick making in India on: (i) the magnitude of annual CO2 emission and (ii) the loss of agricultural production. Currently, 0.7 Mha (million hectare) of agricultural land is under brick kilns that produce ≈250 billion bricks annually. It is estimated that soil organic carbon lost through the firing process of 250 billion bricks is 5.58–6.12 Tg (teragram) (20.48–22.46 Tg CO2), and in conjunction with clay burning and coal combustion the process releases 40.65–42.64 Tg CO2 into the atmosphere per annum. Brick kiln also impacts quality of the exposed subsoil, and may also reduce 60–90% agronomic yield. Therefore, brick making from topsoil exacerbates food and nutritional insecurity by degrading soil quality, and increases risks of climate change through increase in gaseous emissions.