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Abstract Many laboratory and mesocosm studies have demonstrated that earthworms influence nitrogen (N) cycling reactions that produce nitrous oxide (N2O) in well-aerated soils, but whether earthworms can stimulate N2O fluxes in realistic... more
Abstract Many laboratory and mesocosm studies have demonstrated that earthworms influence nitrogen (N) cycling reactions that produce nitrous oxide (N2O) in well-aerated soils, but whether earthworms can stimulate N2O fluxes in realistic field conditions remains to be determined. We conducted two field experiments in southern Quebec in perennial forage agroecosystems for 2 yr and agriculture riparian buffers for 1 yr to compare N2O fluxes from enclosures with ambient and artificially elevated earthworm populations. Despite a short-term ( 0.05) in mean N2O flux from enclosures in either field experiment. The elevated earthworm populations declined and stabilized at the same level as the ambient earthworm populations within 1–2 yr after the field experiments began. The homeostatic regulation of earthworm populations under field conditions could be related to inter- and intra-specific competition and limits to the food supply and habitat preferred by earthworms. Mean N2O fluxes in the perennial forage fields were negatively correlated with soil moisture, but not related to earthworm populations. In the riparian buffers, the average N2O flux was negatively correlated with vegetation cover, and positively correlated with soil moisture and the size of the earthworm population at the end of the study. Our results suggest that the effects of earthworm addition on N2O emissions measured from laboratory studies can not necessarily be extrapolated to field settings. Earthworm field experiments that continue in the longer-term and in a variety of ecosystems should provide better understanding of the seasonal and environmental variability of earthworm activity and N2O balance under field conditions.
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This pot-based study investigated the influence of co-composted wood-derived biochar on lettuce growth performance under salinity and drought stress conditions. Biochar of two particle sizes; > 2 mm and < 1 mm were co-composted with... more
This pot-based study investigated the influence of co-composted wood-derived biochar on lettuce growth performance under salinity and drought stress conditions. Biochar of two particle sizes; > 2 mm and < 1 mm were co-composted with the mixture (1:1 ratio of dry weight) of cow and poultry manures. Co-composted biochars were applied at 5% and 7% rates in soil. Control treatments included the amendment of mixture of biochar with manure in soil. Pots were subjected to slight drought (48-55% water filled pore space (WFPS) of soil) and non-drought conditions (60% WFPS) and under 0 and 1.3 dS m-1 salinity. Results revealed that plants growth performance was significantly better under treatments of co-composted biochar and no salt stress conditions, than when mixture of biochar and manure was applied to soil as non-composted fertilizer. Under no stress condition, small particle-sized co-composted biochar increased root biomass by 786.2% than the large particle-sized co-composted bioc...
Resumen. Se evaluó el efecto del fuego sobre el crecimiento y valor nutritivo del híbrido de Saccharum griffithii Munro ex Boissravennae (Linn.) Murr., una gramínea perenne de baja palatabilidad en la región semiárida de las altas... more
Resumen. Se evaluó el efecto del fuego sobre el crecimiento y valor nutritivo del híbrido de Saccharum griffithii Munro ex Boissravennae (Linn.) Murr., una gramínea perenne de baja palatabilidad en la región semiárida de las altas montañas de Balochistan, Pakistan, durante 2008 y 2009. Se aplicaron tratamientos de fuego prescripto en Febrero 2008 y 2009 en el estado de reposo de la vegetación. Se compararon diferentes parámetros con parcelas control (no quemadas): parámetros de crecimiento (altura de macollas, número de macollas/planta), producción de forraje (fresco, seco) y valor nutritivo (proteína cruda, cenizas). El fuego incrementó el número de macollas, y la producción de forraje fresco y seco en ambos años. El fuego también aumentó los contenidos de proteína cruda. El fuego prescripto en el estado de reposo de la vegetación se puede usar como una herramienta para mejorar la calidad y cantidad de forraje de la especie de gramínea híbrido menos preferida Saccharum griffithii M...
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Scrub rangelands support livestock grazing and provide ecosystem services to their inhabitants. The present study was conducted in Chakwal, an important tract of the Pothwar Plateau, which sustains herds of small domestic and nomadic... more
Scrub rangelands support livestock grazing and provide ecosystem services to their inhabitants. The present study was conducted in Chakwal, an important tract of the Pothwar Plateau, which sustains herds of small domestic and nomadic ruminants. Urbanization and uncontrolled grazing practices have reduced rangeland productivity and increased soil erosion and resulted in poor land conditions. This study assessed the influence of two years of rangeland protection on aboveground vegetation biomass and the chemical composition of plants and aimed to determine the influence of seasonal grazing on the live-weight gain of small ewes. Using the line intercept method, vegetation data from protected and unprotected plots in 2015 and 2016 were collected at two sites, Dhulli and Begal. Vegetation cover was assessed from images using VegMeasure. Results showed that protected study sites displayed higher vegetation biomass (834 and 690 kg ha-1) compared to the unprotected study site (477 and 326 kg ha-1) during April and August of both years. In the seasonal grazing trial, the experimental ewes that grazed on protected rangelands showed higher live-weight gain (33–63 g day-1) compared to live weight of ewes (17–21 g day-1) that grazed on unprotected rangelands during the experimental period of 127 days at both sites. The results suggest that the Chakwal rangeland has tremendous potential to improve vegetation productivity but modern livestock management and seasonal grazing practices are needed to improve carrying capacity and livestock productivity.
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Hazarganji Chiltan National Park in Balochistan, Pakistan was established in 1980 and the protected area was further extended in 1998. Large area of this mountain is still open for unmanaged human disturbances such as collection of wood... more
Hazarganji Chiltan National Park in Balochistan, Pakistan was established in 1980 and the protected area was further extended in 1998. Large area of this mountain is still open for unmanaged human disturbances such as collection of wood for fuel purpose and livestock grazing. Removal of vegetation of rangelands has a significant negative impact on soil organic matter (SOM). This research evaluates litter decomposition in three sites of Hazarganji Chiltan mountain with varying history of human disturbances (unprotected site, young protected site and old protected site). Twigs of Pistacia khinjuk with approximately equal weight and length were placed in litter bags of mesh size 2 mm and were buried in 0-5 cm depth in three sites in January. Half of the twigs of each site received rain simulation in April, August, October, November and January while the other half of the twigs were subjected under natural conditions for 15 months. Twigs from each plot of each treatment of each site wer...
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Balochistan province of Pakistan has more than 50% area that comes under arid climatic conditions of dry summer and cold winters. Under these conditions different arid crops including saffron has great potential to introduce and scale-up.... more
Balochistan province of Pakistan has more than 50% area that comes under arid climatic conditions of dry summer and cold winters. Under these conditions different arid crops including saffron has great potential to introduce and scale-up. Saffron (Crocus sativus L.) cultivation on test trials at PARC-BARDC, Quetta, Balochistan and in some of those areas by local farmers was found to be successful experience. As biochar is well-known to have influenced positively on the crop yield, this study evaluated the influence of the amendment of wood-derived biochar alone or with combination of cow manure compost in 1:1 ratio on the yield of saffron under field conditions of arid region of this province with cold winters and dry summers. The treatments were amendment of biochar at 0.34 t ha-1 and 0.68 t ha-1 rates and amendment of biochar-compost mixture at 1.37 t ha-1 and 2.7 t ha-1 rates. In this experiment, the saffron corms of uniform size (2-2.5 cm in diameter) were used. There were five ...
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Soil amended with biochar is expected to produce less nitrous oxide (N2O), although this may depend on nitrate (NO3-N) availability. Our objective was to determine how pine wood biochar, slow pyrolyzed at 500 °C, affects N2O production in... more
Soil amended with biochar is expected to produce less nitrous oxide (N2O), although this may depend on nitrate (NO3-N) availability. Our objective was to determine how pine wood biochar, slow pyrolyzed at 500 °C, affects N2O production in soil having different denitrification potentials with variable NO3-N concentrations under controlled laboratory conditions. Sandy loam surface soils (0–30 cm, pH 5.7) and sandy clay loam subsurface soils (40–60 cm, pH 5.6) were amended with four biochar rates (0, 10, 20, and 30 g·kg−1), two nitrogen fertilizer rates (0 and 100 mg·kg−1 NO3-N) and two acetylene levels (0% and 10% headspace), arranged as a full factorial. Soil moisture content was adjusted to 80% water-filled pore space, and flasks were incubated at 20 °C for 30 h. Headspace gas was collected from each flask at 25, 26, 28, and 30 h. There was a significant reduction in N2O production with an increasing rate of biochar in the surface soil but not in the subsurface soil. On average, les...
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Cadmium (Cd+2) is a potentially toxic element that inhibits growth and development of several species of plants along with Silybum marianum (L.) Gaertn which is an essential medicinal plant belonging to family Asteraceae. The exogenous... more
Cadmium (Cd+2) is a potentially toxic element that inhibits growth and development of several species of plants along with Silybum marianum (L.) Gaertn which is an essential medicinal plant belonging to family Asteraceae. The exogenous application with 0.25µM Salicylic acid (SA) and 10µM hydrogen peroxide (H2O2) to ameliorate harmful effects of cadmium (500 µM) on milk thistle were studied that were grown at two different ecological zones of Balochistan province of Pakistan i.e. Quetta (Qta) and Turbat (Tbt). The design of experiment was Randomized Complete Block Design (RCBD) with three replicates. Application of SA and H2O2, priming (P), Foliar spray (FS) and combinational treatments (P+FS) were highly helpful in alleviating the negative role of cadmium toxicity. The essential nutrients i.e. nitrate (NO3-), calcium (Ca2+) and potassium (K) were affected by Cd+2 induced toxicity however, the substantial role of SA and H2O2 widely helped to reduce the cadmium stress and boosted up t...
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Present study analysed the influence of slow-pyrolyzed wood-derived biochar on growth performance and heavy metal accumulation in the leaves of spinach grown under groundwater and wastewater irrigation. Biochar was applied in soil as 5%... more
Present study analysed the influence of slow-pyrolyzed wood-derived biochar on growth performance and heavy metal accumulation in the leaves of spinach grown under groundwater and wastewater irrigation. Biochar was applied in soil as 5% (~30 t·ha−1) and 10% (~60 t·ha−1) amendment. According to results, plant biomass was significantly higher under wastewater than groundwater irrigation. Biochar amendment increased significantly the aboveground plant biomass and root biomass and promoted water use efficiency (WUE). Under groundwater irrigation, biochar amendment at 10% application rate, increased the leaf area index (P < 0.05), while amendment of biochar at all application rates significantly reduced leaf area index under wastewater irrigation (P < 0.05). Application of biochar also reduced accumulation of rhizosphere soil around roots under wastewater irrigation, indicating less exudate production in the rhizosphere of plants. Biochar significantly reduced the concentration of ...
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ABSTRACT Present study evaluated the influence of slow-pyrolyzed wood-derived and cow manure-derived biochars on growth performance (i.e., yield production, nitrogen use efficiency (NUE), and phosphorus use efficiency (PUE)) of Pisum... more
ABSTRACT Present study evaluated the influence of slow-pyrolyzed wood-derived and cow manure-derived biochars on growth performance (i.e., yield production, nitrogen use efficiency (NUE), and phosphorus use efficiency (PUE)) of Pisum sativum under groundwater and municipal wastewater irrigation. Biochars were applied at 5, 10, and 15 t ha−1 rates for 2 years. The amendment of biochars did not enhance yield during first year under both irrigation types; rather, small-particle-sized (<0.65 mm) wood-derived biochar reduced significantly yield at higher application rates under groundwater irrigation. During second year, amendment of biochars significantly increased the yield especially at higher application rates under groundwater irrigation while no influence of biochars was observed for wastewater irrigation treatment. The yield was significantly lower under wastewater irrigation for all treatments as compared to first year. The NUE and PUE of pods and stover were not different during first year and second year under both irrigation treatments except for the small-particle-sized wood-derived biochar applied at 10 and 15 t ha−1, which tended to reduce significantly the NUE and PUE of pods and stover under groundwater irrigation during first year of cropping. The NUE and PUE were significantly lower during following year under wastewater irrigation. Our results suggest that amendment of biochars had positive influence on the growth of P. sativum under groundwater irrigation during second year of cropping while these amendments had no influence under wastewater irrigation.
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Whalen, J. K., Gul, S., Poirier, V., Yanni, S. F., Simpson, M. J., Clemente, J. S., Feng, X., Grayston, S. J., Barker, J., Gregorich, E. G., Angers, D. A., Rochette, P. and Janzen, H. H. 2014. Transforming plant carbon into soil carbon:... more
Whalen, J. K., Gul, S., Poirier, V., Yanni, S. F., Simpson, M. J., Clemente, J. S., Feng, X., Grayston, S. J., Barker, J., Gregorich, E. G., Angers, D. A., Rochette, P. and Janzen, H. H. 2014. Transforming plant carbon into soil carbon: Process-level controls on carbon sequestration. Can. J. Plant Sci. 94: 1065–1073. Plants figure prominently in efforts to promote C sequestration in agricultural soils, and to mitigate greenhouse gas (GHG) emissions. The objective of the project was to measure the transformations of plant carbon in soil through controlled laboratory experiments, to further understand (1) root-associated CO2 and N2O production during a plant's life cycle, (2) decomposition of plant residues leading to CO2 production, and (3) stabilization and retention of undecomposed plant residues and microbial by-products in the resistant soil C fraction. Experimental plant materials included transgenic near isolines of Zea mays L. and cell wall mutants of Arabidopsis thaliana,...
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Abstract This study investigated the influence of sixteen years exclosure from unmanaged grazing on aboveground vegetation biomass, soil organic matter (SOM), soil aggregation and nitrogen (N) mineralization in arid shrubland of... more
Abstract This study investigated the influence of sixteen years exclosure from unmanaged grazing on aboveground vegetation biomass, soil organic matter (SOM), soil aggregation and nitrogen (N) mineralization in arid shrubland of Baluchistan, Pakistan. Sampling was carried out from three sites along the chronosequence of secondary succession. One site was located at open-for-grazing area (grazed site) and the other two sites were located in the area that is protected since 1998. One of the protected site is more remote from grazing (protected site 1) where the land is less disturbed and has thick vegetation than the other protected site (protected site 2). Results showed a significant difference for aboveground vegetation biomass across sites and was in the order of protected site 1> protected site 2> grazed site. Soil organic matter was 53% and 46% higher in protected sites than grazed site. Aggregates larger than 2 mm size were not detected in soil from grazed site but represented 4.5% and 3% of the sample soil profile at the protected site 1 and protected site 2, respectively. Rate of N mineralization was lower in soils at the grazed site as compared to soils at the protected sites. Soil moisture contents were significantly lower at grazed site and showed a strong positive correlation with aboveground vegetation biomass. This study demonstrates that unmanaged grazing severely affected aboveground vegetation biomass, soil organic matter, large-sized soil aggregates, nitrogen mineralization and soil moisture contents. Short term exclosure from grazing (~16 years) can enhance aboveground vegetation biomass and soil quality in terms of soil organic matter accumulation, soil aggregation, retention of soil moisture and nitrogen mineralization in this arid rangeland.
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The effect of fire on growth and nutritive value of Saccharum griffithii Munro ex Boiss-ravennae (Linn.) Murr. hybrid, a low palatable perennial grass in the semi-arid region of the highlands of Balochistan, Pakistan, was evaluated during... more
The effect of fire on growth and nutritive value of Saccharum griffithii Munro ex Boiss-ravennae (Linn.) Murr. hybrid, a low palatable perennial grass in the semi-arid region of the highlands of Balochistan, Pakistan, was evaluated during 2008 and 2009. Prescribed fire treatments were applied in February 2008 and 2009 at the dormant stage of vegetation. Different growth parameters (tiller height, tiller number/plant), forage production (fresh, dry) and nutritive value (crude protein, ash) were compared with control (unburnt) plots. Fire increased the number of tillers, and the fresh and dry forage production in both years. Fire also improved the crude protein contents. Prescribed fire at the dormant stage of vegetation can be used as a vegetation tool to improve the forage quality and quantity of the less preferred grass species Saccharum griffithii Munro ex Boiss-ravennae (Linn.) Murr. hybrid.
Two years study was conducted to examine the influence of microhabitats i.e., plant canopies and interspaces on the seedling emergence and survival of Seriphidium quettense in relation to soil temperature and soil moisture in natural... more
Two years study was conducted to examine the influence of microhabitats i.e., plant canopies and interspaces on the seedling emergence and survival of Seriphidium quettense in relation to soil temperature and soil moisture in natural habitat. The growth rate of first year seedlings are also examined. Relative abundance of microhabitats was determined by using square quadrates. Soil temperature and soil moisture of two microhabitats were recorded at 0-5, 5-10 and 10-15 cm depth. Results showed that soil moisture in spring was found critical for seed germination while in summer it had greater impact on the survival of first year seedlings. Precipitations in March and April promoted seed germination while monsoon rains influenced seedling survival. Soil moisture and soil temperature in different microhabitats were significantly different in different months, reflected significant influence upon seedling emergence and their survival. Seedling emergence and survival was higher under plan...
Seed dispersal and soil seed bank attributes of Seriphidium quettense were studied over two years in highland Balochistan. Seed dispersal started in early winter and continued till early spring. Primary dispersal agents were wind and... more
Seed dispersal and soil seed bank attributes of Seriphidium quettense were studied over two years in highland Balochistan. Seed dispersal started in early winter and continued till early spring. Primary dispersal agents were wind and water. Dispersal unit was capitulum, most often without outermost whirl of phyllaries. There was generally one achene per capitulum but occasionally two to three achenes may also be present. Mean dispersal distance was 23 to 40 cm from parent plant to ground surface. Majority of seeds (59-65%) fell under canopy of parent plants. Sampling of soil for seed bank was done before and after seed dispersal of S. quetterise. Soil samples were collected from two depths (0-2 cm, 2-4 cm) and from two microhabitats (under adult individuals and open interspaces) by using soil cores. Seed bank status was determined by observing S. quetterise seedling emergence in the pots. Seriphidium quettense exhibited persistent soil seed bank attribute. High seed densities were f...
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Lignin is a complex phenolic polymer, mainly derived from the three monolignols: p-coumaryl, coniferyl, and sinapyl alcohols. As an important component of secondary cell walls in vascular plants, lignin is the second most abundant plant... more
Lignin is a complex phenolic polymer, mainly derived from the three monolignols: p-coumaryl, coniferyl, and sinapyl alcohols. As an important component of secondary cell walls in vascular plants, lignin is the second most abundant plant derived organic substance after cellulose. Relative to most other plant derived organic substances (i.e. structural and non-structural carbohydrates), lignin is recalcitrant to mineralization by soil microorganisms. The recalcitrance of lignin is due to the fact that only few microorganisms (i.e. white rot fungi and few bacterial species) can completely degrade polyphenols, and catabolism is often required to fully break down plant lignin. Consequently, lignin directly and/or indirectly influences soil microbial community structure, which in turn controls soil quality through the provision of several key ecosystem services: i) reducing the emissions of greenhouse gases from soil, ii) retaining soluble nutrients, iii) promoting soil aggregate formatio...
Soil microbial communities are responsive to biochar amendments. As the residence time of biochar in soil is expected to be hundreds to thousands of years, the changes in microbial community structure and functions could persist for a... more
Soil microbial communities are responsive to biochar amendments. As the residence time of biochar in soil is expected to be hundreds to thousands of years, the changes in microbial community structure and functions could persist for a long period of time. Given that biochar is being applied as a soil amendment in many parts of the world, the long-term consequences for soil microbial communities need to be considered. The objective of this review is to document how biochar creates new habitats and changes the soil environment for microorganisms, which may lead to changes in microbial abundance, community structure and activities. Our meta-analysis revealed that slow pyrolyzed biochars produced from various feedstocks at temperatures from 300oC – 600oC consistently increased some physico-chemical properties (i.e. pH, cation exchange capacity and aggregation) and microbial parameters (i.e. abundance and community structure of microorganisms) in a vast number of soils during short (≤ 90...
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Soil microbial communities are responsive to biochar amendments. As the residence time of biochar in soil is expected to be hundreds to thousands of years, the changes in microbial community structure and functions could persist for a... more
Soil microbial communities are responsive to biochar amendments. As the residence time of biochar in soil is expected to be hundreds to thousands of years, the changes in microbial community structure and functions could persist for a long period of time. Given that biochar is being applied as a soil amendment in many parts of the world, the long-term consequences for soil microbial communities need to be considered. The objective of this review is to document how biochar creates new habitats and changes the soil environment for microorganisms, which may lead to changes in microbial abundance, community structure and activities. Our meta-analysis revealed that slow pyrolyzed biochars produced from various feedstocks at temperatures from 300 �C to 600 �C consistently increased some physico- chemical properties (i.e., pH, cation exchange capacity and aggregation) and microbial parameters (i.e., abundance and community structure of microorganisms) in a vast number of soils during short...
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Soil organic carbon (SOC) has an essential role in controlling ecosystem functions associated with soil physical, chemical and biological properties. Maintaining the SOC pool size in agroecosystems is important to sustain food security,... more
Soil organic carbon (SOC) has an essential role in controlling ecosystem functions associated with soil physical, chemical and biological properties. Maintaining the SOC pool size in agroecosystems is important to sustain food security, protect soil biodiversity and buffer environmental impacts. The SOC pool is dynamic, with losses occurring due to CO2 mineralization and gains from microbially-mediated humification of organic substrates into stable C compounds. Bioenergy production from lignocellulosic feedstock implies that greater amounts of plant residues will be removed from agroecosystems and could deplete the SOC pool, based on empirical models and experimental results from long-term field trials. In northern temperate regions, several management practices are suggested to conserve the SOC pool, such as the application of biochar, judicious use of organic and inorganic fertilizers, crop rotations that include high biomass producing non-bioenergy crops or intercropping systems ...
To investigate the response of rainfed maize to sowing methods and NPK levels, an experiment was undertaken during kharif of 2011 and 2012 at Dryland (Kerawa) Agriculture Research Station, Sher-e-Kashmir University of Agricultural... more
To investigate the response of rainfed maize to sowing methods and NPK levels, an experiment was undertaken during kharif of 2011 and 2012 at Dryland (Kerawa) Agriculture Research Station, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Budgam. The experiment was laid out in a randomized block design with combination of 2 sowing methods (flat sowing, 75 cm apart rows, and ridge sowing, 75 cm apart ridges) and 3 fertility levels (60 : 40 : 20, 75 : 50 : 30, and 90 : 60 : 40 N : P2O5 : K2O kg ha(-1)) with three replications. Various growth characters, namely, plant height, leaf area index, dry matter accumulation, number of days to different phenological stages, and yield, and yield contributing characters namely, cob length, number of grains cob(-1), cob diameter (cm), and 100-seed weight (g), were significantly higher with S2 over S1 during both the years of experimentation. Fertilizer levels F3 (90 : 60 : 40) and F2 (75 : 50 : 30) at par with one another produced significant increase in growth and yield characters, namely, plant height, leaf area index, dry matter production at different growth stages, cob length, number of cobs plant(-1), number of grains cob(-1), and 100-seed weight over F1 (60 : 40 : 20). Significantly higher grain yield was recorded with fertilizer level F3 (90 : 60 : 40) being at par with F2 (75 : 50 : 30) and showed significant increase over F1 (60 : 40 : 20) with superiority of 5.4 and 5.7 per cent during 2011 and 2012, respectively. The findings of the study concluded that ridge method of sowing of maize with NPK levels of 75 : 50 : 30 kg ha(-1) showed better performance of crop in terms of growth, yield, and yield attributes.
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2014. Transforming plant carbon into soil carbon: Process-level controls on carbon sequestration. Can. J. Plant Sci. 94: 1065Á1073. Plants figure prominently in efforts to promote C sequestration in agricultural soils, and to mitigate... more
2014. Transforming plant carbon into soil carbon: Process-level controls on carbon sequestration. Can. J. Plant Sci. 94: 1065Á1073. Plants figure prominently in efforts to promote C sequestration in agricultural soils, and to mitigate greenhouse gas (GHG) emissions. The objective of the project was to measure the transformations of plant carbon in soil through controlled laboratory experiments, to further understand (1) root-associated CO 2 and N 2 O production during a plant's life cycle, (2) decomposition of plant residues leading to CO 2 production, and (3) stabilization and retention of undecomposed plant residues and microbial by-products in the resistant soil C fraction. Experimental plant materials included transgenic near isolines of Zea mays L. and cell wall mutants of Arabidopsis thaliana, selected for their diverse residue chemistry. Phenology, morphology and above-ground biomass affected soil respiration and N 2 O production in root-associated soils. Mineralization o...