Influence of Organic Matter Vis-à-Vis Humic Acid on the Transformation of Inorganic and Organic Forms of Nitrogen in a Typic Haplustept Soil

A laboratory experiment was conducted to study the changes in inorganic and organic forms of nitrogen (N) in a Typic Haplustept soil treated with mustard cake vis-à-vis humic acid in the presence and absence of inorganic N. Results revealed that irrespective of treatments, significantly higher amount of soluble nitrate (NO₃^-), hydrolysable ammonium (NH₄⁺), non-hydrolysable and total N were accumulated in the soil treated with mustard cake in the presence of inorganic N. However, on the other hand, a humic acid-treated system showed significantly higher content of exchangeable NH₄⁺ and hexosamine N. Application of humic acid alone leads to the accumulation of a significantly higher amount of total hydrolysable and unidentified N in the soil. Among the different treatments, NH₄⁺ fixation was more in mustard cake followed by humic acid-treated soil. Humic acid is more susceptible to mineralization than mustard cake, particularly with respect to total N accumulation in soils.     

Carbon and nutrient dynamics under long-term nutrient management in tropical rice-wheat-jute system

Impacts of 43-year nutrient management on carbon (C) and nutrient dynamics were studied in a rice-wheat-jute system in tropical India. Carbon dynamics was investigated on the basis of its distribution of labile (microbial biomass C, permanganate oxidizable C and water soluble C) and slow pools (Walkley Black oxidizable organic C), its indices (C pool index, lability index) and C management index (CMI) at different soil depths. Nutrient dynamics was judged by major nutrients availability, and related soil enzymatic activities. We studied seven treatments including unfertilized control, 100% NPK (N:P₂O₅:K₂O 60:30:60), 50% NPK, 150% NPK, 100% NP, 100% N, 100% NPK + farm yard manure (10 tonnes FYM ha^?1). Nutrients availability and soil enzymatic activities were significantly increased under balanced fertilization (100% NPK + FYM) over other treatments. Labile, slow and total C was also found highest in 100% NPK + FYM. Enhanced C indices under 100% NPK + FYM over 100% NPK and other treatments signified the importance of long term balanced fertilization on soil C stabilization. Lability indexes were lower at sub-soil (30-45cm). In terms of favourable nutrient dynamics and CMI, balanced application of NPK plus organics were recommend for long term sustainability of rice-wheat-jute system in tropics.     

Influence of continuous application of inorganic nutrients to a Maize–Wheat rotation on soil enzyme activity and grain quality in a rainfed Indian soil

To explore long-term impact of organic and inorganic fertilizers on soil health and grain quality, we monitored the enzyme activities and chemical properties of soil; and chemical composition of grain from eight treatments at an experimental field site established in 1996. There were eight treatments applied to both wheat and maize seasons: a control; four inorganic fertilizers, that is, nitrogen and phosphorus (NP), nitrogen and potassium (NK), phosphorous and potassium (PK) and nitrogen, phosphorus and potassium (NPK); farm yard manure alone (FYM) and addition of FYM at two different doses (100 and 50% of recommendation) to NPK that is, NPK + FYM and ½ NPK + FYM. After 11 years of the experiment the NPK + FYM and ½ NPK + FYM treatments had the highest yields, about 5 Mg maize ha⁻¹ and 2 Mg wheat ha⁻¹ with about 2 and 0.5 Mg ha⁻¹, respectively more than the NPK treatments. The dehydrogeanse activity of soils increased significantly in FYM and ½ NPK + FYM. Except urease all other enzymatic activities were increased in those treatments, which received manure. Urease activity was higher in mineral-N applied plots. Grain protein content of both maize and wheat was highest in mineral fertilized plots. Test weight also increased significantly on application of mineral fertilizer. Plots treated with half dose of recommended mineral fertilizer along with FYM were higher in urease, phosphomono and diesterase activities than that of NPK + FYM treated plots. Long-term application of inorganic nutrients along with FYM improved grain mineral composition and yield. Inhibition of few enzymatic activities were also observed upon application of inorganic nutrients either alone or in combination.     

Allometric models for estimation of aboveground biomass of Gmelina arborea Roxb. in pulpwood plantations of Bangladesh

Gmelina arborea Roxb. is a fast-growing, deciduous tree species native to Bangladesh. It has been widely planted since 1992 for commercial production of pulpwood in hilly areas of Bangladesh. The purpose of this study was to derive well-fitting allometric models for estimation of aboveground biomass, and carbon and nutrient (nitrogen, phosphorus and potassium) stocks in G. arborea to ensure sustainable production and management of this species. Eight linear models with 64 regression equations were tested for estimation of aboveground biomass, carbon and nutrient stocks in different parts (leaves, branches, bark and stem) of the plant. The best-fitting allometric models were selected in accordance with various relevant statistical criteria.     

Disposition kinetics,cytotoxicity and residues of fenvalerate in tissues following oral administration to goats

Disposition kinetics in goats of fenvalerate [(RS)-α-cyano-3-phenoxybenzyl (RS)-2-(4-chlorophenyl)-3-methylbutyrate] were studied after oral administration at 5 mg kg^?1. The insecticide persisted in blood for up to 48 h. The V_d(area), t_1/2(β), and t_1/2(Ka), of fenvalerate were 12.14 (±0.39) litre kg^?1, 12.25 (±0.25) h and 0.63 (±0.11)h, while the AUC and Cl_B values were respectively 7.35 (±0.39) μg h ml^?1 and 0.68 (±0.04) litre kg^?1 h^?1. The residues in tissues reached a peak four days after insecticide administration and then started to decline. Maximum residue was found in the adrenal gland, followed by liver, kidney and intestine. Both GOT and GPT activities in kidney tissue, but only GPT activities in liver tissue had decreased significantly 4, 8 and 22 days post-administration. The fenvalerate did not produce any significant effects on serum acetylcholinesterase, cholesterol or protein levels in goats. Histopathological examination showed fatty changes in the periphery of lobule, congestion in sinusoid, haemolysis in central vein, necrosis and periportal fibrosis around the central vein of liver, and necrosis in kidney of fenvalerate-treated goats.     

Antidiarrhoeal activity of Strychnos potatorum seed extract in rats

The antidiarrhoeal activity of the methanol extract of the dried seeds of Strychnos potatorum (MESP) has been evaluated out in rats using different models (castor oil-induced diarrhoea, effects on gastrointestinal motility and on PGE(2)-induced gastric enteropooling. MESP (100, 200 and 400 mg/kg, p.o.) significantly (P<0.001) inhibited the frequency of defaecation and reduced the wetness of faecal droppings in castor oil-induced diarrhoea, decreased the propulsion of charcoal meal through the gastrointestinal tract, and also reduced the PGE(2)-induced enteropooling.     

Antidiabetic potential of Barleria lupulina extract in rats

The methanol extract of aerial parts of Barleria lupulina orally tested at doses of 100, 200 and 300 mg/kg exerted significant antihyperglycemic effect in streptozotocin-induced hyperglycemia in rats [correction].     

Soil carbon stock in relation to plant diversity of homegardens in Kerala,India

Conservation of biodiversity and mitigation of global warming are two major environmental challenges today. In this context, the relationship between biodiversity (especially plant diversity) and soil carbon (C) sequestration (as a means of mitigating global warming) has become a subject of considerable scientific interest. This relationship was tested for homegardens (HG), a popular and sustainable agroforestry system in the tropics, in Thrissur district, Kerala, India. The major objectives were to examine how tree density and plant-stand characteristics of homegardens affect soil C sequestration. Soil samples were collected at four depths (0–20, 20–50, 50–80, 80–100 cm) from HG of varying sizes and age classes, and their total C content determined. Tree density and plant-stand characteristics such as species richness (Margalef Index) and diversity (Shannon Index) of the HG were also determined. Results indicated that the soil C stock was directly related to plant diversity of HG. Homegardens with higher, compared to those with lower, number of plant species, as well as higher species richness and tree density had higher soil carbon, especially in the top 50 cm of soil. Overall, within 1 m profile, soil C content ranged from 101.5 to 127.4 Mg ha⁻¹. Smaller-sized HG (<0.4 ha) that had higher tree density and plant-species density had more soil C per unit area (119.3 Mg ha⁻¹) of land than larger-sized ones (>0.4 ha) (108.2 Mg ha⁻¹). Soil C content, especially below 50 cm, was higher in older gardens. The enhanced soil-C storage in species-rich homegardens could have relevance and applications in broader ecological contexts.

Variability of Nutritional and Cooking Quality in Bean (Phaseolus vulgaris L) as a Function of Genotype

Screening of natural biodiversity for the better quality traits are of prime importance for quality breeding programs. The objective of this investigation was to select candidate accession of bean having high concentrations of protein as well as macro and micro minerals with good cooking quality for use as parents in breeding programme for these compounds. Thirty-five accessions of bean (Phaseolus vulgaris L) were field grown and their seeds were analyzed for their cooking quality and nutritional composition. Wide variations were observed in most of the measurements e.g. protein (18.7–26.2%), iron (79.4–137.6 ppm) and hardness after cooking (4.65–9.88 Kg) suggesting that there are considerable levels of genetic diversity. Across all accessions the concentration of potassium was negatively correlated with protein (r = −0.43, P < 0.05). Concentrations of protein was significantly greater in accessions VIII, XIII and XIX compared to other accessions analyzed. Iron concentrations were greatest (137 ppm) in XIX and lowest (79 ppm) in XXVII. Lines with less cooking time were line III, X, XXVI, XXX and XXXI. Bean line XIX contains high protein (24.9%) with high zinc (33.3 ppm) and highest iron (137.6 ppm), but it has high hardness after cooking (7.32 kg). Four clusters were computed by cluster analysis that explained quite a good variation in the traits. The great variability for these attributes suggests that these selected accessions may be useful as parents in hybridization programs to produce bean with value-added traits. This information was also potentially useful for pulse breeders working on the development of new varieties.