Degradation of AM Nitrification Inhibitor in Soil of Subtropical Region

The aim of the study was to evaluate the degradation and persistence of 2-amino 4-chloro 6-methyl pyrimidine (AM), nitrification inhibitor at 1 and 2 µg g^?1 application rates in soil. The extraction of AM was done by QuEChER’s (Quick, Easy. Cheap. Rugged and Safe) method and the quantitative analysis by high-performance liquid chromatography (HPLC). AM decreased with time at both the levels of application with the decline being faster in the beginning up to 7 d. Dissipation of AM occurred in a single phase with the persistence data fitting well to the first-order kinetics. Half-lives of AM were determined to be 14.33 and 16.7 d at 1 and 2 µg g^–1 levels application rates. Since AM remains effective for an adequate period of time, it can be used for increasing efficiency of nitrogenous fertilizers in rice–wheat cropping systems as well as a safeguard for controlling environmental pollution in subtropical soils.     

Labile soil organic carbon,soil fertility,and crop productivity as influenced by manure and mineral fertilizers in the tropics

In recent years, organic agriculture has been receiving greater attention because of the various problems like deterioration in soil health and environmental quality under conventional chemical‐intensive agriculture. However, little information is available on the comparative study related to the impact of use of mineral fertilizers and organic manures on the soil quality and productivity. A long‐term field experiment was initiated in 2001 to monitor some of the important soil‐quality parameters and productivity under soybean–wheat crop rotation. The treatments consisted of 0, 30, and 45 kg N ha^–1 for soybean and of 0, 120, and 180 kg N ha^–1 for wheat. The entire amount of N was supplied to both the crops through urea and farmyard manure (FYM) alone or in combination at 1:1 ratio. Results indicated that Walkley‐and‐Black C (WBC; chromic acid–oxidizable) exhibited a marginal increase under only organic treatments as compared to control treatment (without fertilizers and manure) after completion of five cropping cycles. In case of labile‐C (KMnO₄‐oxidizable) content in soil, relatively larger positive changes were recorded under organic, mixed inputs (integrated) and mineral fertilizers as compared to WBC. Maximum improvement in the values of C‐management index (CMI), a measure of soil quality was recorded under organic (348–362), followed by mixed inputs (268–322) and mineral fertilizers (198–199) as compared to the control treatment after completion of five cropping cycles. Similarly there was a substantial increase in KCl‐extractable N; in Olsen‐P; as well as in DTPA‐extractable Zn, Fe, and Mn under organic treatments. Although labile soil C positively contributed to the available N, P, K, Zn, Fe, and Mn contents in soil, it did not show any relationship with the grain yield of wheat. After completion of the sixth cropping cycle, organic treatments produced 23% and 39% lower grain yield of wheat as compared to that under urea‐treated plots. Relatively higher amount of mineral N in soil at critical growth stages and elevated N content in plant under mineral‐fertilizer treatments compared to FYM treatments were responsible for higher yield of wheat under mineral fertilizers.     

Aroma profiles of the curry leaf, Murraya koenigii (L.) Spreng. chemotypes: Variability in north India during the year

Murraya koenigii (L.) Spreng. (Rutaceae) is characterized by a large chemical intraspecific variability among the land races. This fact makes it difficult to detect real changes occurring in their essential oil composition during annual cycle. Based on this, variations of essential oil yield and composition in two chemotypes (‘A’ and ‘B’) of M. koenigii were assessed in spring, summer, rainy, autumn and winter seasons under foot hill conditions of northern India. The essential oil yield ranged from 0.15% to 0.18% in chemotype ‘A’, while it varied from 0.12% to 0.14% in chemotype ‘B’. Essential oils of both chemotypes from different seasons were analysed by gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS). A total of fifty-eight constituents representing 93.7-98.8% of chemotype ‘A’ and fifty-six constituents forming 96.1-98.7% of the total composition of chemotype ‘B’ were identified. Chemotype ‘A’ was characterized by higher percentages of α-pinene (34.6-41.9%), sabinene (26.1-36.1%), (E)-caryophyllene (2.4-5.4%) and terpinen-4-ol (1.5-5.3%), whereas chemotype ‘B’ was dominated by higher amount of α-pinene (52.7-65.3%), β-pinene (10.7-12.9%), (E)-caryophyllene (3.1-10.3%) and limonene (5.1-7.8%). Comparative results showed considerable variations in the essential oil composition of both chemotypes due to season of collection. Present study concluded that the M. koenigii leaves of desired quality may be obtained by selecting suitable chemotype and season.     

Short Communication: Stocking Density-Dependant Growth and Survival of Asian Sun Catfish,Horabagrus brachysoma (Gunther 1864) Fry During Hatchery Rearing

The present study was conducted to determine the optimum stocking density of Horabagrus brachysoma fry during fingerling production in the hatchery. For this purpose, four density levels (400, 800, 1200 and 1600 fry/0.6 m³) were considered. The experiment of fry rearing continued for a period of six weeks. The total length and wet weight of fry were significantly highest (P < 0.05) at 400 fry/0.6 m³ density compared to the other three density treatments during the entire rearing period. At harvesting, the length and weight of fry stocked at 1200 and 1600 numbers/0.6 m³ were similar to each other, and both were significantly lower (P < 0.05) than those of fish stocked at 800/0.6 m³. The decreased SGR, percent weight gain, and survival were also observed at the two highest density treatments. But the total biomass was observed to be highest (P < 0.05) at 1600/0.6 m³ density compared to those of the other three densities. If individual size and number of individuals for stocking are not constraints, the maximum number of surviving fry from a minimum rearing space was achieved at a stocking density of 1600 fry/0.6 m³ tank.     

Effects of Brief Summer or Winter Fasting on the Muscle Quality of Cultured Pacific Bluefin Tuna (Thunnus orientalis)

The effects of fasting on the quality of the dorsal and ventral ordinary muscles from cultured Pacific bluefin tuna (Thunnus orientalis) during chilled storage were investigated. Tuna were subjected to fasting for 2 days in the summer or 6 days in the winter prior to harvesting. The breaking strength of the dorsal ordinary muscle sampled in the summer increased until 24 h and then decreased. There were no significant differences in the lipid and glycogen content of the ordinary muscle after 9 h of storage between the controls and either fasting group. The pH of the ordinary muscle subjected to summer and winter fasting was higher than in the controls after 24–48 h of storage. However, the relationship between the pH and glycogen content was unclear. The metmyoglobin content during chilled storage was lower in the ordinary muscles from either fasting group than in the controls. In conclusion, fasting for 6 days in the winter improved the color stability of the ordinary muscle without a decline in its lipid content.     

Influence of organic amendments on dissipation kinetics of two different pesticides in soil: a case study

A study was undertaken to investigate the remedial effect of some soil amendments (farmyard manure (FYM), press mud compost (PMC), cereal straw (CS) at 5 t ha^?1 and fresh cow dung slurry (FCD) @ 0.5 t ha^?1) on dissipation kinetics of imidacloprid and sulfosulfuron under laboratory conditions. Incorporation of CS or FCD was found to be most effective in degrading both the pesticides at faster rates. Dissipation of both the pesticides could be well accounted by two component (1 + 1) first order kinetics. The computed values of parameters revealed that use of organic amendments increased the dissipated fraction of imidacloprid and sulfosulfuron. Incorporation of CS or FCD in soil maintained relatively higher dissipation rate constants for both faster and slower dissipation processes of pesticides in comparison to control. Hence, eco-friendly practices of CS or FCD incorporation as soil amendment in soil can play a vital role in preventing soil and water pollution.     

Steam explosion pretreatment used to remove hemicellulose to enhance the production of a eucalyptus organosolv dissolving pulp

The steam explosion (SE) pretreatment associated with the organosolv process was investigated to produce dissolving pulp from eucalyptus. Prehydrolysis Kraft (PHK) pulping was also done to produce viscose and acetate grade pulps as reference. The organosolv pulps were delignified in two steps with sodium chlorite. Viscose and acetate grade PHK pulps were bleached by OD₀(EH)D₁P and OD₀(EP)D₁PCCE sequences, respectively. Dilute acid-catalyzed (with acid addition) SE pretreatment dissolved more xylan than auto-catalyzed (no acid addition) SE pretreatment. Steam-exploded unbleached organosolv pulps showed lower residual lignin content and screened yield than unbleached organosolv pulps without SE pretreatment. Steam explosion pretreatment helped to decrease lignin content and damaged fiber length of unbleached organosolv pulps. The 1.0% H₂SO₄ organosolv pulp (organosolv dissolving pulp at bioconversion conditions) showed the highest reactivity. Even showing low viscosity for some applications, in general, the organosolv dissolving pulps produced in this study can be used for making lyocell fibers.