Shalini Singh

Emission of nitrous oxide from rice-wheat systems of Indo-Gangetic plains of India.

Nitrous oxide (N2O) accounts for 5%of the total enhanced greenhouse effect and responsiblefor the destruction of the stratospheric ozone. The rice-wheat cropping system occupying 26 million ha ofproductive land in Asia could be a major source ofN2O as most of the fertilizer N in this region isconsumed by this system. Emission of N2O asinfluenced by application of urea, urea plus farm yardmanure (FYM), and urea plus dicyandiamide (DCD), anitrification inhibitor, was studied in rice-wheatsystems of Indo-Gangetic plains of India. Total emissionof N2O-N from the rice-wheat systems varied between654 g ha-1 in unfertilized plots and 1570 g ha-1 in urea fertilized plots. Application of FYM and DCDreduced emission of N2O-N in rice. The magnitude ofreduction was higher with DCD. In wheat also N2O-Nemission was reduced by DCD. FYM applied in rice had noresidual effect on N2O-N emission in wheat. In riceintermittent wetting and drying condition of soilresulted in higher N2O-N emission than that ofsaturated soil condition. Treatments with 5 irrigationsgave higher emissions in wheat than those with 3irrigations. In rice-wheat system, typical of a farmersfield in Indo-Gangetic plains, where 240 kg N isgenerally applied through urea, N2O-N emission is1570 g ha-1 (0.38% of applied N) and application ofFYM and DCD reduced it to 1415 and 1096 g ha-1,respectively.

Methane emission from rice-wheat cropping system in the Indo-Gangetic plain in relation to irrigation, farmyard manure and dicyandiamide application

Abstract Methane (CH4) is one of the important greenhouse gases accounting for 15% of the total enhanced greenhouse effect. Rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system is the most dominating cropping system in the Indo-Gangetic plains (IGPs) of India occupying 10.5xa0millionxa0ha of productive land could be a major source of atmospheric CH4. Effect of irrigation, urea, farmyard manure (FYM), and dicyandiamide (DCD) on emission of CH4 from an alluvial soil (Ustochrept) in rice–wheat cropping system was studied using the closed chamber technique. Total emission of CH4 from the rice–wheat systems ranged from 16.2xa0kgxa0ha−1 in the control treatment to 36.5xa0kgxa0ha−1 in urea plus FYM treatment with an average emission of 20.8xa0kgxa0CH4xa0ha−1. Continuously saturated soil in rice gave higher CH4 emission compared to intermittent wetting and drying soil condition but the yields were lowered. Application of DCD with urea reduced emission of CH4 in rice–wheat system to 70%, while substituting 50% of inorganic N with FYM increased emission to 172% compared to application of entire amount of N through urea. In wheat negative fluxes of CH4 up to 0.1xa0kgxa0ha−1 per day was recorded. There was no difference in CH4 flux in wheat between the various irrigation treatments. In the most common fertilizer practice in IGPs the emission of CH4 is 21.2xa0kgxa0ha−1. Intermittent wetting and drying of soil in rice has a potential to reduce the emission.

Methane emission from two Indian soils planted with different rice cultivars

Abstract In a greenhouse study, methane emissions were measured from two diverse Indian rice-growing soils planted to five rice cultivars under similar water regimes, fertilizer applications and environmental conditions. Significant variations were observed in methane emitted from soils growing different cultivars. Total methane emission varied between 8.04 and 20.92gm–2 from IARI soil (Inceptisol) and between 1.47 and 10.91gm–2 from Raipur soil (Vertisol) planted to rice. In all the cultivars, emissions from IARI soil were higher than from Raipur soil. The first methane flux peak was noticed during the reproductive phase and the second peak coincided with the grain-ripening stage of the rice cultivars.

The role of mungbean residues and Sesbania aculeata green manure in the nitrogen economy of rice-wheat cropping system

Field experiments were carried out to determine the effect of Sesbania aculeata L. green manuring and mungbean, Vigna radiata (L.) residue incorporation on the response of rice to urea-N and their residual effects on a subsequent spring wheat. Compared with a pre-rice fallow, Sesbania green manuring and mungbean residue increased grain yield of rice by 0.4 and 0.3 t ha−1, respectively and of spring wheat by 0.6 and 0.7 t ha−1, respectively when no urea-N was applied to rice and 40 kg urea-N ha−1 as a basal starter dose was applied to wheat. Sesbania green manure and mungbean residue substituted for 43 and 30 kg urea-N ha−1 in rice and subsequently gave a beneficial effect in spring wheat equal to the residual effect of 89 and 112 kg urea-N ha−1 applied to rice, respectively. Mungbean residue remaining after the picking of pods, was found to be at par with Sesbania green manuring towards N contribution to “rice-wheat” cropping system but had an additional advantage of 0.5 to 1.3 t ha−1 seed yield of protein rich mungbeans.

Increased biogas production using microbial stimulants

Laboratory studies were undertaken to evaluate the effect of microbial stimulants Aquasan and Teresan, on biogas yields from cattle dung and combined residues of cattle dung and kitchen waste, respectively. The addition of single dose of Aquasan at the rate of 10, 15 and 20 ppm to cattle dung on the first day of incubation resulted in increased gas yields ranging between 45.1 and 62.1 l/kg dry matter. Subsequent addition of Aquasan at 15 and 20 ppm dosage after a period of 15 days increased the gas yields by 15-16%. The gas production was found to be optimum at a dosage level of 15 ppm and was 39% and 55% higher with single and dual additions, respectively, than untreated cattle dung. In another bench scale study (1:1 dry matter) the addition of Teresan at 10 ppm concentration to the mixed residues of cattle dung and kitchen wastes at different solids concentration, produced 34.8% more gas (272.4 l/kg d.m.) than the uninoculated mixture at 15% TS concentration (202.4 l/kg d.m.).

Effect of green manuring, blue-green algae and neem-cake-coated urea on wetland rice (Oryza sativa L.).

SummaryA field trial was set up to examine the effect of green manuring, blue-green algae, and neem-cake-coated urea on a rice crop. Summer green manuring using Sesbania aculeata increased the crop yield. Inoculation of blue-green algae increased the rice grain yield when 60 kg N ha-1 was applied as prilled urea, but the increase in grain yield was greater when 60 kg N ha-1 was applied as neem-cake-coated urea. The results of the present study show that applications of green manure, neem-cake-coated urea, and blue-green algae are complementary and that the three treatments can be used together in the rice ecosystem. The green manure and the fertilizer treatments had no effect on the algal flora of the soil.

Persistence of α and β isomers of endosulphan and endosulphan sulphate in diverse soils of india as influenced by flooding

Laboratory studies were undertaken to evaluate the persistence of alpha-endosulphan, beta-endosulphan and endosulphan sulphate in four diverse soils under non-flooded and flooded conditions. Significant variations were observed in the extent of persistence of the three chemicals in different non-flooded soils with maximum persistence observed in Alfisol and the least in Mollisol having near neutral pH and higher organic matter. Degradation was more in all the flooded soils than in the non-flooded counterpart but in Vertisol under flooded and non-flooded conditions, the rate of degradation of endosulphan sulphate was found to be nearly same.

Biodegradation of α and β isomers of endosulphan and endosulphan sulphate in Indian soils

Abstract The degradation of α and β isomers of endosulphan and endosulphan sulphate in four sterilized and non sterilized Indian soils under laboratory conditions was studied. Degradation was found to be more in non‐sterilized as compared to the sterilized soil. The half life of α‐endosulphan, β‐endosulphan and endosulphan sulphate was found to be 136.8, 273 and 301 days in sterilized Alfisol and 55, 256 and 277 days in non‐sterilized Alfisol, respectively. α‐Endosulphan degraded more readily than β‐endosulphan and endosulphan sulphate under both sterilized and non‐sterilized soil conditions.

Inter Simple Sequence Repeat Analysis to Confirm Genetic Stability of Micropropagated Plantlets in Three Grape (Vitis spp) Rootstock Genotypes

Three grape rootstock genotypes — Dogridge (Vitis champini), SO4 (V. beriandieri × V. rupestris) and H-144 (V. vinifera × V. labrusca), and their 30 in vitro regenerated plantlets were subjected to Inter Simple Sequence Repeat (ISSR) analysis in order to ascertain the genetic stability of micropropagated plantlets. Out of 35 primers screened initially with three mother plants, 10 were finally selected based on sufficient polymorphism and appearance of clear and scorable banding patterns. Each primer generated a unique set of amplification products ranging in size from 100 to 1800 bp. These ten ISSR primers produced 81 distinct and scorable band classes with an average of 8.1 bands per primer. Based on similarity matrix and cluster analysis the rootstock genotypes and their tissue culture derivatives formed three distinct genetic groups indicating their genetic relationships. Furthermore, no variation was detected among in vitro regenerated grape plantlets and their field-grown mother plants corroborating the high level of clonal fidelity of the in vitro regenerated plantlets and supporting the multiplication protocol utilizing nodal segments as in vitro culture initiation material.

Residual effects of growing mungbean and uridbean on the yield and nitrogen uptake of a succeeding wheat crop

A two year field experiment was carried out at the Indian Agricutural Research Institute, New Delhi - 110012, India to assess the effect of mungbean (Vigna radiata L.) and uridbean (Vigna mungo L.) residues on the yield and N uptake of a succeeding wheat crop as compared to sorghum fodder. Sorghum produced 3.5–7.5 times more dry matter and removed 2–3 times more nitrogen than mungbean or uridbean during same duration (80 ± 10 days) of their growth. Without N application the grain yield of wheat following mungbean and uridbean (without residue incorporation) was 0.45 and 0.48 t ha−1 more than the yield of wheat following sorghum fodder. These yields were equivalent to that predicted when 36 and 38 kg urea-N ha−1, respectively, was directly applied to wheat. The residual effects of these grain legumes were higher when succeeding wheat was fertilized with 60 kg urea-N ha−1; at this level mungbean and uridbean spared 52 and 43 kg urea-N ha−1, respectively, in succeeding wheat. The residual effect of mungbean and uridbean further increased when their residue was incorporated in soil; with this practice they spared 94 and 115 kg urea-N ha−1, respectively, without N application to wheat and 74 and 82 kg urea-N ha−1, respectively, with an application of 60 kg urea-N ha−1 to wheat.Mungbean and uridbean, without residue incorporation, increased aboveground plant-N uptake of succeeding wheat by 11.5–34.9 and 10.8–34.0 kg N ha−1, respectively; whereas with residue incorporation, they increased aboveground plant-N content of succeeding wheat by 26.1–45.8 and 32.7–47.7 kg N ha−1, respectively.The results of the present study indicate that there is both an indirect ‘sparing’ effect and a direct residual effect of mungbean and uridbean on the nitrogen needs of succeeding wheat, more so when their residues are incorporated in soil.