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2011 - 20173
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Subject: Soil Science × Author: Gurpreet Singh × Type: Thesis × Thesis Type: M.Sc ×
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Now showing 1 - 3 of 3
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    Simulation of nitrogen balance in rice as influenced by irrigation, nitrogen and climate change scenario
    (Punjab Agricultural University, Ludhiana, 2017) Gurpreet Singh; Vashisht, B.B.
    Yield potential of rice depends on climatic factors including rainfall, solar radiation and temperature as well as irrigation regime, cultivar and fertilizer nitrogen level. The excessive fertilizer N is being applied by farmers in the quest for higher yields ignoring economic water and N productivities, and environmental pollution. Whole fertilizer N not utilized by rice plants, some portions of N fertilizer are easily lost through various processes, such as NH3 volatilization, leaching and uptake. With prime importance to quantify the nitrogen balance components in rice, field studies were conducted at two different locations at research farms of Department of Soil Science, Punjab Agricultural University, Ludhiana, Punjab, on sandy loam soils during kharif 2016. In the field study, effect of irrigation regimes (irrigation based on two days drainage period, and based on soil water suction (16 kPa)) and nitrogen levels (0, 60, 120 and 180 kg N ha-1) on growth, yield of rice and nitrogen uptake were evaluated. To assess the N balance components, DNDC (Denitrification-Decomposition) model was evaluated and simulations for yield and N balance components were made for past 30 years (1986-2016) and future 30 years (2021-2050) on different soil series of Ludhiana district of Punjab. Averaged over irrigation regimes, rice yield increased significantly with increasing nitrogen levels. Highest rice grain yield was recorded with application of 180 kg N ha-1 (52.9-59.6 q ha-1), which was significantly higher than control, 60 and 120 kg N ha-1 at location 1 but at par with application of 120 kg N ha-1 at location 2. N uptake was also found higher (46.3-56.4 kg ha-1) in the treatments with 180 kg N ha-1. However, treatments with 60 kg N ha-1 gave higher nitrogen use efficiency in terms of agronomic (20-25 kg kg-1) and recovery (54.8-59%) efficiency. Simulated rice yield, N uptake and volatilization would decrease with lower nitrogen levels, coarseness in soil texture and future time slices but leaching losses would increase with higher nitrogen levels, coarseness in soil texture and future time slices. However, percent reduction in yield would be more in end part of mid century (2041-2050). Percent yield reduction would be low at higher nitrogen levels (150-180 kg N ha-1) and in fine textured soils (silt loam). The study suggests that higher N levels could be good option to compensate yield reduction in future however higher nitrogen levels would lead to higher N leaching and volatilization.
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    ASSESSMENT OF MICROBIAL CONSORTIA FOR PADDY STRAW DEGRADATION
    (Punjab Agricultural University, Ludhiana, 2017) Gurpreet Singh; Neemisha
    An experiment was conducted to assess the potential of cellulolytic microorganisms for paddy straw degradation. Twenty seven samples representing hot spots for cellulolytic microorganism were collected from eight different locations. A total of 653 microorganisms were isolated including bacteria (520), fungi (100) and actinomycetes (33). The cultures were screened for cellulolytic activity using both qualitative as well as quantitative assay. Among all the cultures tested, only 48 cultures (44 bacteria, 2 actinomycetes and 2 fungi) exhibited cellulase activity. The zone of hydrolysis varied from 0.3 to 3.2cm and largest zone of hydrolysis was obtained by CDM35 (3.2cm). Hemicellulase activity was exhibited by 24 cultures and largest zone of hydrolysis was produced by CDM 23 (2cm). Quantitative estimation of cellulase enzyme was done using DNS method in which highest cellulase activity of 0.29 IU/ml was shown by CDM 26 followed by 0.19 IU/ml by CDM35. All the cultures were characterized using cultural, morphological and biochemical characterization techniques. The genetic diversity of most efficient bacterial isolates was determined using BOX-PCR, ERIC-PCR and 16S rDNA amplification. The dendrogram obtained from pooled data of BOX and ERIC fingerprints resulted in the formation of two major groups at 15% similarity, subgroups at 23% similarity and the maximum similarity obtained was 57%. Functional characterization revealed IAA production by all the isolates however, only 8 cultures exhibited P solubilization capability. Majority of the microorganisms exhibited optimum growth at 30-45˚C. On the basis of all the qualitative assays, quantitative assays, optimum growth temperature and pH, most efficient microorganisms were selected for assessment of degradation potential under glasshouse and field conditions. Ten most efficient cultures consisting of seven bacteria (CDM5, CDM4, CDM7, CDM3, CDM35, CDM2, CDM23), two actinomycetes strains (CDM26 and CDM42) and one fungal strain (CDM45) were selected for experiment. Under glass house conditions treatments T13, T14. T17 & T20, and under field conditions, treatments T5, T6 & T9 performed efficiently in decreasing ADF and NDF.
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    CHEMICAL POOLS AND DEPTHWISE DISTRIBUTION OF MICRONUTRIENTS IN SOILS UNDER DIFFERENT CROPPING SEQUENCES AND THEIR RELATIONSHIP WITH THE UPTAKE BY CROPS
    (Punjab Agricultural University, Ludhiana, 2011) Gurpreet Singh
    Rice-wheat, maize-wheat and cotton-wheat are predominant cropping systems, being practised by majority of farmers in Punjab. The adoption of these three cropping systems depletes a huge amount of macronutrients (N, P and K) and micronutrients (Zn, Cu, Fe and Mn) causing deficiency of these nutrients mainly in light textured soils. So, to overcome the deficiency of Zn, Cu, Fe and Mn in such soils, alternative cropping systems like maize-potatao-mungbean, cotton-gobhi sarson, groundnut-toria+gobhi sarson etc., are required. Lot of research work has already been done on the predominant cropping systems without inclusion of short duration crops like mungbean, toria, gobhi sarson and onion crop. So, there is need to explore research on inclusion of short duration crops in the main cropping systems, which helps in mobilization of Zn, Cu, Fe and Mn. Therefore, the present research study has been conducted with a prime objective to investigate the transformation (chemical pools) and depthwise distribution of Zn, Cu, Fe and Mn under different cropping systems. Surface (0-15 cm) and profile (0-120 cm) soil samples were collected from an ongoing field experiment (in progress since 2000) with 10 cropping systems at research farm of Department of Agronomy, PAU, Ludhiana. The plant samples (grain and straw) from each cropping system were also collected both for Rabi and Kharif crops. These soil samples collected at different stages were analyzed for DTPA-extractable and total Zn, Cu, Fe, and Mn and their chemical fractions using atomic absorption spectrophotometer (Varion AAS-FS Model). The grain and straw samples were also analyzed for their Zn, Cu, Fe, and Mn concentration with Varion AAS-FS Model. The levels of DTPA-extractable Zn, Cu, Fe, and Mn were significantly higher in soil under all the 10 cropping systems as compared to their initial levels. Higher levels of DTPA-extractable Fe and Mn and Zn and Cu were observed in rice-wheat and cotton-wheat cropping systems, respectively. Among maize based cropping systems, maize-potato-mungbean cropping system reported significantly higher concentrations of DTPA-extractable Zn, Cu, Fe, and Mn. The DTPA-extractable Zn and Cu decreased and Fe and Mn increased in soil under maize-potato-mungbeen cropping system. The DTPA-extractable Zn, Cu and Fe decreased with increase in the soil depth. Among chemical fractions, higher levels of Fe and Mn (WSEX and SpAd) were reported in the rice-wheat cropping system. On the other hand higher fractions of Zn [WSEX, SpAd, MnOX and CFeOX] and Cu [WSEX and OM bound] were reported under maize-potato-mungbean and cotton-gobhi sarson cropping systems respectively. Higher uptake of Fe was reported in rice-wheat cropping system, whereas Zn, Cu and Mn reported their higher uptakes in groundnut-potato-bajra (fodder) cropping system. Our study further, investigated that inclusion of short duration crops like mungbean, toria, gobhi sarson and onion helps in mobilization of Zn, Cu, Fe and Mn to ameliorate their deficiencies. Among fractions, SpAd, held on organic sites, oxide bound and amorphous fractions of Zn, Cu, Fe and Mn contributed towards plant available (water soluble and exchangeable) fraction. However, WSEX, SpAd, oxide bound and organically bound fractions contributed towards uptake of Zn, Cu, Fe and Mn by plant grain and straw.