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ThesisItem Restricted Phosphorus Dynamics in Relation to Carbon Mineralization in Soils Under Different Moisture Regimes(College of Agriculture, Punjab Agricultural University, Ludhiana, 2005) Kaur, Harjinder; Saroa, GSThesisItem Restricted Impact of Continuous Cropping and Fertilization on Crop Yield and Soil Properties Under Maize-Wheat Sequenct(College of Agriculture, Punjab Agricultural University, Ludhiana, 2006) Kaur Brar, Kiranvir; Saroa, GSThesisItem Open Access Interactive effects of zinc and nickel on growth and nutrition of rice (Oryza sativa L)(Punjab Agricultural University, Ludhiana, 2018) Goyal, Diksha; Manchanda, J. S.A pot experiment was conducted to study the interactive effects of Zn and Ni on growth and nutrition of rice. The soils used in the study were i) loamy sand (ls) Typic Ustipssament (pH 7.9, EC 0.25 dS m-1, OC 0.15%, CaCO3 0.13%, DTPA-Zn 1.00 and DTPA-Ni 0.19 mg kg-1 soil) and ii) sandy loam (sl) Typic Haplustept (pH 8.1, EC 0.35 dS m-1, OC 0.32%, DTPA-Zn 1.20 and DTPA-Ni 0.46 mg kg-1 soil). Seven levels of Zn (0, 2.5, 5, 10, 20, 40 and 80 mg Zn kg-1 soil) as zinc sulfate heptahydrate and six levels of Ni (0, 2.5, 5, 10, 20 and 40) as nickel chloride were applied in all possible combinations to eight kg of soil per pot with three replications. Rice (cv PR-126) was grown till maturity and soil, root, grain and straw samples were collected. Soil and plant samples were processed and analysed for DTPA-Zn, DTPA-Ni, various pools of Zn and Ni (exchangeable, specifically adsorbed, manganese oxide bound, amorphous Fe and Al oxides bound, crystalline Fe and Al oxides bound, organically bound and residual mineral fraction) and Zn and Ni concentration in root, grain and straw . The activity of urease enzyme in soil was estimated at maximum tillering and harvesting stage. Mean DTPA-Zn in both the soils decreased with increasing levels of applied Ni, while mean DTPA- Ni in both the soils remained unaffected up to a level of Zn application @ 20 mg kg-1 soil, but significant decrease over control was observed with an application of 40 and 80 mg Zn kg-1 soil. The interaction effect of Zn and Ni levels on DTPA-Zn was also significant. It was observed that DTPA-Zn decreased significantly by 45 and 34 per cent when 40 mg Ni kg-1 soil was applied along with 80 mg Zn kg-1 soil as compared to when only 80 mg Zn kg-1 soil was applied in loamy sand and sandy loam soil, respectively. Nickel and Zn application decreased exchangeable and specifically adsorbed Zn in both the soils. However, applied Zn increased Ni in manganese-oxides and amorphous oxides bound pools. The quadratic response of relative root dry matter yield (RRDMY), grain and straw yield to DTPA-Zn indicated that RRDMY, grain and straw yield increased up to level of 5 mg DTPA-Zn kg-1 soil and thereafter it declined in both the soils. The quadratic response of RRDMY to DTPA-Ni in both the soils indicated that maximum RDMY was produced when soil contained 2 mg DTPA-Ni kg-1 soil. However, quadratic response of relative grain and straw yield to DTPA-Ni indicated that grain and straw yield increased up to level of 3 mg DTPA-Ni kg-1 soil and thereafter yield declined in both the soils. Irrespective of the soil used, about 12.0, 16.5 and 14.5 mg DTPA-Zn kg-1 soil and 5.37, 7.45 and 7.10 mg DTPA-Ni kg-1 soil produced 50 per cent reduction from maximum yield of root, grain and straw, respectively, which may be considered as the upper critical values for rice. Irrespective of the soils, the concentration of Ni in root, grain and straw decreased as the concentration of Zn increased. Thus indicating their antagonism with each other. Nickel uptake by each plant part decreased with increase in DTPA-Zn. With increase in level of applied Zn, activity of urease enzyme significantly decreased at both the stages (Maximum tillering and harvesting stage). Application of Ni significantly increased urease activity up to a level of 10 mg Ni kg-1 soil and thereafter it was reduced in both the soils at both the stages. The results also indicated that antagonistic effect of Zn on activity of urease was more pronounced in loamy sand as compared to sandy loam soil. The farmers should apply Zn to the soils only, if the soil test value is below the critical deficiency level to avoid Zn induced Ni deficiency due to build up of Zn in the soils.ThesisItem Open Access Impact of long-term organic farming on soil quality(Punjab Agricultural University, Ludhiana, 2018) Nima, Dina; Kukal, S. S.The intensive cropping coupled with the continuous use of chemicals as inputs has resulted in various issues including declining soil physical environment and productivity. Organic farming plays a crucial role in improving soil quality by excluding the use of synthetic fertilizers and chemicals. The present study was thus conducted on the impact of long-term (12 years) organic farming on soil quality under different cropping systems in a sandy loam. Soil samples were collected from organic and chemical plots for each cropping system viz green manure (GM)-basmati rice-wheat, GM-basmati rice-gram, soybean-wheat and summer moong-cluster bean-wheat from 0-15 and 15-30 cm soil depths for analyzing physical and chemical parameters, whereas surface soil layer (0-15 cm) was analyzed for biological parameters after harvest of kharif and rabi crops. The study revealed that mean bulk density was lower in organic farming by 7.64 and 3.65 percent in 0-15 and 15-30 cm soil layer, however total soil porosity was higher in organically managed soils in both the soil layers. The mean maximum water holding capacity (MWHC), mean weight diameter (MWD), saturated hydraulic conductivity, steady state infiltration of soil was higher by 42.3, 64.5, 60.7 and 60 per cent under organic farming than in soil under chemical farming. The moisture retention in soils under organic farming increased from 5.17 to 10.3 and 5.46 to 18.6 per cent in surface and sub surface soil layer, respectively compared to chemical farming. No significant difference in the pH of organic (6.96) and chemically (7.22) managed soil was observed. Electrical conductivity of soils of chemical plots (0.17 dS m-1) was higher than in the organic plots (0.14 dSm-1). The soil organic carbon, cation exchange capacity, available P, K and DTPA-micronutrients (Fe, Zn,Mn and Cu) were significantly higher in organic plots than in chemical plots. The dehydrogenase and alkaline phosphatase were higher in soils under organic farming, however urease enzyme was higher in chemical farming. Soil microbial population especially the bacterial, fungal and actinomycetes counts, water soluble carbon and carbohydrate carbon was higher in organic farming plots. Soil physical, chemical and biological parameters were observed to be highest in GM-basmati rice-wheat and lowest in soybean-wheat cropping system. The soil quality index (SQI) of organic farming was better than the chemical farming. Principal component analysis revealed that soil properties were highly correlated with organic farming and GM-basmati rice-wheat cropping system. Mean weight diameter, cation exchange capacity and soil respiration was best soil indicator by principal component analysis.ThesisItem Open Access Soil enzyme activities and carbon pools in soils as influenced by rice straw and nitrogen application in rice-wheat system(Punjab Agricultural University, Ludhiana, 2018) Swarnjeet Singh; Sharma, SandeepThe sustainability of rice-wheat system (RWS) is at threat due to the deterioration of soil health and emerging of new challenges of climate change caused by continuous burning of huge amounts of crop residue. The current study evaluated the effect of N application and rice straw incorporation after 7 year (2010-17) on soil enzyme activities, labile carbon pools and chemical properties in rhizosphere and bulk soils at maximum tillering (MT) and flowering (FL) stage of wheat under RWS. Four main-plot treatments of N application were 0, 90, 120 and 150 kg N ha-1 and four sub-plot treatments of rice straw incorporation were 0, 5, 7.5 and 10 t ha-1. The results showed that 120 kg N ha-1 and rice straw incorporation (7.5 and 10 t ha-1) significantly increased all the soil biochemical properties (enzyme activities, labile carbon pools and chemical properties) except pH and EC. Maximum wheat grain yield observed with application of 120 kg N ha-1 and 7.5 t ha-1 rice straw incorporation. The majority of soil enzyme activities and labile carbon pools were higher in rhizosphere than bulk soil. The enzymatic activities and quantity of carbon pools were 5% and 15% higher at MT as compared to FL stage of wheat. Soil enzyme activities were positively and significantly correlated with labile carbon pools. Principal component analysis (PCs) identified β-glucosidase, L-asparaginase, total carbohydrate carbon and total polysaccharide carbon as most sensitive indicators for assessing soil quality under rice straw incorporated RWS.ThesisItem Restricted Soil aggregate associated organic carbon and its impact on greenhouse gas emissions in different cropping system(Punjab Agricultural University, Ludhiana, 2018) Anmol Singh; Dheri, G. S.Crop production technologies may influence the potential of soil to act as a sink or source of global greenhouse gases (GHGs). Assessment of the impact of fertilizer and cropping system is required to identify best management practices (BMP) for soil carbon (C) sequestration and mitigation of GHG emissions. Nutrient management practices differentially influence organic C present within aggregates, which in time may affect rate of C mineralization and GHG emissions. The present study assessed the impact of long-term application of fertilizer and organic manures in maize-wheat (M-W) and rice-wheat (R-W) systems on aggregate stability, aggregate associated C and GHG emissions. Application of fertilizers and organic manures in both the cropping systems significantly improved the mean weight diameter and aggregate stability as compared to unfertilized control. The maximum increase in macro-aggregates was recorded in 100% NPK+farmyard manure (11.5%) under M-W and 100% NPK+straw incorporation (18.8%) under R-W. The higher concentration of C in recalcitrant fraction under R-W (38.6%) compared to M-W (16.6%) suggest that the soil conditions under R-W were more favorable for C stabilization. Irrespective of treatments total organic C was maximum in > 2 mm aggregate fraction with an average of 8.42 g kg-1 aggregate under M-W and 14.8 g kg-1 aggregate under R-W system. In general, long-term application of fertilizer integrated with organic manures (irrespective of aggregate fractions) improved total C and C fractions significantly as compared to sole application of fertilizer. The emission of CO2 and N2O was higher from macro-aggregates compared to micro-aggregates. Integrated use of fertilizer and organic manures may be the best management option for improving organic C and mitigating GHG emissions by increasing C stabilization and soil aggregation.ThesisItem Open Access Impact of different quality of irrigation water and fertigation on bell pepper (Capsicum annum L.)(Punjab Agricultural University, Ludhiana, 2018) Sidhu, Simranpreet Kaur; Sekhon, K.S.The increasing demand for irrigation water to secure food for ever growing global population with declining fresh water resources carves the path for introduction of alternative ways of using saline water. Long-term irrigation with saline water causes accumulation of salts in the rhizosphere, inducing increased osmotic potential of the soil solution thus impairing plant water and nutrient uptake. In arid-zone agriculture, where underground water is saline, more emphasis is being laid on use of desalinated water and conjunctive use. A long term on-going drip irrigated field experiment being conducted under the NHM sponsored project “Centre of excellence for utilization of brackish water for fruits and vegetable production in S-W Punjab” at PAU RRS Bathinda was selected to study the effect of different qualities of irrigation water namely canal (WQ1), desalinated (WQ2), saline (WQ3) and mixed CW: SW (WQ4) water and three fertigation levels [100% (F1), 80% (F2) and 60% (F3) of recommended NPK dose] on bell pepper and soil properties under un-mulched (M0) and mulched (M1) conditions. The results showed that highest fruit yield was obtained with WQ1, followed by WQ2 and WQ4, while lowest with WQ3. Reducing the salinity from EC 4.22 dSm-1 in WQ3 to EC 0.398 dSm-1 in WQ2 through desalination process, there was increase in fruit yield by 58%, irrespective of mulch and fertigation. Application of silver black polyethylene mulch (25µ) and increasing levels of fertigation significantly increased the fruit yield of bell pepper, irrespective of irrigation water quality. The concentration of Ca, Mg and S in leaves and fruits of bell pepper increased significantly with increasing salinity of irrigation water but Ca, Mg and S content in leaves and fruits of bell pepper in WQ2 was significantly lower than WQ1 at 60 DAT, 90 DAT and at maturity. The content of N, P and K in leaves and fruits decreased with increase in salinity of irrigation water; however, in WQ1 and WQ2 it was comparable at successive stages of growth up to maturity. The pH and electrical conductivity of soil increased significantly in WQ3 and WQ4 in comparison to WQ1 and WQ2 at pre-fertigation stage, and after 24 and 48 hours of 10th and 20th fertigation. Saline water (WQ3 and WQ4) increased the salinity build up away from the drip lateral to a greater extent than non-saline water (WQ1 and WQ2). Soil SAR values were also found to be higher in WQ3 and WQ4 under no mulch and moderated with the application of polyethylene mulch. However EC, pH and SAR values of soil with WQ2 were found to be quite similar to that of WQ1. Available N, P, K and organic carbon content of soil decreased with the increasing salinity of irrigation water and increased with increasing fertigation levels under M0 and M1 for surface (0-15 cm) and sub-surface (15-30 cm) layer of soil at all the sampling stages. To conclude, desalinated water or mixing canal and saline water in equal proportion with an acceptable yield loss can be used for irrigation to bell pepper under drip system in case of scarcity of good quality irrigation water.ThesisItem Restricted Refinement of leaf colour chart based fertilizer nitrogen management technology using PAU-LCC in transplanted rice(Punjab Agricultural University, Ludhiana, 2017) Amandeep Singh; Varinderpal SinghLarge field to field variability in inherent soil nitrogen (N) supply restricts efficient fertilizer N use when soil test based fertilizer N recommendations are used in transplanted rice. A field experiment was conducted at PAU, Ludhiana to study spectral properties of transplanted rice to guide need-based fertilizer N application and to study need of basal N application in new rice varieties i.e. PR 121, PR 122, PR123 and PR 124. The spectral properties of rice leaves at different growth stages measured using PAU-LCC (PAU-Leaf colour chart), SPAD (chlorophyll) meter and GreenSeeker optical sensor correlated well with leaf N concentration except at 10 days after transplanting (DAT). The PAU-LCC and SPAD meter readings were poorly correlated with leaf dry weight at early growth stages but correlation improved as growth progressed. The NDVI values integrate intensity of leaf colour greenness and biomass and are thus well correlated with leaf dry weight at different growth stages. Close linear relationship (R2=0.732, n= 504) between PAU-LCC score and SPAD meter readings suggested that PAU-LCC can be used as economical substitute to SPAD for making need based fertilizer N topdressings in transplanted rice. The PAU-LCC 4 guided N applications produced grain yield equivalent to soil test based N applications with saving of 60 kg N ha-1, and thus led to maximum agronomic (46.7 kg kg-1 N) and recovery efficiency (82.5 per cent) of applied fertilizer N. Whereas, PAU-LCC 4.5 guided N management improved grain yield production by 8.47 percent with the use of fertilizer N equivalent to soil test based N management in new rice varieties (PR 121, PR 122, PR123 and PR 124). The basal N dose can be delayed till 10 DAT while using threshold leaf greenness of PAU-LCC 4.5.ThesisItem Open Access Studies on zinc nutrition of basmati rice (Oryza sativa)(Punjab Agricultural University, Ludhiana, 2018) Khushdeep Singh; Verma, GayatriThe present investigation entitled “Studies on zinc nutrition of basmati rice (Oryza sativa)” was carried out to evaluate effect of different doses of zinc on yield and yield attributes of Basmati rice. A field experiment was conducted at two sites (Zn-deficient and Zn-sufficient) at experimental farm of Regional Research Station, Gurdaspur, Punjab Agricultural University, Ludhiana and another study at farmers’ fields in different villages of Gurdaspur during Kharif 2016. The soil of the experimental farm was silt loam in texture, noncalcareous and alkaline in reaction and the soil at farmers’ fields varied from loam to silt loam in texture and alkaline in reaction. The treatments at two sites (Zn-deficient and Zn-sufficient) comprised of two rice varieties as main plot and seven Zn treatments as sub-plots replicated three times in a split-plot design. In Zn-deficient site (Site-I), a significant increase in grain and straw yield was found with Zn application @ 12.5 kg Zn/ha (T4), 6.25 kg Zn/ha (T3) and 3.12 kg Zn/ha (T2) whereas in Zn sufficient site (Site-II) there was non-significant increase in grain and straw yield with increasing Zn levels. Among the tested varieties, Pusa basmati 1121 recorded significantly higher grain yield in comparison to Punjab basmati 2 in Zn deficient site (Site-I) and non-significant increase was found for varieties in Zn sufficient site (Site-II). Yield attributes showed non-significant increase with increasing Zn levels at both the sites except 1000-grain weight which increased significantly with increasing Zn levels in deficient site. DTPA-Zn showed significant increase in Zn deficient site whereas it was nonsignificant in Zn sufficient site. The Zn content in whole grain, brown rice and straw at both the sites at experimental farm increased significantly with soil applied Zn treatments but maximum Zn content was recorded in treatments which had soil plus foliar Zn application. The amount of Zn extracted by using different extractants in soil samples collected at harvest from different sites at farmers’ field was in the following order: AB-EDTA> Mehlich-3> ABDTPA> DTPA-HCL> 0.1N HCL= DTPA with Zn extraction of 1.14, 0.95, 0.94, 0.73, 0.65 and 0.65 mg kg-1 and critical limit values using Cate & Nelson procedure for these were 0.87, 0.65, 0.69, 0.55, 0.64 and 0.59 mg kg-1, respectively. Different extractants were highly and significantly correlated with each other indicating that they could extract zinc more or less from soil. DTPA-Zn and AB-DTPA-Zn showed the highest correlation (0.966**) while ABDTPA-Zn and DTPA+HCL showed the least (0.755**). Accordingly, DTPA-Zn and ABDTPA-Zn extractant could be used effectively for estimating Zn for Basmati rice grown in Gurdaspur district of Punjab.