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ThesisItem Open Access Dynamics of soil phosphorus in relation to carbon under different cropping systems(Punjab Agricultural University, Ludhiana, 2016) Dhram Prakash; Benbi, D.K.Dynamics of phosphorus in soils were studied in relation to nutrient management and land-use practices. The nutrient management practices evaluated included source (rock phosphate and single superphosphate) and rates of P application in rice-wheat system; and integrated nutrient management (INM) and organic farming practices in basmati-wheat system in field experiments conducted at the research farm of Punjab Agricultural University, Ludhiana. The land-uses studied included ricewheat, maize-wheat, cotton-wheat and poplar based agroforestry systems at farmers’ fields in different districts of Punjab. After seven cycles of rice-wheat cropping, farmyard manure (FYM) and rock phosphate (RP) application increased available P and soil organic carbon (SOC) by 72% and 98%, respectively over control. Inorganic P constituted the largest proportion (88-92%) of total P in soil and relative abundance of different inorganic P fractions in soils followed the order Ca-Al associated > Fe associated > humic bound > water soluble P. In basmati-wheat system, application of recommended rates of NPK and adoption of INM improved available P in soil over unamended control by 75 and 100%, respectively. The comparison of three organic sources revealed that available P was the highest in soil receiving 400 kg N ha-1 through FYM followed by rice straw compost and the lowest in vermicompost-amended plots. Application of FYM significantly increased inorganic, organic and total P, SOC and labile C pools compared to INM treatments. The INM increased inorganic, organic and total P by 77, 82 and 78%, respectively over NPK. Humic-bound organic P constituted major proportion (39.5-49.5%) and water soluble organic P comprised the smallest proportion (0.83-2.5%) of organic P in soils under basmati-wheat system. Beneficial effects of different treatments on soil properties were higher in surface soil (0-7.5 cm), which decreased with soil depth. Generally, soil P fractions were positively correlated with soil C pools. Cumulative P released in 96 hours of equilibration increased with manure and fertilizer application either alone or in combination. Phosphorus release kinetics were best described by Elovich and power function equations (R2≥0.98). Results of land-use studies showed that agroforestry systems had relatively higher proportion of organic P (27%) compared to sole cropping (6-7.7%). Soil organic C was the highest (0.58%) under agroforestry and was significantly correlated with soil P fractions under sole cropping systems. Soil properties viz. clay, organic C, CaCO3 and available P content significantly influenced soil P sorption and release kinetics. Phosphorus release decreased with increase in clay and CaCO3 content. On the contrary, P release increased with increase in available P and organic C. The results suggested that P availability will be higher in coarse-textured, non-calcareous soils having higher levels of organic C and available P. Therefore, for efficient P management it is important to take into account soil texture, the existing soil P level, organic C content and calcareousness of soil. Practices that increase SOC content and ameliorate CaCO3 could lead to improved P use efficiency.ThesisItem Open Access CARBON AND PHOSPHORUS DYNAMICS IN SOIL IN RELATION TO NUTRIENT MANAGEMENT IN RICE-WHEAT SYSTEM(PAU Ludhiana, 2012) Seema Sharma; G. S., SaroaThe study comprised of two field and two laboratory experiments. In field experiment on organic and integrated nutrient management of basmati-wheat sequence, the effect of inorganic, organic and integrated nutrient management was studied on crop yield and soil properties. Water infiltration rate was highest and soil bulk density was lowest in recommended fertilizer + FYM (INM2) treatement. Total water stable aggregates (WSA) in the 0-15 cm soil depth ranged from 58.5 to 82.4 per cent; minimum WSA were observed in control and maximum in INM2 treatment. Among the aggregates 0.11-0.25 mm fraction constituted the greatest proportion and > 2 mm fraction constituted the least proportion. Maximum pH and EC were recorded in control plots and minimum in plots receiving 400 kg N ha-1 through FYM. Soil organic carbon (SOC), aggregate associated C, labile C and hot water soluble C was highest in FYM 400N treatment. Ammonical-N, nitrate-N, Olsen P, Bray I P, ammonium acetate extractable K, soil P fractions and total P in soil were highest in INM2 treatment and lowest in control. Grain yield, straw yield, NPK content and their uptake by basmati and wheat were maximum in INM2 treatment and minimum in control. Basmati and wheat grain yield were significantly correlated with soil P fractions and the highest correlation was observed with saloid-P. In the second experiment, effect of rock phosphate on crop yield and P fractions in soil under rice-wheat sequence was studied. Highest SOC, Olsen P, soil P fractions, ammonium extractable K and non-exchangeable K were recorded in rock phosphate (RP) and FYM treatment and lowest content of all these parameters was observed in control. Highest pH was observed in control P treatment and lowest in treatment where FYM was applied along with RP. Grain yield, straw yield, NPK content and uptake in grain and straw were also highest in plots recieving P from RP along with FYM. Grain and straw yield of both the crops were significantly correlated with all the soil P fractions (Sa-P, Al-P, Fe-P and Ca-P). Highest correlation of paddy grain yield was observed with Sa-P whereas wheat grain yield gave highest correlation with Al-P fraction and lowest with Ca-P. Rock phosphate gave almost similar crop yield and P availability in soil as that with SSP. In laboratory study I, P was extracted by different methods and the lowest amount of P was extracted with AB-DTPA and the highest with Bray-I method. Phosphorus extracted by Olsen, Bray-I, Morgan and AB-DTPA methods gave significant positive correlations with grain yield and nutrient uptake of paddy and wheat. In the soils from long-term experiments with different fertilization history, maximum P adsorption was observed in unammended soil and minimum in soils where FYM was applied alongwith chemical fertilizer. Contrarily, desorption was minimum in control plots and maximum in plots where organic sources along with inorganic fertilizers were applied. Adsorption data fitted well to both Freunlich and Lagmuir models. .ThesisItem Open Access Carbon and phosphorus dynamics in soil in relation to nutrient management in rice-wheat system.(PAU, 2012) Sharma, Seema; Saroa, G. S.The study comprised of two field and two laboratory experiments. In field experiment on organic and integrated nutrient management of basmati-wheat sequence, the effect of inorganic, organic and integrated nutrient management was studied on crop yield and soil properties. Water infiltration rate was highest and soil bulk density was lowest in recommended fertilizer + FYM (INM2) treatement. Total water stable aggregates (WSA) in the 0-15 cm soil depth ranged from 58.5 to 82.4 per cent; minimum WSA were observed in control and maximum in INM2 treatment. Among the aggregates 0.11-0.25 mm fraction constituted the greatest proportion and > 2 mm fraction constituted the least proportion. aximum pH and EC were recorded in control plots and minimum in plots receiving 400 kg N ha -1 through FYM. Soil organic carbon (SOC), aggregate associated C, labile C and hot water soluble C was highest in FYM 400N treatment. Ammonical -N, nitrate-N, Olsen P, Bray I P, ammonium acetate xtractable K, soil P fractions and total P in soil were highest in INM2 treatment and lowest in control. Grain yield, straw yield, NPK content and their uptake by basmati and wheat were maximum in INM2 treatment and minimum in control. Basmati and wheat grain yield were significantly correlated with soil P fractions and the highest correlation was observed with saloid-P. In the second xperiment, effect of rock phosphate on crop yield and P fractions in soil under rice-wheat sequence was studied. Highest SOC, Olsen P, soil P fractions, ammonium extractable K and non-exchangeable K were ecorded in rock phosphate (RP) and FYM treatment and lowest content of all these parameters was observed in control. Highest pH was observed in control P treatment and lowest in treatment where FYM was applied along with RP. Grain yield, straw yield, NPK content and uptake in grain and straw were also highest in plots recieving P from RP along with FYM. Grain and straw yield of both the crops were significantly correlated with all the soil P fractions (Sa-P, Al-P, Fe-P and Ca-P). Highest correlation of paddy grain yield was observed with Sa-P whereas wheat grain yield gave highest correlation with Al-P fraction and lowest with Ca-P. Rock phosphate gave almost similar crop yield and P availability in soil as that with SSP. In laboratory study I, P was extracted by different methods and the lowest amount of P was extracted with AB-DTPA and the highest with Bray-I method. Phosphorus extracted by Olsen, Bray-I, Morgan and AB-DTPA methods gave significant positive correlations with grain yield and nutrient uptake of paddy and wheat. In the soils from long-term experiments with different fertilization history, maximum P adsorption was observed in unammended soil and minimum in soils where FYM was applied alongwith chemical fertilizer. Contrarily, desorption was minimum in control plots and maximum in plots where organic sources along with inorganic fertilizers were applied. Adsorption data fitted well to both Freunlich and Lagmuir models.ThesisItem Open Access Soil water dynamics and water productivity of ricewheat system under different establishment methods(PAU, 2015) Bhatt, Rajan; Kukal, S.S.The prevalent wheat-rice cropping system in Punjab has been taking a toll on the natural resources in the region. The wheat and rice grown with conservation technologies need to be studied for the cropping system as a whole. Field experiments were carried out during 2012- 14 in a sandy loam soil to assess the role of zero tillage and crop establishment method on crop performance, soil water dynamics, soil physical environment and water productivity of the wheat-rice cropping system. The treatments consisted of zero- (ZTW) and conventionaltillage (CTW) as main, establishment methods viz. direct seeded (DSR) and mechanical transplanted rice (MTR) as sub and tillage in rice viz. puddle (P), conventional (CT) and zero till (ZT) as sub-sub treatments. Zero tillage in wheat and rice did not affect the wheat yield during both the years. The grain yield of DSR was similar to MTR during 2013 but was significantly higher during 2014. The land productivity of wheat-rice cropping system was 15.8 and 11.3 per cent higher in CTW than in ZTW plots during 2012-13 and 2013-14, respectively. It was highest in CTW-DSR-P and lowest in ZTW-MT-ZT. The irrigation water productivity of the system (WPI) was highest in CTW-MT-P and lowest in ZTW-DSR-ZT. The WPI of wheat-rice cropping system was significantly higher (16-19.5 per cent) in CTW than in ZTW plots. The WPI of the cropping system was higher in MTR (0.81-0.88 g kg-1) than DSR (0.60-0.77 g kg-1). The WPI of wheat-rice cropping system, though similar in CT (0.76 g kg-1) and ZT (0.71 g kg-1) plots of rice during 2012-13, was 11.2 per cent lower in ZT plots during 2013-14. The evapo-transpiration (ET) losses of the wheat-rice cropping system were higher during 2013-14 (971-1057 mm) than in 2012-13 (908-922 mm). The ET losses of wheat-rice cropping system including the intervening period were not affected by tillage in wheat or rice.ThesisItem Open Access Soil and maize response to compaction, slope steepness and nitrogen fertilization in coarse textured soil(PAU, 2014) Singh, Jagdish; Hadda, M.S.The continuous use of farm machinery and adoption of rice-wheat cropping sequence resulted in the formation of compacted subsoil layer at the depth of 10-40 cm. The subsoil compacted layer affects nearly all soil properties and functions, which in turn affect the growth and productivity of plants. The information on the relationships among the degree of compaction, soil physical properties, N fertilizer rates, slope steepness and annual row crop performance are limited. Thus, the experiment was carried out to quantify the N fertilizer dose in the subsurface compact soils, to evaluate the effects of subsurface compaction and N fertilization on soil physical properties, plant growth and yield of maize and to investigate the effect of subsurface compaction and slope steepness on maize yield. The present investigation was carried out at Research Farm, Department of Soil Science, Punjab Agricultural University, Ludhiana during the years, 2012 and 2013. The experiment-I comprised three subsoil compaction treatments in main plots and three nitrogen levels in sub plots laid out in split-plot design replicated thrice. While, experiment-II comprised three subsoil ompaction levels in main plots and three slope steepness levels in sub plots replicated thrice. The bulk density and penetration resistance was higher under C2 treatment, while total porosity, cumulative infiltration and infiltration rate were lower. The N fertilization did not significantly affect the soil physical properties. Plant height, LAI and dry matter accumulation were negatively affected by subsoil compaction. However N fertilization mitigated the negative effects of subsoil compaction on growth of maize. The C2 treatment reduced heat use efficiency, delayed tasseling and silking stages, while physiological maturity was advanced under C2 treatment than that in C0 treatment. The N2 treatment improved the HUE than that in N0 treatment. The crop growth rate was significantly higher under C0 treatment at 30, 60 DAS and at harvest than that in C1 and C2 treatments. The root mass density was higher in 0-15 cm soil layer under C2 treatment at knee high and pre-tasseling stage than that in C0 treatment. However, root density was higher in C0 treatment than that in C1 and C2 at all other soil depths. The grain yield reduction of 15.5 to 23.5 % was observed under C2 treatment as compared to C0; however N fertilization improved the yield by 14.8 to 16.1 %. The total N uptake was 14.6 and 18.2 % higher under C0 treatment than that in C2 treatment, while N2 treatment had improved the total N uptake by 18.6 and 14.9 % as compared to N0 during the years 2012 and 2013, respectively. The N1 fertilization level can be recommended under subsurface compacted soils as compared to N0 and N2 fertilization. The slope steepness improved the maize grain yield by 4.2-10.2 % and biomass yield by 17-22 %, by reducing the crop lodging and cob barrennessThesisItem Open Access Effect of long-term application of fertilizers and manures on green house gas emission(PAU, 2015) Dhadli, Harmanjit Singh; Brar, B.S.The effect of long-term application of fertilizers and manures on green house gas emissions in maizewheat and rice-wheat cropping systems was studied in two field experiments in progress since 1972 and 1999, respectively, at Research Farm, Punjab Agricultural University, Ludhiana, India. Fluxes of CH4, N2O and CO2 were measured by closed chambers and gas chromatographer. Due to the longterm application of inorganic fertilizers and organic amendments, soil pH decreased while soil organic carbon along with available P and K status improved. Significant variability in various soil C and N forms was observed under various long-term treatments of the two cropping systems. In the maizewheat cropping system, N2O emissions from 100% NPK, 150% NPK, 100%N and FYM treatments in the maize crop season were higher by 130-150 % and in the wheat crop season by 40-60%over the control. Total CO2 emissions in different treatments in the maize season were higher by 55-90% and in the wheat crop season by 44-85% over the control. In the rice-wheat cropping system, CH4 emissions in the rice season were the highest from straw treatment (146 Kg CH4 ha-1), followed by control, FYM, 150% NPK, 100%NPK, GM and 100%N treatments and in the wheat crop season CH4emission was not observed. N2O emissions in various long-term inorganic fertilizers and organic amendment treatments were higher by >100% and >60% over the control in rice and wheat seasons, while CO2 emissions were higher by 40-100% in rice and 30-70% in wheat over the control. Daily N2O fluxes were found significantly controlled by soil NO3⁻-N and total-N along with water input or rainfall. Temporal variations in CO2 fluxes were controlled by soil temperature and soil OC while, CH4 fluxes were controlled by water depth along with water soluble C and total N in soil. Methane fluxes were dependent on dissolved organic C in soil, which increased with the growth of rice plants and increase was comparatively more in the root zone of rice plants grown in soils of the long-term control treatment followed by 100%N treatment. Rate of C and N mineralization was relatively higher in soils of FYM treatment followed by NPK and control of maize-wheat cropping system. Carbon and N mineralization increased significantly with addition of wheat straw or green manure or FYM. Apparently it can be concluded that with the application of fertilizers and manures, GHG emissions increase, but yield scaled global warming potential (GWP) was much higher for control treatments in both the cropping systems, except straw treatment in rice-wheat cropping system, which suggested that to achieve the food security, integrated nutrient management may be adopted.ThesisItem Open Access Interactive effect of deep tillage and irrigation regimes on crop growth and yield of kharif maize(Punjab Agricultural University, Ludhiana, 2016) Harmandeep Kaur; Meharban SinghDeep tillage responses in maize on coarse textured soils are reported to be related with improvement in root growth and plant water status. In a field study on sandy loam soil at the research farm of Department of Soil Science during Kharif 2015; combinations of two tillage systems i.e. conventional tillage (CT) and deep tillage (DT) and two irrigation regimes i.e. irrigation water/pan evaporation ratios of 0.5 (I1) and 1.0 (I2) were evaluated on two maize hybrids i.e. PMH1 (long duration) and PMH2 (short duration). DT with sub soiler loosened soil in chisel furrow up to 35-45 cm depth. Comparatively higher bulk density i.e. 1.66 and 1.69 Mg m-3 was observed in 15.0-22.5 and 22.5-30.0 cm soil layers, in CT and the reduction in bulk density with DT was maximum in these layers. The penetration resistance (PR) was also lower with DT than with CT; however the magnitude of decrease varied with soil depth and position of measurement. Root length density (RLD) at 70 DAS, was higher under DT than CT in the 15-90 cm depth and increased irrigation level produced higher RLD, under DT but not under CT. Root length index (RLI) in the 90 cm soil profile, did not vary with irrigation level but DT increased RLI. Both leaf area index and plant height were generally higher under DT than CT and with I2 over I1, but the effect was significant only for DT. PMH2 was significantly shorter in plant height than PMH1 at all the growth stages. Leaf water potential (LWP) at 66 DAS was significantly higher with DT and with I2 in both the hybrids. Increase in LWP with I2 over I1 was significant under CT only. Soil temperatures in general were lowered with irrigation & DT and were slightly lower in PMH1 than PMH2. Both DT and higher irrigation caused higher chlorophyll content, but effect was significant for DT only. Fifty percent tassel stage under DT as compared to CT, was 3.3 & 1.8 days earlier in PMH1 and 4.8 & 7.2 days earlier in PMH2; in I1 & I2 treatments respectively. Both grain and biological yields (grain plus stover) were significantly higher with DT over CT and with I2 over I1 in both the hybrids. PMH1 as compared to PMH2, produced significantly higher grain (12.5 %) and biological (17.8 %) yields. Percent increase in grain yield with DT over CT, for I1 & I2 respectively, was 33.8 & 30.6 in PMH1 and 24.5 & 16.8 in PMH2. Significant interaction was observed between tillage and cultivar for biological yield only. Harvest index did not vary significantly with tillage and irrigation treatments, but hundred grain weight varied significantly with tillage and cultivar. Soil profile water use was higher in DT over CT; by 43.5 & 24.5 mm in PMH1 and 31.6 & 22.6 mm in PMH2; for I1 & I2 irrigation regimes respectively. Averaged over other two treatments; water productivity (kg ha-1 mm-1) was higher in DT over CT by 21.2 %; in I1 over I2 by 6.0 % and in PMH1 over PMH2 by 10.9 %.ThesisItem Open Access Response of onion (Allium cepa L.) to crop residue mulch and irrigation regimes in a sandy loam soil(Punjab Agricultural University, Ludhiana, 2016) Gurveer Singh; Singh, C.B.Onion requires light, frequent and high number of irrigations because most of the roots are concentrated in upper surface. Moreover depleting groundwater resources in Punjab, demands for optimum irrigation schedule and water saving techniques. Onion productivity is constrained by high soil evaporation and soil temperature during latter part of the growing season. These can be altered through the straw mulching and irrigation. A field experiment was conducted during rabi 2015-16 at the research farm of Punjab Agricultural University, Ludhiana to evaluate the response of onion to crop residue mulch and different irrigation regimes in a sandy loam soil. Main plots comprised of two mulch rates: No mulch (M0) and rice straw mulch @ 6 t ha-1 (M6) and sub plots included three irrigation regimes based on IW/Pan-E=2.0, 1.4 and 0.8 ratios. Results revealed that the soil moisture storage was higher in mulch plots throughout the growing period. Mulch lowered the maximum soil temperature by 1.8 to 8.8 °C over no mulch plots and also changed the minimum soil temperature during the growing season. The maximum soil temperature was higher by 0.1 to 4.5 °C with the irrigation regime based on IW/Pan-E=0.8 over frequently irrigated IW/Pan-E=2.0. Mulch improved onion bulb yields by 5.5 t ha-1 (24 per cent) over no mulch plots (23.0 t ha-1). Irrigation based on IW/Pan-E ratio of 2.0 and 1.4 significantly enhanced average yield of onion by 5.34 and 4.23 t ha-1 over the restricted irrigation with 0.8 ratio (22.6 t ha-1). Onion in mulched plots with IW/Pan-E=0.8 produced same yield as that recorded in no mulch plots with IW/Pan-E=2.0 demonstrating a saving of six irrigations during growing season. Weed infestation was lower by 92 per cent in mulched plots as compared to no mulch plots. With increase in irrigation frequency the weed biomass also increased significantly. Mulch also improved total water use efficiency by 11.09 kg bulb ha-1 mm-1 over no mulch plots (34.8 kg bulb ha-1 mm-1). Water use efficiency progressively increased with decrease in irrigation water inputs and it was 17 and 8.2 kg bulb ha-1 mm-1 higher with 0.8 and 1.4 ratios over the frequently irrigated plots. Mulch recorded more per cent of larger size (>50 mm) bulbs on mass basis.ThesisItem Open Access Saline and sodic irrigation effects on performance of wheat cultivars and soil health(Punjab Agricultural University, Ludhiana, 2016) Pawitar Singh; Choudhary, O. P.The present investigation was conducted to observe the effects of saline and alkali irrigation water on performance of six wheat cultivars and soil health. Five levels of saline (EC 0, EC 3, EC 6, EC 9 and 12 dS m-1) and four levels of alkali water (RSC 0, RSC 3, RSC 6.5 and RSC 10 me L-1) were used for irrigating six wheat cultivars (KRL 210, PBW 621, HD 2967, PBW 590, PBW 658 and Berbet ) during two years of research study. The results revealed that increasing salinity and alkalinity of irrigation water significantly increased soil pH , EC, SAR, ESP and soluble Na+, Cl- and HCO3- and decreased organic carbon , available nutrients (N, P, K and S) , DTPA-Zn and soluble ions (K+, Ca+Mg2+, SO42-) concentration in both years. Soil physical properties such as bulk density and dispersion ratio increased with increasing salinity and alkalinity in irrigation water whereas MWD, SHC, IR and WHC decreased under these treatments. Biological soil properties (MBC, MBN, DHA and CWEC) were significantly reduced to almost 50% at highest level of salinity (EC= 12 dS m-1) and alkalinity (RSC = 10 me L-1) of irrigation water in 2013-14 and 2014-15. In 84 days of incubation study cumulative respiration, MBC, NH4+ and NO3- N was low under saline and alkaline irrigated soil samples which improved on addition of carbon @ 1%. Plant and yield parameters were adversely impacted due to elevated salinity and alkalinity levels of irrigation water in both years. Pooled over two years, among different cultivars the maximum grain yield was produced by PBW 658 (4.23 t ha-1) at highest level of saline water (EC = 12 dS m-1) and by PBW 621 (5.19 t ha-1) for highest level of alkaline water (RSC = 10 me L-1) whereas the minimum yield in both cases was recorded for PBW 590 (3.82 and 3.79 t ha-1), respectively. Among all cultivars performance of HD 2967 was better at EC 9 dSm-1 and RSC 6.5 meL-1, therefore can be grown without much significant loss in grain yield at respective levels but at highest level of salinity and alkalinity of irrigation water PBW 658 and PBW 621 should be preferred to get higher yield.
