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Refinement of leaf colour chart based fertilizer nitrogen management technology using PAU-LCC in transplanted rice
(Punjab Agricultural University, Ludhiana, 2017) Amandeep Singh; Varinderpal Singh
Large 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.
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Medium-term impact of resource conservation technologies on physical environment of soil in rice-wheat system
(Punjab Agricultural University, Ludhiana, 2017) Jashanjeet Kaur; Manmohanjit Singh
Rice-wheat system is a predominant cropping system in India in general and Punjab in specific. Repeated puddling for rice cultivation and extensive tillage during wheat has adversely affected the physical environment of soil. Keeping in view the long-term sustainability of the conventional rice-wheat systems, there has been more emphasis nowadays on adopting and promoting resource conservation technologies. Therefore, a medium term study was conducted to evaluate the impact of tillage, mulch and establishment methods on soil physical, biochemical and microbial characteristics of sandy loam and loam soil. In sandy loam soil the experiment started in year 2010 with four treatments i.e. conventional tillage both in wheat and direct sown rice (CTDSR/CTW), zero tillage both in wheat and direct sown rice (ZTDSR/ZTW), conventional tillage both in wheat and direct sown rice with mulch (CTDSR/CTW+M) and zero tillage both in wheat and direct sown rice with mulch (ZTDSR/ZTW+M) and in loam soil the experiment started in year 2011 with two treatments i.e. zero tillage both in wheat and direct sown rice (ZTDSR/ZTW) and conventional tilled wheat followed by transplanted rice (PTR/CTW). In mulch treatments, rice residues were retained in wheat and in without mulch treatments, rice residues were removed. Soil physical characteristics like water stable macro aggregates > 0.25 mm (WSMacA), water stable micro aggregates (WSMicA), mean weight diameter (MWD), bulk density (BD), infiltration rate (IR), soil moisture characteristics, soil organic carbon (SOC), soil enzymatic activities (dehydrogenase, alkaline and acid phosphatase and urease), microbial biomass carbon and soil respiration were evaluated. In sandy loam soil, in zero tillage treatments in the surface layer (0-15 cm), the soil physical characteristics like WSMacA were 8.2% higher, MWD was 31.8% higher and BD was 4% higher as compared to conventional tillage. In the sub- surface soil layer (15-30 cm), WSMacA and MWD showed the similar trend, but BD was lower (5.6 %) in zero tillage treatments. With addition of mulch, WSMacA increased by 16%, MWD by 39% and BD decreased by 2 % in the surface layer. The SOC increased by 9 % at 0–15 cm, and 25% at 15–30 cm soil depths with ZT over CT. Mulched plots showed significant increase in SOC by 18% than CT. Higher steady state IR was observed under zero tillage plots, in spite of the fact that surface soil layer was having high BD in these treatments, which show the predominant effect of higher SOC in these treatments. Higher values were observed for soil enzymatic activities (dehydrogenase, akaline and acid phosphatase and urease), microbial biomass carbon and soil respiration in the conservational agriculture based treatments (ZT and mulching). In loam soil, physical and biological characteristics of soil after 5 years of continuous ZT and CT in rice- wheat system were analyzed. BD was higher in surface layer under ZTDSR/ZTW than PTR/CTW and showed significant decline in sub-surface soil layer. SOC, WSMacA, IR, soil water retention at different soil matric potentials, soil enzymatic activities (dehydrogenase, akaline and acid phosphatase and urease), microbial biomass carbon and soil respiration showed significant improvement under ZTDSR/ZTW as compared to PTR/CTW. Thus our medium- term study on both sandy loam and loam soils suggest that resource conservation technologies like direct dry-seeded rice (DSR), zero tillage (ZT) and mulching improves soil physical characteristics and these needs to be promoted for sustainable soil health.
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Assessment of seasonal variations on soil biochemical properties under different land use systems in sub montane Punjab
(Punjab Agricultural University, Ludhiana, 2017) Asima; Sharma, Vivek
Land degradation due to improper land use management leads to deterioration of soil health. Increasing population, urbanization and demand for food enforced the system to convert the forest to agricultural land results in decline of soil fertility and productivity. Maintenance of soil heath is a key component of agriculture sustainability and soil biochemical properties are considered as sensitive indicators of soil health. Hence it is essential to study the effect of different land use systems on key indicators of soil health viz. soil biochemical properties and soil organic carbon for sustainable agricultural system. A study was conducted to determine the effect of different land use systems (forestry, agroforestry, agri-horticulture, horticulture, agriculture and eroded land) and seasonal variations (summer, rainy and winter season) on soil biochemical properties under rainfed conditions in sub montane Punjab. A total of 180 soil samples were collected from two locations i.e. Balachaur (SBS Nagar) and Talwara (Hoshiarpur). Soil samples were collected in summer, rainy and winter season from same place using global positioning system to study the seasonal changes. The results revealed that soils were slightly alkaline (7.3-7.9) at Balachaur and slightly acidic at Talwara (6.4-6.9) with electrical conductivity varied from 0.31-0.61 dSm-1 at Balachaur and 0.09-0.23 dSm-1 at Talwara, respectively. Soils were loamy sand to sandy loam in texture at both the locations. The organic carbon content, available nitrogen, phosphorus and potassium content in soil ranged from 0.20 to 0.63 per cent, 110 to 381, 29.8 to 32.6 and 99 to 196 kg ha-1 at Balachaur and 0.14 to 083 per cent, 86 to 406, 29.3 to 32.6 and 65 to 226 kg ha-1 at Talwara, respectively. Among DTPA extractable micronutrient cations, DTPA-Mn, DTPA-Fe, DTPA-Cu and DTPA-Zn content in soil varied from 9.5 to 15.1, 9.0 to 25.2, 0.31 to 1.02 and 0.71 to 0.96 mg kg-1 at Balachaur and 10.3 to 21.2, 12.1 to 34.5, 0.34 to 1.01 and 0.76 to 1.15 mg kg-1 at Talwara region, respectively. Among soil biochemical properties, dehydrogenase, acid and alkaline phosphatase, basal soil respiration and urease activity were higher under agri-horticulture and forestry based land use systems. In sub systems, the soil dehydrogenase activity varied from 5.4 to 10.9 µg TPFg-1h-1 and 7.4 to 12.8 µg TPFg-1h-1 at Balachaur and Talwara, respectively. The acid and alkaline phosphatase activities varied from 17.0 to 36.5 µg pNPg-1h-1, 36.3 to 61.3 µg pNPg-1h-1and 22.3 to 34.5 µg pNPg-1h-1, 43.4 to 60.1 µg pNPg-1h-1 at Balachaur and Talwara, respectively. The urease activity was observed to be highest for guava based agri-horticulture system at Balachaur and mango based agri-horticulture system at Talwara. The microbial biomass carbon was observed to be higher in mango based agri-horticulture system at Balachaur and eucalyptus based agroforestry sub system in Talwara. The total and easily extractable glomalin content was observed to be higher in guava and mango based agri-horticulture land use systems in Balachaur and Talwara, respectively. The soil carbon fractions (labile fractions, organic matter fractions, total organic carbon and carbon management index) were observed to be higher in agri-horticulture system and forestry system as compared to other land use systems. Among seasons, rainy season had higher soil properties as compared to the winter and summer seasons. The principal component analysis revealed that the soil properties were highly correlated with agri-horticulture system and rainy seasons. The dehydrogenase activity, urease, basal soil respiration and total organic carbon were observed to be best soil quality indicators among the land use systems and seasons in sub montane region of Punjab.
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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 carbon pools as affected by agricultural land-uses in soils of south-western Punjab
(Punjab Agricultural University, Ludhiana, 2017) Mandal, Agniva; Toor, A.S.
The present investigation was aimed to study the effect of agricultural land-uses on organic carbon (OC) content and carbon (C) pools in the south-western plains of Punjab. Three sites were selected in and around Dhanaula (Site 1) in district Barnala; Bhucho (Site 2) and Phul (Site 3) in district Bathinda. Three land-uses viz. cropland, horticultural land and uncultivated land were selected. On an average, all land-uses were more than ten years old. In all sites, soil pH varied from slightly alkaline to moderately alkaline. Higher EC was observed in uncultivated and cropland whereas slightly moderate salinity hazard reported particularly from site 2. Samples were mostly of sandy loam to loamy sand in texture. Uncultivated and cropland had higher bulk density in all sites. Mostly horticultural land contained higher available N while available P and K were recorded high in cropland. Zn, Fe and Mn contents were rated high in horticulture where Cu content was sufficient in almost all sites irrespective of land-uses. Both water stable aggregates (WSA) and mean weight diameter (MWD) were recorded highest in horticultural land in all three sites. Horticultural land (9.73 g kg-1) had highest SOC content. Macro-aggregates (0.25 - > 2 mm) were found to be main carrier of organic carbon and highest OC was associated with 1-2 mm sized aggregates. At site 1, horticultural land-use was recorded with highest amount of total particulate organic carbon (TPOC) (5154.25 mg kg-1), KMnO4-oxidizable C (1295.39 mg kg-1) and cropland was observed with highest inorganic carbon (IC) (1520 mg kg-1). At site 2, horticultural land was found to be associated with highest TPOC (4180.34 mg kg-1), KMnO4-C (1442.39 mg kg-1), mineralizable carbon (MC) (442.8 mg kg-1) and uncultivated land with highest IC (1790 mg kg-1). Similar to site 2, at site 3, TPOC (3537.01 mg kg-1), KMnO4-C (1805.33 mg kg-1) and MC (865.6 mg kg-1) were highest in horticultural land whereas IC (1100 mg kg-1) was noted maximum in cropland at site 3. Significant differences among different land-uses were more pronounced in surface layer than deeper layers regarding different C fractions. Positive correlation was reported among different C pools. The potential for C sequestration was found high in horticultural land-use than other two land-uses.
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Copper substituted nano-phosphate mineral for its use as a novel fertilizer
(Punjab Agricultural University, Ludhiana, 2017) Parminder Singh; Kukal, S. S.
Copper containing nanomaterials in apatite-mineral receptacles are envisioned as environmental compliable nutrient supplier to plants. Therefore, this study aimed to fabricate apatite mineral using wet chemistry technique followed. The selected apatite was functionalized, and brought to nanoform by top-down method. The Copper based products were obtained by reacting apatite receptacles in nanostate with copper (Cu2+) which were characterized through nanotechnology tools. Scanning and Transmission Electron micrographs depicted roughly rectangular to square rhomboidal structures existing as short and long columns, thick plates-like and needle-like aggregatesand particle shapes varied from roughly spherical, oval, oblong to cylindrical/ tubular for nano-apatite samples. The SEM-Energy Dispersive Spectroscopy (EDS) detected perceptible adsorption of copper on apatite and confirmed occurrence of 6.69 percent of Cu atom in nanoapatite receptacle. While the SEM-X-ray mapping exhibited spheroid shaped distribution of Cu2+on nanoapatite receptacle. TheFT-IR spectra depicted the characteristic symmetric and asymmetric valence oscillations of the phosphate bond. The HAp showed strong X-ray reflections and most intense peaks appeared in the range of 2θ ~ 12.4 to 40º.The XRD pattern of nanohydroxyapatite shows the occurrence of broad and diffuse peaks which indicate towards low crystallization degree of the sample crystals further accentuating their nanoscale crystal size. Moreover, copper substitution resulted in increase in the peak count only at 002 while it decreased the peak height of (300), (202), (130) these (h,k,l) planes The in vitro hydroponic based corn-seed germination test showed the potential of the nano-product to support plant growth. Therefore, the Cu adsorbed nano-apatite receptacles can be utilized as a beneficial plant-nutrient supplier.
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Use of biochar as amendment to reclaim saline and sodic soils
(Punjab Agricultural University, Ludhiana, 2017) Rajanbeer Singh; Mavi, M.S.
Information is limited about ameliorating effect of biochar on irrigation water induced salt-affected soils, although increasing data have shown that biochar amendment can improve soil fertility and crop production. Therefore, in the present investigation, soil samples varying in EC and SAR levels, were amended with different rates or types of biochar, for the laboratory incubation experiments at 250C for 8 weeks. First experiment was conducted to determine the effect of addition of different rates of rice residue biochar (0, 1, 2, 4% w/w) on soil properties under varying EC [2 (control), 8 and 16 dSm-1] and SAR [2.5 (control), 20, 30] levels whereas, the second experiment was conducted to compare the ability of biochar (added at the rate 2%) derived from maize stover (MB), poultry manure (PB) and rice residues (RB) in ameliorating salt-affected soils. Soil samples were analyzed to determine dissolved organic C, microbial biomass C, mineral N, pH, EC and SAR, available N, P, K, SOC, CEC in experiment 1 or 2. The study showed that addition of rice-residue biochar increased C mineralization both in saline and sodic soils, greater so at higher rates of addition (2-4%). However, compared to unamended soils, biochar addition at the rate 1% did not significantly affect C mineralization and MBC both on day 14 and 56 at various EC and SAR levels. Consistent with the C mineralization, a positive linear relationship was observed between MBC and increasing rate of biochar addition in all the soils. Moreover, DOC concentration increased in the biochar amended saline and sodic soils and followed the order (B4> B2> B1> B0). NO3--N concentrations increased with increase in period of incubation and the biochar rates whereas, NH4+-N concentration was higher upto day 14 in both soils. Further, soils amended with the poultry manure biochar showed greater C mineralization; MBC and DOC than those amended with rice residue or maize stover biochar suggesting greater release of easily decomposable material by the former for microbial activity and growth. Further, higher available N observed in soil amended with poultry manure biochar compared to rice residue and maize stover biochar in the present study could be due to its lower C: N ratio and thus higher N mineralization. Similarly, concentration of available P was found higher in PB than RB and MB amended soils due to its higher ash content (62%). Correspondingly, rice residue biochar with its greater reserve of potassium can serve as good source of available K in both saline and sodic soils. Thus, the positive effects of biochar addition on C mineralization and the improvement in measured soil parameters like MBC, DOC, SOC, CEC and available N, P and K in the study clearly showed the potential of biochar to be used as an organic amendment in ameliorating saline and sodic soils. The study also showed greater ability of poultry manure biochar in improving the soil properties under stressed condition due to its higher decomposibility and release of plant available nutrients.
Open Access
Phosphorus availability in soils amended with biochar
(Punjab Agricultural University, Ludhiana, 2017) Mukherjee, Subham; Mavi, M.S.
The current system of agricultural crop production is severely constrained by soil available P deficiency in soils and costs associated with mineral P fertilizers to address this constraint in arable lands. Thermo-chemical conversion of surplus biomass to produce biochar is an emerging ameliorating strategy in the context of sustainable P and biomass waste management. Two incubation studies (90 and 60 days respectively) were conducted to investigate the interactive effects of rice residue biochar and the inorganic-P fertilizer on phosphorous availability in soils with varying P status and contrasting pH. For the first incubation study, four rates of the rice residue biochar (0, 10, 20 and 40 g kg-1) in combination with three levels of the inorganic-P (KH2PO4) (0, 25 and 50 mg kg-1) were added into the medium and the high P status soils. Increasing biochar addition rates alone or in combination with the inorganic-P resulted in significant increase in the P pools (plant available Olsen-P, microbial biomass P and the inorganic-P fractions), greater so in the high P than the medium P status soils. In the second incubation experiment, two rates of rice residue biochar (0 and 20 g kg-1) with three rates of inorganic-P (KH2PO4) (0, 25 and 50 mg kg-1) were added into the three contrasting pH soils (acidic, neutral and alkali soils). Biochar addition alone or in combination with inorganic-P resulted in significant increase in organic and inorganic P pools (microbial biomass-P, plant available Olsen-P and mineral bound inorganic-P fractions) and followed the order neutral soil > alkali soil > acid soil. The biochar mediated changes in P availability in both experiments were attributed to: 1) high available P content in the biochar itself and; 2) biochar induced reduction in the P sorption capacity of soils due to increase in competition for the P sorption sites by the released P and the surface functional groups present in the biochar. Further, lower alkaline and acid phosphatase activity with increasing rates of biochar addition in the soils of both experiments elucidates biochar’s ability to act not only as a source but also as a sink of P. Therefore, it may be concluded that the rice residue biochar can be used as a promising amendment in meeting the crop P demand, and thus has the potential to supplement or replace the exhaustible mineral P fertilizers.
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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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