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Effect of organic amendments on boron availability in calcareous soils under raya (Brassica juncea L.) and soybean (Glycine max.L.)
(Punjab Agricultural University, Ludhiana, 2019) Sukhvir Kaur; Sharma, Sandeep
A pot experiment was conducted during rabi (2016-2017) and kharif (2017) season to study the response of raya (Brassica juncea L.) (cv. PBR 357) and soybean (Glycine max L.) (cv. SL 958) to different levels of boron (B) and different organic manures in boron deficient calcareous soils of Punjab. Three different soils with varying calcium carbonate content viz. 0.65 (soil I), 4.1 (soil II) and 5.4 per cent (soil III) were collected from Ludhiana, Sudhar (Ludhiana) and Bathinda Districts for experimental study. The treatments comprised six levels of boron for soil application viz. 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mg B kg-1 and two levels of farmyard manure viz. control and FYM @10 t ha-1. The experiment was laid out in CRD factorial design with three replications. Yield and yield attributing characters at different crop growth stages (grand growth and maturity stage) increased significantly at 1.5 mg B kg-1 with FYM irrespective of the soils. The boron content and its uptake was higher in leaves followed by stem, grains and root, respectively both in raya and soybean crop. Among calcareous soils, soil I with lowest calcium carbonate was the best soil in respect of yield, yield components, boron content and its uptake in comparison to soil with medium and high calcium carbonate content. Boron transformation in soil after the harvesting of raya and soybean crop revealed that readily soluble was higher in soil I compared with soil II and soil III. Specifically adsorbed, oxide bound, residual and total boron were more in soil III however, oxide and organically bound fractions were higher in soil II. The coefficient of determinations (R2) for Langmuir adsorption isotherm were lower compared with Freundlich adsorption isotherm which proved that Freundlich adsorption isotherm to be more valid for adsorption studies. It indicated that B adsorption data fits excellent to Freundlich adsorption isotherm. The highest value of adsorption maxima (b) (45.0 mg kg-1) was recorded in silty clay. However, the highest bonding energy constant (k) (0.111 L kg-1) value was recorded in sandy soil whereas; the (k) lowest value 0.047 mg L-1 was recorded in silty clay. The Freundlich bonding energy constant increased with increase in soil clay content having minimum value in sandy soil 1.405 mg kg-1 and maximum (2.29 mg kg-1) in silty clay soil. In incubation study, the availability of boron in soil was studied with six varying levels of boron (0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mg B kg-1), five organic amendments (control, farmyard manure, press mud, poultry manure and rice straw compost) with three levels of calcium carbonate content (0.64, 4.1 and 5.4 per cent) at 15, 30 and 60 days of intervals. The soil was incubated in a temperature controlled room at 25oC. Boron availability increased as a function of time and treatment for different soils. The mean boron content was highest in soil application of 2.5 mg B kg-1 with farmyard manure followed by press mud, poultry manure, rice straw and control (no-amendment) in different types of soils. Availability of boron was highest in soil with low calcium carbonate content and decreased with increasing levels of calcium carbonate content over time period.
Open Access
Nitrogen, phosphorus and potassium management for wheat in poplar based agroforestry system
(Punjab Agricultural University, Ludhiana, 2019) Janpriya Kaur; Baljit Singh
The present studies were conducted to evaluate the influence of different levels of N, P and K on wheat productivity in poplar plantations. Litterfall addition, return and release of nutrients through decomposition of litterfall were also evaluated. Wheat intercropped with different aged (2, 3, 5 and 6 year) poplar plantation and sole wheat was treated with different levels of N (0, 60, 90, 120, 150, 180 kg N/ha and LCC based-115 kg N/ha) and also different levels of nutrients (P and K) i.e. 0:0, 60:0. 60:30, 60:90, 90:0, 90:30 and 90:60 kg P2O5:K2O kg/ha in another experiment. Results indicated that growth, yield parameters, yield and nutrient (N, P and K) uptake by wheat grains and straw decreased significantly with increasing tree age but increased significantly with N fertilization. The best N level for wheat growth, yield, nutrient use efficiency and nutrient uptake under trees was LCC based application followed by 180 kg N/ha. Highest grain yield (44.2 q/ha), nutrient uptake by grains (kg/ha) i.e. N (86.1), P (14.27) and K (33.8) were obtained on fertilization with 180 kg N/ha while agronomic efficiency was maximum (18.4 kg grains/kg N applied) in LCC based treatment. Nutrient content and soil properties (OC, available N, P and K) showed a significant increase with tree age and N fertilization to maximum with 180 kg N/ha. Results of experiment with variable P, K levels indicated that wheat growth, yield, nutrients content, uptake and soil properties (OC, available N, P and K) under trees increased on fertilization with nutrients to maximum in T7 (90:60 kg P2O5:K2O/ha). In another experiment litterfall addition and return of nutrients showed significant increase with advancing tree age (2 to 6 years) and months of litterfall (October to December). The highest litterfall (5.51 t/ha) and among macronutrients maximum return of Ca (104.8 kg/ha) and in micronutrients highest return of Fe (7529 g/ha) was observed in 6 year plantation. Macronutrient return followed trend Ca>N>Mg>K>S>P and micronutrients Fe>Mn>Zn>Cu. Release of nutrients from litter under 2 and 5 year poplar with 120 and 180 kg N/ha increased with increasing N levels and time of decomposition to maximum with 180 kg N/ha 2 year plantation. Order of nutrient release was K>P>N. In incubation study, available N, P and K increased to maximum in soil amended with 0.3 % leaf litter levels treated with 75 mg N/kg soil at 90 days of incubation.
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.
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Need-Based Fertilizer Nitrogen Management in Spring Maize
(Punjab Agricultural University, Ludhiana, 2019) Jagdeep Singh; Varinderpal Singh
Synchronizing fertilizer nitrogen (N) supply and plant N demand remains a major constraint due to spatial variability in soil N supply especially when fixed time fertilizer N applications are made as per soil test-based recommendations. Precision N management strategies to define in-season optimum N dose and appropriate topdressing timings are desired to achieve high N use efficiencies while sustaining potential grain yield. Field experiments were conducted at PAU, Ludhiana and KVK, Gurdaspur with spring maize cultivars DKC- 9108 and PMH-10 for two years to study spectral properties of spring maize to help guide need-based fertilizer N applications using leaf color chart (LCC), chlorophyll meter (SPAD meter) and GreenSeeker (GS) optical sensor. The spectral properties measured using the gadgets were strongly correlated with leaf N, plant biomass, biomass N content and grain yield at different crop growth stages. A close linear relationship (R2 = 0.75) between SPAD meter readings and LCC score indicated that LCC can be used as an inexpensive and reliable substitute of SPAD for real-time need-based N applications in spring maize. The statistical analysis of spectral reflectance recorded at different growth stages revealed that NDVI readings at V9 growth stage could precisely predict the in-season N requirements for spring maize production. Algorithm to predict grain yield and to draw in-season need-based fertilizer N topdressing decisions using GreenSeeker optical sensor was established. Fertilizer N topdressings based on threshold leaf greenness of LCC 5, SPAD 50 and sufficiency index value of SPAD 0.95 and NDVI 0.90 produced significantly higher grain yield with improved recovery and agronomic efficiencies of applied fertilizer N in comparison to soil-test based N recommendations. The improved congruence of fertilizer N supply and crop N demand in LCC, SPAD and NDVI-based N management treatments reduced N2O emission and global warming potential, produced more number of grains per cob and plant height than soil testbased N management. Insignificant differences in N indices of different soil layers between no N control and fertilizer N treatments expressed that higher fertilizer N applications were not helpful in increasing total soil N and N supplying capacity of the soil.
Open Access
Contribution of different chemical pools of potassium towards wheat nutrition
(Punjab Agricultural University, Ludhiana, 2019) Harpreet Kaur; Gill, Roopinder Singh
The field and pot experiments were conducted to study the effect of potassium (K) application on availability of K to wheat and contribution of exchangeable and non exchangeable K towards wheat nutrition. In pot experiment, twenty bulk soil samples having a range in available K were used and K was applied @ 0, 15, 20, 25 and 30 kg K ha-1soil. Wheat (cv PBW 725) was grown as a test crop. The different potassium fractions i.e. water soluble, exchangeable, available and non exchangeable K were determined. The amount of corresponding forms ranged between 8.86 to 23.7, 66.1 to 379.8, 75.1 to 403.1 and 898.4 to 1861.3 mg kg-1 soil in these soils. The mean grain yield varied from 8.43 to 20.58 g pot-1. All the forms of K showed positive and significant correlation with grain & straw yield, K content and K uptake. The highest positive and significant correlation of wheat grain yield was found to be with water soluble K (r = 0.905*) followed by available K (r = 0.836*), exchangeable K (r = 0.831*) and non exchangeable K (0.815*). In K deficient oils, grain yield of wheat increased significantly with graded levels of applied K. However, in K sufficient soils, grain yield increased significantly up to application of 25 kg K ha-1. In both K deficient and sufficient soils, K concentration and uptake by grain and straw of wheat increased significantly with incremental levels of applied K. About 83.6 per cent variation in grain yield of wheat was due to the combined influence of water soluble and exchangeable potassium while available and non exchangeable form of potassium explained only 2.3 per cent variation in grain yield of wheat. However, in K deficient soils, contribution of non exchangeable K towards grain yield was higher as compared to K sufficient soils. The critical limit of available and non exchangeable potassium for wheat as determined by graphical method was 168 and 1338 kg K ha-1, respectively. The field experiment was conducted at two sites, at the Research Farm of Department of Soil Science, Punjab Agricultural University (PAU), Ludhiana (medium in available potassium i.e. 228.9 kg ha-1) and at Regional Research Station, Gurdaspur (low in available potassium i.e. 125.6 kg ha-1). The K was applied @ 0, 10, 15, 20, 25, 30, 35 and 40 kg K ha-1 soil and wheat (cv PBW 725) was grown as test crop. The mean grain yield in PAU, Ludhiana and RRS, Gurdaspur soil was found 47.5 and 42.5 q ha-1, respectively. In PAU, Ludhiana soil, the significant response of wheat to applied potassium was recorded up to 25 kg K ha-1 soil, however, in RRS, Gurdaspur soil response was recorded up to 40 kg K ha-1. The water soluble, exchangeable, available and non exchangeable K were found to be 13.8, 75.9, 84.5 and 1053.6 mg kg-1 soil, respectively in PAU, Ludhiana soil and 10.1, 61.1, 70.5 and 969.7 mg kg-1 soil, respectively, in RRS, Gurdaspur soil. The kinetics of non-exchangeable K release from ten bulk soil samples having a range in available K was investigated using 0.01 M oxalic acid. The cumulative amount of K released in 200 h ranged between 86 and 253 cmol kg-1 x 10-2. The highest amount of non exchangeable K release (253 cmol kg-1 x 10-2) was found in Mansa soil (sufficient in K) and lowest amount (86 cmol kg-1 x 10-2) was recorded in Gurdaspur soil (deficient in K). Kinetics of non exchangeable K release from soils were adequately described by Elovich, first order, power function and parabolic diffusion models while zero order model was not suitable to describe K release.
Open Access
Effect of residue management tillage and irrigation on water balance of direct seeded rice and wheat
(Punjab Agricultural University, Ludhiana, 2019) Gurpreet Singh; Singh, K. B.
Adoption of proper tillage and residue management practices are must for sustaining soil and crop productivity. Residue retention or incorporation with proper irrigation scheduling improves soil water storage, soil physical characteristics and crop productivity. However, the tillage and residue management practices are very site specific. Therefore, field experimets were conducted during rabi 2015-16 and 2016- 17 and kharif 2016 and 2017. Wheat was sown with three residue management tillage systems (residue incorporation, residue standing and residue removal) under flood and drip irrigation. Rice seeds were directly sown in previously established main plots of residue management tillage (same as in wheat) and further wheat residue incorporation and removal in sub-plots along with flood and drip irrigation. The data indicated that during 2015-16 and 2016-17, all growth attributes of wheat i.e., plant height, leaf area index (LAI) and dry matter accumulation (DMA) were highest in reisdue incorporation with drip iriigation. The yield attributes i.e., grain yield and biological yield were also highest in residue incorporation with drip irrigation (RI+D) and lowest in residue removal with flood irrigation (RR+F). During 2015-16 and 2016- 17, maximum amount of irrigation water was received by RR+F (29.76 and 29.07 cm) and lowest amount of irrigation water was received by RI+D (20.51 and 19.66 cm). Maximum soil water contribution to wheat crop was also observed from RI+D. Irrespective of irrigation treatments, residue incorporation also resulted in 2.65% lower bulk density and 11.67% higher saturated hydraulic conductivity at 0-7.5 cm soil depth and 28.57% higher final infiltration rate, 41.46% higher mean weight diameter and 29.03% higher organic carbon as compared residue removal treatment after 2 years. Crop water productivity was significantly more under drip irrigation as compared to flood irrigation during 2016-17. However, apparent water productivity was significantly higher under residue incorporation as compared to residue standing and residue removal. In direct seeded rice, during 2016 and 2017, all growth attributes i.e., plant height, LAI and DMA of DSR was highest in the treatment which received double incorporation (incorporation of paddy straw and wheat straw). Combination of residue incorporation with drip irrigation resulted in highest values of crop growth attributes. The yield attributes i.e., grain yield and biological yield was 20.31 and 17.59% higher in residue incorporation as compared to residue removal during 2017. All flood irrigated plots received same amount of irrigation 109.53 and 116.95 cm during 2016 and 2017, respectively. The lowest amount of irrigation 98.12 and 103.61 cm during 2016 and 2017 was received by RI-RI+D. Residue incorporation also resulted in lowest drainage and more soil moisture storage at harvesting of direct seeded rice during both years. Residue incorporation resulted in significant reduction in soil bulk density of surface soil (0-15 cm) after harvesting of rice during both years. Saturated hydraulic conductivity and soil infiltration rate also improved under residue incorporation. The study finally concluded that residue incorporation along with drip irrigation saves irrigation water and improves soil moisture storage and crop performance.
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Evaluation of rabi oilseeds and pulses genotypes for response to boron
(Punjab Agricultural University, Ludhiana, 2018) Dhaliwal, Jaspreet Singh; Bhatti, Deedar Singh
A pot experiment was conducted to evaluate the response of rabi oilseed genotypes to boron (B) application in a B deficient soil (HWS-B; 0.39 mg kg-1 soil). Eight kg of well processed soil was filled in plastic pots with three replications. Boron was applied @ 0, 0.25, 0.50, 1.00, 2.00 and 4.00 mg kg-1 soil as borax. Pots were allowed to equilibrate for 20 days at field capacity. Six seeds of different genotypes of raya (RLC 3, PBR 357, PBR 210, PBR 97, PBR 91) and gobhi sarson (GSC 7, GSC 6, PAC 401, GSL 1, PC 6) were sown during rabi season of 2015-16, which were thinned to 3 plants per pot after germination. Application of B @ of 0.50 mg kg-1 soil significantly increased the seed yield and B concentration in both raya and gobhi sarson. The genotypes PBR 210 and PAC 401were found to be B efficient. The genotype RLC 3 of raya was susceptible to B toxicity while PC6 (african sarson) was resistant to B toxicity. The critical levels of HWS-B in soil to produce 90% of the maximum seed yield were 0.57, 0.58, 0.47, 0.60, 0.38, 0.49 and 0.70 mg kg-1 for RLC3, PBR357, PBR210, PBR97, GSC6, PAC401 and GSL1, respectively. The corresponding values of B concentration in seed to produce 90% of maximum seed yield were observed as 18.1, 14.1, 11.0, 14.4, 20.6, 15.7 and 16.3 µg g-1.Another pot experiment was conducted in a similar manner in which five genotypes each of chickpea (PBG 7, PBG 5, GPF 2, PBG 1, L552) and lentil (LL 931, LL 699, LH84-8, LH82-6, HM 1) were supplied with five levels of B (0, 0.25, 0.50, 1.00 and 2.00 mg kg-1 soil) as borax. Seed yield of chickpea and lentil increased significantly with B application @ 0.25 mg kg-1 soil. The critical levels of HWS-B in soil to produce 90% of the maximum seed yield were 0.41, 0.45, 0.41, 0.51, 0.45, 0.41, 0.53 and 0.48 mg kg-1 soil for PBG 7, PBG 5, GPF 2, PBG 1, L 552, LL 931, LH 82-6 and HM 1, respectively. The corresponding values of B concentration in seed to produce 90% of maximum seed yield were observed as were 18.7, 19.9, 19.4, 21.1, 23.0, 16.0, 13.6 and 12.9 µg g-1. The chickpea genotype L 552 was found to be resistant to B deficiency as well as toxicity. The lentil genotype LL 931 was B efficient and LH 84-8 and HM 1 were found to be resistant to B toxicity. A pot experiment was also conducted to study the relative efficiency of soil and foliar applied B in rabi oilseeds and pulses. Boron was applied @ 0, 0.25, 0.50, 1.00, 2.00, 3.00, 4.00 and 5.00 mg kg-1 soil as borax and foliar application of 0.2 % borax at 30 DAS and pre flowering stage. Foliar application of B was found to be relatively more superior to soil application in increasing the seed yield of raya. In gobhi sarson soil applied B @ 0.50 mg kg-1 soil and two foliar sprays of B were equally effective to produce significant response over control. For chickpea, B application @ 0.25 mg B kg-1 soil and one foliar application at 30 DAS were equally effective, but for lentil, foliar applications were not effective. Transformation studies of B in soil after the harvesting of oilseed and pulses crops revealed that content of B in different pools increased with its application to soil. The readily soluble and specifically adsorbed B decreased after harvesting of crops either due to plant uptake or conversion to other pools. Oxide and organically bound fractions increased whereas residual forms remained unaffected with cropping. In a B adsorption study it was observed that both Freundlich and Langmuir adsorption isotherms satisfactorily explained the B adsorption behavior of five different textured soils (sand, loamy sand, sandy loam, loam and clay loam). Highest values of bonding energy constant (Kf) predicted by Freundlich adsorption isotherm (2.291 mg kg-1) was observed for clay loam soil whereas lowest was recorded with sandy soils (1.409 mg kg-1). Bonding energy constant was also significantly correlated with organic carbon (r=0.803*) and clay content in soil (r=0.837*) which signified the increased adsorption of B with increased clay and organic matter in soils.
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Soil water balance, land and water productivity of direct seeded rice-wheat and maize-wheat system in relation to differential tillage and irrigation regimes
(Punjab Agricultural University, Ludhiana, 2018) Dhaliwal, Jeevanjot; Kahlon, M.S.
The field experiments were carried out during 2016-18 in a sandy loam soil to assess the role of differential tillage and irrigation regime on crop performance, land productivity, soil water balance and water productivity of direct seeded rice (DSR)-wheat and maize-wheat system. First experiment consisted of DSR-wheat with two irrigation regimes in main plots [4-days (4-d) and 8-days (8-d) interval in DSR; IW/PAN-E=1.0 (I1.0) and 0.5 (I0.5) in wheat] and six differential tillage in sub-plots viz. DSRDT2-CTW: Deep tillage (DT) before DSR in both season + Conventional tilled (CT) wheat, DSRCT-WDT2 : CT-DSR + DT before wheat in both season, DSRDT1-WCT: DT before DSR in first season + CT wheat, DSRCT-WDT1 :CT-DSR + DT before wheat in first season, DSRCT-WCT: CT- DSR + CT wheat, DSRCT-WZT: CT- DSR + Zero tilled wheat with residue retention). The land productivity was significantly higher under frequently irrigated conditions (4-d/I1.0) during both the years but the difference was statistically significant during 2016-17. It was significantly higher under DSRDT1-WCT, DSRCT-WZT, DSRCT-WDT1 than DSRCT-WCT during 2016-17. The DT during second year did not resulted in significant increase in land productivity of the system. The Evapotranspiration (ET) losses were higher under frequently irrigated (4d/I1.0) as compared to less frequently irrigated (8d/I0.5) conditions. Among different tillage practices the ET losses were comparable for the system as a whole. The water productivities (total input, irrigation and ET-based) of the rice-wheat system were higher in plots irrigated less frequently. The DT helped in increasing the water productivities of the rice-wheat as compared to CT plots during both the years. Second experiment consisted of maize-wheat system with two irrigation regimes in main plots (IW/PAN-E=1.2 (I1.2) and 0.8 (I0.8) in maize; IW/PAN-E=1.0 (I1.0) and 0.5 (I0.5) in wheat). There were five differential tillage treatments in sub plots viz. MDT2-WCT: DT before maize in both season + CT wheat, MCT- WDT2: CT maize + DT before wheat in both seasons, MDT1-CTW: DT before maize in first season + CT wheat, MCT- WDT1: CT maize + DT before wheat in first season, MCT-WCT: CT maize + CT wheat. The land productivity of the maize-wheat system was significantly higher under frequently irrigated conditions during both the years. It was higher by 9.5 and 11.4 percent under I1.2/I1.0 than I0.8/I0.5 during 2016-17 and 2017-18, respectively. It was higher under DT than CT during both the years, like DSR-wheat system, the DT during second years did not result in significant increase in land productivity. The ET losses were higher under frequently irrigated (I1.2/I1.0) than less frequently irrigated (I0.8/I0.5) conditions. The water productivities of maize-wheat system were higher in plots irrigated less frequently the difference being significant during 2017-18. And they were significantly higher under DT than CT during both the years.
Open Access
Effect of tillage, green manuring, rice establishment methods and crop residue management practices on micronutrient uptake and transformation under rice-wheat cropping system
(Punjab Agricultural University, Ludhiana, 2018) Mandeep Kaur; Dhaliwal, S.S.
The present study was carried out under two on-going field experiments at research farm, Department of Soil Science, Punjab Agricultural University, Ludhiana in split plot design with three replications. The soil of both experimental fields was loamy sand in texture, taxonomically classified as Typic Ustrochrept. The first experiment comprised of twelve treatment combinations among which the main plots consisted of four rice establishment methods viz. direct seeded rice under zero tillage (DSR-ZT), conventional tillage (DSR-CT), reduced tillage (DSR-RT) and puddled transplanted rice (PTR) and three subplots in wheat viz. conventional tillage (CTW-R), zero tillage without rice straw (ZTW-R) and zero till with rice straw (ZTW+R). In this study, soil samples were analyzed for basic chemical indices of soil quality. The DTPA-extractable micronutrient cations (Zn, Fe, Mn and Cu) and their different chemical fractions were analyzed using atomic absorption spectrophotometer (Varion AAS-FS Model). The ZTW+R showed marked increase in concentration of DTPA-extractable Zn, Fe, Mn and Cu and their transformation from occluded fractions towards bio-available forms. Residual fraction of all the micronutrient cations was found to be the most dominant fraction and water soluble + exchangeable fraction was found to be least dominant in soil. Organically bound fraction of all the micronutrient cations studied was found to be most important fraction contributing towards micronutrient uptake by both rice and wheat crops. The ZTW+R produced significantly higher wheat grain yield than ZTW-R. Moreover, rice grain yield under PTR and DSR-RT was comparable but significantly higher than DSR-CT and DSR-ZT. The second experiment consisted of twelve treatment combinations among which the four main plots comprised of puddled transplanted rice with no wheat straw retained (PTRW0), puddled transplanted rice with 25% anchored wheat straw retained (PTRW25), PTRW0 + GM and PTRW25 + GM. Similarly, three subplot treatments included conventional tillage wheat without rice residue (CTWR0) zero tillage wheat without rice residue (ZTWR0) and ZTW with 100% rice residue retained as mulch (ZTWR100) in subsequent wheat crop. The results of the study revealed that soil pH decreased however, SOC and availability of DTPA-extractable micronutrients increased with crop residue retention and GM incorporation in soil. The DTPA-extractable Zn, Cu, Fe and Mn showed sharp decrease from 0-7.5 cm to 7.5-15 cm soil depth and afterwards the decrease was gradual with further increase in soil depth. The transformation of Zn, Cu, Fe and Mn was found higher under PTRW25 + GM treatment from occluded (AFeOx and CFeOx) fractions to mobile (WSEX) ones. Highest productivity and Zn, Cu, Fe and Mn uptake by grain and straw of rice and wheat were also recorded under PTRW25 + GM treatment. In nutshell, green manure incorporation and crop residue retention over the soil surface substantially increased the crop productivity and availability of Zn, Fe, Mn and Cu in soil.

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