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Impact of variable quality organic matter and nitrogen levels on rice wheat productivity, nutrient availability and soil carbon accretion
(Punjab Agricultural University, 2024) Raagjeet Kaur; Dr. M.S. Mavi
In recent years, the intensification of the irrigated rice wheat (R W) system has led to the generation of substantial quantities of crop residues, particularly rice straw. On farm rice straw burning is the most widespread method to manage the surplus crop residue among the Indian farmers due to time constraints for wheat sowing, insufficient farm mechanization and low acceptability of paddy straw as fodder. This practice contributes to environmental pollution, health concerns, and loss of nutrients. To tackle these issues, there is an urgent need for the adoption of appropriate Rice Residue Management Practices (RRMPs). In addition, excessive use of nitrogen (N) fertilizers in rice wheat system has resulted in environmental issues like soil and water pollution, greenhouse gas emissions, and soil health degradation. To address these problems, adoption of integrated nutrient management could be an option. Therefore, a long term field experiment (8 years) was conducted to understand how different RRMPs and N fertilizer rates interact to influence R W productivity and soil functions. The treatments consisted of five RRMPs comprising of rice straw removal (RR), rice straw incorporation at the rate 6 t ha 1 (RI), Rice straw burning (RB), Rice straw biochar applied at 2 t ha 1 (RBC1) and 4 t ha 1 (RBC2) in the main plot and five N levels i.e. N0 (0 kg N ha 1), N1 (60 kg N ha 1), N2 (90 kg N ha 1), N3 (120 kg N ha 1) and N4 (150 kg N ha 1) in the sub plots. Results showed that RI, RBC1 and RBC2 plots significantly increased mean wheat and rice grain yield by 4 11%, compared with the RR plots at different rates of N fertilization. The RI, RBC1 and RBC2 plots receiving N2 level of fertilization showed statistically comparable or even higher mean wheat & rice grain yield, in comparison with RR plots receiving N3 level of N fertilizer. Among all RRMPs, RBC2 recorded the maximum wheat & rice productivity, emphasising its potential as an effective agricultural amendment for maximizing crop performance. The RI, RBC1 and RBC2 plots significantly enhanced the nutrient availability in the soil profile, particularly the N forms, ensuring a consistent nutrient supply to the plants. Biochar and straw incorporation positively impacted the physical properties of the soil by reducing bulk density, increasing water holding capacity, and promoting the formation of aggregates and subsequently carbon (C) stabilization within aggregates as well as enhanced the microbial activity in the soil. Greater soil organic C, total C stocks and lesser C dioxide emissions in the biochar amended plots compared with other RRMPs indicates that it can be successfully used for C accretion under R W system. Key findings emphasized the superiority of biochar application and residue incorporation over the conventional practices, even at lower N rates. The outcomes suggested that biochar and residue incorporation offered a viable pathway for achieving both crop productivity and soil health in a resource efficient and environmentally sustainable manner.
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Deficit micro-irrigation and mulching effects on system productivity, water use efficiency and water dynamics in maize-wheat cropping system
(Punjab Agricultural University, 2024) Jaspreet Singh; Manmohanjit Singh
Maize-wheat is the third most important cropping system after the rice-wheat and rice-rice in India. Maize-wheat crop rotation is mostly practiced under rainfed or limited available water conditions. Optimum use of limited available irrigation water using micro-irrigation and in-situ water management practices is utmost important keeping on view the changing climatic scenario. The present study entitled “Deficit micro-irrigation and mulching effects on system productivity, water use efficiency and water dynamics in maize-wheat cropping system” was conducted at Regional Research Station, Ballowal Saunkhri, SBS Nagar, Punjab, during 2021-22 and 2022-23. The field experiment comprised four irrigation levels (I0: Rainfed, I1: Irrigation to compensate 50% available water depletion (AWD), I2: Compensate 75% AWD, I3: Compensate 100% of AWD) and three levels of mulch (M0: no mulch, MR: residue mulch (7.5 ton/ha crop residues) and MP: Plastic mulch (Silver black coloured mulch sheet) replicated thrice in randomized block design. The significantly higher soil moisture content was observed under I3 irrigation level leading to better plant growth of maize and wheat during both years. The grain and straw yield of maize (42.64 and 67.18 q/ha) were significantly higher under I3 irrigation level as compared to I1 and I0, but it was statistically similar to I2 irrigation level. However, in case of wheat, the grain and straw yield under I3 (39.87 and 28.61 q/ha) were significantly higher than I2, I1 and I0. The system productivity (85.60 and 85.36 q/ha) obtained under I3 treatments was significantly higher as compared to I2, I1 and rainfed treatments during both years. The simulated soil profile moisture content using HYDRUS-1D model was comparable to observed values at different growth stages of the crops. It can be concluded that in case of maize the irrigation level I2 (compensating 75% of AWD) and in case of wheat I3 (compensate 100% of AWD) was suitable for obtaining higher crop yield with maximum water use efficiency under maize-wheat cropping system in limited water conditions.
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Residue mulch, tillage and irrigation effects on crop and water productivity of pigeonpea-wheat cropping system
(Punjab Agricultural University, 2022) Satinder Singh; K.B. Singh
A two-year field experiment on effect of variable irrigation regimes, crop residue mulch and tillage treatments on pigen pea was conducted in loamy sand and sandy loam soil at research farm of Department of Soil Science. The treatments were combination of three irrigation regimes of 0, 0.2 and 0.4 (based on IW/ Pan-E ratios) in main plots, tillage practises (conventional (CT) and deep tillage (DT)) and two rice straw mulch rates (0 and 6 t ha-1) in sub plots. Irrigation regime I2, Soil temperature recorded under I2 was lower than I1 and I0 irrigation regime. Rice straw mulch and CT reduced soil temperature at 0.5 m depth during both years. Frequent irrigation (I2) with mulching recorded higher periodic soil moisture content and storage than limited irrigation regimes without mulch. Leaf water potential, relative leaf water content, soil plant analysis development (SPAD), normalized difference vegetation index (NDVI), leaf area index (LAI) , periodic biomass and plant height were significantly higher in I2 compared to I1 and I0, in DT compared to CT and in mulching compared to no mulch. With I2, DT and mulching significantly higher pigeon pea grain and stover yield were recorded as compared to I1 and I0, CT and no mulch. In grain and stover yield significant intercations were observed between irrigation x mulch, tillage x mulch and irrigation x tillage x mulch. The residual effect of different treatments imposed in pigeon pea on yield and yield attributing of wheat were non significant. The simulated seasonal water balance in pigeon pea was in proximate agreement with observed values for irrigation regimes, tillage and mulching treatments. Good coefficient of determination between simulated and predicted values of LAI, biomass and evapotranspiration indicated that the DSSAT (CROPGRO) model simulations were satisfactory.
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Evaluating amelioration potential of long term addition of organic amendments in soils irrigated with poor quality water in rice-wheat system
(Punjab Agricultural University, 2023) Sharma, Gargi; Choudhary, O.P.
Indiscriminate use of poor quality water to exploit harvestable potential in rice-wheat cropping system is adversely impacting agricultural productivity and soil health due to irrigation induced salinization and sodification. To ameliorate the effect of salinity and sodicity, some kind of amendment is needed such as gypsum or organic amendments or crop residues, that helps maintain a balanced nutrient profile. Keeping this into consideration, the present research was conducted to study the amelioration potential of long-term addition of crop residue in soils irrigated with poor quality water in rice-wheat system. The reported effects were studied during 2019 to 2021. The long-term experiment (since 2006) had sixteen treatments involving four irrigation water quality: canal water irrigation (CW), sodic water with residual sodium carbonate (RSC) 12.5 meq l-1 (SW), sodic water plus gypsum applied @ 50 % gypsum requirement (SW+G) and saline water with EC 4 dSm-1 (SaW). The crop residue treatments were wheat straw @ 6 t ha-1 to rice crop (RWS), rice straw @ 6 t ha-1 to wheat crop (WRS), rice straw and wheat straw @ 6 t ha-1 each (RWSWRS) and unamended (R0W0). Irrigation with sodic (SW) and saline (SaW) water significantly increased soil pH, EC, sodium adsorption ratio (SAR), exchangeable sodium percentage (ESP), and decreased organic carbon, microbial biomass carbon, dehydrogenase and urease activity and available nutrients in soil. The minimum value of rice grain yield (5.96 and 6.11 t ha-1) was recorded in plots irrigated with saline water (SaW) whereas sodic water irrigated plots (SW) recorded minimum grain yield (5.13 and 5.32 t ha-1) in wheat in both the years of study. Incorporation of gypsum with sodic water effectively reduced pH, ESP, SAR and improved other soil functions, leading to increase grain yields of both rice and wheat. Significant interaction between irrigation water quality and crop residue treatment on soil pH, EC and SOC at 0-15 cm depth was recorded. Increase in rice grain yield (8-9%) and wheat grain yield (6-7%) in RWSWRS treatment over R0W0 treatment was recorded in both years. There is a limited understanding on the effects of organic amendments applied in combination with nitrogen (N) on soil functions and crop yield at varying level of salinity. Hence, to study the interactive effect of different organic amendments i.e. Rice straw (RS), Farmyard manure (FYM) and Biochar (BC) at variable N (control, 75, 100 and 125% RDN) levels on soil functions and crop yield at varying levels of irrigation water salinity i.e. Canal water (CW), Saline water-4 dS m-1 (SaW4) and Saline water-8 dS m-1 (SaW8) a one year pot experiment was conducted in screenhouse at PAU, Ludhiana. Farmyard manure recorded higher grain and straw yield of wheat and rice than rice straw and biochar and this magnitude increased with increase in N rate. Hence, it may be concluded that by adding organic amendments, the negative effects of poor-quality water irrigation on physicochemical and biological properties and thereby adverse effect on crop productivity can be reduced.
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Measuring and modelling the impact of management interventions on water and nitrogen dynamics in rice and wheat
(Punjab Agricultural University, 2023) Jyolsna T.; Vashisht, B.B.
Field experimentation along with the use of crop models explore complex weather, soil, and management interactions. In this context a split-split plot designed field experiment on the rice-wheat cropping system was conducted for two years (2020-2022) at two locations. The treatments for rice consisted of two varieties (PR122 (V1) and PR126 (V2)) in the main plot, two irrigation levels (irrigation at 2 days drainage period (I1) and on soil water suction 16 kPa (I2)) in the sub plot and two nitrogen levels (120 (N1) and 90 kg (N2) N ha-1) in the sub-sub plot. The treatments for wheat consisted of two varieties (Unnat PBW343 (V1) and Unnat PBW550 (V2)) in the main plot, two irrigation levels (irrigation based on IW/CPE ratio of 1.2 (I1) and 0.9 (I2)) in the sub plot and two nitrogen levels (120 (N1) and 90 (N2) kg N ha-1) in the sub-sub plot. The treatment V1I2N1 recorded highest yield and yield attributes in rice, while V1I1N1 showed maximum yield and attributes in wheat. The I1 irrigation in rice and I2 in wheat had higher water use efficiency and less water footprint. HYDRUS 1D modeling showed higher soil water storage and root water uptake in I2 treatment in rice and I1 treatment in wheat. The leaching of NO3-N to lower depths in rice was more in I2 treatment. DSSAT simulations suggested shifting rice irrigation to 3 days drainage period and increasing wheat nitrogen dose to 150 kg ha-1 for achieving similar yields as present recommended practice.
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Long-term effect of conservation agriculture practices on soil biochemical properties in rice-wheat and maize-wheat systems
(Punjab Agricultural University, 2023) Angmo, Padma; Sharma, Sandeep
Long-term resource conservation strategies are considered a pre-requisite for improved soil health and ecosystems’ sustainability for cropping systems. The present study quantified the impact of tillage regimes, methods of irrigation, rate of nitrogen and straw return in conventional and conservation agriculture-based rice-wheat and maize-wheat systems on soil enzyme activities, labile soil carbon pools and microbial diversity in earthworm casts and guts. The results revealed that all the extracellular enzyme activities (EEA) were highest at the surface soil layer (0-10 cm) and decreased with an increase in soil layers. Among different growth stages, the maximum tillering stage of wheat and rice, and maize at knee-high stage were registered the highest EEA with zero tillage and residue retention practices. Similarly, conservation agriculture-based residue management practices i.e., reduced tillage, zero tillage, and permanent bed planting with residue retention significantly (p<0.05) increased the biochemical properties and carbon (C) pools within aggregates and microbial diversity in earthworm casts and guts than the conventional tillage (CT). Whereas, phenol oxidase and peroxidase were in reverse trend. Large macroaggregates had higher dehydrogenase, fluorescein diacetate, cellulase, xylanase, β-glucosidase, total carbohydrate carbon, C pools, and total organic C than the macro and microaggregates. The microbial diversity within earthworm guts and the cast were significantly higher in conservation tillage practices as compared with CT. The wheat grain yield under DSRRT/ZTW+R was 10.6% higher as compared with PTR/CTW-R. However, in maize-wheat systems, treatments PBM+RN120/ ZTW+RN120 led to an increase in maize grain yield by 23.2%, wheat grain yield by 7.4%, and system grain productivity by 16.4% as compared to FBM-RN120/CTW-RN120. Wheat grain yield under DSRN120D/ZTW+RN120D was 5.57 t ha-1 and 5.37 t ha-1 was under PTRN120F/ CTW-RN120F. The principal component analysis elucidated xylanase and phenol oxidase in rice-wheat systems; total polysaccharides carbon and total carbohydrate carbon in maize-wheat systems were sensitive indicators of soil quality. In rice-wheat and maize-wheat systems, Lampito mauritii and Metaphire posthuman were the dominating earthworm species. The sequencing results identified the bacteria species as Stenotrophomonas rhizophila and the fungus species as Torula fici, Fusarium fujikuroi, and Fusarium niskaloi. Thus, our study suggests that conservation agriculture-based residue management practices can be beneficial to the overall improvement of biological pools, aggregation and microbial diversity in earthworm cast and guts.
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Effects of rice residue and nitrogen management on wheat yield, nitrogen use efficiency and soil properties
(Punjab Agricultural University, 2023) Vicky Singh; Gupta, R. K.
Field experiments were conducted on two soils (sandy loam and clay loam) having four rice residue management treatments and seven nitrogen (N) application methods to study the effects of rice residue and N management on wheat yield, N use efficiency and soil properties in the rice-wheat system during the 2020-21 and 2021-22. In zero tillage, wheat sown using a happy seeder with rice straw retained as surface mulch (T2) showed 4 %, rice residue was incorporated with a super seeder machine at sowing (T4) was found to 2.4%, and rice residue incorporated using MB plough at three weeks before wheat sowing (T3) recorded 1.8% higher grain yield than conventional tillage after removal of straw (T1) during the year 2020-21, respectively which was ascribed to an increase in yield contributing traits due to moderation of soil temperature, increased nutrient availability and soil moisture content due to residues retained at the surface. In 2021-22 the overall increase in grain yield in T2, T4 and T3 was 6.5%, 2.6% and 1.3% over T1, respectively. Application of N fertilizer significantly increased the wheat yield by 61.1 to 71.1% and 65.4 to74.1% on sandy loam, and 51.8 to 60.7% and 58.0 to 67.0% on clay loam over no N control in 2020-21 and 2021-22, respectively. On sandy loam, the wheat grain yield of 5.63 t/ha in 2020-21 and 5.24 t/ha in 2021-22 obtained in N7 (drilled 50 % N through nitrophosphate) at the time of sowing, 40% N as urea at first irrigation and remaining 10 % N as the foliar application was significantly higher than the other modes of N application. The maximum grain yield (5.77 t/ha and 5.41 t/ha) was recorded in the N7 treatment, which was at par with the grain yield (5.70 t/ha and 5.34 t/ha) of the N4 treatment during 2020-21 and 2021-22, respectively. In 2021-22 terminal heat due to higher canopy temperature significantly reduced grain yield on both soils in T1, T3, and T4 in comparison to T2. At 1st irrigation, the concentration of ammoniacal (NH4+) and nitrate (NO3-) was less in the zero-tillage but afterwards concentration increased in T2. The maximum AEN was recorded in T2 on sandy loam and clay loam soil (15.2 and 14.7 kg grain kg-1 N respectively) during 2021–2022. The highest AEN on sandy and clay loam soil was recorded (19.4 and 18.6 kg grain kg-1 N) and (17.9 and 18.1 kg grain kg-1N) respectively in N7 treatment during 2020-21 and 2021-22. Highest recovery efficiency (%) was also witnessed on sandy and clay loam soil in T2 treatment. In N7 attained highest recovery efficiency (59.7 and 55.9%) on sandy loam and maximum recovery efficiency (60.1 and 57.9%) on clay loam soil during 2020–2021 and 2021–2022. Again, N7 led to a considerable increase in partial factor productivity (46.7 and 43.6 kg ha-1) on sandy loam and clay loam (48.1 and 45.1 kg ha-1) soil during 2020-21 and 2021-22, respectively. The straw retention resulted in an optimistic effect on soil health with improved SOC, available N, K and micronutrients. Soil physical parameters such as infiltration rate, volumetric water content, bulk density, mean weight diameter and water stable aggregates (WSA), saturated hydraulic conductivity, and root distribution showed enhancement with straw retention. Soil penetration resistance was observed less in residue retained treatment as compared to residue removed or incorporated fields. Favorable interaction of optimum N fertilizer application methods and residue management options improved soil health and wheat productivity.
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Micronutrients distribution in soil orders under prominent land use systems of Punjab
(Punjab Agricultural University, Ludhiana, 2022) Gowthamchand, N. J.; Sharma, Vivek
The present research study has been conducted with a prime objective to characterize the soil orders viz., Entisol, Inceptisol, Alfisol and Aridisol for their physico-chemical properties, micronutrients cations (Zn, Cu, Fe and Mn) and their transformation (chemical fractions) in soil under three land use systems (agriculture, horticulture and forestry) of Punjab. With the help of an auger, soil samples from both surface (0-15 cm) and depth-wise (0-20 cm, 20-40 cm, 40-60 cm, 60-80 cm and 80-100 cm) were collected from five locations for each land use systems under three different soil orders in each region (Majha, Malwa and Doaba) of Punjab. Standard procedures were followed to analyze soil samples for different physico-chemical properties and chemical fractions of micronutrients in the soil. Among different soil orders, Aridisols recorded the highest soil pH, EC, CaCO3 and lowest soil organic carbon levels, and their distribution across different land uses is highly varied. In all soil orders, the horticulture and forest land use systems had the greatest levels of soil OC. Regardless of the soil orders and land use systems, the soil EC, OC, phosphorus, potassium and micronutrients (Zn, Cu, Fe and Mn) content decreased with an increase in soil depth, whereas soil pH and CaCO3 content increased with depth. The status of available phosphorus, potassium and micronutrients was found to be significantly varied and no particular pattern was observed among the different land use systems under each soil orders in all three regions of Punjab. In Majha region, Entisols had the highest DTPA-extractable and chemical fractions of Zn, Cu, Fe and Mn, followed by Inceptisols and Alfisols. In Malwa region, among different soil orders, the maximum concentration of DTPA-extractable and chemical fractions of Zn, Cu, Fe and Mn was observed in Entisols, followed by Inceptisols and Aridisols. In Doaba region, the distribution of DTPA-extractable micronutrients and chemical fractions of Zn, Cu, Fe and Mn was highest in Alfisols, followed by Entisols and”Inceptisols, As a result, it is inferred that land use systems and their management practices influenced the distribution of physicochemical properties and altered the availability of micronutrients among different soil orders. The outcomes of the current study might be of great importance to researchers, state agricultural officers and farmers to implement nutrient management strategies in different soils.
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Water productivity of subsurface drip irrigated spring maizerice-potato cropping system
(Punjab Agricultural University, Ludhiana, 2022) Amanpreet Kaur; K.B. Singh
The present study “Water productivity of subsurface drip irrigated spring maize-rice-potato cropping system” was carried out at Punjab Agricultural University, Ludhiana during two consecutive years from October 2018 to October 2020. The experiment was laid out in split plot design with three nitrogen levels {100 % of recommended (N1), 80 % of recommended (N2) and 60% of recommended (N3)} in main plots and seven irrigation regimes {six subsurface drip (at 20 cm depth) and one surface drip in sub plots}. In maize and potato, the sub surface irrigation regimes were (100% of Epan at alternate day ( I1) and two day interval (I2), 80% of Epan at alternate ( I3) and two day interval (I4), 60 % of Epan at alternate day (I5 ) and two day interval (I6) and surface drip at 80% of Epan at alternate day (I7). However, in direct seeded rice the irrigation levels were { 100 % of Epan at alternate day (I1) and two day interval (I2), 80 % of Epan at alternate day(I3) and two day interval (I4), 120 % of Epan at alternate day ( I5) and two day interval (I6) and surface drip at 1.5 times Epan (I7)}. During both years, dry matter accumulation, leaf area index, grain and yield attributed in spring maize were at par with N1 and N2 but significantly higher over N3. Among irrigation levels, grain yield and yield attributes of spring maize was at par with I1 and I3 but significantly higher over all other treatments. Interaction results revealed that grain yield obtained was at par N1I1, N1I3, N1I7 and N2I3. Real water productivity (WPET) of spring maize during both the years was at par with N1I1, N1I3 and N2I3. Results revealed that decreasing irrigation level to 80% and fertilizer nitrogen to 80% under subsurface drip could be best option for obtaining higher yield and water productivity. In direct seeded rice, grain yield and yield attributes decreased significantly with decrease in nitrogen level from recommended dose (N1) during both the years. Grain yield of DSR with N1 was 11.1 and 27.7 % higher over N2 and N3 during 2019 and 10.5 and 34.2 % higher during 2020. During 2020, grain yield of rice was at par with I5 and I7. Grain yield in I7 was 10.6, 14.8, 20.2, 24.2, 3.3 and 6.2 % higher over I1, I2, I3, I4, I5 and I6. Highest WPET (0.92 and 0.96 kgm-3) was obtained with highest level of nitrogen (N1) and decreased significantly at N2 (0.83 kg m-3, 0.87 kg m-3) and at N3 (0.74 kg m-3, 0.73 kg m-3) during 2019 and 2020, respectively. Real water productivity of DSR was highest with I7, was significantly higher over all the other treatments during 2020. In Potato, dry matter accumulation, leaf area index, tuber yield and yield attributes were at par with N1 and N2 but decreased significantly at N3 level. During both the years, tuber yield obtained was at par with I1, I2, I3 but significantly higher over all the other treatments. Highest WPET in potato was obtained with N1I3 treatment combination. Modelling analysis showed DSSAT-CERES -maize, DSSAT- CERES-rice, DSSAT-SUBSTOR-potato performed well in predicting grain yield of spring maize, rice and potato with R2 value 0.90, 0.86,0.95, RMSE 4.6, 3.5, 24.2 qha-1 nRMSE 6.1, 7.0, 7.5 % and NSE 0.8 ,0.6, 0.5 for spring maize, rice and potato respectively.

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