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Open Access
Customized nutrient management for rice (Oryza sativa L.) in the Southern Laterites (AEU8)
(Department of Agronomy, College of Agriculture,Vellayani, 2019) Sheeba, S S; KAU; Shalini Pillai, P
The study entitled “Customized nutrient management for rice (Oryza sativa L.) in the Southern Laterites (AEU 8)” was undertaken at College of Agriculture, Vellayani during 2016 to 2019. The main objectives were to assess and rate the available nutrient status of rice soil in the Southern Laterites (AEU 8), to develop a Zn – B mix for rice and to evaluate the effect of the mix on rice, at different N/K ratios. The study was carried out in three parts. The first part was on assessment and rating of available nutrient status of rice soil in Southern Laterites (AEU 8). Southern Laterites is spread over five blocks (Athiyannoor, Parassala, Nemom, Perumkadavila and Vellanad). Parassala, Nemom and Perumkadavila were selected for the study since paddy cultivation was observed in comparatively larger area in these blocks. One hundred and fifty, geo-referenced soil samples were collected from the rice fields during April to May 2017, at random from the 11 panchayats spread over these three blocks. The soil samples were analysed and rated for 14 soil fertility parameters and block wise digital maps were prepared with ArcGIS 10.1. Based on the nutrient index, it was observed that organic carbon, available Ca, Mg, S, Cu, Zn and B recorded low nutrient indices (< 1.5) in all the three blocks. While available N was low in Nemom and Perumkadavila, it was medium (1.5 – 2.5) in Parassala block. Available P showed high index (> 2.5) in Parassala and Perumkadavila and medium index in Nemom. While Parassala and Nemom blocks could be rated as medium with respect to available K, Perumkadavila exhibited high index for K. Available Fe and Mn were high in all the blocks. The rice soils of Southern Laterites were observed to be strongly acidic with a mean pH of 5.27 ± 0.58, normal in electrical conductivity (0.77 ± 0.31) dS m-1, low in organic carbon (0.52 ± 0.23) % and available N (263.70 ± 49.32) kg ha-1, high in available P (90.40 ± 59.78) kg ha-1 and medium in available K (228.94 ± 87.84) kg ha-1. The soils were low in available Ca (15.78 ± 4.96) mg kg-1, available Mg (5.87 ± 1.85) mg kg-1 and available S (1.34 ± 0.83) mg kg-1. Among the micronutrients tested, the rice soils exhibited deficiency of available Cu (0.44 ± 0.22) mg kg-1, Zn (0.77 ± 0.19) mg kg-1 and B (0.315 ± 0.002) mg kg-1. The second part of the study comprised development of a Zn – B mix for rice. The Zn and B requirement was calculated based on the difference between the crop requirement and Zn and B status of the soil. Crop requirement of Zn and B was computed as the product of the potential yield and whole plant nutrient composition. Accordingly, the Zn and B requirement could be calculated as 4.088 kg ha-1 and 0.738 kg ha-1 respectively. The Zn – B mix for rice was formulated by mixing zinc sulphate heptahydrate (ZnSO4.7H2O) and boric acid (H3BO3) in the ratio 4 : 1. The third part of the study was a field experiment to assess the effect of the Zn – B mix on rice, at different N/K ratios. The experiment was conducted during the second crop season (September to January) of 2017 and 2018. The experiment was located in the Chenkal panchayat of Parassala block, in a farmer’s field where Zn and B deficiency was identified from the first part of the study. The experiment was laid out in randomised block design with 13 treatments (12 + 1), replicated thrice. The treatments T1 to T4 were combinations of N/K (1.0 : 0.5) + foliar application of 0.5 % and 1.0 % Zn – B mix at maximum tillering (MT) and panicle initiation (PI) stages, T5 to T8 were N/K (1.0 : 1.0) + foliar application of 0.5 % and 1.0 % Zn – B mix at MT and PI stages, T9 to T12 were N/K (1.0 : 1.5) + foliar application of 0.5 % and 1.0 % Zn – B mix at MT and PI stages and T13 was control (KAU POP for rice). The variety used for the study was Uma (MO 16). The soil of the experimental site was sandy clay loam, strongly acidic in reaction, low in organic carbon, medium in available N and K, high in available P and deficient in available Ca, Mg, Zn and B. In all treatments except control, nutrients were applied on soil test basis. The results revealed that growth attributes were significantly influenced by N/K ratio and foliar application of Zn- B mix and the treatments were observed to be superior to control (KAU POP). Mean tiller count and leaf area index were significantly higher with N/K (1.0 : 1.5) + foliar application of 0.5 % Zn – B mix at PI stage (T10) at MT and PI stages. It was on a par with T9, T11 and T12. However, the mean total dry matter production (12356 kg ha-1) was significantly higher with T12 (N/K (1.0 : 1.5) + foliar application of 1.0 % Zn – B mix at PI stage) and was comparable with T10. Among the yield attributing characters, mean number of productive tillers m-2 (488.35) and grain weight per panicle (2.78 g) were significantly higher with T12 and were at par with T10. The treatments T10 and T12 were comparable with respect to the number of spikelets per panicle, filled grains per panicle and sterility percentage. The treatment T12 resulted in significantly higher mean grain yield (5.67 t ha-1) and was comparable with T10 (5.61 t ha-1). Straw yield was higher with T12 (6.89 t ha-1) and was on a par with T10 (6.83t ha-1). The treatments were superior to control (KAU POP), with T10 recording 43.9 per cent improvement in grain yield. Crude protein content of grain and uptake of major nutrients, Ca, Zn and B were significantly higher with T12 and was comparable with T10. Incidence of rice bug (at the milk stage) and false smut disease (at harvest) was observed during both the years. Mean benefit cost ratio was higher (1.72) with T10 and was comparable with T12 (1.69) as against a BCR of 1.16 for the KAU POP. The present study revealed that the fertility status of rice soils of the Southern Laterites (AEU 8) need to be addressed in terms of soil acidity, low organic carbon status, build-up of phosphorus and deficiency of secondary nutrients and micronutrients like Zn, B and Cu, on soil test basis. Based on the crop requirement and nutrient status of the soil, a Zn – B mix was formulated, as a mixture of zinc sulphate heptahydrate and boric acid in the ratio 4 : 1. Application of nitrogen and potassium in the ratio 1.0 : 1.5 along with foliar application of 0.5% Zn – B mix at panicle initiation stage was observed to be effective in enhancing the growth and yield attributes, yield and economics of rice in the Southern Laterites (AEU 8) of Kerala
Open Access
Vetiver based Organic Mediculture Technologies for the Sustainable development of Watersheds
(Department of Agronomy, College of Agriculture,Vellayani, 2019) Ishrath, P K; KAU; Anilkumar, A S
An investigation entitled “Vetiver based organic mediculture technologies for the sustainable development of watersheds” was carried out during 2016 to 2019 at the Instructional farm, College of Agriculture, Vellayani. The investigation comprised of three field experiments and one pot culture study. The objectives were to standardise nursery management practices for quality planting material production, develop vetiver based biological systems for soil and water conservation and to explore the phytoremediation potential of vetiver for waste water and degradable solid waste utilization. The vetiver variety “ODV-3”, turmeric variety “Varna”, cowpea variety “Bhagyalakshmi” and a local variety of greater galangal were used for the study. The techniques for quality planting material production were standardised by testing planting materials (a1- slips; a2- clumps), planting systems (b1- planting strips; b2- shallow basins), rooting medium (c1- coirpith compost: soil: cowdung (2:1:1) + inoculation with Azospirillum and AM Fungi); c2- c1 + cowdung slurry at monthly interval) and moisture regimes (d1- irrigation at 8 mm CPE; d2- irrigation at 16 mm CPE) in a 24 factorial Randomised Block Design with three replications. Conclusions were drawn after two and four months of planting. Inoculation of vetiver clumps with biofertilizers and planting in shallow basins filled with enriched rooting medium and application of cowdung slurry at monthly interval with irrigation scheduling at 16 mm CPE resulted in the production of higher number of planting materials (10.67 tillers per plant) and the highest benefit cost ratio (2.83) after two months of planting. Considering the dual benefit of planting material production and root yield, inoculation of vetiver slips with biofertilizers and planting in polythene mulched trenches, filled with enriched rooting medium followed by application of cowdung slurry at monthly interval and irrigation scheduling at 8 mm CPE resulted in the highest net income (₹.5.84 lakhs ha-1) and benefit cost ratio (2.96) after four months of planting. The study on “Vetiver based alley cropping systems for soil and water conservation” was undertaken in 32 factorial Randomised Block Design with three replications. Combinations of vetiver vegetative barriers were developed in three different planting geometries, i.e., a1- normal row planting (50 cm x 50 cm), a2- paired row planting (25/75 cm x 50 cm); a3- high density planting (25/75 cm x 25 cm) with three different sequential intercropping systems, i.e., b1- turmeric- cowpea- turmeric, b2- greater galangal and b3- control (without intercropping). High density planting of vetiver followed by continuous alley cropping of greater galangal (a3b2) resulted in the highest vetiver equivalent yield (14.44 t ha-1), net income (₹.4.05 lakhs ha-1) and benefit cost ratio (2.27). Substantial reduction in runoff (95 %), soil loss (166 %) and nutrient erosion (76 %) could be achieved through a3b2 within a period of 18 months, extending from June 2017 to December 2018. Considerable improvement in soil health with respect to physical properties of soil, viz., bulk density (33 %), porosity (28 %), water holding capacity (47 %) and infiltration rate (72 %) and build-up of soil organic carbon (43 %) were also observed in a3b2 compared to initial soil status. To develop vetiver systems for waste water utilization in agriculture, an experiment was laid out in Completely Randomised Block Design with seven types of waste water in three replications. The treatments were, a1- waste water from coconut husk retting yards, a2- kitchen waste water, a3- waste water from fish market, a4- coirpith leachate, a5-sewage water, a6- Vellayani lake water and a7- nutrient solution. Vetiver was proved as a good phytoremediator with respect to decontamination and water purification properties (nutrient and heavy metal uptake). In general, the morphological characters (number of leaves and tillers) and root characters (root weight, spread, volume and drymatter) were significantly improved by growing vetiver in fish-waste water. To explore the phytoremediation potential of vetiver for degradable solid waste utilization, a study was conducted in 4 x 2 x 2 factorial Randomised Block Design with three replications. Four ratios of degradable land fill materials (sewage sludge) and virgin soil (a1- 1:0; a2- 1:1; a3- 1:3; a4- 1:5), two crop establishment techniques (nursery grown rooted slips with enriched rooting medium (b1) and without enriched rooting medium (b2)); foliar nutrition (c1-sequential application of cow‟s urine, vermiwash and fermented plant juice; c2- sequential application of NPK fertilizer grade of 19:19:19, KNO3 and Ca(NO3)2 at monthly interval) were tested in this study. It could be concluded that, production of vetiver slips inoculated with Azospirillum and AM Fungi in enriched rooting medium and transplanting in the main field with sewage sludge and virgin soil (1:5) followed by sequential application of foliar fertilizers @ 0.50 per cent (19:19:19, KNO3 and Ca(NO3)2 ) resulted in the highest root yield (4.11 t ha-1), net income (₹.1.01 lakhs ha-1) and benefit cost ratio (1.97). Vetiver based mediculture technologies in relation to cost effective quality planting material production, alley cropping systems for soil and water conservation and phytoremediation techniques for waste water and biosolid utilization were developed for the sustainable development of watersheds.
Open Access
Bioefficacy and soil health impact of flucetosulfuron in wet seeded rice (Oryza sativa L.)
(Department of Agronomy, College of Agriculture, Vellayani, 2018) Arya, S R; KAU; Elizabeth, K Syriac
The investigation entitled "Bioefficacy and soil health impact of flucetosulfuron in wet seeded rice (Oryza sativa L.) was carried out at College of Agriculture, Vellayani, Thiruvananthapuram during the period of 2015-2018. The objectives were to evaluate the bioefficacy of flucetosulfuron in wet seeded rice; to assess its impact on soil health by determining the microbial count, earthworm population, enzyme status and herbicide residue in soil through bioassay using indicator plant as well as to assess the weed seed bank. It was also envisaged to study the in vitro sensitivity of biofertilizer organisms and biocontrol agents to flucetosulfuron. Field experiment was conducted during the I and II crop seasons of 2016- ’17, in a farmer’s field in Kalliyoor Panchayat, Nemom block, Thiruvananthapuram district, Kerala, with 12 treatments replicated thrice in Randomized Block Design. The treatments were: T1 : Flucetosulfuron @ 20 g ha-1 at 2-3 DAS, T2 : Flucetosulfuron @ 25 g ha-1 at 2-3 DAS, T3 : Flucetosulfuron @ 30 g ha-1 at 2-3 DAS, T4 : Flucetosulfuron @ 20 g ha-1 at 10-12 DAS, T5 : Flucetosulfuron @ 25 g ha-1 at 10-12 DAS, T6 : Flucetosulfuron @ 30 g ha-1 at 10-12 DAS, T7 : Flucetosulfuron @ 20 g ha-1 at 18-20 DAS , T8 : Flucetosulfuron @ 25 g ha-1 at 18- 20 DAS , T9 : Flucetosulfuron @ 30 g ha-1 at18-20 DAS, T10: Bispyribac sodium @ 25 g ha-1 at 15 DAS, T11: Hand weeding at 20 and 40 DAS and T12 : Weedy check. The short duration variety Kanchana was used for the trial. The weed flora in the experimental field comprised of four species of grasses, six species of broad leaved weeds and three species of sedges. Based on density and dry weight, sedges were the predominant group in the experimental field followed by broad leaved weeds and grasses. Application of flucetosulfuron @ 20, 25 and 30g ha-1 at 10-12 and 18-20 DAS (T4, T5, T6, T7, T8 and T9) recorded lower total weed density, total weed dry weight and nutrient removal by weeds and higher total weed control efficiency and were on par with the hand weeding treatment (T11). Yield reduction due to weeds was found to be 52.33 and 55.61 per cent during the I and II crop seasons respectively. The highest grain yield was recorded by the application of flucetosulfuron @ 25 g ha-1 at 10-12 DAS (T5) and flucetosulfuron @ 20 g ha-1 at 10-12 DAS (T4) during the first and second crop seasons respectively. The same trend was observed in the case of dry matter production also. Pooled analysis of the grain yield for the two seasons indicated the superiority of T5 which recorded the highest grain yield of 8.33 t ha-1. This treatment was on par with the other levels of flucetosulfuron viz., 20 and 30 g ha-1 at 10-12 DAS (T4 and T6) and hand weeding treatment (T11). Higher yield attributes, harvest index and nutrient uptake were also recorded for these treatments. However, net income and B:C ratio were significantly lower for hand weeding treatment. Herbicide application did not cause any significant inhibitory effect on the earthworm population and spider count. Application of herbicides increased the microbial population in herbicide treated plots. Flucetosulfuron, at the tested doses (20, 25 and 30 g ha-1) and time of application (2-3, 10-12 and 18-20 DAS), did not show any adverse impact on the activity of soil enzymes (dehydrogenase, acid phosphatase and urease) and soil organic carbon status. To identify the most suitable indicator plant for assessing flucetosulfuron residue in soil, four separate pot culture experiments were conducted using barnyard millet, cucumber, sunflower and maize. Sunflower was identified as the most sensitive indicator plant and shoot length of sunflower was adjudged as the best parameter to assess the flucetosulfuron residue in soil. Bioassay after each field experiment using sunflower revealed that there was no residual toxicity of flucetosulfuron in the post experiment soil. Pot culture experiments were carried out before and after each field experiment, to study the weed seed bank dynamics. Results revealed that non- herbicidal plots recorded higher weed count compared to herbicide applied plots. In all the herbicide treated plots, effective reduction in weed seed bank could be obtained irrespective of the dose of the herbicide. Regarding the time of application, application of flucetosulfuron at 10-12 and 18-20 DAS caused significant depletion of weed seed bank during both the seasons compared to its application at 2-3 DAS. In vitro sensitivity of biofertilizer organisms viz., Azospirillum lipoferum, Azotobacter chroococcum, Bacillus megaterium and Frateuria aurantia to flucetosulfuron indicated that growth of none of the organisms were significantly inhibited by the tested doses of flucetosulfuron. Similarly, in vitro sensitivity to biocontrol agent Trichoderma viride revealed that, at all the tested concentrations of flucetosulfuron, it showed a colony diameter of 9 mm uniformly with zero per cent inhibition indicating the compatibility of the herbicide. The compatibility studies with Pseudomonas fluorescens also revealed the safety of the herbicide. The present study revealed that application of flucetosulfuron @ 20, 25 and 30 g ha-1 at 10-12 DAS was very effective in controlling the weeds and recorded significantly higher grain yield and monetary benefits in wet seeded rice. Application of flucetosulfuron @ 20, 25 and 30 g ha-1 at 2-3/10-12/18-20 DAS had no adverse impact on soil health and was found compatible with the tested biofertilizer organisms (Azospirillum lipoferum, Azotobacter chroococcum, Bacillus megaterium and Frateuria aurantia) and biocontrol agents (Trichoderma viride and Pseudomonas fluorescens).
Open Access
Agro techniques in bhindi for precision farming
(Department of Agronomy, College of Agriculture, Vellayani, 2019) Ammu Punnoose; KAU; Sajitha Rani, T
The investigation entitled “Agro techniques in bhindi for precision farming” was conducted during 2016 to 2019 at the Instructional Farm, College of Agriculture, Vellayani. The objectives were to standardize the spacing and response of bio inoculants for bhindi under rain shelter and open field conditions and to evaluate the effect of fertigation and foliar nutrition on improving the growth, yield and quality of bhindi and to work out the economics of different cultivation systems. The first experiment was to standardise the spacing and bio inoculants suitable for the cultivation of bhindi under rain shelter and open field conditions. A field experiment was conducted using the variety Varsha Uphar, during May to August- 2017. The treatments consisted of three spacings (S1 - 60 cm x 30 cm, S2- 60 cm x 45 cm and S3 - 60 cm x 60 cm) as first factor and three bio inoculant treatments (B1- Bio inoculant- PGPR mix 1, B2 - Bio inoculant - Arbuscular mycorrhizal fungi, B3 - No Bio inoculant) as second factor. The experiment was carried out in RBD with three replications. Under both open and rain shelter conditions, taller plants were obtained with closer spacing of 60 cm x 30 cm whereas, numbers of leaves and branches per plant, tap root length and root volume were significantly higher at wider spacing (60 cm x 60 cm). Among the bio inoculants, application of PGPR mix 1 resulted in significantly taller plants, more number of leaves and branches at all growth stages and longer tap root and root volume at final harvest. LAI was found to be significant among spacings at 60 and 90 DAT under open field condition. Yield attributes like number of flowers and fruits per plant, length of fruit, weight of fruit and weight of fruits per plant were found to be significantly higher at 60 cm x 60 cm and inoculation with PGPR mix 1. Wider spacing of 60 cm x 60 cm along with PGPR mix 1 was found to be superior to the other combinations with respect to growth and yield attributes. Fruit yield was significantly influenced by spacing and bio inoculant application and was higher at 60 cm x 30 cm (17.03 t ha-1 under rain shelter and 14.07 t ha-1 under open field condition) and PGPR mix 1 (16.83 t ha-1 under rain shelter and 13.50 t ha-1 under open field condition). Their interaction was also found to be significant (18.78 t ha-1 under rain shelter and 16.36 t ha-1 under open field condition) under both conditions. Dry matter production was significantly higher for 60 cm x 30 cm spacing and PGPR mix 1. Crop growth rate (CGR) was significantly higher at 60 cm x 30 cm and PGPR mix 1 under rain shelter and open field condition. Among the spacings, 60 cm x 60 cm and among bio inoculants, PGPR mix 1 were found superior with respect to relative growth rate (RGR) under both conditions. Among the fruit quality aspects, significant difference was observed for protein content inside rain shelter. NPK uptake showed an increasing trend with decreased plant to plant spacing. Application of PGPR mix 1 resulted in higher nutrient uptake. Available P status of soil after the experiment was significantly higher for 60 cm x 60 cm spacing under rain shelter. AMF treated soil showed significantly higher available P under open field condition. Available K was significantly higher for 60 cm x 60 cm spacing and PGPR mix 1 under rain shelter and open field condition. Higher bacterial and actinomycetes population were found in 60 cm x 30 cm spacing and PGPR mix 1 under both conditions. Higher fungal population was observed in AMF treated soil. Significantly higher water use efficiency was observed with 60 cm x 30 cm spacing and PGPR mix 1 and their interaction under rain shelter and open field condition. Net return and B: C ratio were also higher at 60 cm x 30 cm spacing (B: C ratio of 1.76 under rain shelter and 1.63 under open field) and PGPR mix1 (B: C ratio of 1.75 under rain shelter and 1.58 under open field) and their interaction under both condition (B: C ratio of 1.94 under rain shelter and 1.90 under open field). The first experiment revealed that growing bhindi at a spacing of 60 cm x 30 cm along with seedling inoculation with PGPR mix 1 resulted higher yield, and profit under rain shelter and open field condition The second experiment for standardization of nutrient schedule of bhindi under rain shelter and open field condition was conducted during September to December, 2017 and May to August, 2018. The best treatments from the first experiment were used for this trial. The trial was laid out in split plot design with five replications. The main plot treatments consisted of four levels of fertigation; 50 % adhoc POP recommendation for precision farming (F1), 75 % adhoc POP recommendation for precision farming (F2), 100 % adhoc POP recommendation for precision farming (F3), 125 % adhoc POP recommendation for precision farming (F4) and the sub plot treatments consisted of two foliar levels; poly feed fertilizer (19:19:19 at 0.5 %) (L1) and nano NPK (4: 4: 4 at 0.3 %) (L2). The variety used for the experiment was Varsha Uphar. Growth characters such as plant height, number of leaves per plant, number of branches per plant, LAI at monthly intervals, tap root length and root volume at harvest were significantly higher for the fertigation level F3 and foliar application of L1 under rain shelter, and F4 and L1 under open field condition. Yield attributes viz., number of flowers and fruits per plant, fruit set percentage, length of fruit, fruit weight, total fruit weight per plant, and yield per hectare were higher for the fertigation level of F3 and was on par with F4 and foliar level of L1 under rain shelter. Under open field condition, regarding yield attributes, fertigation level of F4 was on par with F3 and foliar level of L1 was significantly higher than L2. Considering the interaction, under rain shelter, f3 l1 recorded higher fruit yield per hectare and under open field condition, interaction of f4 l1 was on par with f3l1. CGR, RGR and NAR recorded by F4 and F3 were comparable and among the foliar levels, L1 was found to be significantly higher under both conditions. Under both growing conditions, higher chlorophyll content was observed under the fertigation level F4. Chlorophyll content was significantly higher with L2. Under rain shelter, F3 and L1 recorded higher dry matter production. Under open field condition, the highest dry matter production was recorded by F4 was on par with F3 among the fertigation levels and L1 among the foliar levels. Fruit quality parameters were significantly higher at F4 and L2 under both conditions. Higher NPK uptake was found for F3 and F4 under rain shelter and open field condition respectively. Available nutrients in the soil after the experiment showed an increasing trend with increasing fertigation levels under both conditions. Higher fertigation level (F4) resulted in higher microbial count under both conditions. Foliar level with L2 resulted in higher microbial count inside rain shelter. Higher water use efficiency was recorded for F3 and L1 under rain shelter and F4 and L1 under open field condition. Highest net return and B: C ratio was obtained for F3 (B: C ratio of 2.05 during Sept-Dec, 2017 and 2.12 during May- Aug, 2018) and was on par with F4 (B: C ratio of 1.93 during Sept –Dec, 2017 and 2.11 during May – Aug, 2018) among the fertigation levels under rain shelter. Under open field condition, F4 (B: C ratio of 1.64 during Sept -Dec, 2017 and 2.03 during May- Aug, 2018) was on par with F3 (B: C ratio of 1. 60 during Sept –Dec, 2017). Among the foliar levels, L1 recorded the highest B: C ratio under both growing conditions. The study revealed that growing bhindi at a spacing of 60 cm x 30 cm and seedling inoculation with PGPR mix 1 resulted in higher yield and profit under rain shelter and open field conditions. Nutrient scheduling of 98: 25: 136 kg NPK ha-1 (100 % Adhoc POP recommendation) along with foliar application of poly feed (19:19:19) at 0.5 % at fortnightly intervals enhanced the growth, yield and profit under rain shelter condition. Fertilizer dose of 122: 31: 170 kg NPK ha-1 (125 % Adhoc POP recommendation) or 98: 25: 136 kg NPK ha-1 (100 % Adhoc POP recommendation) with foliar application of poly feed (19:19:19) at 0.5 % at fortnightly intervals was beneficial for open field condition. Application of 125 % Adhoc POP recommendation along with foliar spray of nano NPK at 0.3 % at fortnightly intervals improved the fruit quality under both conditions.
Open Access
Herbicide mixtures for weed management
(Department of Agronomy,College of Agriculture, Vellayani, 2016) Sheeja, K Raj; KAU; Elizabeth, K Syriac
The experiment entitled "Herbicide mixtures for weed management in direct seeded puddled rice Oryza saliva L." was carried out at College of Agriculture, Vellayani, during the period from 2013 - 2016, to assess the bioefficacy of two post emergence herbicide mixtures viz., bispyribac sodium + metamifop and penoxsulam + cyhalofop butyl in direct seeded rice; to study the residual effect in soil; to investigate the impact on microbial and earth worm population, soil enzyme activity and weed seed bank and also to assess the in vitro sensitivity to soil borne pathogen, Rhizoctonia solani, bio control agents and bio fertilizer organisms. Field experiment was undertaken during first and second crop seasons of 2014-15 at Nemom block at farmer's field. The experiment was laid out in RED with 12 treatments and three replications. Bispyribac sodium + metamifop @ 60, 70, 80 and 90 g ha"*,penoxsulam + cyhalofop butyl @ 120, 125, 130 and 135 g ha"*, bispyribac sodium @ 25 g ha"', penoxsulam @ 22.5 g ha"', hand weeding twice and weedy check constituted the treatments. The higher three tested doses of penoxsulam + cyhalofop butyl v/z.,125, 130 and 135 g ha ' and the highest tested dose of bispyribac sodium + metamifop viz., 90 g ha"' were better than other weed management treatments in improving the growth and yield attributes of rice. Pooled analysis indicated the superiority of penoxsulam + cyhalofop butyl @ 135 g ha"' which recorded the highest grain yield (8463 kg ha ' ) and it was statistically on par with its lower doses (130 and 125 g ha*'). Straw yield was not significantly influenced by the weed control treatments. Penoxsulam + c^lofop butyl @ 135 g ha"' recorded the highest net returns (93744 ha *) and B: C ratio (2.43), which was on par with its lower dose (130 g ha"'). Penoxsulam + cyhalofop butyl @ 135 g ha"' was more effective in reducing the total density of weeds. With regard to the control of sedges and BLW, penoxsulam + cyhalofop butyl was more effective, but with respect to grasses, both the herbicide mixtures were more or less similar in effectiveness. Penoxsulam + cyhalofop butyl @ 135 and 136 registered higher weed control efficiency and lower weed index than other treatments. Uncontrolled weed growth caused a yield reduction of 50.38 per cent. Herbicide treatments significantly reduced the nutrient uptake by weeds and enhanced the nutrient uptake by crop over weedy check. The higher doses of penoxsulam + cyhalofop butyl (125,130 and 135 g ha"') and bispyribac sodium + metamifop (70, 80 and 90 g ha*') were more effective in maintaining higher nutrient content in soil. Dynamics of soil microbial population, earthworm population, soil enzyme status and organic carbon content of soil consequent to the application of herbicide mixtures revealed that, both penoxsulam + cyhalofop butyl and bispyribac sodium + metamifop at their tested doses did not have any inhibitory effect. Results of screening trial revealed that maize was the most sensitive indicator plant for both the herbicide mixtures. Dry weight and fresh weight of maize shoot were adjudged as the best parameters for assessing the residual effect of bispyribac sodium + metamifop and penoxsulam + c>^Iofop butyl in soil respectively. Pot culture bioassay studies revealed that the tested herbicide mixtures and their doses did not have any residual effect. In vitro sensitivity studies of bispyribac sodium + metamifop and penoxsulam + cyhalofop butyl to Rhizoctonia solani pointed out that both the herbicide mixtures inhibit the growth of Rhizoctonia solani. Studies on the in vitro effect of herbicide mixtures to Trichoderma viride indicated that bispyribac sodium + metamifop was safe to the fungus, whereas penoxsulam + cyhalofop butyl was moderately toxic. Compatibility studies revealed that both the herbicide mixtures were highly compatible with Psetidomonas fluorescenSy Azospirillum lipoferum and Azotobacter chroococciim. Weed seed bank assay results indicated the effectiveness of the higher doses of penoxsulam + cylialofop butyl (135, 130 and 125 g ha'') in depleting the seed bank compared to other treatments. The present study revealed the superiority of heibicide mixtures over individual herbicides in the management of weeds in wet seeded rice. Application of penoxsulam + cyhalofop butyl @ 135 or 130 g ha*', at 15 DAS could be adjudged as the most economic and ecofriendly weed management practice for wet seeded rice as evidenced by high weed control efficiency, net returns and B: C ratio; environmental safety, high inhibitory effect to Rhizoctonia solani and good compatibility with bio control agents and bio fertilizer organisms.
Open Access
Management of blood grass(isachne miliacea roth ex roem et schult) in wetland rice ecosystem
(Department of Agronomy, College of Agriculture, Vellayani, 2018) Renjan, B; KAU; Sansamma George
The study entitled “Management of blood grass (Isachne miliacea Roth ex Roem et Schult) in wetland rice ecosystem” was carried out at College of Agriculture, Vellayani during the period 2016 - 2018. The objectives were to study the eco-biology and habitat affinity of blood grass, to develop an effective strategy for managing the weed, to study the influence of the management practices on weed dynamics, to work out the economics of the weed management practices and also to assess the impact of the herbicides on the soil microorganisms. The weed biology was studied by observing sample plants for a period of one year. The results revealed that blood grass which propagated through both seeds and rooted stem bits flourished in the rice field all throughout the year. The seeds showed no dormancy and could germinate soon after shedding. However direct sunlight was found essential for germination of the weed seeds. The stored seeds retained > 80 per cent viability upto six months and after that there was a sharp decline in germination percentage. Effect of water regime and soil depth on weed propagation was assessed by conducting two separate lab studies by subjecting the seeds and stem cuttings to varying soil and water depth. The design was CRD and there were 5 x5 treatments (Factor I. Water depth (W): 0, 2.5, 5.0, 7.5, 10.0 cm and Factor II. Soil depth (S): 0, 2.5, 5.0 ,7.5, 10.0 cm ) and three replications. From the results, it was inferred that soil depth was the major factor that determined the germination and establishment of blood grass which emphasized the significance of land preparation in managing blood grass. Plant and soil samples from heavily infested rice field sites in four agro ecological units (AEU 10-North central laterite; AEU 4- Kuttanad; AEU 9- South central laterite; AEU 8- Southern laterite) were collected and analysed and correlated with weed dry weight to assess the habitat affinity of the weed. The results indicated that the biomass production of blood grass has significant positive correlation with soil organic carbon and available nitrogen while EC was negatively correlated. Water level also had significant negative correlation with plant dry weight. The field experiments to develop an effective strategy for managing the weed were conducted during the first and second crop seasons of 2016 at the State seed farm, Kottarakkara, Kerala. the initial infestation intensity of blood grass was 84 per cent. The experiment was laid out in split plot design with three replications and the crop variety used was Sreyas released from Rice Research station Moncombu, Kerala. Combinations of tillage (P) and water regimes (W) were the main plot treatments and weed management practices (M) were the subplot treatments. The tillage practices included were: P1- intensive tillage (three ploughings fb puddling) and P2 farmers‟ practice (two ploughings fb puddling). The water regimes tried were W1-continuous deep water ponding i.e., > 7.5 cm from 7 days after transplanting (DAT) till grain filling stage, W2- >7.5 cm water from 7 DAT till panicle initiation stage and W 3- maintaining about 5cm water level with intermittent drainage (KAU, 2011). The weed management practices in the subplots were M1 - oxyflourfen @ 0.15 kg ha-1 fb one hand weeding (HW), M2 - azimsulfuron @ 35 g ha-1 , M3- (bispyribac sodium + metamifop) 70 g ha-1 , M4- fenoxaprop- p-ethyl @ 60 g ha-1 , M5- hand weeding twice at 20 and 40 DAT and M6 - unweeded control. Oxyflourfen was applied as pre- plant three days before transplanting and the post emergence herbicides were applied at 15 days after transplanting (DAT). The second crop of rice was taken immediately after the first crop without disturbing the field layout. The results of the field experiments revealed that an integrated strategy involving intensive tillage (three ploughings fb puddling), deep water ponding (ie., > 7.5 cm upto panicle initiation and saturation thereafter ) and application of azimsulfuron @ 35 g ha-1 at 3-5 leaf stage of the weed was the most efficient treatment for managing the weed in terms of weed control efficiency (WCE), crop performance and net income. Preplant application of oxyflourfen @ 0.15 kg ha-1 fb hand weeding when combined with deep water ponding and intensive tillage recorded high WCE but was inferior in terms of economics. Combinations of these modified cultural practices with manual weeding though uneconomic, was efficient in managing the weed and recorded high yield also and hence could be an option for organic rice cultivation. The results from soil seed bank studies revealed that the density of blood grass propagules in the soil could be significantly reduced through intensive tillage and continuous maintenance of > 7.5 cm water level in the field. Among the weed management practices, application of azimsulfuron recorded the lowest weed seed density in the soil. When compared to the weedy check combinations, the soil seed bank was considerably lower in all the other treatments. The response of the microbial community to varying concentrations of the herbicides included in the study was assessed by conducting a separate field experiment which was laid out in RBD with 3 replications. The treatments were : oxyflourfen @ 150, 300, 450 g ha-1, azimsulfuron 35, 70, 105 g ha-1, bispyribac sodium +metamifop @ 70 , 140, 210 g ha-1, fenoxyprop- p-ethyl @ 60, 120, 180 g ha-1 and untreated control. The results showed that the bacterial population was stimulated with each increment of the herbicide concentrations. The fungal and actinomyctes population declined significantly immediately after the herbicide application but the negative impact was only transient and in most of the treatments the population recovered within two weeks. The soil enzyme activity was also found positively influenced by the herbicide application. From the results it was concluded that an integrated strategy involving intensive tillage (three ploughings fb puddling), deep water ponding (ie., > 7.5 cm upto panicle initiation and saturation thereafter ) and application of azimsulfuron @ 35 g ha-1 at 3-5 leaf stage of the weed was very effective for managing blood grass. Similarly application of oxyflourfen, bispyribac sodium + metamifop and fenoxyprop- p-ethyl at the recommended dose did not show any negative impact on the microbial community in the wetland rice ecosystem.
Open Access
Productivity and soil health of rice based cropping systems under organic management
(Department of Agronomy, College of Horticulture, Vellanikkara, 2018) Rajanand Hiremath; KAU; Usha, K E
The study entitled “Productivity and soil health of rice based cropping systems under organic management” was conducted in the Department of Agronomy, College of Horticulture, Vellanikkara during 2015-2017 to find out the suitable rice based cropping system under organic management. The experiment was laid out in randomized block design with three replications. Rice was grown under four different cropping systems for two consecutive years with and without foliar spray of liquid organic manures (LOMs). The rotations followed were rice-rice-njavara rice, rice-rice-salad cucumber, rice-rice- vegetable cowpea, rice-rice-amaranthus and rice-rice-fallow. The management practices were followed as per the Package of practices recommendations: (Ad hoc) for organic farming: Crops of the Kerala Agricultural University. Jeevamrurtham, Panchagavyam, green leaf extract and fish amino acid were the liquid organic manures sprayed at 15 days intervals after transplanting. The growth and yield parameters of all the crops were found to be better with the application of liquid organic manures. All the crops performed well in the second year due to the significant effect of crop diversification, residual effect of manures applied for the preceding crop and the improvement in soil health. There was significant reduction in the number of weeds, pests and diseases associated with rice due to crop rotation under organic management. Rice-rice-salad cucumber with and without LOMs produced significantly higher rice equivalent yield (29.58 and 24.67 t ha-1 respectively) and system productivity (81.03 and 67.58 kg ha-1 day-1 respectively) than rest of the sequences. Better sustainability yield index was recorded in rice-rice-vegetable cowpea with LOMs (0.26) followed by the same system without LOMs (0.20). With 300% cropping intensity, rice-rice-salad cucumber with and without LOMs recorded higher gross return (11,20,180/ 9,57,423 ₹ ha-1 respectively) and net return 237 (7,25,126/ 5,74,416 ₹ ha-1 respectively) compared to rice-rice-fallow with 200% cropping intensity (3,27,039 ₹ ha-1 gross return and 1,72,539 ₹ ha-1 net return). Among the sequences, the B:C ratio was found to be the highest in rice-rice-vegetable cowpea with and without LOMs (2.99 and 2.76 respectively). The soil characters were also significantly influenced by the treatments. The decreasing trend in bulk density is an indication of improvement in porosity and water holding capacity of the soil in the long run. Rice-rice-vegetable cowpea with LOMs recorded the highest organic carbon (1.46%), available N and P content (192.04 and 71.11 kg ha-1 respectively) while rice-rice-salad cucumber with LOMs had the highest available K content (332.78 kg ha-1). Total microbial biomass (bacteria, fungi and actinomycetes) and dehydrogenase activity were found to be the highest with rice-rice- vegetable cowpea with and without LOMs followed by rice-rice-salad cucumber with and without LOMs. The highest soil health index was registered by rice-rice-vegetable cowpea with and without LOMs (3.34 and 3.00 respectively) followed by rice-rice- amaranthus. The study revealed that foliar application of liquid organic manures enhanced the soil health and productivity of rice as well as other crops grown in rotation. Rice-rice- salad cucumber was found to be the best rice based cropping system with maximum net return, whereas rice-rice-vegetable cowpea system improved the soil physical, chemical and biological properties and thus sustained the soil health.
Open Access
Invasion impact of greater club rush (Scirpus grossus L.f) on wetland rice ecosystem
(Department of Agronomy, College of Agriculture, Vellayani, 2017) Gayathri Karthikeyan, P; KAU; Sansamma George
The study entitled “Invasion impact of greater club rush (Scirpus grossus L. f) on wetland rice ecosystem” was conducted at College of Agriculture, Vellayani during 2015-2017. The objectives were to study the invasive characteristics, habitat affinity and distribution of greater club rush, to assess its invasion impact on biodiversity and ecosystem functioning of the wetland ecosystem and also to develop an ecofriendly management strategy for recovering the invaded fields. To achieve the objectives, the study covered four aspects, i.e. Part I. Weed mapping and habitat analysis, Part II. Study of invasive characteristics of greater club rush, part III. Invasion impact on biodiversity and ecosystem functioning of wetlands, Part IV. Management of greater club rush. A preliminary survey on the presence of the emergent hydrophyte in Thiruvananthapuram district indicated that the invasion was mainly concentrated in some pockets in the wetlands adjoining the Vellayani fresh water lake. Hence, the wetland ecosystem of the Vellayani lake watershed was selected as the geographical unit for conducting the investigation. Under Part I, the extent of greater club rush invasion in the wetlands of Thiruvananthapuram district was assessed and mapped using Global Positioning System (GPS) and Geographical Information System (GIS). As per local enquiries, the invasion was noticed for the first time about 15 - 20 years back and was spreading fast in waterlogged paddy fields. However, it was not clear how this alien weed was introduced and naturalised in Kerala. The results of the weed mapping studies revealed that greater club rush invasion was concentrated mainly in the north - western side of wetlands adjoining the Vellayani lake. From the drainage and land use maps, it was inferred that there was a flood plain formed in the locality due to indiscriminate wetland reclamation resulting in impeded drainage. The total area under invasion was approximately 65 ha (47.70 per cent of the rice fallows). During the mapping studies, it was also observed that the ownership of a major portion of these paddy fields was vested with absentee landlords who leave the land uncultivated for a long time thus providing open niches for further spread of the weed. Correlation studies on weed density and dry weight with soil and water parameters of the invaded fields indicated that the weed has high level of habitat tolerance and ecological flexibility and was able to thrive under a wide range of field conditions. Under Part II, the invasive nature of greater club rush was assessed by observing the growth and development characteristics of the weed under field conditions. From the results, it was inferred that, tall stature (1.52 m), dense growth habit (342.23 ramets m-2), low light infiltration (4.36 per cent), high relative growth rate (0.028 g g-1 day-1), efficient propagation (rhizomes, stolons and corms combine for multiplication and perennation), huge biomass (30 t ha-1) and abundance of aerenchyma along with ecological flexibility imparts intense competitiveness for greater club rush making it a successful invader. The major part of the study was to assess the impact of greater club rush invasion on the wetland ecosystem (Part III). Based on the weed mapping and habitat analysis, three heavily infested padasekharams, located within a distance of 5 km were selected for the impact study and monitored for two years. The methodology used was Multisite comparison of the co- existing flora and fauna community, between invaded vs uninvaded sites. Alterations in nutrient cycling and microbial activity due to the invasion were studied by collecting and analyzing soil samples from selected sites during three seasons. The results indicated that greater club rush invasion was depleting the diversity of native vegetation in the wetland ecosystem in terms of species richness and also density. Soil seed bank studies also confirmed the negative impact of the invasion on flora diversity. However, the invaded fields were observed to be rich in faunal diversity and an ideal home for several water birds especially purple moorhen. The thick stand of the weed was found to provide refuge to small animals like rats and snakes also; and these in general were causing trouble to rice farmers in adjacent areas. Contrary to several earlier reports, the impact on the ecosystem functioning parameters was negligible, probably due to occasional flooding and sedimentation in the selected locality. To develop an eco-friendly strategy for managing the weed, an experiment was undertaken in a heavily infested paddy field (Part IV) with eight treatments and three replications and the design was RBD. The treatments were: T1 - (Bensulfuron methyl + Pretilachlor) @ 660g ha-1 on the next day of tilling., T2 - (Bensulfuron methyl + Pretilachlor) @ 1320g ha-1 on the next day of tilling, T3 –Azimsulfuron @ 35g ha-1 at 3-5 leaf stage , T4 -Azimsulfuron @ 70 g ha-1 at 3-5 leaf stage, T5 - (Glyphosate @ 1.0 kg ha-1 + 2, 4 – D sodium salt @ 2.0 kg ha-1) at active growth stage, T6 - (Glyphosate @ 0.5 kg ha-1 + 2, 4 – D @ 1.0 kg ha-1) at reproductive stage, T7 -Tillage (Farmer’s practice) and T8 – Control (Uninterrupted weed growth). Among the various treatments, application of Glyphosate @ 0.5 kg ha-1 + 2, 4 – D @ 1.0 kg ha-1 at the reproductive stage was found to be the best, giving complete weed kill with no further regrowth. The opportunities for utilising the weed and thereby managing it were also investigated during the study. The results revealed that greater club rush with its huge biomass production (>30 t ha-1) could remove many of the heavy metals (arsenic, copper, zinc, lead, chromium, cobalt, nickel and chromium) from contaminated soils more efficiently than water hyacinth which is a well known phytoremediator. The nutritive value of the weed biomass (crude protein - 7.5 per cent, crude fibre- 26.79 per cent) was shown to be comparable with that of guinea grass (crude protein - 8 to14 per cent, crude fibre - 28 to 36 per cent). The K/(Ca+Mg) ratio was 1.39 which is considered to be within safe limits in a livestock feed. However being a phytoextractor, further studies needs to be done for justifying its use as a forage. The study revealed that greater club rush has high level of ecological flexibility and competitiveness which make it a successful invader. The weed has already invaded considerable area of wetland rice ecosystem and is likely to spread further in areas left fallow for long periods. It was found that the invaded fields could be efficiently recovered by application of a tank mixture of glyphosate @ 0.5 kg ha-1 + 2, 4 – D sodium salt @ 1.0 kg ha-1 at the reproductive stage. The major negative impact of the invasion on ecosystem was the decline in species richness and density of native weed community. At the same time, the thick weed growth provided ideal habitat for many faunal species. The weed was found to have the potential to be used for phytostabilisation of heavy metal contaminated soils and the luxuriant biomass had reasonable nutritive value also. The overall conclusion is that greater club rush invasion can become a potential threat to the wetland rice ecosystem, if left undisturbed.
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Acidity amelioration and nutrient management practices for mitigating yield constraints of rice in Vaikom Kari
(Department of Agronomy, College of Agriculture, Vellayani, 2017) Devi, V S; KAU; Kumari Swadija, O
An investigation entitled “Acidity amelioration and nutrient management practices for mitigating yield constraints of rice in Vaikom Kari” was carried out as two field experiments in Vaikom Kari soils of Kuttanad during the period from 2014 to 2017 to standardize acidity amelioration and nutrient management practices for rice to overcome yield constraints in Vaikom Kari and to work out the economics of cultivation. Experiment I entitled “Evaluation of acidity amelioration practices for rice in Vaikom Kari” was conducted in farmer’s field in Kallara panchayat in Kottayam district during November 2014 to March 2015. The experiment was laid out in RBD with seven treatments in three replications with rice var. Uma. The treatments included lime, dolomite and rice husk ash (RHA) applied as two splits- as basal + 30 DAS or as basal + one week before third dose of fertilizer application and a control without ameliorants. Lime, dolomite or RHA, irrespective of time of application, could produce taller plants with higher LAI and tiller number at maximum tillering (MT), panicle initiation (PI) and harvest stages. The same treatments recorded higher number of panicles m-2 and 1000 grain weight and lower sterility percentage. Lime, dolomite or RHA as basal + 30 DAS produced significantly higher grain yield over control. Grain yield was significantly and positively correlated with LAI at MT and PI stages and panicle number m-2. Higher straw yield was obtained with lime or dolomite as basal + 30 DAS and RHA treatments. Application of lime, dolomite or RHA as basal + 30 DAS resulted in higher dry matter production at harvest. Soil ameliorants improved the uptake of macronutrients and micronutrients. Uptake of N and K were significantly higher for lime, dolomite or RHA applied as basal + 30 DAS while dolomite as basal + 30 DAS recorded the highest P uptake. The highest uptake of Ca was found with lime as basal + 30 DAS and that of Mg and S with dolomite as basal + 30 DAS. The highest uptake of Mn and Zn were observed with lime as basal + 30 DAS, Cu with RHA as basal + 30 DAS and that of B with lime, dolomite or RHA applied as basal + 30 DAS. The control treatment and RHA applied as basal + one week before PI registered lower Na uptake and both RHA treatments registered higher Al uptake. There was significant and positive correlation of grain yield with uptake of nutrients except Fe, Zn and Al. Lime and dolomite treatments were more effective in reducing soil acidity and improving dehydrogenase activity and nutrient availability in the soil. The ameliorated plots showed higher organic carbon status compared to control. Lime as basal + one week before PI and dolomite treatments recorded higher soil available N at seedling stage and at tillering and PI stages, any treatment except control could register higher available N in the soil. Any liming material applied as basal + 30 DAS improved soil available P status. No significant effect of treatments on available K was observed. Lime or dolomite treatments resulted in higher availability of Ca while dolomite treatments registered higher availability of Mg in the soil. At all stages except harvest, the control plots recorded significantly higher status of available S and Fe and lower status of Mn in the soil. Significant and positive correlation of pH with available Ca and negative correlation with available Fe was observed at all stages of crop growth. Soil available Cu status was the highest with control at PI stage and with dolomite at harvest stage. Dolomite treatments recorded higher available B in the soil. The highest Na content in the soil was registered by dolomite treatments at seedling stage and by control at tillering stage. There was an increase in the availability of Na at all stages of experimentation but the content was below the critical level of toxicity. Soil exchangeable Al status was significantly higher in the control. Lime, dolomite or RHA applied as basal + 30 DAS gave higher net income and BCR while the control recorded the lowest net income and BCR. Experiment II entitled “Standardization of nutrient management practices for rice in Vaikom Kari” was conducted during August to December 2015 and 2016 in farmers` fields in Thalayazham panchayat in Kottayam district. The experiment was laid out in RBD with 16 treatments (formulated based on the results of the Experiment I) in three replications with rice var. Uma. The treatments were dolomite, lime + MgSO4 or RHA + MgSO4 along with 100% POP alone or with 100% POP + foliar spray of 13:0:45 (1%) or borax (0.5%) or 13:0:45 + borax at PI stage. Lime + MgSO4 + 75% POP + 13:0:45 + borax as well as lime without MgSO4 + 100% POP combined with 13:0:45 or borax or both were also included as treatments. The treatments involving dolomite and lime with or without MgSO4 produced taller plants, higher tiller number m-2 and higher LAI during both the years. Dolomite + POP + 13:0:45 produced the highest number of panicles m-2. Higher test weight and lower sterility percentage were observed with dolomite + POP + 13:0:45 and dolomite + POP + 13:0:45 + borax. Higher grain yield of 5.42 and 5.57 t ha-1 during 2015 and 2016 respectively were produced by dolomite + POP + 13:0:45 followed by dolomite + POP + 13:0:45 + borax and lime + MgSO4 POP + 13:0:45. Grain yield was significantly and positively correlated with LAI at MT and PI stages and with panicle number m-2. Pooled analysis also proved the significance of the above treatments in producing higher grain yield. Lower yields were produced by the treatments involving RHA and 75% POP during both the years and in the pooled data. In general, higher straw yields were noticed with the treatments involving dolomite or lime along with foliar spray of 13:0:45 or 13:0:45 + borax. Higher dry matter production was noticed with dolomite + POP along with 13:0:45 or borax during first year and with dolomite + POP or lime + MgSO4 + POP along with 13:0:45 or 13:0:45 + borax during second year. In general, higher uptake of macronutrients and micronutrients was observed with dolomite or lime + MgSO4 treatments along with 100% POP during both the years. Uptake of Na was the highest with RHA + MgSO4 + POP + 13:0:45 during first year and with dolomite treatments during second year. Higher Al uptake was observed with lime + POP + 13:0:45 with or without MgSO4. Significant and positive correlation of grain yield with uptake of P, K, Ca, Mg, S, Mn, Zn, Cu and B and negative correlation with Fe was observed during first year. During second year, the yield was significantly and positively correlated with uptake of nutrients except Na and Al. The treatments involving dolomite, lime with or without MgSO4 performed better in ameliorating soil acidity than RHA treatments during both the years. The treatments involving RHA showed higher EC values. All the treatments except those involving RHA helped in improving dehydrogenase enzyme activity in the soil during the cropping period. The initial soil organic carbon status was maintained during the cropping period due to nutrient management practices. Availability of N in the soil improved due to treatments involving dolomite + POP during seedling stage and due to those involving lime + POP without MgSO4 at other stages. The treatments involving dolomite + POP and lime + POP with or without MgSO4 recorded higher available P during all crop stages. In general, higher status of available K was registered by the treatments involving RHA or lime without MgSO4. All treatments involving lime or dolomite registered higher soil available Ca and those involving dolomite or lime + MgSO4 showed higher availability of Mg in the soil. In general, available S in the soil decreased from initial status during the cropping period. The treatments involving dolomite registered lower status of soil available Fe and higher status of available Mn and B. Higher status of available Zn was registered by the treatments involving dolomite or lime + MgSO4. The treatments involving dolomite, lime + MgSO4 or RHA + MgSO4 along with POP registered higher available Cu in the soil. Dolomite treatments recorded lower status of Na and exchangeable Al in the soil. Soil pH was significantly and positively correlated with available P and significantly and negatively correlated with available Fe and exchangeable Al in the soil. The economics of cultivation in terms of net income and BCR were the highest with dolomite + POP + 13:0:45 during both the years which was closely followed by dolomite + POP + 13:0:45 + borax. The treatments involving RHA and 75% POP registered lower net income and BCR. The results of the study revealed the superiority of dolomite for ameliorating soil acidity in Vaikom Kari soil compared to lime or rice husk ash. Split application of dolomite as basal dose and at 30 DAS proved more effective than application as basal dose and one week prior to fertilizer application at panicle initiation stage. Soil acidity amelioration with dolomite @ 500 kg ha-1 (300 kg as basal dose and 200 kg ha-1 at 30 DAS) and soil application of 90:45:45 kg NPK ha-1 (full P as basal and N and K in three equal splits at 20 DAS, 35 DAS and PI stage) along with foliar spray of 13:0:45 (1%) or combined spray of 13:0:45 (1%) and borax (0.5%) at panicle initiation stage resulted in higher productivity and profitability from rice cultivation in Vaikom Kari soil.

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