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Subject: Soil Sciences × Start date: 2018 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Evaluation of STCR based targeted yield equations of amaranthus (Amaranthus tricolor L.) in southern laterite soils of (AEU-8) of Kerala
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellayani, 2023-05-06) Dara Hadassah Eunice; KAU; Visveswaran, S
    The current work, entitled "Evaluation of STCR-based targeted yield equations of Amaranthus (Amaranthus tricolor L.) in southern laterite soils (AEU-8) of Kerala," was conducted in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani from the period March 2022 to June 2022. In this work, a field experiment based on randomized block design was carried out to test and validate the targeted yield equation produced by STCR 2014 for the cultivation of Amaranthus at (AEU-8), Instructional farm, College of Agriculture, Vellayani, Thiruvananthapuram. The five treatments used in the experiment were the organic and conventional package of practices based nutrient management as T1 and T2 and three levels of Soil test crop response (STCR) based on targeted yield with T3, T4 and T 5 having nutrient management for a targeted yield of 20, 22.5 and 25 t ha-1 . The following equation targeted yield equation used in the study was developed by All India Co-ordinated Research Project on STCR at the College of Horticulture, Kerala Agricultural University, Vellanikkara: FN = 3.50T – 0.10SN – 0.19ON FP2O5 = 1.44T – 2.58SP – 0.30OP FK2O = 1.35T – 0.06SK – 0.13OK Where, FN, SN and ON are fertilizer nitrogen dose which was added through fertilizer, soil available nitrogen and nitrogen contribution of organic sources respectively. FP2O5, SP and OP are fertilizer phosphorus dose which is added through fertilizer, soil available phosphorus and phosphorous contribution of organic sources respectively. FK2O, SP and OP are fertilizer potassium dose which is added through fertilizer, soil available potassium and potassium contribution of organic sources respectively. The nutritional status of organic manures used in the experiment and initial soil fertility levels of the field were analysed to calculate the quantity of fertilizer dose in T3, T4 and T5. Biometric observations, yield parameters, pre-and post-harvest physicochemical properties of soil and the nutrient content in shoot, root, leaf and dry matter production were recorded to study their effect on yield. Among all the treatments T5 recorded the highest values for biometric observations and yield parameters. The treatment T5 recorded a yield of 24.79 t ha-1 . Similarly, the dry matter 143 production, number of leaves per plant and height of the plants were 55.33 g plant-1 , 36.86 and 42.17 cm respectively. The plant height and the number of branches per plant and the dry matter production too were the highest for this treatment (T5). The post-harvest analysis of soil physical properties such as particle density, bulk density and porosity showed no significant difference among the treatments. However, a significant difference was found in water holding capacity and was highest in T1. The treatment T1 recorded the lowest level of macronutrients while the highest level was recorded in T5. All the treatments resulted in an increase in the organic carbon content of the soil after the experiment. Thus, treatments had negligible influence on overall soil health status as indicated by an insignificant difference among the treatments with respect to dehydrogenase activity and the microbial biomass carbon of the post-harvest soil samples. The lowest uptake of macronutrients was observed in T1 which recorded the lowest yield. The highest uptake of macronutrients was observed in T5 which recorded the highest yield. This suggests that among the treatments higher levels of fertilizer application for the targeted yield range of 20 to 25 t ha-1 have a direct influence on nitrogen, phosphorous and potassium uptake and therefore an increase in crop production. There was a significant difference between the treatments with respect to secondary and micronutrient content of soil and plant respectively. These nutrients were maintained within a sufficiency range by application of amendments and organic matter. The biometric parameters and yield were positively correlated. Also, a positive correlation was observed between yield parameters and yield. There was a positive correlation for yield with the post-harvest soil nutrient status of nitrogen, phosphorus and potassium respectively. The yield showed a significantly positive correlation with the nutrient content of the leaf and shoot. Similarly, a positive correlation was observed between yield and plant nitrogen, phosphorus and potassium uptake. The economics of cultivation indicate that treatment T5 had the highest profit and benefit cost ratio compared to the other treatments. It can be concluded that the Soil test crop response-integrated plant nutrient system based targeted yield equation with organic manure management for cultivating Amaranthus tricolor can be adopted and extended to agro ecological unit 8 of Trivandrum district of Kerala, India with a yield target of 25 t ha-1 . Therefore, the present study confirmed the possibility of optimizing of the yield of Amaranthus sustainably with nutrient management alone using targeted yield equations.
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    ThesisItemOpen Access
    Transformation of zinc in soil and zinc nutrition in lowland rice under different levels of Phosphorus
    (Kerala Agricultural University, 2021) Najiya Rinthas, K; KAU; Moossa, P P
    Phosphorus and zinc are two important essential elements required by the plants for various metabolic activities, functions and associated with membrane structure. Continuous use of phosphatic fertilisers with less zinc, aggravates zinc shortage also phosphorus applied will be accumulated in the soil leading to formation of zinc phosphate complex that affect zinc translocation to various plant parts. There are contradictions regarding phosphorus zinc interaction that is controlled by native P and Zn status. In this context an investigation entitled “Transformation of zinc in soil and zinc nutrition in lowland rice under different levels of phosphorus” was conducted. Two separate experiments were carried out at Regional Agricultural Research Station, Pattambi. In the first experiment, fractions of Zn under different P levels was studied in Long Term Fertilizer Experiment (LTFE) with six treatments on rice in RBD with four replications. The soil samples were taken after the paddy harvest of kharif 2020 and sequential extraction of Zn (water soluble + extractable, organically bound Zn, amorphous sesquioxide Zn and crystalline sesquioxide Zn) and P (sol-P, Al-P, Fe-P, sesquioxide occluded P and Ca-P) were carried out. In the second experiment phosphorus and zinc interactions was studied using pot culture experiment on rice in factorial CRD with 3 replications. Samples from different locations of Palakkad district having native P 24 kg ha-1 and native Zn 3 mg kg-1 were collected. Sixteen treatment combinations were applied with 4 levels of P (0, 25, 50,100 mg kg-1 ) as KH2PO4 and 4 levels of Zn (0, 5, 10, 15 mg kg-1 ) as ZnSO4.7H20 through solution for studying the nutrient uptake and yield. The results of fractionation study showed that continuous use of inorganic fertilisers with organic manures in T5 (100% NPK + FYM) increased various Zn fractions except amorphous sesquioxide Zn fraction which was highest in the control. Even though the increase in P application increased different P fractions significantly higher content was observed in 100% NPK+ FYM and these were proved to be beneficial towards increasing different P fractions. But Ca-P fraction was more in the lime treated plot. Correlation study concluded that most of the phosphorus fractions have negative impact on different zinc fractions. The results of the pot experiment elucidated that P and Zn application increased number of productive tillers and thousand grain weight but higher zinc application decreased plant height. Among different soils, soil type S2 (P > 24 kg ha-1 ) registered higher grain and straw yield, P in grain and straw, total P uptake of paddy, but Zn uptake and Zn in grain and straw were more in soil type S3 (Zn > 3 mg kg-1 ). Combined application of 100 mg kg-1 P and 10 mg kg-1 Zn recorded higher grain (57.27 g pot-1 ) and straw yield (66.82 g pot-1 ). Phosphorus application significantly increased the P content in grain and straw but zinc addition had antagonistic effect on them and treatment combination of P100Zn0 registered higher P content in grain (0.26%) and straw (0.214%). The Zn in grain and straw significantly increased by the application of zinc, but phosphorus was having an adverse effect and treatment combination of P0Zn15 registered higher Zn content in grain (61.28 mg kg-1 ) and straw (44.19 mg kg-1 ). Total P and Zn uptake of paddy increased by the application of both phosphorus and zinc with higher content obtained at P100Zn15 (28.47 mg pot-1 ) and P50Zn10 (0.458 mg pot-1 ) treatment combination. Correlation study concluded that phosphorus and zinc application affected P and Zn uptake in high zinc containing soil (S3) and high P soil (S3), respectively. In future this work can be used to study the changes in various P and Zn fractions under continuous crop removal, various management practices to mobilise fixed P in high phosphorus containing soil and also to study Q/I relationship of both phosphorus and zinc.