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ThesisItem Open 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 PPhosphorus 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.ThesisItem Open Access Feasibility of phosphogypsum as an ameliorant for soil acidity in laterite soil(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2003) Jeena Mathew, KAU; Manorama Thampatti K C, K CAn investigation was carried out at College of Agriculture. Vellayani, to study the feasibility of using phosphogypsum as an ameliorant for correcting soil acidity in laterite soil with cowpea as the test crop. The experiment comprises of an incubation study and a micro plot field experiment. The incubat{on study was carried out to understand the kinetics of dissolution of phosphogypsum and the nutrient release pattern in laterite soils after its application with the following seven treatments T I (absolute control) T2 (Lime @ full LR), T3 (PG @ full LR) T4 (Lime @ half LR), r, (PG @ half LR) T6 (Lime and PG each @ half LR) T7 (Lime as per POP). The study was conducted for a period of 60 days and the chemical parameters were analysed at an interval of 12 days as per standard procedures. The results revealed the enhanced solubility of phosphogypsum which was evident from the higher EC values in the treatments with phosphogypsum through out the study period. Most of the plant available nutrients were solubilised by the 24 th day of incubation. A reduction in exchangeable acidity was noticed by the application of phosphogypsum after a peri,od of 24 days, which is mainly due to reduction in exchangeable aluminium. But this was not efficient as lime in decreasing the exchangeable H+ and hence the pH, remained unaltered. The micro plot field experiment was laid in RBD with a main crop and a residue crop of cowpea var. Kanakamoni. The treatments include TI (POP), T2 (Lime @ full LR), T 3 (PG @ full LR), T 4 (Lime @ half LR), T s (PG @ half LR), T 6 (Lime and PG each @ half LR), T 7 (Lime and PG each @ 14 LR) and T 8 (absolute control). Fertilizers and amendments were applied on the basis of soil test data except in T I where, they were applied on the basis of POP of Kerala Agricultural University. In the residue crop, the amendments were not added and was taken immediately after the main crop. The available nutrients in soil like, P, Ca and S were increased by the application of phosphogypsum. However, considerable leaching was noticed in the case of Mg and K. The growth characteristics of cowpea were improved by the application of phosphogypsum. The highest grain yield was recorded with phosphogypsum applied at full LR and was on par with the combination treatment which received the amendments at one fourth LR. But considering the cost factor treatment with phosphogypsum at full LR is the best. Its B: C ratio was also the highest among other treatments. The yield attributes were also improved by the treatment with phosphogypsum at full LR. The concentration and uptake of N, P, K, Ca, and S in bhusa were favourably influenced by the application of phosphogypsum either at full LR or at halfLR. The residual effect of phosphogypsum was visualized in the crop, taken after the main crop. The application of phosphogypsum increased the organic carbon content, P, and S. The leaching of calcium, Mg and K beyond the root zone was much pronounced in the residue crop. The yield attributes of cowpea were also positively related with phosphogypsum treatment. But by the time of residue crop, the bhusa yield was more for lime treated plots'. The concentration of N, Ca and Mg were more in lime treated plots, but the uptake of nutrients was more for treatment with phosphogypsum. This also emphasizes the mobility and downward leaching property of phosphogypsum. The micronutrient content and uptake were also influenced by the application of phosphogypsum. Phosphogypsum is hence highly beneficial in increasing the yield and yield attributes of cowpea, by mitigating the adverse effects of soil acidity, such as aluminium toxicity, which in effect is the major reason for acidity in laterite soils. Further, utilization of an industrial by product, which otherwise remain unutilized is also facilitated.ThesisItem Open Access Fertiliser scheduling for the short duration cassava variety vellayani hraswa(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2004) Sekar, J; Harikrishnan Nair, KCassava (Manihot esculenta Crantz), popularly known as tapioca, is one of the world’s most important staple food crops. It ranks sixth among the major contributors of food in the world. It has been a major contributor of food, nutrition and income especially for the poor. Its biological efficiency and multi use characteristics warrant for crop management strategies to exploit its production potential to the maximum. Due to the high cost of labour and lack of timely availability of labour, the farmers show interest to introduce cassava as a substitute for rice in his crop cafeteria. “Vellayani Hraswa” is a short duration variety of cassava released by the Kerala Agricultural University recently. Branching habit and short duration nature coupled with greater production potential make this variety physiologically unique and outstanding compared to other cassava varieties ever released. These characters warrant for separate package in nutrient management. Keeping these views in mind, an experiment entitled “Fertilizer scheduling for short duration cassava variety “Vellayani Hraswa” was conducted with the objective of studying the influence of NPK fertilizers on the performance of short duration cassava variety “Vellayani Hraswa” and to arrive at a fertilizer recommendation for the same. The experiment was laid out at the Instructional Farm, College of Agriculture, Vellayani during the period from 25th June to 25th December 2003 in a 33 Factorial Randomized Block Design (FRBD) with two replications and three factors (NPK) each with three levels (50,75 and 100 kg ha-1). The crop was raised adopting the agronomic practices for cassava outlined in the Package of Practices Recommendation: Crops of Kerala Agricultural University KAU (2002). The results of the experiment are summarized as follows. There was no significant difference on the plant height at all the growth stages of the plant due to the treatments. However, there was an increasing trend on the height of the plant as the dose of nitrogen increased. Higher dose of nitrogen increased the number of leaves produced in cassava at all the growth stages. At harvest stage, the plants retained maximum number of leaves for all the treatments which indicates that the leaf fall is minimum, a peculiar characteristic of the variety. Tuber production was influenced significantly by all the treatments. Application of 100 kg K ha-1 resulted maximum tuber yield. NPK @ 50: 50: 100 kg ha-1 produced maximum tuber yield (47.09 t ha-1). This variety favours a 1:1:3 NPK ratio for higher tuber production. Length of tubers was not influenced by different levels of N, P and K. However, NPK @ 75:50:75 kg ha-1 produced tubers with maximum length in cassava. Girth of tubers was significantly increased due to the application of nitrogen alone @ 100 kg ha-1 in cassava. Application of NPK @ 75:100:100 kg ha-1 produced the highest quantity of dry matter. No significant influence on LAI due to the application of N, P and K fertilizers was observed. Stomatal conductance in cassava leaves was maximum due the application of P and K @ 75 kg ha-1 (p2k2) with significant effect. Chlorophyll content of cassava leaves was not influenced significantly due to different levels of N, P, K application. The highest dose of NPK (n3p3k3) recorded highest chlorophyll content. Phosphorus has influenced significantly on tuber starch content. An increasing trend due to incremental doses of K up to 100 kg ha-1 was also observed. Treatment n3p3k3 (100:100:100 kg ha-1) recorded the highest starch content in tubers. Crude protein content was significantly influenced by the nutrients NPK. Application of N @ 100 kg ha-1 registered the highest protein content. NPK @ 100:100:75 kg ha-1 produced tubers with maximum protein content. Hydrocyanic acid content was mainly affected by higher doses of nitrogen. Nitrogen alone @ 100 kg ha-1 produced maximum HCN content in the tuber. But there was significant decline in HCN content as the dose of K increased. When the treatment n3p3k1 (100:100:50 kg ha-1) produced tubers with the highest HCN content, the treatment n1p2k3 produced tubers with lowest HCN content. Cooking quality of tubers was significantly influenced by potash. Maximum cooking quality could be obtained when K was increased to 75 kg ha-1. In general, the uptake of N, P and K by plants was maximum for the highest doses of N, P, K. A fertilizer dose of N, P, K @ 50:50:100 kg ha-1 produced maximum tuber yield (47.09 t ha-1) with moderate cooking quality of tubers. The moderate fertilizer cost resulted high BC ratio of 3.32 for the treatment n1p1k3, the best dose arrived at and to be recommended for the short duration cassava variety “Vellayani Hraswa”. It has to be concluded that the cassava variety “Vellayani Hraswa” is most economical due to its short duration (about 6 months), high yield (45-50 t ha-1) good cooking quality (1.5) and moderate fertilizer requirement (50:50:100 NPK ha-1).ThesisItem Open Access Assessment of selective retention sites of cadmium and lead in tomato (Lycopersicon esculentun Mill)(Department of Soil Science Agricultural Chemistry,College of Horticulture,Vellanikkara, 2004) Vanisri, K; KAU; Sam Kurumthottical, TThe bio-availability of the toxic heavy metals like cadmium and lead together with its selective retention sites in tomato (Lycopersicon esculentum Mill.) was one of the major concerns in the crop. For this, pro-calculated quantities of cadmium and lead were applied to the soil mainly as water-soluble sources (cadmium chloride and lead nitrate respectively) to assess the finite objectives envisaged in the study. In order to meet the objectives, a pot culture experiment was conducted in the Vegetable Research Farm attached to the Department of Olericulture, College of Horticulture, Vellanikkara during the rabi season of 2003 with five treatments and four replications. Pre-treatment analyses of all basic inputs and soil were carried out to quantify the possible inclusion of heavy metals from them. After providing pre-calculated quantities of metals in pots, 42 day old and uniformly grown tomato plants of variety Sakthi were transplanted to pots. The plants were allowed to establish till majority of the plants (50 per cent) were at the turning stage. Biometric observations on the plants due to the impact of the metals were recorded. Fruits as and when they turned ripe were harvested with proper acknowledgment to their identity in treatments for yield and its subsequent dry weight. At harvest, the plants were carefully uprooted, cleaned properly and separated into root and shoot portions. After recording the weight of each portions, these parts were taken for analysis. Post-harvest soil samples were also collected and analysed to see the extent of availability of major nutrients and heavy metals, particularly cadmium and lead. All the inputs including soil maintained variable amounts of cadmium and lead, with maximum metal load contributed from phosphatic sources. It is seen that growth of tomato plants in pots, particularly under the influence of different levels of cadmium and lead, manifested differential growth and development. Internally also, the plants exhibited differential metal load and retention patterns apart from recording variation in the uptake of major nutrients. A brief resume of the major influence of different levels of cadmium and lead in soil and on the tomato plants is presented hereunder. Variation in cadmium levels in soil could influence significant variations In the available nutrient status in post-harvest soil samples. Accordingly, an increase in metal load permitted enhanced potassium availability in soil while the same status had an opposite effect particularly with respect to the available phosphorus and nitrogen. The nitrogen content of root and shoot of tomato plants was seen to be positively influenced with higher levels of cadmium application. However, a reverse trend in nitrogen content was observed with lower levels of application except for the shoot portions observed from Treatment 4. Among the various plant parts analysed, the fruits maintained the maximum nitrogen content and this content was roughly observed to be twice as that of its content in roots. Enhancement in cadmium level in soil resulted in a corresponding increase in the phosphorus content of roots, shoot and fruits. As observed for nitrogen, fruit portion maintained the maximum phosphorus content. A very similar trend was noted for the potassium content in tomato, consequent to the application of different levels of cadmium. Much before an apparent growth or' yield reduction was noted in tomato with cadmium application, the tomato plants readily exhibited certain characteristic symptoms, which could be associated with the metal toxicity on that plant. Preliminary indications appeared on leaves with such leaves picking up yellowing and inter-veinal chlorosis depending upon the metal load. At high concentrations of the metal, invariable splitting up of the stem at the collar region leading to complete death of such plants has been noted. As concentration of the cadmium load increased beyond 1.5 mg kg" soil, the tomato plants failed to fruit and at the highest concentration of the metal envisaged in the study (2.0 mg Cd kg" soil), the very establishment of the transplanted tomato crop was questioned. However, the successful survival and fruiting of the transplanted tomato plants was noted only at lower levels of cadmium addition (0.5 and 1.0 mg Cd kg" soil). Lower doses of addition of cadmium had exhibited negative influence on growth and development in tomato with the manifestation of significant reduction in number of branches, leaf length, leaf number, plant height, the production of trusses and subsequent reduction in yield. Reduction in growth and yield of tomato plants from different levels of application of cadmium, necessarily brought significant reduction in dry matter yield, whose influence is clearly reflected in the roots, shoot and fruits portions underlining a negative influence of cadmium on the dry matter production. At all levels of cadmium application, there was sufficient retention of the metal in plant whether it is root, shoot or fruits Roots of tomato are seen to preferentially harbour more of cadmium than its other plant parts particularly at higher levels of addition. However, at lower levels of addition, shoots preferred to maintain more cadmium than its root portions. Increasing levels of lead invariably decreased the root nitrogen content . significantly while shoots content of nitrogen increased generally with lower doses of metal addition. Variation in, lead levels permitted a significant increase in the phosphorus content in roots, shoot and fruits. No specific trend was noted in the retention of potassium by roots while shoot portions indicated significant influence of the same by offering differential content of potassium in them. Among all the plant parts, fruits maintained the maximum nitrogen, phosphorus and potassium content. Higher doses of lead rendered some fruits, if not all with certain malformations. This together with the total absence of any phyto-toxicity testifies that the tomato plants are able to tolerate high concentrations of lead inside them. Quite contrary to the expectations, an unusual increase in dry matter production was observed from lead treated tomato plants. Lead application in soil, irrespective of its levels, permitted maximum accumulation of the metal in fruits followed by shoots and roots. All accumulations noted in the plant were observed to be significant, projecting serious concern for the silent inclusion of lead in the economically important part of the plant. Variable amounts of cadmium and lead have been detected in the post-harvest soils indicating that the entire quantity of the applied cadmium and lead could not be completely absorbed by the plant.ThesisItem Open Access Vermicompost Enriched with Organic Additives for Sustainable Soil Health(Department of Soil Science and Agricultural Chemistry College of Agriculture, Vellayani, 2004) Sheeba, P S; KAU; Ushakumari, KAn investigation was carried out at the Instructional Farm, attached to the College of Agriculture, Vellayani to evaluate the effect of vermicompost enriched with organic additives viz., neem cake and bone meal on physico-chemical and biological properties of soil, to evaluate its impact on crop performance and the feasibility of substituting farmyard manure and inorganic fertilizer using amaranthus as test crop. The study consist of three parts 1) Preparation and analysis of vermicompost and enriched vermicompost 2) laboratory incubation experiment 3) Field experiment. On enriching biowastes with neem cake and bone meal, improved the manurial value of vermicompost produced using earthworm species Eudrillus eugeniae. C/N ratio was reduced by enrichment. Microbial population also increased considerably by enriching vermicompost with organic additives. Second part of our investigation was an incubation study and it was conducted to evaluate relative efficiency of enriched vermicompost to release nutrients from soil and its influence on physico-chemical and biological properties of soil. The results revealed that available nitrogen, phosphorus and potassium content of the soil increased upto 45 days of incubation then the availability slowly declined. Organic carbon, pH and EC increased whereas bulk density reduced due to the effects of various organic sources. Application of organic matter had a positive effect on microbial count also. Third part of the study was field experiment, and it was laid out in RBD with 10 treatments and three replications. The biometric observations viz., plant height, number of leaves, number of branches, stem girth, leaf stem ratio all were significantly influenced by different treatments. Significant differences were observed among yield attributing characters like yield per cutting (t ha-1), total yield per plant (g plant-1), total marketable yield (t ha-1), and total dry matter production (t ha-1). Highest yield per cutting was recorded by the treatments T0 (FYM + full NPK), T4 (EVC – NC two per cent + full NPK) and T8 (EVC – NC 1 per cent + BM 1 per cent + full NPK]. With respect to plant contents of nutrients, for nitrogen, highest value was recorded by the treatment T4 (EVC – NC two per cent + full NPK), for P, highest value was recorded by T6 (EVC – BM two per cent + full NPK) and for K, highest value was recorded by the treatment T8 (EVC – NC 1 per cent + BM 1 per cent + full NPK). For plant uptake highest values were registered by the treatments T4, T6 and T8 for N, P and K respectively. With respect to quality characters, treatments with organic sources of plant nutrients viz., T8 [EVC- NC 1 per cent + BM 1 per cent + full NPK) recorded highest value for -carotene content in all the three cuttings, for moisture content T3 (VC+1/2NPK) recorded the highest value in all cuttings, for protein T4 (EVC – NC two per cent + full NPK) recorded the highest value in all cuttings. For fibre content treatment T1(Full NPK as mineral fertilizer) recorded the highest value and T2 (VC + full NPK) recorded the lowest value. Oxalate content is also influenced by different treatments. Vermicompost enriched with bone meal and treatment received NPK alone recorded highest oxalate content. Post harvest analysis of the soil indicated that organic carbon, available phosphorus, pH, EC and microbial count were increased by applying enriched vermicompost. But available nitrogen and available potassium were slightly decreased. Bulk density was found to be influenced favourably. From the investigation it was proved that enriched vermicompost established its superiority over other organic sources and POP recommendation with respect to soil health and quality of amaranthus. Study also revealed the feasibility of substituting FYM and inorganic fertilizer with enriched vermicompost.ThesisItem Open Access Organic nutrition for soil health and productivity of chilli (Capsicum annuum L.)(Department of Soil Science and Agricultural Chemistry,College of Agriculture,Vellayani, 2011) Lekshmi, V; Ushakumari, KAn investigation was carried out at the Instructional farm, attached to the College of Agriculture, Vellayani to evaluate the effect of two enriched composts viz. BM compost and EM compost at different rates alone as well as in combination with two growth promoters viz, Panchagavya and vermiwash on physico-chemical and biological properties of soil and also their impact on crop performance using chilli variety Vellayani Athulya as test crop. The results from the field experiment revealed that the plant growth characters viz. height of the plant at 30, 60 and 90 DAT and primary branches per plant at 90 DAT showed significant variation due to the application of 75% N as BM compost along with Panchagavya. The treatments did not significantly affect the biometric observation, ‘days to 50% flowering’. Significant differences were observed among yield attributing characters viz. number of fruits per plant, fruit length (cm), fruit girth (cm), fruit weight (g), green fruit yield per (g plant-1), total fruit yield (t ha-1) and total dry matter yield (t ha-1). The treatment T8 (75% N as BM compost + Panchagavya) recorded the highest values for all these characters but it was found to be on par with T7 (75% N as EM compost + Panchagavya). This shows that BM compost can be substituted with EM compost when used along with Panchagavya. With respect to quality characters, the treatment T8 (75% N as BM compost + Panchagavya) registered the highest values for capsaicin, ascorbic acid and shelf life of fruits. However ‘oleoresin’ was not influenced by different treatments. Disease incidence percentage (Colletotrichum fruit rot) was found to be reduced by the treatments with organic sources. The treatment T8 (75% N as BM compost + Panchagavya) reduced the incidence of pests and diseases to a considerable extent. Highest BC ratio also was recorded by the same treatment T8 (75% N as BM compost + Panchagavya). Post harvest analysis of the soil indicated that organic carbon, available macro and micro nutrients pH, EC and microbial load and dehydrogenase activity were increased by the combined application of enriched manures viz. 75% N as BM compost and Panchagavya or 75% N as EM compost and Panchagavya. Bulk density was found to be reduced favourably. From the results it was clearly indicated that 75% N as BM compost and Panchagavya or 75% N as EM compost and Panchagavya was superior to all other organic sources in promoting soil health and yield and quality of chilli.ThesisItem Open Access Soil test crop response studies on ginger in laterite soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Horticulture,Vellanikkara, 2001) Jayalakshmi, M; KAU; Hassan M ATo establish soil test based balanced fertilizer prescription for ginger variety Maran in laterite soils of Kerala, an investigation was undertaken at the College of Horticulture, Vellanikkara. The field study consisted of fertility gradient experiment and STCR experiment. The fertility gradient experiment was conducted during March-April 2000 in the farm attached ,to the College. The desired gradient in soil fertility was created in "<; - .t one and the same field by applying graded doses of N, P and K fertilizers and raising fodder maize var. Co. I. The STCR experiment was conducted in the same field during May-Nov 2000 using the test crop, ginger variety Maran. The treatments consisted of fractional factorial combinations of four levels of N (0, 50, 100 and 200 kg ha-I), three levels of P (0,37.5, 75kg P205 ha-I) and five levels of K (0, 37.5, 75, 150 and 300kg K20 ha-I) along with three levels of farmyard manure (0, 15 and 30 t / ha) fitted in a response surface desi~n. Using multiple regression model, the fertilizer adjustment equation for N at varying soil test values for available N for maximum rhizome yield (t ha-I) of ginger in laterite soil was derived as FN = 153 - O.28SN where FN is fertilizer N (kg hal) and SN is soil available N (kg ha-l ). At varying soil test values for organic carbon % (OC) and Phosphorous kg / ha the above equations become FN = 312.94 - 518.4 OC and FP = 79.8 - O.94SP for maximum rhizome yield. The behaviour of fertilizer K was found to produce responses other than 'normal' and hence optimization could not be done for fertilizer K for maximum rhizome tuber yield at varying soil test values. The nutrient requirements of ginger variety Maran were estimated to be 2.1, 0.3, S.6kg N, P20S and K20 respectively to produce one kg of rhizome. In the laterite soil, the efficiencies of contribution of nutrients from the soil for ginger were calculated as 10.1,6.9 and 44% N, P20S and K20 respectively. The fertilizer efficiencies were worked out as 27.3, 10.9 and S3.2% N, P20S and K20 respectively. The efficiencies of contribution of nutrients from farmyard manure were calculated as 30, 7 and 60% N, P20S and K20 respectively. From the above basic data, fertilizer prescription equations for specific yield targets of ginger var. Maran in the laterite soil were derived as given below. Without FYM FN =7.8T - 0.37 SN FP =2 .. 8T - 0.64 SP FK = 10.6T - 0.833 K With FYM FN = 7.8T - 0.37SN - 1.11 ON FP = 2.8T - 0.64 SP - 0.7 OP FK = 10.6T - 0.835 SK - 1.13 OK. Where, FN, FP, FK - Fertilizer N, P20S, and K20 respectively in Kglha. T - Target of fresh rhizome yield in t/ha. SN, SP, SK - Soil available N, P and K in kg/ha respectively. ON,OPOK - quantities of N, P and K supplied through organic manure in kg/ha. Based on the fertilizer prescription equations ready reckoners were developed for different yield targets. The study has revealed the superiority of fertilizer application over the semi quantitative approach followed in the soil testing laboratories and the generalized package of practices recommendation followed in the state for the crop. The fertilizer dose can be adjusted based or. the specific objective and available resources of the farmer. To know the influence of native elements on yield soil and plant samples were analyzed for micronutrient contents. In soil Ca, Mg and Mn showed positive correlations and Zn, Fe showed negative correlations with yield. In plant leaf magnesium and rhizome manganese showed positive correlation and rhizome iron showed negative correlation. Further path analysis was carried out to know the nutrient interactions.ThesisItem Open Access Dynamics and interaction of zinc and boron with phosphorus in ultisol(Department of soil science and Agricultural chemistry, College of Horticulture,Vellanikkara, 2015) Semsheer, M; KAU; Sureshkumar, PThe recent soil fertility assessment of the entire state has revealed that more than 60% of the soils in the state are having high P status due to continuous application of P fertilizers like factomphos and bone meal. It was also established that 15% of the soils are deficient in zinc and about 60% of soils are deficient in boron. Antagonistic interaction of P with zinc has already been well established. However studies on interaction of P with boron are limited. Thepresent study was undertaken in the above background in the Dept. of Soil Science and Agricultural Chemistry during the period from 2013-2015 to understand the chemistry, dynamics and bioavailability of zinc and boron with respect to the P status of the soil, which in turn will help in modifying the fertilizer prescription in terms of quantity and method of application of these nutrients. In order to achieve the objective of elucidating the dynamics of Zn and B as influenced by P status in lateritic soils and to optimize the level of P for balanced nutrition of cowpea with respect to Zn and B, 18 lateritic soil samples (Ultisol), six each coming under low, medium and high P status were identified from an initial 100 soil samples and characterized. A potculture experiment with cowpea as a test crop was conducted in three soils, one each with low, medium and high average P status. Soil and plant samples were collected at flowering and at harvesting stages and analyzedfor nutrient content. The distribution of fractions of inorganic P in the three soils showed that Fe bound P was the dominant fraction contributing to more than 50% of the total inorganic P. The soluble P fraction was about 6% in all the three soils. Fe and Al-P were the main fractions contributing to the available pool initially.Among the fractionsof boron, readily soluble boron recorded the lowest, where as the contribution of residual boron was the highest. Available P status in soils with low and medium P increased due to the application of P while it decreased in soil with high P. The soil with high P soil showed that the application of phosphorus lead to the fixation of phosphorus in to insoluble forms whereas, if P was not applied there was solubilisation of Fe-P and Al- P resulting in increased its availability. Plant adsorbed P from soluble P led to its depletion at the end of vegetative phase. Applied P got transformed into Fe-P and Al- P initially, which along with native occluded P got transformed to calcium bound P which is contributing to the available pool at later stages. Application of Zn was found to reduce Al-P and Fe-P due to the formation of insoluble zinc phosphate. Application of Zn and B reduced the Ca-P, probably due to the formation of zinc phosphate and Calcium borate. In case of zinc fractions, water soluble + exchangeable fraction and organic matter occluded zinc was directly contributing to the available pool. The other Zn fractions except amorphous iron oxide occluded zinc were contributing to the available pool indirectly through water soluble + exchangeable fraction. Application of P reduced the water soluble + exchangeable zinc fraction where as the application of boron enhanced the transformation of zinc into this fraction especially when boron was applied without P. Application of P resulted in adsorption of zinc into specifically adsorbed zinc. With respect to boron fractions, readily soluble boron and oxide bound boron were directly contributing to the available pool where as binding of boron with organic matter as well as its transformation to residual boron reduced boron availability. All the fractions of boron were contributing to available pool indirectly through readily soluble fraction of boron. Application of phosphorus was found to reduce the readily soluble boron due to anion competition. The applied boron either remained in the soluble form or getting transformed to specifically adsorbed, oxide bound, organic matter bund boron. Boron application along with P reduced the readily soluble boron. Application of Zn increased the Zn content in plant. However, the application of P with and without B reduced the Zn content in plants. Application of P and Zn reduced the boron content in plants and application of boron with and without phosphorus recorded the highest boron content. The highest grain yield was recorded in soil with medium P, while the high P status in soil either due to native P or due to applied P reduced the yield resulting from induced lower uptake of zinc and boron. Thus, at high levels of P, enough quantities of soluble zinc should be assured, over and above the quantities of this element precipitated as zinc phosphate, both by optimizing the pH and applying enough quantities of Zn. Similarly H3BO3 and H2BO3 - ions should be enough to overcome competition from H2PO4 - ion at root surface.ThesisItem Open Access Characterisation of soil and water of Palakkad eastern plains in relation to growth and nitrogenase content of Azolla spp.(Department of soil science and agricultural chemistry, College of horticulture,Vellanikara, 2015) Bhavyasree, K T; KAU; Jayasree Sankar, SA study intended for “Characterization of soil and water of Palakkad eastern plains in relation to growth and nitrogenase content of Azolla spp.” was undertaken in the Department of Soil Science &Agricultural Chemistry, College of Horticulture, KAU, Vellanikkara during 2013-2015. The objectives of the study were to conduct a survey of Azolla spp. in the rice growing tracts of Palakkad eastern plains and to identify soil and water quality parameters congenial for the growth and nitrogenase content of Azolla spp. The preliminary survey conducted in the four block panchayaths of Palakkad eastern plains to identify the prevalence of Azolla revealed two blocks viz. Chittoor and Kollengode to be positive with respect to Azolla and hence, further study was restricted to the grama panchayaths of these blocks. Characterization of soil and water was done in both Azolla growing and non-growing regions. Composition of Azolla collected from different locations was also determined. In order to ascertain the nitrogenase enzyme activity, samples of Azolla collected from five different locations were subjected to Acetylene Reduction Assay (ARA). Among the soil parameters, significant difference was noticed between Azolla growing and non-growing locations with respect to pH , EC, organic carbon, available N, P , total Fe, Mn and Zn in contrast to potassium and copper which did not show any pronounced variation. Soil pH, EC, available P, total Fe, Mn and Zn were comparatively lower in Azolla growing regions. However, available nitrogen in soil was more in Azolla growing locations. Heavy metals like Cd, Cr, Ni and Pb were below the detectable limits in soil. Analysis on flood water quality showed significant effect in the Azolla growing regions on parameters like pH, temperature and dissolved oxygen, Fe, Mn, Zn and Cu. Soil analysis data revealed the pH, EC, soluble Fe, Mn, Zn and Cu to be lower under Azolla growing conditions. Heavy metals like Cd, Cr, Ni and Pb were below the detectable limits. Presence of Azolla decreased the flood water temperature but increased the dissolved oxygen content. On comparison, the composition of Azolla revealed a prominent and significant correlation with location on its content of carbon, nitrogen, phosphorus, potassium and also the C/N ratio. Moisture content varied from 94 to 95 per cent, variation in carbon and nitrogen content was from 22.9 to 39.5 per cent and 2 to 4 per cent respectively among the locations studied. The C/N ratio ranged from 9 to 14. Crude protein content of Azolla registered values between 16 and 22 per cent. The content of phosphorus ranged between 0.20 and 0.23 per cent whereas that of potassium was in the range of 1.2 to 1.5 per cent. Correlation worked out between soil parameters and composition of Azolla disclosed a significant positive effect of soil P on the nitrogen, crude protein and phosphorus content of Azolla. However, soil P was negatively correlated with the C/N ratio of Azolla. Nitrogenase enzyme activity quantified was profoundly affected by the locations. The amount of ethylene produced extended from 192 to 236 nmole ethylene g-1 h-1. It showed a significant negative correlation with soil pH and EC. The study has given valuable information on the influence of soil and flood water quality parameters and locations on Azolla which could be used for further investigations on its nutrient dynamics.
