Phosphorus Adsorption and Desorption Characteristics in Acid Soil under Intensive Cropping Systems

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dc.contributor.advisorDas, Kulendra Nath
dc.contributor.authorDutta, Boishali
dc.date.accessioned2024-09-23T08:15:18Z
dc.date.available2024-09-23T08:15:18Z
dc.date.issued2023
dc.description.abstractThe present study was carried out during 2022-2023 to investigate phosphorus adsorption and desorption characteristics in acid soil under intensive cropping systems in the on-going experimental trial on “Identification of cropping systems module for different farming systems” since 2018-2019 under All India Coordinated Research Project on Integrated Farming Systems at Instructional-cum-Research farm AAU, Jorhat. The experiment was laid out in randomized block design consisting of three replications of ten different treatments viz., T1: Winter Rice- Autumn Rice, T2: Winter rice-Toria, T3: Winter rice-Pea-Cowpea, T4: Green manure-Toria-Black gram, T5: Winter rice-Rajmah-Cowpea, T6: Winter rice-Toria-Black gram, T7: Teosinte-Oat-Cowpea, T8: Maize-Oat-Rice bean, T9: Ridge gourd-Broccoli-Lady’s finger, T10: Bitter gourd-Tomato-French bean. Phosphate adsorption and desorption studies were conducted on surface soil samples (0-15 cm) and the adsorption data were fitted into Langmuir and Freundlich equations. The soils were acidic in reaction (pH 5.15 -5.37) with significant variations in soil organic carbon, available NPK, free Fe and Al oxides, CEC and exchangeable Ca2+ and Mg2+. The inorganic P fractions of soils under cropping systems followed the trend of Fe-P>Al-P>Ca-P>Sa-P. All these fractions were positively correlated with total-P (624.43-766.23 mg kg-1) indicating dynamic equilibrium amongst them. The organic P ranged from 94.92-135.92 mg kg-1 and was positively correlated with soil organic carbon. Phosphorus adsorption study revealed an increase in the absolute amount of adsorbed P (x/m) and decrease in per cent of added P adsorbed (Xad) and distribution coefficient (Kd) with increasing P levels (Co) in all the studied soils. Phosphorus adsorption was highest in T2 consisting of winter rice-toria cropping system (18.0-1240.5 μg P ml-1) and was lowest in T4 containing green manure-toria-black gram (16.7- 609.8 μg P ml-1). Freundlich adsorption isotherm showed a better fit of adsorption data with higher levels of significance (R2≥ 0.98) than Langmuir adsorption isotherms. The Langmuir adsorption maxima (b) and Freundlich K showed highest values in treatment T2 and the lowest values in treatment T4. Similar but reverse trend was observed in desorption study in the above treatments with special reference to treatment T4 where P desorption was highest. The desorption data were well fitted to Freundlich equation (R2=0.99). It was observed that, only small portion of adsorbed P was desorbed suggesting partial reversibly in P adsorption. The respective values of phosphate adsorption and desorption were highest and lowest in nearby virgin soil than all the cropping systems. Changes in soil properties under the influence of different management aspects in cropping sequences were responsible for such observations. The Phosphorus Supply Parameter (SP) at various initial concentrations gradually increased with increasing exogenous P. Strong positive and negative correlation of SP at a given level of added P with soil pH and free iron and aluminium oxides, respectively, implied their influences on P availability. Thus, the present study revealed that, inclusion of green manure and legume crops in the cropping sequence lowered P adsorption and increased P desorption resulting in higher P supply to crops and hence intensive (triple) cropping tended to eliminate negative impacts on P adsorption in soil systems under long term cultivation.
dc.identifier.urihttps://krishikosh.egranth.ac.in/handle/1/5810214805
dc.language.isoEnglish
dc.subSoil Sciences
dc.themePhosphorus Adsorption and Desorption Characteristics in Acid Soil under Intensive Cropping Systems
dc.these.typeM.Sc
dc.titlePhosphorus Adsorption and Desorption Characteristics in Acid Soil under Intensive Cropping Systems
dc.typeThesis
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