Prabhat Pramanik

Humic substrates application in diluted form enhanced availability of phosphorus (P) and its uptake by tea bushes in the tea-growing soil of Northeast India

ABSTRACT Tea (Camellia sinensis L.) is an evergreen perennial crop, which is cultivated for its shoots in acidic soil under sub-tropical humid climatic condition. The availability of phosphorus (P) to plants is naturally limited in acidic tea-growing soils. Humic substrates (HS) are often applied to enhance availability of nutrients, especially P in horticultural and vegetable crop fields. However, its effect on soil of a perennial crop like tea was not studied before. In this study, application of HS enhanced P availability mainly by facilitating growth of phosphate-solubilizing bacteria (PSB) and enhancing phosphatase activity in soil. Application of same amount of HS in diluted form was more effective to enhance PSB population and phosphatase activity, which in turn increased P availability in soil and P uptake by tea bushes. This experiment indicated that application of 1.5 kg HS ha−1 as 0.3% solution might be applied to enhance P availability to improve P availability and P uptake by plants in tea-growing soil.

Humic substrates facilitated nitrogen uptake in tea bushes by influencing biochemical and microbiological properties in soil of Northeast India

Abstract Several groups of microorganisms are involved in converting applied urea into plant-available nitrate nitrogen (N) in soil. The objective of this study was to evaluate efficacy of humic substrates (HS) for maximizing crop yield by enhancing N availability in soil. In this experiment, HS was applied in soil of tea garden in such a way that active substrate was applied at 0, 400, 800, 1,200, 1,600, and 2,000u2009g ha−1 in six treatments. Chemical fertilizers were applied in all the treatments (including control) following the recommended doses. This study indicated that applied HS enhanced tea shoot yield and N uptake by tea bushes. Improved biochemical and microbiological properties increased N availability in HS-treated soil and that in turn facilitated N uptake by tea bushes. It was determined that HS substrate application at 1.2u2009kg ha−1 could enhance the yield of tea shoots up to 18% higher than control treatment.

An indigenous strain of potassium-solubilizing bacteria Bacillus pseudomycoides enhanced potassium uptake in tea plants by increasing potassium availability in the mica waste treated soil of northeast India

Potassium (K) is one of the three major nutrients required of plant growth and muriate of potash (MoP) is the only recognized chemical fertilizer used in agriculture. In many countries, 100% of the applied MoP is imported costing huge revenue. Application of suitable potassium‐solubilizing bacteria (KSB) as biofertilizer could be an integral part of K management in arable soil. The object of this study was to evaluate K‐solubilizing ability of a ubiquitous micro‐organism as KSB to supplement K in soil.

Shredded Hard Stems of Pruning Litters Supported the Growth of Young Tea Plants by Supplementing Nitrogen in Soil: Evaluating Suitable Combination of Urea and Prunings

ABSTRACT Tea is an evergreen shrub, and tea bushes (plants) are periodically pruned at 3-year intervals. This practice generates tons of pruning litters (leaves and stems) in tea gardens. In spite of availability, the hard nature and slow decomposition rate limit the use of pruning litters as soil amendments. In this study, an attempt was made to cycle pruning litters in shredded form to evaluate their effect on young tea plants under greenhouse condition. It was observed that shredded prunings were decomposed in soil within study duration and enhanced nitrate-N content in the soil. The study revealed that different parameters like plant height, biomass weight, and N uptake were enhanced due to the application of suitable combinations of pruning litter and urea in the soil. Based on this study, it could be concluded that application of shredded prunings had potential to replace up to 15% of recommended urea during tea cultivation.

Pruned tea bushes secrete more root exudates to influence microbiological properties in soil

ABSTRACT Pruning is adopted at 3–4 years interval as an agronomic practice during tea cultivation. It was hypothesized that biomass loss during pruning will imply stress on tea bushes. The aim of this study was to quantify changes in different parameters (labile organic carbon fractions, phosphatase activity, microbial biomass and microbial respiration) in tea rhizosphere due to pruning by collecting soil samples from the rhizosphere of ten of each pruned and un-pruned tea bushes. Hot-water extractable and dissolved organic C contents in rhizosphere soil of pruned tea were significantly (P ≤ 0.05) higher than those in the soil of un-pruned tea bushes. Analysis of phospholipid fatty acids (PLFA) revealed that the rhizosphere of pruned tea plants had higher population of Gram (+) and Gram (-) bacteria, fungi, actinomycetes and lower denitrifying bacterial population as compared to un-pruned tea plants. Activity of acid phosphatase enzyme in soil was also increased due to pruning. A separate study revealed that de-centering may induce production of up to 50% more labile organic carbon compounds by young tea as compared to un-pruned plants. Therefore, it could be concluded that pruned tea bushes secrete more root exudates to influence microbiological and biochemical properties in rhizosphere.

Comparative effects of composting and vermicomposting on quality of organic amendments prepared from MSW and nitrogen rich Guatemala plant residues

High heavy metal contents and low nutrient status limit municipal solid waste (MSW) application in agricultural fields. In this study, high nitrogen (N) containing plant residues of Guatemala were mixed with MSW to evaluate its effect on quality of final composts and vermicomposts. Composting leads to 49.9-56.3% organic C loss from organic substrates; while 53.0-62.1% organic C was lost during vermicomposting of same treatments. In this study, total N content was increased up to 75.2-100.7% and 94.4-135.0% during composting and vermicomposting, respectively. Vermicomposts had lower heavy metal contents than composts. Mixing of Guatemala with MSW leads to the significantly higher total N content in the final product and reduced heavy metal contents only during vermicomposting. Therefore, 20% mixing (w/w basis) of N-rich plant residues with MSW may be effective to improve quality of organic amendments through vermicomposting.

Integration of geoinformatics and wireless sensors for smart agriculture in tea

To develop an efficient system for tea production management, the first and foremost requirement is quick availability of accurate data. Manual decision making takes unusually long time even with the most sophisticated analytical techniques. Moreover, as geographical spread of tea gardens are huge and sometimes exceeds few hundred hectares, getting information about the entire garden through conventional methods would be time consuming. Quick decision making based on quality data at section (a garden unit varying in area) level in a tea garden can enhance tea production. Geoinformatics and spatial analysis algorithms provide a great opportunity to gather information of unknown locations in a tea plantation based on some known locations. The present work demonstrates the application of an integrated Wireless Sensors Network (WSN) system associated with GPS and GIS to achieve the goal of Smart Agriculture. In this study a portable WSN system has been developed for instant data generation on soil physico-chemical properties and provide decision support for tea plantation management. Soil pH, soil moisture and soil temperature were collected in selected locations in a tea garden and plotted on digital garden maps based on their GPS locations. Suitable interpolation algorithms were applied on the collected soil data to generate information about the soil properties in entire plantation. An empirical equation is being developed for each soil parameter to compensate the errors in their predicted values based on values in the sample locations. The present system is an attempt towards achieving the goal of implementation of precision agriculture in tea plantation management.