From long term experiments of 5 to 10 years, important cost effective technologies were developed such as organic farming through waste recycling as vermicompost, arecanut + livestock mixed farming models for different holdings, nutrient recommendations for HYV's and cropping system models, water harvesting structures, drip irrigation and fertigation and sustainable cropping system models involving arecanut and valued added intercrops like pepper, banana, cocoa, coffee, medicinal and aromatic crops, and vanilla. The irrigation and nutrition schedule of mango+groundnut agri-horti system was worked out for dryland Alfisols. Optimum nutrient limits for arecanut and laterite soils were established to address existing and emerging problems like excess soil fertility, nutritional disorders and yellow leaf disease in arecanut through on-station and on farm experiments at Sampaje, Sringeri and Shimoga areas in Karnataka. The deficiency of Zinc is identified as major reason for nutrient disorders in arecanut in different soil types due to anatgonistic nutrient interactions under excess soil fertility conditions. Soil fertility status in clay and laterite soil belt of arecanut growing regions was assessed. Nutreint uptake pattern in arecanut and cocoa was quantified based on biomass partitioning and yield. The 4-yr onfarm study on Yellow Leaf Disease in arecanut suggested that the predisposing factors for YLD might be nutrient imbalance in the soil leading to deficit of major nutrients in plant due to poor root growth, excess soil fertility and zero tillage. Precision application of NPK in frequent splits is important in YLD belt. Drip fertigation schedule for arecanut+cocoa system was standardised. Water and organic nutrition package was standardized for vanilla intercropped in arecanut. Nutrient removal for rose (cut and loose) and gerbera genotypes was quantified based on biomass partition, nutrient accumulation and yield level to optimise input use. The 8-yr study revealed that arecanut based mixed farming system is profitable and the contribution of livestock to total outflows was high (82 to 87%) except in establishment year of dairy unit (54%).The farm gate nutrient surplus was 5 times higher than utilization in mixed farming that enables farmers to earn higher profits. Extension activities like farmers meetings, agri-clinic services, kisan melas and trainings to farmers and officials, and field demonstrations on cocoa in Andhra Pradesh were undertaken.Several technicalbulletins/popular articles were published in English, Telugu and Kannada.
- Bhat Ravi, Sujatha, S. and Balasimha D. 2007. Impact of drip fertigation on productivity of arecanut (Areca catechu L.). Agricultural Water Management 90(1-2): 101-111.
- Bhat Ravi and Sujatha, S. 2009. Soil fertility and nutrient uptake by arecanut (Areca catechu L.) as affected by level and frequency of fertigation in a laterite soil. Agricultural Water Management 96(3):445-456.
- Sujatha, S. and Bhat Ravi. 2010. Response of vanilla (Vanilla planifolia A.) intercropped in arecanut to irrigation and nutrition in humid tropics of India. Agricultural Water Management. 97 (7): 988-994.
- Sujatha, S., Bhat Ravi, Kannan, C. and Balasimha, D. 2011. Impact of intercropping of medicinal and aromatic plants with organic farming approach on resource use efficiency in arecanut (Areca catechu L.) plantation in India. Industrial Crops and Products. 33(1):78-83.
- Bhat Ravi and Sujatha, S. 2012. Influence of biomass partitioning and nutrient uptake on yield of arecanut (Areca catechu L.) grown on a laterite soil. Commun. Soil Sci. Plant Anal. 43(13), 1757-1767.
- Sujatha, S. and Bhat Ravi. 2012. Impacts of vermicompost and nitrogen, phosphorus, and potassium application on soil fertility status in arecanut grown on a laterite Soil. Communications in Soil Science and Plant Analysis. 43 (18), 2400-2012.
- Bhat Ravi, Sujatha, S. and Jose, C. T. 2012. Assessing soil fertility of a laterite soil in relation to yield of arecanut (Areca catechu L.) in humid tropics of India. Geoderma189-190:91-97.
- Bhat Ravi and Sujatha, S. 2013. Establishing leaf nutrient norms for arecanut by boundary line approach. J Plant Nutrition 36 (6), 849-862 DOI: 10.1080/01904167.2013.770524
- Sujatha, S. and Bhat Ravi, 2013. Impact of vermicompost and Nitrogen-Phosphorus-Potassium application on biomass partitioning, nutrient uptake and productivity of arecanut (Areca catechu L.). J Plant Nutrition 36 (6): 975-988 DOI: 10.1080/01904167.2013.766206
- Sujatha, S. and Bhat Ravi. 2013. Impact of drip fertigation on arecanut-cocoa system in humid tropics of India. Agroforestry Systems. 87 (3): 643-656
- Bhat Ravi, and Sujatha, S. 2014. Soil Fertility Status and Disorders in Arecanut (Areca Catechu L.) Grown on Clay and Laterite Soils of India, Communications in Soil Science and Plant Analysis, 45:12, 1622-1635, DOI: 10.1080/00103624.2014.907910
- Sujatha, S. and Bhat Ravi. 2015. Soil fertility changes due to drip fertigation in arecanut-cocoa system. Communications in Soil Science and Plant Analysis. 46 (16):1981-1997 DOI: 10.1080/00103624.2015.104411110
- Sujatha S., Ravi Bhat and P Chowdappa. 2015. Recycling potential of organic wastes of arecanut and cocoa in India: A short review. Environmental Technology Reviews. 4(1):97-102. DOI: 10.1080/09593330.2015.1077897
- Sujatha S. and Ravi Bhat. 2015. Resource use and benefits of mixed farming approach in arecanut ecosystem in India. Agricultural Systems 141: 126-137 DOI: 10.1016/j.agsy.2015.10.005 8.91 8.45
- Sujatha, S. and Ravi Bhat. 2016. Impact of organic and inorganic nutrition on soil-plant nutrient balance in arecanut (Areca catechu L.) on a laterite soil. Journal of Plant Nutrition 39(5):714-726. DOI:1080/01904167.2015.1087561
- Bhat Ravi, S. Sujatha and C. T. Jose. 2016. Role of nutrient imbalance on yellow leaf disease in smallholder arecanut systems on a laterite soil in India. Communications in Soil Science and Plant Analysis 47 (15): 1738-1750. DOI: 10.1080/00103624.2016.1206915
- Chowdappa, P., Biddappa, C. C. and Sujatha, S. 1999. Efficient recycling of organic wastes in arecanut and cocoa plantations through vermicomposting. Indian Journal of Agricultural Sciences 69(8): 563-566.
- Sujatha, S., Rao, J.V. and Reddy, N.N. 2006 Economic feasibility of drip irrigation and nutrient management in mango (Mangifera indica). Indian J. of Agric. Sci. 76(5): 312-314.
- Sujatha, S., Rao, J.V. and Reddy, N.N. 2006. Effect of drip irrigation and nutrient management on mango (Mangifera indica L.) in Alfisols of Semi-arid tropics. Indian J. of Agric. Sci. 76(10): 618-622.
- Bhat Ravi and Sujatha, S. 2008. Root distribution of arecanut (Areca catechu L.) as influenced by drip fertigation in a laterite soil. Indian J. of Agric. Sciences. 78(9): 804-807.
- Sujatha S., Ravi Bhat and P. Chowdappa. 2016. Cropping systems approach for improving resource use in arecanut plantation - A review. Indian Journal of Agricultural Sciences 86 (9): 1113-112
- Abdul Haris, A., Balasimha, D, Sujatha, S., Bhat Ravi and Khader, K. B. A. 1999. The influence of drip irrigation and fertilizer on yield and photosynthetic characteristics of cocoa in mixed cropping system with arecanut. Journal of Plantation Crops. 27(2):131-135.
- Sujatha, S., Bhat Ravi, Reddy, V. M. and Abdul Haris, A. 1999. Response of high yielding varieties of arecanut to fertilizer levels in coastal Karnataka. Journal of Plantation Crops. 27(3):187-192.
- Sujatha S and Abdul Haris, A. 2000. Root distribution pattern as influenced by different irrigation methods in young arecanut (Areca catechu L.) palms. Journal of Plantation Crops. 28(2): 117-122.
- Mathew A C., Shajatnan K. H. and Sujatha, S. 2004. Water movement in the active root zone of arecanut under drip irrigation. J. Plantation Crops. 32(Supplement): 248-252.
- Sujatha, S., Bhat Ravi, Balasimha, D. and Kannan, C. 2006. Crop diversification in arecanut plantation through intercropping of medicinal and aromatic plants. J. Plant. Crops. 34(3): 318-322.
- Bhat Ravi and Sujatha S. 2006. Cost-Benefit analysis of ferti-drip irrigation in arecanut (Areca catechu L.). J. Plant. Crops. 34(3): 263-267.
- Bhat Ravi, Sujatha, S., Upadhyay, A. K. and Ashalatha, B. V. 2007. Effect of ferti-drip irrigation on nutrient mobility in a laterite soil in arecanut basin. J. Plantation Crops 35(2): 68-72.
- Bhat Ravi and Sujatha, S. 2007. Soil fertility status as influenced by arecanut based cropping system and nutrient management. J. Plantation Crops 35(3): 158-165.
- Bhat Ravi and Sujatha, S. 2008. Rainfall interception in arecanut based cropping system. J. Plantation Crops. 36(1): 58-60.
- Bhat Ravi, Sujatha, S. and George V. Thomas. 2008. Soil microbiological and enzymological response to organic matter recycling and chemical fertilization in arecanut based cropping system. J. Plantation Crops. 36(3): 281-289
- Mathew A C., Shajatnan K. H. and Sujatha, S. 2008. Development and Management of water harvesting structure in laterite soils for irrigating arecanut through conjunctive use of harvested and surface water. J. Plantation Crops. 36(3): 304-309.
- Reddy N N, Rao V S, Rao J V, Lakshmi N Jyothi, Sankar GR Maruthi, Sujatha S. 2009. Effect of irrigation and nutrition on growth, fruit yield and quality parameters in mango (Mangifera indica) under semi-arid alfisols. Indian Journal of Dryland Agricultural Research and Development 24(2): 32-38
- Sujatha S., Ravi Bhat and P. Chowdappa. 2017. Status of arecanut production systems in India - A review. International Journal of Innovative Horticulture 6 (1): 7-24
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