Effect of Organic Farming on Soil Quality, Nutrient Uptake, Yield and Quality of Indian Spice.
Sadanandan A.K Dr and S. Hamza. Indian Institute of Spices Reseach, Calicut- 673 012, Kerala, India, Calicut- 673 012, India
Organic Farming (OF) is expanding globally due to increased consumer interest, environmental protection and EU polices. Global trade in organically produced products in 2003 is estimated at US $26 billion and is projected to increase $102 billion by 2020, due to increasing demand in Europe, USA, Japan and Australia. In India attention is being received in Organic agriculture particularly in spices. The project organic farming in spices was conceptualized in 1992 and implemented at IISR and tested in the farmer's fields over a decade. The objectives were to study the best organic fertilizers (plant residues-compost/vermicompost, animal manures/de-oiled cakes that contains nutrients in complex organic forms, bio-fertilizers), its impact on soil quality, quality of major tropical spices and its economics in important spice crops under humid tropical conditions of South India. Soil characteristic, plant analysis, and quality were determined by following standard procedures. The results of the green house and field experiments conducted are discussed. In black pepper the effect of commercial organic manures was evaluated (based on their nutrient equivalents) and compared with NPK chemical fertilizers and farmers practice. The study was taken under green house condition (1993-'96) in CBD design. Investigations revealed that irrespective of the sources, application of organics increased the soil pH, nutrient availability in the soil and crop uptake. Poultry manure followed by goat manure was significantly superior with regard to yield, nutrient uptake, and enhanced piperine and oleoresin content of black pepper. On farm trails conducted in the 51 farmer's holdings in 30,000 vines for five years corroborated the findings. The OF technology was further extended in farmer's fields in three important black pepper growing States of South India viz., Kerala, Karnataka and Tamil Nadu during 2000- '03. Liming acid soils @ half the lime requirement of the soil enhanced the microbial population, nutrient availability, and dehydrogenase enzyme activity. Application of the recommended dose of N as organic (FYM + de-oiled cakes-neem (Azadirachta / pea-nut, P as phosphate rock + bone meal and K as wood ash, in conjunction with bio-fertilizers (Azospirillum and Phosphobacteria each applied @ 40kg per ha per year enhanced the spiking intensity of the vine, yield and nutrient uptake. The FYM application significantly decreased the bulk density irrespective of the soils. Soil quality indicators tested were positively correlated (p<0.005) with yield. Among the soil quality attributes, organic carbon and CEC are most discriminating attributes in all the three locations. The soil organic matter and CEC contributed substantially to the ability of the soil to accept, hold, and release nutrients to pepper vines. Adoption of OF was effective in the bio-management of the Phytophthora disease incidence to around two per cent over the years against 10 percent in the control. Black pepper quality- volatile oil, oleoresins, boldness of pepper corn (>4 mm diameter) were increased due to OF. Field studies in Cardamom has shown that application of recommended NPK nutrients as organic fertilizers (50 per cent N each as FYM and neem cake + 50 per cent P each as bone meal and phosphate rock + 50 per cent K as wood ash) were effective in increasing the yield and quality of cardamom. Field experiments (1992-95) conducted in ginger and turmeric, using six de-oiled organic cakes in comparison with the recommended FYM and NPK fertilizers showed that in general application of cakes increased not only soil nutrient availability, but also nutrient uptake. Organic cakes enhanced the water holding capacity and reduced soil bulk density. In ginger, among the cakes, pea-nut registered maximum organic C, Bray-P and exchangeable K in the soil and registered maximum dry recovery (4077 kg ha-1). This was followed by neem, cotton, NPK fertilizer. Neem cake registered highest oleoresin production (320 kg ha-1) of ginger. Neem cake was effective in the bio-management of rhizome rot disease incidence in ginger to 5%. In turmeric increased yield and curcumin recovery were observed due to organic OF. Residual effect of organic fertilizers was conspicuous in the successive second crop of turmeric. In Vanilla soil application of organic fertilizers (50 per cent N as FYM/vermicompost + 50 per cent N as de-oiled cakes+ 50 per P as bone meal + 50 per cent K as wood ash+ bio-fertilizers) were effective compared to recommended inorganic NPK fertilizers in increasing the yield and quality of the beans. Pilot study conducted (2001-04) in the high ranges of Western Ghat in the growing of Garcinia indica in Wayanad district (Kerala) and clove and nutmeg in Maramalai/ Mahandragiri hill areas in kanyakumari district (Tamil Nadu) revealed that Garcinia is grown as a self sown crop in traditional farming and can be claimed as default organic. Similarly nutmeg and clove grown in the region by following traditional/indigenous agriculture by applying FYM and without any synthetic chemical fertilizers and/or pesticides calls for characterizing the cultivation practices on the lines of national standards for organic production. It can be concluded that organic fertilizers play a significant role in improving soil and crop quality and sustainability. There is, however 10-20 per cent reduction in crop yield that should be compensated by premium pricing of organic produce. Keywords: organic fertilizers, tropical spices, soil quality, spice oil, oleoresin.