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Title: Perspectives of using acidulated cow dung slurry/extract to enhance availability of indigenous and added micronutrients in calcareous soils
Authors: Annum Sattar
Keywords: Applied Sciences
Agriculture & related technologies
Issue Date: 2017
Abstract: Micronutrient are required for the proper growth and development of plants, animals and human beings. Their role is not ignorable in plants, as they play a vital role in many cellular and physiological processes as well as have a key role in important processes in human. Unfortunately, owed to climatic conditions and calcareous nature (>7.5) of Pakistani soils, plants are suffering from micronutrients deficiency. Nutrients deficient crops are becoming source of various major diseases of humans and animals as well as cause severe yield reduction in plants. Various strategies have been adopted to fortify plants/grains with nutrients. Elemental sulfur is commonly practiced for calcareous soils to solubilize the locked nutrients in soil through biological oxidation. This strategy is still accompanied by economic constraints because huge amount of Sº could not be paid by farmers. The present study was planned to prepare an acidulated organic amendment through bio-augmentation of S° added cow dung with sulfur oxidizing bacteria (SOB) to determine its effect on micronutrient bio-availability in calcareous soils. This research included a series of incubation, lab, green house and field studies. Sulfur oxidizing bacteria were screened based on pH reduction, SO4 -2 production, micronutrient (Zn, Fe, Mn) solubilizing abilities. Next step was preparation of acidified amendment through bio-augmentation of S° added cow manure with SOB. Product preparation was optimized at different conditions and minimum pH 2.2 at 15th day was attained at 55-60% moisture, 0.5% rate of molasses, in presence of strain AR-13 at 35ºC temperature. Rate optimization of amendment was conducted via incubation studies in lab through release of micronutrients from soil. Three different rates (5, 10 and 15% dilutions) of acidified extract at the rate of 100 liter/acre were applied at four different time points. Application of product decreased the soil pH from 7.98 to 7.32 and enhanced the micronutrient mobilization and microbial count, but, very next day, nutrients availability was again decreased and same trend was observed after each application. Both 10% and 15% rates of dilution showed same trend in term of pH lowering, nutrient release and microbial population, so, 10% rate was selected for proceeding studies. Then, 10% extract was applied in pot trial on maize @ 100 liter/acre at four different stages; trial consisted of 7 treatments with different rates of micronutrients (25, 50, 75 and 100% of the recommended micronutrients) + acidified extract, alone micronutrients, alone extract and a control. Treatments 100, 75 and 50% of recommended micronutrients + acidified extract showed non-significant results within and significant results over all other treatments in all growth and yield parameters. However, on the basis of economics 50% of the recommended micronutrient + extract found more beneficial and improved yield by 46.27% and grain Zn, Fe and Mn concentration by 42.95, 117.38 and 128.55% over control, respectively. Field trial on maize was also conducted with same treatments to determine the efficacy of extract in field. All growth, physiological, quality, nutrients uptake, yield parameters and nutrients mobilization in soil were determined and maximum results were found where micronutrients were applied with acidified extract. Like pot trial treatment with 100, 75, and 50% of recommended micronutrients + acidified extract showed maximum results and 50% rate was found more beneficial. Grain yield and grain Zn, Fe and Mn concentration for 50% of recommended micronutrients + acidified extract was 13967 kg/ha, 56 mg/kg, 81.50 20 20 mg/kg and 66.67 mg/kg, respectively. Hence, by application of 50% of the recommended micronutrients + acidified extract at four different peak required stages, maximum benefit can be attained and additional 50% fertilizer can be saved. Concluding, this product can improve the grain micronutrient contents and resultantly, humans micronutrient deficiency would be uplifted, proving it to be a novel strategy to improve growth, yield, grains micronutrients concentration and quality of maize. Furthermore, this product is less costly, easily prepared and eco-friendly for farmers as compared to other approaches.
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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