A Study Of Organic Nitrogen Mineralisation In Soils Fertilised With Biochars On The Soil Properties And Yield Of Maize
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Date
2017
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Abstract
This study determined the carbon and nitrogen ratios of biochars from maize stover and African teak. It also assessed the soil properties, physiological performance and the yield of maize when these biochars were applied as soil amendments. This was with a view to providing information on the effects of biochar mineralization on maize production.
The field experiment was carried outat the Teaching and Research Farm, Obafemi Awolowo University (OAU), Ile-Ife. The viable seeds of maize variety, BR-9928-DMR-SR-Ywas obtained from the Institute of Agricultural Research and Training (IAR & T), Ibadan. Biochars produced from maize stover and African teak using a local charcoal-fired reactor were used. The chemical properties of the two biochars were determined using standard methods. The experimental plots were cleared once using a tractor. The experimental plot size of 11.0 m x 15.0 m was mapped out into block sizes,each plot measuring 2 m x 3 mwith an alley of 1.0 m between blocks and 1.0 m within blocks to give a total of 16 sub-plots, which arranged in Randomized Complete Block Design.The test crop was sown at three seeds per hole using 75cm×50cm planting distance. Two weeks after sowing, the treatments;100% maize stover (MAS), 100%African teak (AFT) and 50% MAS+ 50% AFT each at the rate of ten tonnes per hectare withzero biochar application as control were applied.The maize seedlings were later thinned to two stands at two weeks after sowing to give a total of 53,333 maize plants per hectare. Manual weeding was carried out at two, five and seven weeks after sowing. Data on growth parameters such as plant height, number of leaf, and stem girth were collected from two weeks after sowing and fortnightly till harvesting stage. Maize ears were harvested per treatment at maturity. Pre- and post-cropping soil analyses which included; soil pH, organic carbon, total nitrogen, cation exchangeable capacity, available phosphorus, soil particle size, Zn, Fe and Mn were done using standard methods. Data collected weresubjected to appropriate descriptive and inferential statistics.
The results showed that the pre-cropping soil pH 1:1 soil to water suspension was 6.12 while the soil texture was sandy loam. Plots with 50% MAS + 50% AFT had the highest maize mean plant height with 189.5 ± 2.0 cm. All the plots with biochar treatments (MAS, AFT and 50% MAS + 50% AFT) had similar and highest mean number of leaves (12 ± 1) while MAS plots had highest mean stem girth of 6.8 ± 0.3 cm. Plots with MAS had the highest mean grain yield of 8.57 ± 0.13 t ha-1 while the control had the lowest mean yield of 5.50 ± t ha-1 with no significant difference at p < 0.05 level of probability.Maize stover biochar had C∕N ratio of 12:1 as against 14:1 for African teak biochar. Soil properties such as pH, organic carbon, total nitrogen, available P, exchangeable bases, and micronutrients were significantly improvedby the addition of biochars.
The study concluded that biochar made from maize stover had fastest decomposition and nutrient release rates when compared with other treatments. Also the use of maize stover biochar had superior effect on the yield of maize.
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Keywords
maize, stover, biochars, carbon, nitrogen, Organic, Nitrogen