The acidulation effects of nitrogenous fertilizers on selected chemical and microbiological properties of soil

Abstract

The acidulation effects of the prolonged use of nitrogenous fertilizers on selected chemical and microbiological properties of a silt loam soil (Typic Ochraqualf) were assessed.Soil samples were collected from experimental plots initially established in 1971 that were annually treated with ten N fertilizer treatments and planted to corn. Residual soil acidity found to be associated with 9 annual applications of the N fertilizers was of the order: (NH 4 ) 2 SO 4 > NH 4 C1 > anhydrous NH 3 (at 300 kg N/ha) = NH 4 NO 3 > urea = ureaform = anhydrous NH 3 (at 150 kg N/ha) > Ca(NO 3 ) 2 NaNO 3 . Extractable P, Fe, Mn and Al followed a pattern of increasing availability with a decrease in soil pH. Exchangeable Ca and Mg levels were significantly higher in those treatments that did not show a significant decrease in soil pH over the 9-year duration.Significant differences by N treatment among selected microbial groups were also determined. The annual mean counts of soil 1377 1378 KHONJE, VARSA, AND KLUBEK fungi were significantly higher for the most and least acidifying treatments, namely ammonium sulfate and sodium nitrate.However, the mean counts of soil bacteria and actinomycetes were non-significant for any of the fertilizer treatments although the counts of both microbial groups declined with the addition of N.Significant differences in the mean counts of nitrifying and denitrifying bacteria were obtained with the ammonium sulfate treatment showing the greatest reduction in MPN counts. Microbial diversity (H') indices were also determined and correlated with soil pH. A quadratic relationship was determined for phyleal diversity (the total population of bacteria, actinomycetes and fungi) with soil pH, while a linear function best described physiological diversity (the nitrifying and denitrifying bacteria) versus soil pH.

Effect of Potassium and Crop Residue Levels on Potassium Solubilizers and Crop Yield under Maize-Wheat Rotation

“…K solubilising bacterial population activity was increased markedly by K-mineral fertilization along with seed inoculation of KSB in both crops and variability of microbial population in the present study might have been resulted from growth hormone production and release of organic acid by KSB inoculants with seed in soil. This result is also comparable with Basavesh (2013) and fertilizer directly improve the plant root growth and development and root exuded provide the required nutrients for microbes it intern enhance microbial growth and may affect the composition of microbial communities and similar result was also reported by (Khonje et al, 1989;Naher et al, 2013).…”

Acidification of a kaolinitic Alfisol under continuous cropping with nitrogen fertilization in West Africa

“…Differences in the rate of soil acidification with the three N sources are based on their potential acidification, which is twice that of urea for AS, and 85% that of urea for CAN (Stumpe and Vlek, 1991). Greater soil acidification with AS than with UA or CAN was previously found under field conditions by Brochado-Miranda (1976), Fox and Hoffman (1981), Jones (1976) and Khonje et al (1989) and under laboratory conditions by Stumpe and Vlek (1991). The ).…”

Role of Plant Cation/Anion Uptake Ratio in Soil Acidification

“…High rainfall, lack of plant uptake, and factors favoring nitrification enhance nitrate leaching. Application of NH 4 ϩ -based fertilizers increases and while application of NO 3 Ϫ decreases acidification [39] (see later). If all N in a legume is obtained through N 2 fixation, growing such a species would increase the acidity of the root medium by the amount equivalent to the content of excess cations or ash alkalinity of the plant.…”