Effect of cropping sequences on soil biological activity in semiarid region of western Canada
Soil productivity and environmental sustainability hinge on the physical, chemical and biological properties of the soil. Soil dehydrogenases (DHs) are one of the major classes of intracellular oxidoreductase enzymes involved in energy metabolism of living cells. The soil DHs activity is used as an indicator of overall soil microbial activity. This study employed the soil DHs assay to examine the effect of different cropping sequences including wheat, mustard and pulse crops in 4-year rotation on the soil biological activity. The DHs assay used in this study was originally developed by Le Casida et al. (1964). In this method, triphenyltetrazolium chloride (TTC) is used as an indicator dye that helps to observe electron transport system activity. The DHs involved in electron transport system reduce the colourless soluble TTC (substrate) and convert it into an insoluble red colour product, known as triphenylformazan (TPF). TPF can be quantified by spectrophotometry at the visible wavelength of 485 nm. Higher the intensity of the red colour in the soil extract solution, higher is the concentration of TPF and hence the higher DHs activity. In this study, the results of DHs assay of the final year (2014) of different 4-year crop rotations are presented. The study clearly showed that frequent inclusion of pulse crops especially chickpea in the cropping systems is conducive to the soil biological activity.
Soils and Crops Workshop