CHEMICAL FERTILIZATION AND ORGANICAMENDMENTS IMPACT ON SOIL BIOLOGICAL,CHEMICAL PROPERTIES ANDCARBON, NITROGEN LABILITY

摘要

Soil organic matter (SOM) management to sustain soil quality requires integrated management practices. The goal of our study was to evaluate the long-term (1996 to 2012) effects of annual chemi-cal fertilization and various organic amendments on soil biological and chemical properties and lability of carbon and nitrogen as indicator of SOM man-agement. Treatments including the control, chemi-cal fertilization, compost, cow manure, and mycor- rhizal inoculated compost amendments were estab-lished for a corn (Zea m a y s L.) - wheat (Triticumaestivum L、 rotation in a randomized complete block design. Composite soils were randomly col-lected from 0 to 20 cm depth and analyzed for soil biological and chemical proporties. Besides, carbon and nitrogen la b ility as w ell as management indices were calculated from measured carbon and nitro-gen fractions. Results showed that both compost and cow manure amendments significantly in -creased total m icrobial biomass (by 1.8 to 2.2 fold), basal respiration (by 1.3 to 1.9 fold), potentially mineralizable carbon (by 1.1 to 1.4 fold), total or-ganic carbon (6 to 11%), oxidizable carbon (28 to 33%), particulate organic cabon (4.2 to 4.5 fold), soluble carbon (1.3 to 1.7 fold), extractable carbon (1.7 to 1.9 fold), total nitrogen (10 to 12%), availa-ble nitrogen (2.8 fold), and PON (4.5 to 4.7 fold) w ith a significant decrease in qCo2 (20 to 23%), as compared w ith the control. Moreover, both com-post- and cow manure-amended soils had signifi-cantly higher values of basal respiration, soluble carbon, extractable carbon, oxidizable carbon, par-ticulate organic cabon, and particulate organic n i-trogen than the chemically fertilized soils. The POC and PON la b ility and management indices consist-ently accounted and predicted the management- induced qualitative and quantitative changes in TOC and TN, over other C and N fractions.