The effects of conservation tillage practices and fertiliser management on soil structural properties at an experimental farm

摘要

Crop rotation and reduced tillage under conservation agriculture (CA) practices may induce higher soil organic carbon (SOC) and nitrogen (N) levels compared with conventional (Con) tillage practices. Soil organic carbon may increase soil aggregate stability (AS). The study site was a rain-fed CA field trial with a randomised split-plot design. The effects were evaluated over four experimental seasons of CA and Con on AS, SOC, soil N and on temporal trends of soil properties. Soil aggregate samples were taken annually on plots representing two tillage practices and four fertiliser/crop systems. Standard laboratory and statistical procedures were performed to determine soil properties and to test for relationships between soil properties and differences between treatments. Soil aggregate stability significantly (p<0.001) increased from 90 to 140 cm~3 as SOC and total N increased from 11.5 to 21.5g kg~(-1) and 0.77 to 1.43g kg~(-1), respectively. Reduced tillage increased AS and SOC to 126.6cm~3 and 17.2g kg~(-1), respectively, compared with Con. Seasonal trends showed increases of AS and SOC under reduced tillage compared with Con, whereas under both tillage practices increasing trends in total and inorganic soil N were observed. Conservation agriculture practices that retain large quantities of crop residues are recommended to enhance AS.