Responses of corn physiology and yield to agricultural practices: A 3-yr study in middle Tennessee
Different agricultural practices tend to have significant impacts on crop physiology and yield. However, multiple agricultural practices such as tillage, biochar application and different nutrient applications have seldom been investigated together. A field study was conducted over three years (2012 to 2014) to investigate the responses of corn physiology, yield, and soil respiration to six different agricultural practices. The six practices comprised of convenient tillage (CT) and no tillage (NT), with different nitrogen types and application methods: CT-urea (CT, normal applications of liquid UAN), NT-urea (NT, normal applications of liquid urea), NT-inhibitor (NT-urea+denification inhibitor), NT-biochar (NT-urea+biochar), NT-litter (NT, chicken litter), and NT-split (NT, multiple applications of liquid urea). A randomized complete block design was used with six replications. Leaf photosynthetic rate, stomatal conductance, transpiration, soil respiration, plant height and yield were measured, and water use efficiency was calculated based on the photosynthetic/transpiration rate of the crop.
Results of the study showed that the treatments had significant effects on plant physiology, growth and yield, but the effect on LAI, biomass and root:shoot ratio were insignificant. All variables measured showed remarkable variations within the 3 years of study. The average corn yield in the NT-urea was 28.9% more than in the CT-urea. However, there was no significant difference in corn yield within the NT treatments. Subsequently, the CT-urea treatments had the lowest leaf photosynthesis, transpiration and yield while the NT-urea had the lowest soil respiration. Water use efficiency in the NT-litter was the highest suggesting the water conservation potential of no-till practice. Our results indicate that no-tillage system can improve corn physiology and yield, while different nitrogen fertilizer applications have limited influences on plant physiology.